Ting Yu

Graphene was deposited on a transparent and flexible substrate, and tensile strain up to ∼0.8% was loaded by stretching the substrate in one direction. Raman spectra of strained graphene show significant red shifts of 2D and G band (−27.8 and −14.2 cm−1 per 1% strain, respectively) because of the elongation of the carbon−carbon bonds. This indicates that uniaxial strain has been successfully applied on graphene. We also proposed that, by applying uniaxial strain on graphene, tunable band gap at K point can be realized. First-principle calculations predicted a band-gap opening of ∼300 meV for graphene under 1% uniaxial tensile strain. The strained graphene provides an alternative way to experimentally tune the band gap of graphene, which would be more efficient and more controllable than other methods that are used to open the band gap in graphene. Moreover, our results suggest that the flexible substrate is ready for such a strain process, and Raman spectroscopy can be used as an ultrasensitive method to determine the strain.

Investigations of two-dimensional transition-metal chalcogenides (TMCs) have recently revealed interesting physical phenomena, including the quantum spin Hall effect1,2, valley polarization3,4 and two-dimensional superconductivity5, suggesting potential applications for functional devices6–10. However, of the numerous compounds available, only a handful, such as Mo- and W-based TMCs, have been synthesized, typically via sulfurization11–15, selenization16,17 and tellurization18 of metals and metal compounds. Many TMCs are difficult to produce because of the high melting points of their metal and metal oxide precursors. Molten-salt-assisted methods have been used to produce ceramic powders at relatively low temperature19 and this approach20 was recently employed to facilitate the growth of monolayer WS2 and WSe2. Here we demonstrate that molten-salt-assisted chemical vapour deposition can be broadly applied for the synthesis of a wide variety of two-dimensional (atomically thin) TMCs. We synthesized 47 compounds, including 32 binary compounds (based on the transition metals Ti, Zr, Hf, V, Nb, Ta, Mo, W, Re, Pt, Pd and Fe), 13 alloys (including 11 ternary, one quaternary and one quinary), and two heterostructured compounds. We elaborate how the salt decreases the melting point of the reactants and facilitates the formation of intermediate products, increasing the overall reaction rate. Most of the synthesized materials in our library are useful, as supported by evidence of superconductivity in our monolayer NbSe2 and MoTe2 samples21,22 and of high mobilities in MoS2 and ReS2. Although the quality of some of the materials still requires development, our work opens up opportunities for studying the properties and potential application of a wide variety of two-dimensional TMCs. Molten-salt-assisted chemical vapour deposition is used to synthesize a wide variety of two-dimensional transition-metal chalcogenides.

We have clearly discriminated the single-, bilayer-, and multiple-layer graphene (<10 layers) on Si substrate with a 285 nm SiO2 capping layer by using contrast spectra, which were generated from the reflection light of a white light source. Calculations based on Fresnel's law are in excellent agreement with the experimental results (deviation 2%). The contrast image shows the reliability and efficiency of this new technique. The contrast spectrum is a fast, nondestructive, easy to be carried out, and unambiguous way to identify the numbers of layers of graphene sheet. We provide two easy-to-use methods to determine the number of graphene layers based on contrast spectra: a graphic method and an analytical method. We also show that the refractive index of graphene is different from that of graphite. The results are compared with those obtained using Raman spectroscopy.

Abstract Nanoflakes of α‐Fe 2 O 3 were prepared on Cu foil by using a thermal treatment method. The nanoflakes were characterized by X‐ray diffraction, scanning electron microscopy, high‐resolution transmission electron microscopy, and Raman spectroscopy. The reversible Li‐cycling properties of the α‐Fe 2 O 3 nanoflakes have been evaluated by cyclic voltammery, galvanostatic discharge–charge cycling, and impedance spectral measurements on cells with Li metal as the counter and reference electrodes, at ambient temperature. Results show that Fe 2 O 3 nanoflakes exhibit a stable capacity of (680 ± 20) mA h g –1 , corresponding to (4.05 ± 0.05) moles of Li per mole of Fe 2 O 3 with no noticeable capacity fading up to 80 cycles when cycled in the voltage range 0.005–3.0 V at 65 mA g –1 (0.1 C rate), and with a coulombic efficiency of &gt; 98 % during cycling (after the 15th cycle). The average discharge and charge voltages are 1.2 and 2.1 V, respectively. The observed cyclic voltammograms and impedance spectra have been analyzed and interpreted in terms of the ‘conversion reaction' involving nanophase Fe 0 –Li 2 O. The superior performance of Fe 2 O 3 nanoflakes is clearly established by a comparison of the results with those for Fe 2 O 3 nanoparticles and nanotubes reported in the literature.

Different C–N bonding configurations in nitrogen (N) doped carbon materials have different electronic structures. Carbon materials doped with only one kind of C–N bonding configuration are an excellent platform for studying doping effects on the electronic structure and physical/chemical properties. Here we report synthesis of single layer graphene doped with pure pyridinic N by thermal chemical vapour deposition of hydrogen and ethylene on Cu foils in the presence of ammonia. By adjusting the flow rate of ammonia, the atomic ratio of N and C can be modulated from 0 to 16%. The domain like distribution of N incorporated in graphene was revealed by the imaging of Raman spectroscopy and time-of-flight secondary ion mass spectrometry. The ultraviolet photoemission spectroscopy investigation demonstrated that the pyridinic N efficiently changed the valence band structure of graphene, including the raising of density of π states near the Fermi level and the reduction of work function. Such pyridinic N doping in carbon materials was generally considered to be responsible for their oxygen reduction reaction (ORR) activity. The 2e reduction mechanism of ORR on our CNxgraphene revealed by rotating disk electrode voltammetry indicated that the pyridinic N may not be an effective promoter for ORR activity of carbon materials as previously expected.

Graphene has attracted a lot of interest for fundamental studies as well as for potential applications. Till now, micromechanical cleavage (MC) of graphite has been used to produce high-quality graphene sheets on different substrates. Clear understanding of the substrate effect is important for the potential device fabrication of graphene. Here we report the results of the Raman studies of micromechanically cleaved monolayer graphene on standard SiO2 (300 nm)/Si, single crystal quartz, Si, glass, polydimethylsiloxane (PDMS), and NiFe. Our data suggests that the Raman features of monolayer graphene are independent of the substrate used; in other words, the effect of substrate on the atomic/electronic structures of graphene is negligible for graphene made by MC. On the other hand, epitaxial monolayer graphene (EMG) on SiC substrate is also investigated. Significant blueshift of Raman bands is observed, which is attributed to the interaction of the graphene sheet with the substrate, resulting in the change of lattice constant and also the electronic structure.

Graphene field effect transistors commonly comprise graphene flakes lying on SiO2 surfaces. The gate-voltage dependent conductance shows hysteresis depending on the gate sweeping rate/range. It is shown here that the transistors exhibit two different kinds of hysteresis in their electrical characteristics. Charge transfer causes a positive shift in the gate voltage of the minimum conductance, while capacitive gating can cause the negative shift of conductance with respect to gate voltage. The positive hysteretic phenomena decay with an increase of the number of layers in graphene flakes. Self-heating in a helium atmosphere significantly removes adsorbates and reduces positive hysteresis. We also observed negative hysteresis in graphene devices at low temperature. It is also found that an ice layer on/under graphene has a much stronger dipole moment than a water layer does. Mobile ions in the electrolyte gate and a polarity switch in the ferroelectric gate could also cause negative hysteresis in graphene transistors. These findings improved our understanding of the electrical response of graphene to its surroundings. The unique sensitivity to environment and related phenomena in graphene deserve further studies on nonvolatile memory, electrostatic detection, and chemically driven applications.

Large-area triangular single crystals of WS2 monolayer are synthesised from a chemical vapor deposition process and their optical properties are systematicly studied. This work paves the way to fabricate large-area single crystalline 2D semiconductors and study their fundamentals. It must be very meaningful for exploiting the great potential of WS2 for future optoelectronics. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Time-resolved fluorescence measurements of graphene oxide in water show multiexponential decay kinetics ranging from 1 ps to 2 ns. Electron-hole recombination from the bottom of the conduction band and nearby localized states to wide-range valance band is suggested as origin of the fluorescence. Excitation wavelength dependence of the fluorescence was caused by relative intensity changes of few emission species. By introducing the molecular orbital concept, the dominant fluorescence was found to originate from the electronic transitions among/between the non-oxidized carbon regions and the boundary of oxidized carbon atom regions, where all three kinds of functionalized groups C-O, C = O and O = C-OH were participating. In the visible spectral range, the ultrafast fluorescence of graphene oxide was observed for the first time.

The fabrication of epitaxial graphene (EG) on SiC substrate by annealing has attracted a lot of interest as it may speed up the application of graphene for future electronic devices. The interaction of EG and the SiC substrate is critical to its electronic and physical properties. In this work, the Raman spectroscopy was used to study the structure of EG and its interaction with SiC substrate. All the Raman bands of EG blueshift from that of bulk graphite and graphene made by micromechanical cleavage, which was attributed to the compressive strain induced by the substrate. A model containing $13\ifmmode\times\else\texttimes\fi{}13$ honeycomb lattice cells of graphene on carbon nanomesh was constructed to explain the origin of strain. The lattice mismatch between graphene layer and substrate causes the compressive stress of $2.27\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ on graphene. We also demonstrate that the electronic structures of EG grown on Si- and C-terminated SiC substrates are quite different. Our experimental results shed light on the interaction between graphene and SiC substrate, which are critical to the future applications of EG.

Monolayer molybdenum disulfide (MoS2) has attracted tremendous attention due to its promising applications in high-performance field-effect transistors, phototransistors, spintronic devices and nonlinear optics. The enhanced photoluminescence effect in monolayer MoS2 was discovered and, as a strong tool, was employed for strain and defect analysis in MoS2. Recently, large-size monolayer MoS2 has been produced by chemical vapour deposition, but has not yet been fully explored. Here we systematically characterize chemical vapour deposition-grown MoS2 by photoluminescence spectroscopy and mapping and demonstrate non-uniform strain in single-crystalline monolayer MoS2 and strain-induced bandgap engineering. We also evaluate the effective strain transferred from polymer substrates to MoS2 by three-dimensional finite element analysis. Furthermore, our work demonstrates that photoluminescence mapping can be used as a non-contact approach for quick identification of grain boundaries in MoS2.

Abstract We report the synthesis of a novel branched nano‐heterostructure composed of SnO 2 nanowire stem and α‐Fe 2 O 3 nanorod branches by combining a vapour transport deposition and a facile hydrothermal method. The epitaxial relationship between the branch and stem is investigated by high resolution transmission electron microscopy (HRTEM). The SnO 2 nanowire is determined to grow along the [101] direction, enclosed by four side surfaces. The results indicate that distinct crystallographic planes of SnO 2 stem can induce different preferential growth directions of secondary nanorod branches, leading to six‐fold symmetry rather than four‐fold symmetry. Moreover, as a proof‐of‐concept demonstration of the function, such α‐Fe 2 O 3 /SnO 2 composite material is used as a lithium‐ion batteries (LIBs) anode material. Low initial irreversible loss and high reversible capacity are demonstrated, in comparison to both single components. The synergetic effect exerted by SnO 2 and α‐Fe 2 O 3 as well as the unique branched structure are probably responsible for the enhanced performance.

Highly ordered TiO2@α-Fe2O3 core/shell arrays on carbon textiles (TFAs) have been fabricated by a stepwise, seed-assisted, hydrothermal approach and further investigated as the anode materials for Li-ion batteries (LIBs). This composite TFA anode exhibits superior high-rate capability and outstanding cycling performance. The specific capacity of the TFAs is much higher than that of pristine carbon textiles (CTs) and TiO2 nanorod arrays on carbon textiles (TRAs), indicating a positive synergistic effect of the material and structural hybridization on the enhancement of the electrochemical properties. This composite nanostructure not only provides large interfacial area for lithium insertion/extraction but should also be beneficial in reducing the diffusion pathways for electronic and ionic transport, leading to the improved capacity retention on cycling even at high discharge–charge rates. It is worth emphasizing that the CT substrates also present many potential virtues for LIBs as flexible electronic devices owing to the stretchable, lightweight and biodegradable properties. The fabrication strategy presented here is facile, cost-effective, and scalable, which opens new avenues for the design of optimal composite electrode materials for high performance LIBs.

Bio-inspired multifunctional composite films based on reduced poly(vinyl alcohol)/graphene oxide (R-PVA/GO) layers are prepared by a facile solution casting method followed by a reduction procedure. The resulting films with nacre-like, bricks-and-mortar microstructure have excellent mechanical properties, electrical conductivity, and biocompatibility.

In this paper, a highly ordered three‐dimensional Co 3 O 4 @MnO 2 hierarchical porous nanoneedle array on nickel foam is fabricated by a facile, stepwise hydrothermal approach. The morphologies evolution of Co 3 O 4 and Co 3 O 4 @MnO 2 nanostructures upon reaction times and growth temperature are investigated in detail. Moreover, the as‐prepared Co 3 O 4 @MnO 2 hierarchical structures are investigated as anodes for both supercapacitors and Li‐ion batteries. When used for supercapacitors, excellent electrochemical performances such as high specific capacitances of 932.8 F g −1 at a scan rate of 10 mV s −1 and 1693.2 F g −1 at a current density of 1 A g −1 as well as long‐term cycling stability and high energy density (66.2 W h kg −1 at a power density of 0.25 kW kg −1 ), which are better than that of the individual component of Co 3 O 4 nanoneedles and MnO 2 nanosheets, are obtained. The Co 3 O 4 @MnO 2 NAs are also tested as anode material for LIBs for the first time, which presents an improved performance with high reversible capacity of 1060 mA h g −1 at a rate of 120 mA g −1 , good cycling stability, and rate capability.

The false-color (3D type) image of the intensity of the Raman spectra of monolayer MoS2 versus both peak positions and polar angles is plotted. It shows that the strongest E2g (1+) and E2g (1-) peaks appear at different angles, reflected as the alternation of the maxima of the intensity within the frequency range of the E2g (1) mode, which is the consequence of the crystallographic orientation relevant to the strain direction as predicted by theoretical analysis.

Using a simple method of direct heating of bulk copper plates in air, oriented CuO nanowire films were synthesized on a large scale. The length and density of nanowires could be controlled by growth temperature and growth time. Field emission (FE) measurements of CuO nanowire films show that they have a low turn-on field of 3.5–4.5 V µm−1 and a large current density of 0.45 mA cm−2 under an applied field of about 7 V µm−1. By comparing the FE properties of two types of samples with different average lengths and densities (30 µm, 108 cm−2 and 4 µm, 4 × 107 cm−2, respectively), we found that the large length–radius ratio of CuO nanowires effectively improved the local field, which was beneficial to field emission. Verified with finite element calculation, the work function of oriented CuO nanowire films was estimated to be 2.5–2.8 eV.

We report the properties of a field effect transistor (FET) and a gas sensor based on CuO nanowires. CuO nanowire FETs exhibit p-type behavior. Large-scale p-type CuO nanowire thin-film transistors (10(4) devices in a 25 mm(2) area) are fabricated and we effectively demonstrate their enhanced performance. Furthermore, CuO nanowire exhibits high and fast response to CO gas at 200 degrees C, which makes it a promising candidate for a poisonous gas sensing nanodevice.

In this work, graphene layers on SiO2/Si substrate have been chemically decorated by radio frequency hydrogen plasma. Hydrogen coverage investigation by Raman spectroscopy and micro-X-ray photoelectron spectroscopy characterization demonstrates that the hydrogenation of single layer graphene on SiO2/Si substrate is much less feasible than that of bilayer and multilayer graphene. Both the hydrogenation and dehydrogenation process of the graphene layers are controlled by the corresponding energy barriers, which show significant dependence on the number of layers. The extent of decorated carbon atoms in graphene layers can be manipulated reversibly up to the saturation coverage, which facilitates engineering of chemically decorated graphene with various functional groups via plasma techniques.

Abstract Hollow and hierarchical nanostructures have received wide attention in new‐generation, high‐performance, lithium ion battery (LIB) applications. Both TiO 2 and Fe 2 O 3 are under current investigation because of their high structural stability (TiO 2 ) and high capacity (Fe 2 O 3 ), and their low cost. Here, we demonstrate a simple strategy for the fabrication of hierarchical hollow TiO 2 @Fe 2 O 3 nanostructures for the application as LIB anodes. Using atomic layer deposition (ALD) and sacrificial template‐assisted hydrolysis, the resulting nanostructure combines a large surface area with a hollow interior and robust structure. As a result, such rationally designed LIB anodes exhibit a high reversible capacity (initial value 840 mAh g −1 ), improved cycle stability (530 mAh g −1 after 200 cycles at the current density of 200 mA g −1 ), as well as outstanding rate capability. This ALD‐assisted fabrication strategy can be extended to other hierarchical hollow metal oxide nanostructures for favorable applications in electrochemical and optoelectronic devices.

Monolayer WS2 (1L-WS2), with a direct band gap, provides an ideal platform to investigate unique properties of two-dimensional semiconductors. In this work, light emission of a 1L-WS2 triangle has been studied by using steady-state, time-resolved, and temperature-dependent photoluminescence (PL) spectroscopy. Two groups of 1L-WS2 triangles have been grown by chemical vapor deposition, which exhibit nonuniform and uniform PL, respectively. Observed nonuniform PL features, i.e., quenching and blue-shift in certain areas, are caused by structural imperfection and n-doping induced by charged defects. Uniform PL is found to be intrinsic, intense, and nonblinking, which are attributed to high crystalline quality. The binding energy of the A-exciton is extracted experimentally, which gives direct evidence for the large excitonic effect in 1L-WS2. These superior photon emission features make 1L-WS2 an appealing material for optoelectronic applications such as novel light-emitting and biosensing devices.

Abstract Transition‐metal disulfide with its layered structure is regarded as a kind of promising host material for sodium insertion, and intensely investigated for sodium‐ion batteries. In this work, a simple solvothermal method to synthesize a series of MoS 2 nanosheets@nitrogen‐doped graphene composites is developed. This newly designed recipe of raw materials and solvents leads the success of tuning size, number of layers, and interplanar spacing of the as‐prepared MoS 2 nanosheets. Under cut‐off voltage and based on an intercalation mechanism, the ultrasmall MoS 2 nanosheets@nitrogen‐doped graphene composite exhibits more preferable cycling and rate performance compared to few‐/dozens‐layered MoS 2 nanosheets@nitrogen‐doped graphene, as well as many other reported insertion‐type anode materials. Last, detailed kinetics analysis and density functional theory calculation are also employed to explain the Na + ‐ storage behavior, thus proving the significance in surface‐controlled pseudocapacitance contribution at the high rate. Furthermore, this work offers some meaningful preparation and investigation experiences for designing electrode materials for commercial sodium‐ion batteries with favorable performance.

Uniform carbon fibers evolved from bamboo chopsticks garbage are achieved by a facile hydrothermal method, exhibiting competitive electrochemical behavior with commercial graphite, or pretty high anodic performance after being optimized.

Graphene–gold metasurface architectures that can provide significant gains in plasmonic detection sensitivity for trace-amount target analytes are reported. Benefiting from extreme phase singularities of reflected light induced by strong plasmon-mediated energy confinements, the metasurface demonstrates a much-improved sensitivity to molecular bindings nearby and achieves an ultralow detection limit of 1 × 10−18 m for 7.3 kDa 24-mer single-stranded DNA. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Since its discovery in less than five years ago, graphene has become one of the hottest frontiers in materials science and condensed matter physics, as evidenced by the exponential increase in number of publications in this field. Several reviews have already been published on this topic, focusing on single and multilayer graphene sheets. Here, we review the recent progresses in this field by extending the scope to various types of two-dimensional carbon nanostructures including graphene and free-standing carbon nanowalls/nanosheets. After a brief overview of the electronic properties of graphene, we focus on the synthesis, characterization and potential applications of these carbon nanostructures.

The $1+1$ layer folded graphene sheets that deviate from $AB$ stacking are successfully fabricated and their electronic structures are investigated by Raman spectroscopy. Significant blueshift of the 2D band of folded graphene compared to that of single layer graphene (SLG) is observed. This is attributed to SLG-like electronic structure of folded graphene but with slowing down of Fermi velocity (as much as $\ensuremath{\sim}5.6%$). Different amount of blueshift of 2D band is observed for different folded graphenes, which may correspond to the different twist angle and/or separation between the two layers, resulting in different Fermi velocity of folded graphenes. Electronic structure of $1+1$-folded graphene samples with different stacking order (twist and separation between the two layers, and in-plane shift of the two layers) can be investigated by Raman spectroscopy.

Elemental sulfur cathodes for lithium/sulfur cells are still in the stage of intensive research due to their unsatisfactory capacity retention and cyclability. The undesired capacity degradation upon cycling originates from gradual diffusion of lithium polysulfides out of the cathode region. To prevent losses of certain intermediate soluble species and extend lifespan of cells, the effective encapsulation of sulfur plays a critical role. Here we report an applicable way, by using thin-layered nickel-based hydroxide as a feasible and effective encapsulation material. In addition to being a durable physical barrier, such hydroxide thin films can irreversibly react with lithium to generate protective layers that combine good ionic permeability and abundant functional polar/hydrophilic groups, leading to drastic improvements in cell behaviours (almost 100% coulombic efficiency and negligible capacity decay within total 500 cycles). Our present encapsulation strategy and understanding of hydroxide working mechanisms may advance progress on the development of lithium/sulfur cells for practical use.

We demonstrate a simple, efficient, yet versatile method for the realization of core–shell assembly of graphene around various metal oxide (MO) nanostructures, including nanowires (NWs) and nanoparticles (NPs). The process is driven by (i) the ring-opening reaction between the epoxy groups and amine groups in graphene oxide (GO) platelets and amine-modified MO nanostructures, respectively, and (ii) electrostatic interaction between these two components. Nearly every single NW or NP is observed to be wrapped by graphene. To the best of our knowledge, this is the first report that substrate-supported MO NWs are fully coated with a graphene shell. As an example of the functional properties of these compound materials, the graphene@α-Fe2O3 core–shell NPs are investigated as the lithium-ion battery (LIB) electrode, which show a high reversible capacity, improved cycling stability, and excellent rate capability with respect to the pristine α-Fe2O3. The superior performance of the composite electrode is presumably attributed to the effectiveness of the graphene shell in preventing the aggregation, buffering the volume change, maintaining the integrity of NPs, as well as improving the conductivity of the electrode.

Self-assembled well-ordered whisker-like manganese dioxide (MnO2) arrays on carbon fiber paper (MOWAs) were synthesized via a simple in situ redox replacement reaction between potassium permanganate (KMnO4) and carbon fiber paper (CFP) without any other oxidant or reductant addition. The CFP serves as not only a sacrificial reductant and converts aqueous permanganate (MnO4−) to insoluble MnO2 in this reaction, but also a substrate material and guarantees MnO2 deposition on the surface. The electrochemical properties were examined by cyclic voltammograms (CV), galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS) in a three-electrode cell. According to the CV results, the ordered MOWAs yield high-capacitance performance with specific capacitance up to 274.1 F g−1 and excellent long cycle-life property with 95% of its specific capacitance kept after 5000 cycles at the current density of 0.1 A g−1. The high-performance hybrid composites result from a synergistic effect of large surface area and high degree of ordering of the ultrathin layer of MnO2 nanowhisker arrays, combined with the flexible CFP substrate and can offer great promise in large-scale energy storage device applications.

Abstract The effect of vacuum annealing on the properties of graphene is investigated by using Raman spectroscopy and electrical measurement. Heavy hole doping on graphene with concentration as high as 1.5 × 10 13 cm −2 is observed after vacuum annealing and exposed to an air ambient. This doping is due to the H 2 O and O 2 adsorption on graphene, and graphene is believed to be more active to molecular adsorption after annealing. Such observation calls for special attention in the process of fabricating graphene‐based electronic devices and gas sensors. On the other hand, because the quality of graphene remains high after the doping process, this would be an efficient and controllable method to introduce heavy doping in graphene, which would greatly help on its application in future electronic devices. Copyright © 2009 John Wiley &amp; Sons, Ltd.

We present the electronic structure evolution from graphite oxide to thermally reduced graphite oxide. Most functional groups were removed by thermal reduction as indicated by high resolution X-ray photoelectron spectroscopy, and the electrical conductivity increased 6 orders compare with the precursor graphite oxide. X-ray absorption spectroscopy reveals that the thermally reduced graphite oxide shows several absorption peaks similar to those of pristine graphite, which were not observed in graphite oxide or chemically reduced graphite oxide. This indicates the better restoration of graphitic electronic conjugation by thermal reduction. Furthermore, the significant increased intensity of Raman 2D band of thermally reduced graphite oxide compared with graphite oxide also suggests the restoration of graphitic electronic structure (π orbital). These results provide useful information for fundamental understanding of the electronic structure of graphite oxide and thermally reduced graphite oxide.

A new type of scrolled structure of Co3O4/reduced graphene oxide (r-GO) is facilely prepared through a two-step surfactant-assisted method. This assembly enables almost every single Co3O4 scroll to connect with the r-GO platelets, thus leading to remarkable electrochemical performances in terms of high specific capacitance and good rate capability.

Plasmon-free surface enhanced Raman scattering (SERS) based on the chemical mechanism (CM) is drawing great attention due to its capability for controllable molecular detection. However, in comparison to the conventional noble-metal-based SERS technique driven by plasmonic electromagnetic mechanism (EM), the low sensitivity in the CM-based SERS is the dominant barrier toward its practical applications. Herein, we demonstrate the 1T′ transition metal telluride atomic layers (WTe2 and MoTe2) as ultrasensitive platforms for CM-based SERS. The SERS sensitivities of analyte dyes on 1T′-W(Mo)Te2 reach EM-comparable ones and become even greater when it is integrated with a Bragg reflector. In addition, the dye fluorescence signals are efficiently quenched, making the SERS spectra more distinguishable. As a proof of concept, the SERS signals of analyte Rhodamine 6G (R6G) are detectable even with an ultralow concentration of 40 (400) fM on pristine 1T′-W(Mo)Te2, and the corresponding Raman enhancement factor (EF) reaches 1.8 × 109 (1.6 × 108). The limit concentration of detection and the EF of R6G can be further enhanced into 4 (40) fM and 4.4 × 1010 (6.2 × 109), respectively, when 1T′-W(Mo)Te2 is integrated on the Bragg reflector. The strong interaction between the analyte and 1T′-W(Mo)Te2 and the abundant density of states near the Fermi level of the semimetal 1T′-W(Mo)Te2 in combination gives rise to the promising SERS effects by promoting the charge transfer resonance in the analyte-telluride complex.

For the first time, nitrogen and phosphorus codoped hierarchically porous carbon (NPHPC) has been explored as an efficient host for sulfur. The material is fabricated based on a scalable, one-step process involving the pyrolysis of melamine polyphosphate synthesized via a simple and versatile organic approach by using low cost industrial raw materials (melamine and polyphosphoric acid). The key features of NPHPC are the hierarchically porous structure and high surface area (1398 m2 g−1) that not only benefit for maximum sulfur loading but also capable of suppressing the dissolution of polysulfides through physisorption. Meanwhile, the N and P codopants together with the thermally stable functionalities are favorable for binding polysulfides via chemisorption. Benefitting from the synergistic effect of structural confinement (physisorption) and chemical binding (chemisorption), the NPHPC/S composite with a high sulfur content of 73 wt% delivers high capacity (1580 mAh g−1 at 0.02 C) and long lifespan (200 cycles with 71% retention) for Li-S batteries. The present work highlights the importance of adopting heteroatom-doped hierarchically porous carbon for improving the performance of Li-S batteries, which may further stimulate more efforts in exploring advanced carbon-based hosts in the near future.

Heavy metal-containing wastewater can be treated by adsorption technology to obtain ultra-low concentration or high-quality treated effluent. Due to the constraints of the specific surface area, surface electrical structure and spatial effect of conventional adsorbents, it is often difficult to obtain adsorbents within high adsorption capacity. Graphene has characteristics of large specific surface area, small particle size, and high adsorption efficiency. It is considered as one of the research hotspots in recent years. However, despite graphene’s unique properties, graphene-based adsorbents still have some drawbacks, i.e. graphene nanosheets are easier to be stacked with each other via π–π stacking and van der Waals interactions, which affect the site exposure, impede the rapid mass transport and limit its adsorption performance. Special strategy is needed to overcome its drawbacks. This work summarizes recent literatures on utilization of three strategies-surface functionalization regulation, morphology and structure control and material composite, to improve the adsorption properties of graphene-based adsorbent towards heavy metal removal. A brief summary, perspective on strategies to improving adsorption properties of graphene-based materials for heavy metal adsorption are also presented. Certainly, this review will be useful for designing and manufacturing of graphene-based nanomaterials for water treatment.

Atomically thin layered two-dimensional (2D) materials have provided a rich library for both fundamental research and device applications. Bandgap engineering and controlled material response can be achieved from artificial heterostructures. Recently, excitonic lasers have been reported using transition metal dichalcogenides; however, the emission is still the intrinsic energy bandgap of the monolayers. Here, we report a room temperature interlayer exciton laser with MoS2/WSe2 heterostructures. The onset of lasing was identified by the distinct kink in the "L-L" curve and the noticeable spectral linewidth collapse. Different from visible emission of intralayer excitons in monolayer components, our laser works in the infrared range, which is fully compatible with the well-established technologies in silicon photonics. Long lifetime of interlayer excitons relaxes the requirement of the cavity quality factor by orders of magnitude. Room temperature interlayer exciton lasers might open new perspectives for developing coherent light sources with tailored optical properties on silicon photonics platforms.

Chlorine-resistant bacteria (CRB) are commonly defined as bacteria with high resistance to chlorine disinfection or bacteria which can survive or even regrow in the residual chlorine. Chlorine disinfection cannot completely control the risks of CRB, such as risks of pathogenicity, antibiotic resistance and microbial growth. Currently, researchers pay more attention to CRB with pathogenicity or antibiotic resistance. The microbial growth risks of non-pathogenic CRB in water treatment and reclamation systems have been neglected to some extent. In this review, these three kinds of risks are all analyzed, and the last one is also highlighted. In order to study CRB, various methods are used to evaluate chlorine resistance. This review summarizes the evaluating methods for chlorine resistance reported in the literatures, and collects the important information about the typical isolated CRB strains including their genera, sources and levels of chlorine resistance. To our knowledge, few review papers have provided such systematic information about CRB. Among 44 typical CRB strains from 17 genera isolated by researchers, Mycobacterium, Bacillus, Legionella, Pseudomonas and Sphingomonas were the five genera with the highest frequency of occurrence in literatures. They are all pathogenic or opportunistic pathogenic bacteria. In addition, although there are many studies on CRB, information about chlorine resistance level is still limited to specie level or strain level. The difference in chlorine resistance level among different bacterial genera is less well understood. An inconvenient truth is that there is still no widely-accepted method to evaluate chlorine resistance and to identify CRB. Due to the lack of a unified method, it is difficult to compare the results about chlorine resistance level of bacterial strains in different literatures. A recommended evaluating method using logarithmic removal rate as an index and E. coli as a reference strain is proposed in this review based on the summary of the current evaluating methods. This method can provide common range of chlorine resistance of each genus and it is conducive to analyzing the distribution and abundance of CRB in the environment.

The drastic need for development of power and electronic equipment has long been calling for energy storage materials that possess favorable energy and power densities simultaneously, yet neither capacitive nor battery-type materials can meet the aforementioned demand. By contrast, pseudocapacitive materials store ions through redox reactions with charge/discharge rates comparable to those of capacitors, holding the promise of serving as electrode materials in advanced electrochemical energy storage (EES) devices. Therefore, it is of vital importance to enhance pseudocapacitive responses of energy storage materials to obtain excellent energy and power densities at the same time. In this Review, we first present basic concepts and characteristics about pseudocapacitive behaviors for better guidance on material design researches. Second, we discuss several important and effective material design measures for boosting pseudocapacitive responses of materials to improve rate capabilities, which mainly include downsizing, heterostructure engineering, adding atom and vacancy dopants, expanding interlayer distance, exposing active facets, and designing nanosheets. Finally, we outline possible developing trends in the rational design of pseudocapacitive materials and EES devices toward high-performance energy storage.

Advanced oxidation processes are widely recognized as effective techniques for the removal of organic pollutants from water. In recent years, encapsulated transition-metal nanoparticle catalysts have exhibited excellent performance in inducing AOPs for elimination of organic contaminants due to their unique physicochemical properties. Taking advantage of the synergy between transition-metal nanoparticles and encapsulation materials, the catalytic activity, stability and selectivity of the catalysts can be adjusted and improved. Particularly, the carbon shell might benefit pollutant enrichment, accelerate charge transfer, enable confinement effect, and protect the transition-metal core from aggregation or deterioration. This review presents recent advances in the applications of encapsulated transition-metal nanoparticle catalysts for AOPs to degrade organic pollutants. Firstly, the structure and composition types of encapsulated transition-metal nanoparticle catalysts were introduced and then the synthetic methods of the catalysts were described. Subsequently, the applications of encapsulated transition-metal nanoparticles as heterogeneous catalysts to degrade organic pollutants in AOPs, including Fenton reactions, photocatalysis, persulfate activation, etc., were discussed with the underlying reaction mechanisms revealed. Finally, the article concludes by highlighting the major challenges and opportunities associated with encapsulated transition-metal nanoparticle catalysts in these AOPs, providing valuable insights for future research and development.

A robust neural interface with intimate electrical coupling between neural electrodes and neural tissues is critical for stable chronic neuromodulation. The development of bioadhesive hydrogel neural electrodes is a potential approach for tightly fixing the neural electrodes on the epineurium surface to construct a robust neural interface. Herein, we construct a photopatternable, antifouling, conductive (∼6 S cm-1), bioadhesive (interfacial toughness ∼100 J m-2), soft, and elastic (∼290% strain, Young's modulus of 7.25 kPa) hydrogel to establish a robust neural interface for bioelectronics. The UV-sensitive zwitterionic monomer can facilitate the formation of an electrostatic-assembled conductive polymer PEDOT:PSS network, and it can be further photo-cross-linked into elastic polymer network. Such a semi-interpenetrating network endows the hydrogel electrodes with good conductivity. Especially, the photopatternable feature enables the facile microfabrication processes of multifunctional hydrogel (MH) interface with a characteristic size of 50 μm. The MH neural electrodes, which show improved performance of impedance, charge storage capacity, and charge injection capability, can produce effective electrical stimulation with high current density (1 mA cm-2) at ultralow voltages (±25 mV). The MH interface could realize high-efficient electrical communication at the chronic neural interface for stable recording and stimulation of a sciatic nerve in the rat model.

Advanced MaterialsVolume 17, Issue 13 p. 1595-1599 Communication Controlled Growth and Field-Emission Properties of Cobalt Oxide Nanowalls† T. Yu, T. Yu Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, SingaporeSearch for more papers by this authorY. W. Zhu, Y. W. Zhu Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore National University of Singapore Nanoscience and Nanotechnology Initiative, Blk S13, 2 Science Drive 3, Singapore 117542, SingaporeSearch for more papers by this authorX. J. Xu, X. J. Xu National University of Singapore Nanoscience and Nanotechnology Initiative, Blk S13, 2 Science Drive 3, Singapore 117542, Singapore Department of Mechanical Engineering, National University of Singapore, Blk E3A, 9 Engineering Drive 1, Singapore 117576, SingaporeSearch for more papers by this authorZ. X. Shen, Z. X. Shen Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, SingaporeSearch for more papers by this authorP. Chen, P. Chen Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, SingaporeSearch for more papers by this authorC.-T. Lim, C.-T. Lim National University of Singapore Nanoscience and Nanotechnology Initiative, Blk S13, 2 Science Drive 3, Singapore 117542, Singapore Department of Mechanical Engineering, National University of Singapore, Blk E3A, 9 Engineering Drive 1, Singapore 117576, SingaporeSearch for more papers by this authorJ. T.-L. Thong, J. T.-L. Thong National University of Singapore Nanoscience and Nanotechnology Initiative, Blk S13, 2 Science Drive 3, Singapore 117542, Singapore Department of Electrical and Computer Engineering, National University of Singapore, Blk E4, 4 Engineering Drive 3, Singapore 117576, SingaporeSearch for more papers by this authorC.-H. Sow, C.-H. Sow [email protected] Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore National University of Singapore Nanoscience and Nanotechnology Initiative, Blk S13, 2 Science Drive 3, Singapore 117542, SingaporeSearch for more papers by this author T. Yu, T. Yu Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, SingaporeSearch for more papers by this authorY. W. Zhu, Y. W. Zhu Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore National University of Singapore Nanoscience and Nanotechnology Initiative, Blk S13, 2 Science Drive 3, Singapore 117542, SingaporeSearch for more papers by this authorX. J. Xu, X. J. Xu National University of Singapore Nanoscience and Nanotechnology Initiative, Blk S13, 2 Science Drive 3, Singapore 117542, Singapore Department of Mechanical Engineering, National University of Singapore, Blk E3A, 9 Engineering Drive 1, Singapore 117576, SingaporeSearch for more papers by this authorZ. X. Shen, Z. X. Shen Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, SingaporeSearch for more papers by this authorP. Chen, P. Chen Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, SingaporeSearch for more papers by this authorC.-T. Lim, C.-T. Lim National University of Singapore Nanoscience and Nanotechnology Initiative, Blk S13, 2 Science Drive 3, Singapore 117542, Singapore Department of Mechanical Engineering, National University of Singapore, Blk E3A, 9 Engineering Drive 1, Singapore 117576, SingaporeSearch for more papers by this authorJ. T.-L. Thong, J. T.-L. Thong National University of Singapore Nanoscience and Nanotechnology Initiative, Blk S13, 2 Science Drive 3, Singapore 117542, Singapore Department of Electrical and Computer Engineering, National University of Singapore, Blk E4, 4 Engineering Drive 3, Singapore 117576, SingaporeSearch for more papers by this authorC.-H. Sow, C.-H. Sow [email protected] Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore National University of Singapore Nanoscience and Nanotechnology Initiative, Blk S13, 2 Science Drive 3, Singapore 117542, SingaporeSearch for more papers by this author First published: 01 July 2005 https://doi.org/10.1002/adma.200500322Citations: 243 † The authors acknowledge the support of NUSARF and NUSNNI. T. Yu acknowledges the support of Fellowship from Singapore Millennium Foundation. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract Vertically oriented single-crystalline Co3O4 nanowalls (see Figure) have been successfully fabricated by directly heating Co foil in air using a hot plate. The morphologies of the Co3O4 nanowalls can be controlled by varying the growth temperature and time. The Co3O4 nanowalls show promising field-emission performance that is comparable to many other nanomaterials. Citing Literature Volume17, Issue13July, 2005Pages 1595-1599 RelatedInformation

Advanced MaterialsVolume 18, Issue 5 p. 587-592 Communication Multiwalled Carbon Nanotubes Beaded with ZnO Nanoparticles for Ultrafast Nonlinear Optical Switching† Y. Zhu, Y. Zhu Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, Singapore National University of Singapore (NUS), Nanoscience and Nanotechnology Initiative, S13, 2 Science Drive 3, 117542, SingaporeSearch for more papers by this authorH. I. Elim, H. I. Elim Department of Chemistry and Biomolecular Engineering, National University of Singapore (NUS), 4 Engineering Drive 4, 117576, SingaporeSearch for more papers by this authorY.-L. Foo, Y.-L. Foo Institute of Materials Research and Engineering, 3 Research Link, 117602, SingaporeSearch for more papers by this authorT. Yu, T. Yu Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, SingaporeSearch for more papers by this authorY. Liu, Y. Liu Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, SingaporeSearch for more papers by this authorW. Ji, W. Ji Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, SingaporeSearch for more papers by this authorJ.-Y. Lee, J.-Y. Lee Department of Chemistry and Biomolecular Engineering, National University of Singapore (NUS), 4 Engineering Drive 4, 117576, SingaporeSearch for more papers by this authorZ. Shen, Z. Shen School of Physical and Mathematical Sciences, Nanyang Technological University, 1 Nanyang Walk, 637616, SingaporeSearch for more papers by this authorA. T. S. Wee, A. T. S. Wee Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, Singapore National University of Singapore (NUS), Nanoscience and Nanotechnology Initiative, S13, 2 Science Drive 3, 117542, SingaporeSearch for more papers by this authorJ. T. L. Thong, J. T. L. Thong National University of Singapore (NUS), Nanoscience and Nanotechnology Initiative, S13, 2 Science Drive 3, 117542, Singapore Department of Electrical and Computer Engineering, National University of Singapore (NUS), 4 Engineering Drive 3, 117576, SingaporeSearch for more papers by this authorC. H. Sow, C. H. Sow [email protected] Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, Singapore National University of Singapore (NUS), Nanoscience and Nanotechnology Initiative, S13, 2 Science Drive 3, 117542, SingaporeSearch for more papers by this author Y. Zhu, Y. Zhu Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, Singapore National University of Singapore (NUS), Nanoscience and Nanotechnology Initiative, S13, 2 Science Drive 3, 117542, SingaporeSearch for more papers by this authorH. I. Elim, H. I. Elim Department of Chemistry and Biomolecular Engineering, National University of Singapore (NUS), 4 Engineering Drive 4, 117576, SingaporeSearch for more papers by this authorY.-L. Foo, Y.-L. Foo Institute of Materials Research and Engineering, 3 Research Link, 117602, SingaporeSearch for more papers by this authorT. Yu, T. Yu Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, SingaporeSearch for more papers by this authorY. Liu, Y. Liu Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, SingaporeSearch for more papers by this authorW. Ji, W. Ji Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, SingaporeSearch for more papers by this authorJ.-Y. Lee, J.-Y. Lee Department of Chemistry and Biomolecular Engineering, National University of Singapore (NUS), 4 Engineering Drive 4, 117576, SingaporeSearch for more papers by this authorZ. Shen, Z. Shen School of Physical and Mathematical Sciences, Nanyang Technological University, 1 Nanyang Walk, 637616, SingaporeSearch for more papers by this authorA. T. S. Wee, A. T. S. Wee Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, Singapore National University of Singapore (NUS), Nanoscience and Nanotechnology Initiative, S13, 2 Science Drive 3, 117542, SingaporeSearch for more papers by this authorJ. T. L. Thong, J. T. L. Thong National University of Singapore (NUS), Nanoscience and Nanotechnology Initiative, S13, 2 Science Drive 3, 117542, Singapore Department of Electrical and Computer Engineering, National University of Singapore (NUS), 4 Engineering Drive 3, 117576, SingaporeSearch for more papers by this authorC. H. Sow, C. H. Sow [email protected] Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, Singapore National University of Singapore (NUS), Nanoscience and Nanotechnology Initiative, S13, 2 Science Drive 3, 117542, SingaporeSearch for more papers by this author First published: 02 March 2006 https://doi.org/10.1002/adma.200501918Citations: 198 † The authors acknowledge support from the NUS Academic Research Fund. Y. Zhu thanks K. C. Chin for his help on sputtering, and J. L. Kwek, W. Y. Kan, and X. Y. Leong for their help on the morphology characterization. T. Yu acknowledges the support of the Singapore Millennium Foundation. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract A hybrid system of ZnO nanoparticles on multiwalled carbon nanotubes (MWNTs) is fabricated by simply heating Zn-coated MWNTs on a hot plate in air. Ultrafast optical switching and three-photon adsorption are observed from this hybrid system, and the absorption coefficient can be readily adjusted by changing the Zn-coating thickness. These results provide opportunities for cost-effectively integrating carbon nanotubes with functional oxide nanoparticles in future nanodevices. REFERENCES 1 A. P. Alivisatos, Science 1996, 271, 933. 2 Z. Tang, N. A. Kotov, Adv. Mater. 2005, 17, 951. 3 E. C. Walter, B. J. Murray, F. Favier, R. M. Penner, Adv. Mater. 2003, 15, 396. 4 S. Fullam, D. Cottel, H. Rensmo, D. Fitzmaurice, Adv. Mater. 2000, 12, 1430. 5 Y. P. Sun, W. Huang, Y. Lin, K. Fu, A. Kitaygorodskiy, L. A. Riddle, Y. J. Yu, D. L. Carroll, Chem. Mater. 2001, 13, 2864. 6 M. Endo, Y. A. Kim, M. Ezaka, K. Osada, T. Yanagisawa, T. Hayashi, M. Terrones, M. S. Dresselhaus, Nano Lett. 2003, 3, 723. 7 W. Q. Han, A. Zettl, Nano Lett. 2003, 3, 681. 8 X. Li, J. Niu, J. Zhang, H. Li, Z. Liu, J. Phys. Chem. B 2003, 107, 2453. 9 F. E. Osterloh, J. S. Martino, H. Hiramatsu, D. P. Hewitt, Nano Lett. 2003, 3, 125. 10 W. A. de Heer, P. Poncharal, C. Berger, J. Gezo, Z. Song, J. Bettini, D. Ugarte, Science 2005, 307, 907. 11 L. Fu, Z. Liu, Y. Liu, B. Han, P. Hu, L. Cao, D. Zhu, Adv. Mater. 2005, 17, 217. 12 X. Xiao, J. W. Elam, S. Trasobares, O. Auciello, J. A. Carlisle, Adv. Mater. 2005, 17, 1496. 13 B. M. Quinn, C. Dekker, S. G. Lemay, J. Am. Chem. Soc. 2005, 127, 6146. 14 S. Agrawal, A. Kumar, M. J. Frederick, G. Ramanath, Small 2005, 1, 823. 15 K. C. Chin, A. Gohel, W. Z. Chen, H. I. Elim, W. Ji, G. L. Chong, C. H. Sow, A. T. S. Wee, Chem. Phys. Lett. 2005, 409, 85. 16 J. S. Ye, H. F. Cui, X. Liu, T. M. Lim, W. D. Zhang, F. S. Sheu, Small 2005, 1, 560. 17 Z. L. Wang, J. Phys.: Condens. Matter 2004, 16, R829. 18 Z. L. Wang, Mater. Today 2004, 8 (6), 26. 19 Z. Y. Jiang, Z. X. Xie, X. H. Zhang, S. C. Lin, T. Xu, S. Y. Xie, R. B. Huang, L. S. Zheng, Adv. Mater. 2004, 16, 904. 20 L. Mädler, W. J. Stark, S. E. Pratsinis, J. Appl. Phys. 2002, 92, 6537. 21 Z. Wang, H. Zhang, L. Zhang, J. Yuan, S. Yan, C. Wang, Nanotechnology 2003, 14, 11. 22 J. Joo, S. G. Kwon, J. H. Yu, T. Hyeon, Adv. Mater. 2005, 17, 1837. 23 C. Pacholski, A. Kornowski, H. Weller, Angew. Chem. Int. Ed. 2002, 41, 1188. 24 H. Kim, W. Sigmund, Appl. Phys. Lett. 2002, 81, 2085. 25 S. Y. Bae, H. W. Seo, H. C. Choi, J. Park, J. Park, J. Phys. Chem. B 2004, 108, 12318. 26 J. Sun, L. Gao, M. Iwasa, Chem. Commun. 2004, 832. 27 L. Jiang, L. Gao, Mater. Chem. Phys. 2005, 91, 313. 28 L. Zhao, K. L. Kelly, G. C. Schatz, J. Phys. Chem. B 2003, 107, 7343. 29 J. F. Scott, Phys. Rev. 1970, 2, 1209. 30 H. T. Ng, B. Chen, J. Li, J. Han, M. Meyyappan, J. Wu, S. X. Li, E. E. Haller, Appl. Phys. Lett. 2003, 82, 2023. 31 J. G. Ma, Y. C. Liu, C. L. Shao, J. Y. Zhang, Y. M. Lu, D. Z. Shen, X. W. Fan, Phys. Rev. B: Condens. Matter Mater. Phys. 2005, 71, 125430. 32 K. A. Alim, V. A. Fonoberov, A. A. Balandin, Appl. Phys. Lett. 2005, 86, 53103. 33 K. A. Alim, V. A. Fonoberov, M. Shamsa, A. A. Balandin, J. Appl. Phys. 2005, 97, 124313. 34 T. C. Damen, S. P. S. Porto, B. Tell, Phys. Rev. 1966, 142, 570. 35 C. Geng, Y. Jiang, Y. Yao, X. Meng, J. A. Zapien, C. S. Lee, Y. Lifshitz, S. T. Lee, Adv. Funct. Mater. 2004, 14, 589. 36 Y. Du, M. S. Zhang, J. Hong, Y. Shen, Q. Chen, Z. Yin, Appl. Phys. A: Mater. Sci. Process. 2003, 76, 171. 37 S. Cho, J. Ma, Y. Kim, G. K. L. Wong, J. B. Ketterson, Appl. Phys. Lett. 1999, 75, 2761. 38 V. Srikant, D. R. Clarke, J. Mater. Res. 1997, 12, 1425. 39 T. Yatsui, T. Kawazoe, T. Shimizu, Y. Yamamoto, M. Ueda, M. Kourogi, M. Ohtsu, G. H. Lee, Appl. Phys. Lett. 2002, 80, 1444. 40 M. H. Huang, Y. Wu, H. Feick, N. Tran, E. Weber, P. Yang, Adv. Mater. 2001, 13, 113. 41 I. Shalish, H. Temkin, V. Narayanamurti, Phys. Rev. B: Condens. Matter Mater. Phys. 2004, 69, 245401. 42 A. van Dijken, J. Makkinje, A. Meijerink, J. Lumin. 2001, 92, 323. 43 Joint Committee on Powder Diffraction Standards (JCPDS) Card No. 80-0075. 44 L. Pan, K. K. Lew, J. M. Redwing, E. C. Dickey, Nano Lett. 2005, 5, 1081. 45 Y. Shan, L. Gao, Nanotechnology 2005, 16, 625. 46 L. Chen, B. L. Zhang, M. Z. Qu, Z. L. Yu, Powder Technol. 2005, 154, 70. 47 A. M. Bond, W. Miao, C. L. Raston, Langmuir 2000, 16, 6004. 48 N. I. Kovtyukhova, T. E. Mallouk, L. Pan, E. C. Dickey, J. Am. Chem. Soc. 2003, 125, 9761. 49 H. Ago, T. Kugler, F. Cacialli, W. R. Salaneck, M. S. P. Shaffer, A. H. Windle, R. H. Friend, J. Phys. Chem. B 1999, 103, 8116. 50 M. Liu, Y. Yang, T. Zhu, Z. Liu, Carbon 2005, 43, 1470. 51 J. D. Ye, S. L. Gu, F. Qin, S. M. Zhu, S. M. Liu, X. Zhou, W. Liu, L. Q. Hu, R. Zhang, Y. Shi, Y. D. Zheng, Y. D. Ye, Appl. Phys. A: Mater. Sci. Process. 2005, 81, 809. 52 Y. Xing, L. Li, C. C. Chusuei, R. V. Hull, Langmuir 2005, 21, 4185. 53 M. T. Martinez, M. A. Callejas, A. M. Benito, M. Cochet, T. Seeger, A. Anson, J. Schreiber, C. Gordon, C. Marhic, O. Chauvet, J. L. G. Fierro, W. K. Maser, Carbon 2003, 41, 2247. 54 H. I. Elim, W. Ji, G. H. Ma, K. Y. Lim, C. H. Sow, C. H. A. Huan, Appl. Phys. Lett. 2004, 85, 1799. 55 W. Ji, Y. Qu, J. Mi, Y. Zheng, J. Y. Ying, Chin. Opt. Lett. 2005, 3, 1671. 56 M. Sheik-Bahae, A. A. Said, T. Wei, D. J. Hagan, E. W. Van Stryland, IEEE J. Quantum Electron. 1990, 26, 760. 57 D. Li, Y. Liu, H. Yang, S. Qian, Appl. Phys. Lett. 2002, 81, 2088. 58 S. Wang, W. Huang, H. Yang, Q. Gong, Z. Shi, X. Zhou, D. Qiang, Z. Gu, Chem. Phys. Lett. 2000, 320, 411. 59 G. N. Ostojic, S. Zaric, J. Kono, M. S. Strano, V. C. Moore, R. H. Huage, R. E. Smalley, Phys. Rev. Lett. 2004, 92, 117402. 60 S. Y. Set, H. Yaguchi, Y. Tanaka, M. Jablonski, J. Lightwave Technol. 2004, 22, 51. 61 S. Yamashita, Y. Inoue, S. Maruyama, Y. Murakami, H. Yaguchi, M. Jablonski, S. Y. Set, Opt. Lett. 2004, 29, 1581. 62 Y. H. Wang, J. Lin, C. H. A. Huan, G. S. Chen, Appl. Phys. Lett. 2001, 79, 680. 63 Y. W. Zhu, T. Yu, C. H. Sow, Y. J. Liu, A. T. S. Wee, X. J. Xu, C. T. Lim, J. T. L. Thong, Appl. Phys. Lett. 2005, 87, 023103. Citing Literature Volume18, Issue5March, 2006Pages 587-592 ReferencesRelatedInformation

We present a new type of CeO2 nanodevice in which a single CeO2 nanowire was used as the sensing unit. It was found that incorporation of Pt nanocrystals on CeO2 nanowire could significantly increase the sensor response. A possible mechanism was discussed based on the study of morphology and surface bond states of the nanowire using local electron energy loss spectroscopy and X-ray photoemission spectroscopy. The results provide a pathway to improve the performance of gas sensors with a good understanding of the nanowire’s surface physics and chemistry.

Raman imaging of single layer micromechanical cleavage graphene was carried out. The intensity of disorder-induced Raman feature (D band at ∼1350cm−1) was found to be correlated to the edge chirality: it is stronger at the armchair edge and weaker at the zigzag edge. This shows that Raman spectroscopy is a reliable and practical method to identify the chirality of graphene edge and hence the crystal orientation. The determination of graphene chirality is critically important for fundamental study of graphene as well as applications of graphene-based devices.

Charged impurity (CI) scattering is one of the dominant factors that affects the carrier mobility in graphene. In this paper, we use Raman spectroscopy to probe the charged impurities in suspended graphene. We find that the 2D band intensity is very sensitive to the CI concentration in graphene, while the G band intensity is not affected. The intensity ratio between the 2D and G bands, I(2D)/I(G), of suspended graphene is much stronger compared to that of nonsuspended graphene, due to the extremely low CI concentration in the former. This finding is consistent with the ultrahigh carrier mobility in suspended graphene observed in recent transport measurements. Our results also suggest that at low CI concentrations that are critical for device applications, the I(2D)/I(G) ratio is a better criterion in selecting high quality single layer graphene samples than is the G band blue shift.

Highly ordered treelike Si/ZnO hierarchical nanostructures are successfully prepared in a large scale by combining two common techniques, viz., photolithography-assisted wafer-scale fabrication of Si nanopillars and bottom-up hydrothermal growth of ZnO nanorods. Silver nanoparticles are decorated onto the nanotrees by photochemical reduction and deposition. The Si/ZnO/Ag hybrid nanotrees are employed as SERS-active substrates, which exhibit good performance in terms of high sensitivity and good reproducibility. In addition to the SERS application, such ordered Si/ZnO arrays might also find potential applications in light-emitting diodes and solar cells.

Rod-shaped CuO nanostructures were successfully synthesized by a one-step annealing process in air using copper plates as starting material. Phase analysis was carried out using X-ray diffraction, transmission electron microscopy and micro-Raman scattering and the results confirmed the nanorods as single-phase CuO. For the first time, single individual CuO nanorods with different aspect ratios were investigated by polarized micro-Raman scattering in this work. An obvious anisotropy in the intensity of Raman modes was observed when the electric field vector of the incident laser beam is parallel and perpendicular to the long axis of a nanorod. The mechanism responsible for the observed polarized Raman spectra was attributed to the polarization effect produced by the large length to diameter ratio of the nanorods and the large dielectric contrast between these nanorods and their surrounding environment.

A poly(vinyl alcohol) (PVA) based nanocomposite using fully exfoliated graphene oxide (GO) sheets and multi-walled carbon nanotubes (CNTs) were prepared via a simple procedure. It is confirmed from optical imaging that dispersion of CNTs in the PVA matrix can be significantly improved by adding GO sheets. Molecular dynamics (MD) simulations suggest that the GO–CNT interaction is strong and the complex is thermodynamically favorable over agglomerates of CNTs. The GO–CNT scroll-like structure formed with the hydrophilic outer surface of GO can be well dispersed in water. More important, a synergistic effect arises from the combination of CNT and GO, the GO–CNT/PVA composite films show superior mechanical properties compared to PVA composite films enhanced by GO or CNT alone, not only the tensile strength and Young's modulus of the composites are significantly improved, but most of the ductility is also retained. The enhanced mechanical properties of the GO–CNT/PVA composite film can be attributed to the fully exploited reinforcement effect from GO and CNT via good dispersion.

Bernal (ABA stacking order) and rhombohedral (ABC) trilayer graphene (3LG) are characterized by Raman spectroscopy. From a systematic experimental and theoretical analysis of the Raman modes in both of these 3LGs, we show that the G band, G' (2D) band, and the intermediate-frequency combination modes of 3LGs are sensitive to the stacking order of 3LG. The phonon wavevector q, that gives the double resonance Raman spectra is larger in ABC than ABA, which is the reason why we get the different Raman frequencies and their spectral widths for ABA and ABC 3LG. The weak electron-phonon interaction in ABC-stacked 3LG and the localized strain at the boundary between ABC- and ABA-stacked domains are clearly reflected by the softening of the G mode and the G' mode, respectively.

We report here the direct electron transfer of GOD and a novel glucose biosensor based on carbon-decorated ZnO(C–ZnO) nanowire array electrode. The C–ZnO nanowire array provides a novel platform for fast direct electrochemistry of GOD, and its based biosensor shows very high sensitivity and low detection limit. Based on the direct electrochemistry of horseradish peroxidase (HRP), the H2O2 biosensing application is further demonstrated using this new C–ZnO array architecture. The high conductivity of carbon and good electron transfer capability of ZnO nanowires, along with their low cost and biocompatibility make the C–ZnO nanowire array a promising platform for direct electrochemistry of enzymes and mediator-free enzymatic biosensors.

In this work, we show that the maximum thermopower of few layers graphene (FLG) films could be greatly enhanced up to ∼700 μV/K after oxygen plasma treatment. The electrical conductivities of these plasma treated FLG films remain high, for example, ∼104 S/m, which results in power factors as high as ∼4.5 × 10−3 W K−2 m−1. In comparison, the pristine FLG films show a maximum thermopower of ∼80 μV/K with an electrical conductivity of ∼5 × 104 S/m. The proposed mechanism is due to generation of local disordered carbon that opens the band gap. Measured thermopowers of single-layer graphene (SLG) films and reduced graphene oxide (rGO) films were in the range of −40 to 50 and −10 to 20 μV/K, respectively. However, such oxygen plasma treatment is not suitable for SLG and rGO films. The SLG films were easily destroyed during the treatment while the electrical conductivity of rGO films is too low.

Single crystal and vertically aligned cobalt oxide (Co3O4) nanowalls were synthesized by directly heating Co foil on a hot-plate under ambient conditions. The vertically aligned Co3O4 nanowalls grown on the plate show excellent mechanical property and were facilely attached to the surface of a glassy carbon (GC) electrode using conductive silver paint. The prepared Co3O4 nanowalls electrode was then applied to study the electrocatalytic oxidation and reduction of hydrogen peroxide (H2O2) in 0.01 M pH 7.4 phosphate buffer medium. Upon the addition of H2O2, the Co3O4 nanowalls electrode exhibits significant oxidation and reduction of H2O2 starting around +0.25 V (vs. Ag/AgCl), while no obvious redox activity is observed at a bare GC electrode over most of the potential range. The superior electrocatalytic response to H2O2 is mainly attributed to the large surface area, minimized diffusion resistance, high surface energy, and enhanced electron transfer of the as-synthesized Co3O4 nanowalls. The same Co3O4 nanowalls electrode was also applied for the amperometric detection of H2O2 and showed a fast response and high sensitivity at applied potentials of +0.8 V and −0.2 V (vs. Ag/AgCl), respectively. The results also demonstrate that Co3O4 nanowalls have great potential in sensor and biosensor applications.

Nanocrystalline nickel ferrite (NiFe2O4) particles were successfully synthesized in situ in an amorphous silica matrix by mechanical activation at room temperature. Phase development in the amorphous precursors, derived via a modified sol–gel synthesis route, with increasing mechanical activation time was studied in detail by employing transmission electron microscopy, x-ray diffraction, and Raman spectroscopy. NiFe2O4 nanoparticles of 8.05 nm in mean particle size with a standard deviation of 1.24 nm, which were well dispersed in the silica matrix, were realized by 30 h of mechanical activation. The phase formation of nanocrystalline NiFe2O4 particles involves the nucleation of Fe3O4 in amorphous silica at the initial stage of mechanical activation, followed by the growth of nickel ferrite by incorporation of Ni2+ caions into Fe3O4. Their magnetic anisotropy, surface spin disorder, and cation distribution are investigated by considering both the strain imposed by silica matrix and the buffer effect during mechanical activation.

Single-crystalline Cr-doped ${\text{In}}_{2}{\text{O}}_{3\ensuremath{-}\ensuremath{\delta}}$ nanostructures with diverse morphologies including nanotowers, nanowires, and octahedrons are synthesized by using a vapor transport method. X-ray photoelectron spectroscopy results indicate that the as-grown samples contain $3\text{ }\text{at}\text{.}\text{ }%$ Cr and are significantly oxygen deficient. The large surface-to-volume ratio in the nanostructures enhances their susceptibility to the postsynthesis treatments; high-temperature annealing in air boosts the oxygen contents in the samples, which is accompanied by a weakened defect-related emission in the photoluminescence spectra. Magnetization measurements on the as-grown and the annealed nanostructures suggest room-temperature ferromagnetism, and importantly the ferromagnetism is stronger in samples with higher oxygen deficiency. Electronic band alterations as a result of the Cr doping and the oxygen vacancies as well as the formation of bound magnetic polarons are suggested to play important roles in stabilizing the long-range ferromagnetism.

Abstract Graphene has attracted much attention since its first discovery in 2004. Various approaches have been proposed to control its physical and electronic properties. Here, it is reported that graphene‐based intercalation is an efficient method to modify the electronic properties of few‐layer graphene (FLG). FeCl 3 intercalated FLGs are successfully prepared by the two‐zone vapor transport method. This is the first report on full intercalation for graphene samples. The features of the Raman G peak of such FLG intercalation compounds (FLGIC) are in good agreement with their full intercalation structures. The FLGICs present single Lorentzian 2D peaks, similar to that of single‐layer graphene, indicating the loss of electronic coupling between adjacent graphene layers. First principle calculations further reveal that the band structure of FLGIC is similar to single‐layer graphene but with a strong doping effect due to the charge transfer from graphene to FeCl 3 . The successful fabrication of FLGIC opens a new way to modify properties of FLG for fundamental studies and future applications.

The optical conductivities of graphene layers are strongly dependent on their stacking orders. Our first-principle calculations show that, while the optical conductivities of single-layer graphene (SLG) and bilayer graphene (BLG) with Bernal stacking are almost frequency-independent in the visible region, the optical conductivity of twisted bilayer graphene (TBG) is frequency-dependent, giving rise to additional absorption features due to the band folding effect. Experimentally, we obtain from contrast spectra the optical conductivity profiles of BLG with different stacking geometries. Some TBG samples show additional features in their conductivity spectra, in full agreement with our calculation results, while a few samples give universal conductivity values similar to that of SLG. We propose that those variations of optical conductivity spectra of TBG samples originate from the difference between the commensurate and incommensurate stackings. Our results reveal that the optical conductivity measurements of graphene layers indeed provide an efficient way to select graphene films with desirable electronic and optical properties, which would greatly help the future application of those large-scale misoriented graphene films in photonic devices.

High-aspect-ratio V2O5 nanoribbons are synthesized by thermal vapor deposition technique. Our results reveal that the nanoribbons can serve as effective active optical waveguides. In addition, the observation of strong Raman signals collected at the end of the ribbon indicate that the unique nanostructure could play a vital role in Raman amplifers and other nonlinear photonic components.

We report the first optical waveguide based on perylene diimide (PDI) crystalline microwires. The birefringence, polarized photoluminescence emission, long distance light waveguide as well as electrical-optical modulation were studied. PDI is a good polymeric electro-optic material because of its low relative permittivity, low operating voltage, high thermal and photo-stability, and easy integration on flexible substrates. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

The electrochemical performance of supercapacitors relies not only on the exploitation of high-capacity active materials, but also on the rational design of superior electrode architectures. Herein, a novel supercapacitor electrode comprising 3D hierarchical mixed-oxide nanostructured arrays (NAs) of C/CoNi3 O4 is reported. The network-like C/CoNi3 O4 NAs exhibit a relatively high specific surface area; it is fabricated from ultra-robust Co-Ni hydroxide carbonate precursors through glucose-coating and calcination processes. Thanks to their interconnected three-dimensionally arrayed architecture and mesoporous nature, the C/CoNi3 O4 NA electrode exhibits a large specific capacitance of 1299 F/g and a superior rate performance, demonstrating 78% capacity retention even when the discharge current jumps by 100 times. An optimized asymmetric supercapacitor with the C/CoNi3 O4 NAs as the positive electrode is fabricated. This asymmetric supercapacitor can reversibly cycle at a high potential of 1.8 V, showing excellent cycling durability and also enabling a remarkable power density of ∼13 kW/kg with a high energy density of ∼19.2 W·h/kg. Two such supercapacitors linked in series can simultaneously power four distinct light-emitting diode indicators; they can also drive the motor of remote-controlled model planes. This work not only presents the potential of C/CoNi3 O4 NAs in thin-film supercapacitor applications, but it also demonstrates the superiority of electrodes with such a 3D hierarchical architecture.

Though graphene has been intensively studied by Raman spectroscopy, in this letter, we report a study of the second-order overtone and combination Raman modes in a mostly unexplored frequency range of 1690-2150 cm(-1) in nonsuspended commensurate (AB-stacked), incommensurate (folded) and suspended graphene layers. On the basis of the double resonance theory, four dominant modes in this range have been assigned to (i) the second order out-of-plane transverse mode (2oTO or M band), (ii) the combinational modes of in-plane transverse acoustic mode and longitudinal optical mode (iTA+LO), (iii) in-plane transverse optical mode and longitudinal acoustic mode (iTO+LA), and (iv) longitudinal optical mode and longitudinal acoustic mode (LO+LA). Differing from AB-stacked bilayer graphene or few layer graphene, single layer graphene shows the disappearance of the M band. Systematic analysis reveals that interlayer interaction is essential for the presence (or absence) of the M band, whereas the substrate has no effect on the presence (or absence) of the M band. Dispersive behaviors of these "new" Raman modes in graphene have been probed by laser excitation energy-dependent Raman spectroscopy. It is found that the appearance of the M band strictly depends on the AB stacking, which could be used as a fingerprint for AB-stacked bilayer graphene. This work expands upon the unique and powerful abilities of Raman spectroscopy to study graphene and provides another effective way to probe phonon dispersion, electron-phonon coupling, and to exploit the electronic band structure of graphene layers.

A novel strategy of utilizing supramolecular polymerization for fabricating nitrogen doped porous graphene (NPG) with high doping level of 12 atom% as the anode material for lithium ion batteries is reported for the first time. The introduction of supramolecular polymer (melamine cyanurate) functions not only as a spacer to prevent the restacking of graphene sheets but also as a sacrificial template to generate porous structures, as well as a nitrogen source to induce in situ N doping. Therefore, pores and loose‐packed graphene thin layers with high N doping level are very effectively formed in NPG after the annealing process. Such highly desired structures immediately offer remarkably improved Li storage performance including high reversible capacity (900 mAh g −1 after 150 cycles) with good cycling and rate performances. The effects of annealing temperature and heating rates on the final electrochemical performance of NPG are also investigated. Furthermore, the low cost, facile, and scalable features of this novel strategy may be helpful for the rational design of functionalized graphene‐based materials for diverse applications.

As one of the most important research areas in lithium-ion batteries (LIBs), well-designed nanostructures have been regarded as key for solving problems such as lithium ion diffusion, the collection and transport of electrons, and the large volume changes during cycling processes. Here, hierarchical graphene-wrapped TiO2@Co3O4 coaxial nanobelt arrays (G-TiO2@Co3O4 NBs) have been fabricated and further investigated as the electrode materials for LIBs. The results show that the yielded G-TiO2@Co3O4 NBs possess a high reversible capacity, an outstanding cycling performance, and superior rate capability compared to TiO2 and TiO2@Co3O4 nanobelt array (TiO2@Co3O4 NBs) electrodes. The core–shell TiO2@Co3O4 NBs may contain many cavities and provide more extra spaces for lithium ion storage. The introduction of graphene into nanocomposite electrodes is favorable for increasing their electrical conductivity and flexibility. The integration of hierarchical core–shell nanobelt arrays and conducting graphene may induce a positive synergistic effect and contribute to the enhanced electrochemical performances of the electrode. The fabrication strategy presented here is facile, cost-effective, and can offer a new pathway for large-scale energy storage device applications.

In this paper, we propose and analytically demonstrate a biosensor configuration based on the excitation of surface electromagnetic waves in a graphene-based one-dimensional photonic crystal (1D PC). The proposed graphene-based 1D photonic crystal consists of alternating layers of high (graphene) and low (PMMA) refractive index materials, which gives a narrow angular reflectivity resonance and high surface fields due to low loss in PC. A differential phase-sensitive method has been used to calculate the sensitivity of the configuration. Our results show that the sensitivity of the proposed configuration is 14.8 times higher compared to those of conventional surface plasmon resonance (SPR) biosensors using gold thin films. This novel and effective graphene-based 1D PC will serve as a promising replacement of metallic thin film as a sensor head for future biosensing applications.

We report room temperature ferromagnetism in partially hydrogenated epitaxial graphene grown on 4HSiC(0001). The presence of ferromagnetism was confirmed by superconducting quantum interference devices measurements. Synchrotron-based near-edge x-ray absorption fine structure and high resolution electron energy loss spectroscopy measurements have been used to investigate the hydrogenation mechanism on the epitaxial graphene and the origin of room temperature ferromagnetism. The partial hydrogenation induces the formation of unpaired electrons in graphene, which together with the remnant delocalized π bonding network, can explain the observed ferromagnetism in partially hydrogenated epitaxial graphene.

Different metal films (Co, Ni, Au, and Ag) were deposited on graphene and the interactions between these metals and graphene were studied by Raman spectroscopy. The Raman peaks were shifted after the deposition of metal films. The electron doping of graphene with cobalt contacts and the hole doping with the nickel contacts are the main reasons for Raman peak shift. However, for gold contacts and silver contacts with graphene, strain effect dominates Raman peak shift instead of charge transfer.

CNT/Ni hybrid nanostructured arrays (NSAs) are synthesized on a stainless steel substrate through a one-step chemical-vapor-deposition (CVD) method using nullaginite NSAs as starting materials. During the CVD process, the nullaginite NSAs are transformed into Ni NSAs, which can further act as the catalysts to initiate the simultaneous in situ growth of CNTs on their surface, leading to an intriguing three-dimensional (3D) hybrid nanostructure. The resulting ordered CNT/Ni NSAs are highly porous and conductive, which are believed to be quite favorable for electrochemical applications. As a proof-of-concept demonstration of the functions of such a well-designed architecture in energy storage, the CNT/Ni NSAs are tested as the working electrodes of electrochemical capacitors (ECs). After being activated, the composite electrode exhibits both well-defined pseudo-capacitive and electrical double-layer behavior with high areal capacitance (up to ∼0.901 F cm−2), excellent cyclability (nearly 100% capacitance retention after 5000 cycles), and outstanding rate capability. The unique interconnected hybrid structure and virtues inherited from the conductive CNT network and porous NSAs are believed to be responsible for the excellent performance.

Self-assembled hierarchical graphene@polyaniline (PANI) nanoworm composites have been fabricated using graphene oxide (GO) and aniline as the starting materials. The worm-like PANI nanostructures were successfully obtained via a simple polymerization route. The graphene-wrapped hierarchical PANI nanoworm structures could be prepared using a three-step process by dispersing the PANI nanoworms sequentially into the relevant solution. The morphologies and microstructures of the samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Electrochemical properties were also characterized by cyclic voltammetry (CV) and galvanostatic charge–discharge. The results indicated that the integration of graphene and the worm-like PANI nanocomposites possessed excellent electrochemical properties. These hierarchical worm-like graphene@PANI nanostructures could afford an interconnected network with a lot of well-defined nanopores, and further provided more active sites and excellent electron transfer path for improving the electric conductivity as well as good mechanical properties. Supercapacitor devices based on these self-assembled nanocomposites showed high electrochemical capacitance (488.2 F g−1) at a discharge rate of 0.5 A g−1, which also could effectively improve electrochemical stability and rate performances.

In this article, we report the first successful preparation of single- and few-layers of tantalum diselenide (2H-TaSe₂) by mechanical exfoliation technique. Number of layers is confirmed by white light contrast spectroscopy and atomic force microscopy (AFM). Vibrational properties of the atomically thin layers of 2H-TaSe₂ are characterized by micro-Raman spectroscopy. Room temperature Raman measurements demonstrate MoS₂-like spectral features, which are reliable for thickness determination. E₁g mode, usually forbidden in backscattering Raman configuration is observed in the supported TaSe₂ layers while disappears in the suspended layers, suggesting that this mode may be enabled because of the symmetry breaking induced by the interaction with the substrate. A systematic in-situ low temperature Raman study, for the first time, reveals the existence of incommensurate charge density wave phase transition in single and double-layered 2H-TaSe₂ as reflected by a sudden softening of the second-order broad Raman mode resulted from the strong electron-phonon coupling (Kohn anomaly).

An efficient method for the preparation of benzoxazole and benzimidazole covalently grafted graphene and their application as high performance electrode materials for supercapacitors is reported. The synthesis of such covalently functionalized graphene materials first involves a cyclization reaction of carboxylic groups on graphene oxide with the hydroxyl and aminos groups on o-aminophenol and o-phenylenediamine, and subsequent reduction by hydrazine. Results of Fourier transformed infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) have confirmed that the covalent functionalization of graphene is achieved through the formation of benzoxazole and benzimidazole on the graphene sheets. The functionalized graphene materials are revealed to consist of corrugation and scrolling morphologies with less aggregation, indicating the effectiveness of functionalization in preventing restacking/aggregation of the graphene sheets. Furthermore, when applied as supercapacitor electrodes, the functionalized graphene materials exhibit good electrochemical performances in terms of high specific capacitance (730 and 781 F g−1 for benzoxazole and benzimidazole grafted graphene, respectively, at a current density of 0.1 A g−1) and good cycling stability, implying their potential for energy storage applications.

The stacking faults (deviates from Bernal) will break the translational symmetry of multilayer graphenes and modify their electronic and optical behaviors to the extent depending on the interlayer coupling strength. This paper addresses the stacking-induced band splitting and folding effect on the electronic band structure of twisted bilayer graphene. Based on the first-principles density-functional theory study, we predict that the band folding effect of graphene layers may enable the $G$ band Raman double resonance in the visible excitation range. Such prediction is confirmed experimentally with our Raman observation that the resonant energies of the resonant $G$ mode are strongly dependent on the stacking geometry of graphene layers.

Zeolitic imidazolate framework (ZIF-8)-derived ZnO/nanoporous carbon (NPC) aligned in a three-dimensional porous carbon network (3DPCN) is designed to form a multiporous network nanostructure to absorb electromagnetic waves. The porous 3DPCN structure acts as the electronic pathway and the nucleation locus for ZIF-8 particles. Meanwhile, the conductive networks could also provide more routes for electron transfer. With good impedance matching and attenuation characteristics, ZnO@NPC/3DPCN shows enhanced microwave response where the minimum reflection loss of −35.7 dB can be achieved with a 10 wt % filler. Our study not only exploits the new system of lightweight absorbers but also further reveals the changing of electromagnetic parameters and absorbing properties by heat treatment, which may lead to a new way to design novel lighter multiporous network nanostructures.

To explore the role of the interaction between the adsorbed molecules and substrates for the charge transfer (CT) induced Raman enhancement, we systematically study the surface enhanced Raman scattering (SERS) on graphene, graphene oxide (GO) and reduced graphene oxide (r-GO) using rhodamine 6G (R6G) as the probe molecule. The Raman spectra of R6G molecules deposited on these three SERS substrates show remarkable difference in spectral features due to the different enhancement contributions from the local chemical groups and the global π-conjugation network of the substrates. What is more surprising is that for 1–4 layers graphene-based materials, the Raman signals of R6G on GO are found to increase intensity with the number of GO layers, while the Raman signals of R6G on different graphene/r-GO layers show inverse trends due to dominant π–π stacking mechanism. Our results provide a comprehensive understanding of the influence of local chemical groups and the global π-conjugation network on the SERS enhancements. In addition to high reproducibility, low cost, and good biocompatibility of GO, the rich chemical structures and the absence of electromagnetic enhancement make it an excellent choice as a tunable substrate to study the chemical enhancement resulting from the adsorbent–substrate interaction.

Three dimensional, self-supported α-Fe2O3/Ppy composite electrode with enhanced specific areal capacity and rate performance was successfully fabricated by a simple, low-cost, two-steps process consisting of direct heating of iron foil in air and subsequent coating of conducting polymer Ppy on the α-Fe2O3 nanoflakes. By using α-Fe2O3/Ppy as the anode materials with iron foil as the current collector, the unique structure affords a highly conductive pathway for electron, a short diffusion length for ions, a fast mass transport channel for electrolyte, and sufficient void space for accommodating large volume variations during Li intercalation/diintercalation for Li-ion battery. A relatively high specific capacity of 0.42 mA h/cm2 can be achieved at 0.1 mA/cm2 even after 100 charge/discharge cycles, with a plateau potential of 1 V and nearly 100% Coulombic efficiency, suggesting the feasibility to use this unique 3D nanostructured hybrid composite for microbattery in both small and large scale applications.

Here, we report the fabrication of a graphene-based Bragg grating (one-dimensional photonic crystal) and experimentally demonstrate the excitation of surface electromagnetic waves in the periodic structure using prism coupling technique. Surface electromagnetic waves are non-radiative electromagnetic modes that appear on the surface of semi-infinite 1D photonic crystal. In order to fabricate the graphene-based Bragg grating, alternating layers of high (graphene) and low (PMMA) refractive index materials have been used. The reflectivity plot shows a deepest, narrow dip after total internal reflection angle corresponds to the surface electromagnetic mode propagating at the Bragg grating/air boundary. The proposed graphene based Bragg grating can find a variety of potential surface electromagnetic wave applications such as sensors, fluorescence emission enhancement, modulators, etc.

Two-dimensional materials, e.g. graphene and molybdenum disulfide (MoS2), have attracted great interest in recent years. Identification of the thickness of two-dimensional materials will improve our understanding of their thickness-dependent properties, and also help with scientific research and applications. In this paper, we propose to use optical imaging as a simple, quantitative and universal way to identify the thickness of two-dimensional materials, i.e. mechanically exfoliated graphene, nitrogen-doped chemical vapor deposition grown graphene, graphene oxide and mechanically exfoliated MoS2. The contrast value can easily be obtained by reading the red (R), green (G) and blue (B) values at each pixel of the optical images of the sample and substrate, and this value increases linearly with sample thickness, in agreement with our calculation based on the Fresnel equation. This method is fast, easily performed and no expensive equipment is needed, which will be an important factor for large-scale sample production. The identification of the thickness of two-dimensional materials will greatly help in fundamental research and future applications.

Hierarchical TiO2 nanobelts@MnO2 ultrathin nanoflakes core–shell arrays (TiO2@MnO2 NBAs) have been fabricated on a Ti foil substrate by hydrothermal approach and further investigated as the electrode for a supercapacitor. Their electrochemical properties were examined using cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) in a three-electrode cell. The experimental observations clearly show that the fabricated TiO2@MnO2 NBAs electrode possesses superior rate capability and outstanding cycling performance due to its rationally designed nanostructure. A specific capacitance as high as 557.6 F g−1 is obtained at a scan rate of 200 mV s−1 (454.2 F g−1 at a current density of 200 mA g−1) in 1 M Na2SO4 aqueous solution. The energy density and power density measured at 2 A g−1 are 7.5 Wh kg−1 and 1 kW kg−1 respectively, demonstrating its good rate capability. In addition, the composite TiO2@MnO2 NBAs electrode shows excellent long-term cyclic stability. The fabrication method presented here is facile, cost-effective and scalable, which may open a new pathway for real device applications.

More than 10% of the people in the world still suffer from inadequate access to clean water. Traditional water disinfection methods (e.g., chlorination and ultraviolet radiation) include concerns about the formation of carcinogenic disinfection byproducts (DBPs), pathogen reactivation, and/or excessive energy consumption. Recently, a nanowire-assisted electroporation–disinfection method was introduced as an alternative. Here, we develop a new copper oxide nanowire (CuONW)-modified three-dimensional copper foam electrode using a facile thermal oxidation approach. An electroporation–disinfection cell (EDC) equipped with two such electrodes has achieved superior disinfection performance (>7 log removal and no detectable bacteria in the effluent). The disinfection mechanism of electroporation guarantees an exceedingly low operation voltage (1 V) and level of energy consumption (25 J L–1) with a short contact time (7 s). The low operation voltage avoids chlorine generation and thus reduces the potential of DBP formation. Because of irreversible electroporation damage on cell membranes, no regrowth and/or reactivation of bacteria occurs during storage after EDC treatment. Water disinfection using EDCs has great potential for practical applications.

In reverse osmosis (RO) system for wastewater reclamation, biofouling is an inevitable issue. Chlorine disinfection is commonly used in pretreatment to control biofouling. Some chlorine-resistant bacteria could survive after chlorine disinfection and the microbial community structure in feed water changes significantly, thus leading to the change of biofouling potential. In this study, the effect of chlorine disinfection on the biofouling of RO membrane was investigated using a laboratory cross-flow RO system. Chlorine disinfection inactivated most bacteria in feed water. However, during the operation of RO system, with the increase of chlorine dosage the flux decline became more severe after a period of operation. The final normalized flux after 21 days was 0.27, 0.26, 0.20, and 0.21 with 0, 1, 5, and 15 mg-Cl2/L chlorine as pretreatment, respectively. After the operation, the numbers of active bacteria in the foulants on the fouled membrane were on the same level regardless of the chlorine dosage, whereas the thickness of the foulants increased with the chlorine dosage significantly. Additionally, the higher total organic carbon concentration indicated more extracellular polymeric substances (EPS) in foulants. Microbial community structure analysis showed that the abundance and the species number of chlorine-resistant bacteria increased significantly with the chlorine dosage. Typical chlorine-resistant bacteria, including Methylobacterium, Pseudomonas, Sphingomonas, and Acinetobacter, were identified as significantly distinctive genera in the foulants after the pretreatment by 15 mg-Cl2/L chlorine. Compared with the bacteria without chlorine disinfection, these remaining bacteria produced more EPS with higher molecular weight, which could be the major contribution to more severe RO membrane fouling after chlorine disinfection.

Despite the fascinating Li storage properties of organic carbonyl compounds, e.g., high therotical capacity and fast kinetics, it is still lack of a facile and effective way that capable of large‐scale producion of advanced carbonyl cathodes for Li‐ion batteries (LIBs). Here, a generic strategy is proposed by combining sonication and hydrothermal techniques for scalable synthesis of high performance organic carbonyl cathodes for LIBs. A series of commercialized vat dyes with abundant electroactive conjugated carbonyl groups are confined in between the graphene layers, forming a compatible 3D hybrid architecture. The unique structure affords good Li + ions accessibility to the electrode and short Li + ions diffusion length. Meanwhile, each sandwiched graphene layer functions as a miniature current collector, ensuring fast electron transport throughout the entire electrode. Consequently, the cathodic performances of LIBs using the composites as electrodes, for example, Vat Green 8/graphene, Vat Brown BR/graphene, and Vat Olive T/graphene, possess high specific capacity, exceptional cycling stability, and excellent rate capability. The effect of vat dye content on the morphology, structure, and the final electrochemical performance of the composites is investigated as well. This work provides a versatile and low‐cost platform for large‐scale development of advanced organic‐based electrodes toward sustainable energy fields.

Of all of the strategies for controlling reverse osmosis (RO) membrane fouling, chemical cleaning is indispensable. To study the effects of chemical cleaning on membrane foulant removal, a comparative analysis of RO membranes before and after common alkaline and acid cleaning was conducted by dissecting lead and terminal RO membranes in a full-scale municipal wastewater reclamation plant. Most foulants on the membranes were removed by chemical cleaning processes. Calcium was the major inorganic component of the foulants because of its highest concentration in the feed water. Aluminum and iron were also abundant elements on the membranes due to their high deposition ratios and low removal efficiencies. Hydrophilic neutrals (HIN) and hydrophobic neutrals (HON) were the two largest dissolved organic matter (DOM) fractions on the membranes before cleaning. HIN and hydrophilic acids (HIA) were not effectively removed. Chemical cleaning removed 94% and 90% of the total bacteria on the lead and tail membranes and considerably changed the structure of the microbial communities. Bacteria excessively producing extracellular polymeric substance (EPS), such as Pseudomonas and Zoogloea, were much more resistant to the chemical cleaning process. After cleaning, the membrane microbial community structures were more similar to those in the feed water than the structures on the membranes before cleaning. These results shed light on the effects of cleaning in a full-scale RO plant, improves our understanding of the removal of foulants and provides potential research directions for cleaning methods and RO pretreatment processes.

Abstract 2D nanomaterials are well suited for energy conversion and storage because of their thickness‐dependent physical and chemical properties. However, current synthetic methods for translating 2D materials from the laboratory to industry cannot integrate both advantages of liquid‐phase method (i.e., solution processibility, homogeneity, and massive production), and gas‐phase method (i.e., high quality and large lateral size). Here, inspired by Chinese Sugar Figure Blowing Art, a rapid “gel‐blowing” strategy is proposed for the mass production of 2D nonlayered nanosheets by thermally expanding the viscous gel precursors within a short time (≈1 min). A wide variety of 2D nanosheets including oxides, carbon, oxides/carbon and metal/carbon composites are synthesized on a large scale and with no impurities. Importantly, this method unifies the merits of both liquid‐phase and gas‐phase syntheses, giving rise to 2D products with high uniformity, nanometer thickness, and large lateral sizes (up to hundreds of micrometers) simultaneously. The success of this strategy highly relies on the speed of “blowing” and control of the amount of reactants. The as‐synthesized nanosheet electrodes manifest excellent electrochemical performance for alkali‐ion batteries and electrocatalysis. This method opens up a new avenue for economical and massive preparation of good‐quality nonlayered 2D nanosheets for energy‐related applications and beyond.

Abstract Sodium‐ion batteries are gradually regarded as a prospective alternative to lithium‐ion batteries due to the cost consideration. Here, three kinds of tin (IV) sulfide nanosheets are controllably designed with progressively exposed active facets, leading to beneficial influences on the Na + storage kinetics, resulting in gradient improvements of pseudocapacitive response and rate performance. Interestingly, different forms of kinetics results are generated accompanying with the morphology and structure evolution of the three nanosheets. Finally, detailed density functional theory simulations are also applied to analyze the above experimental achievements, proving that different exposed facets of crystalline anodes possess dissimilar Na + storage kinetics. The investigation experiences and conclusions shown in this work are meaningful to explore many other proper structure design routes toward the high‐rate and stable metal‐ions storage.

Tailored sulfur cathode is vital for the development of a high performance lithium-sulfur (Li-S) battery. A surface modification on the sulfur/carbon composite would be an efficient strategy to enhance the cycling stability. Herein, we report a nickel hydroxide-modified sulfur/conductive carbon black composite (Ni(OH)2@S/CCB) as the cathode material for the Li-S battery through the thermal treatment and chemical precipitation method. In this composite, the sublimed sulfur is stored in the CCB, followed by a surface modification of Ni(OH)2 nanoparticles with size of 1-2 nm. As a cathode for the Li-S battery, the as-prepared Ni(OH)2@S/CCB electrode exhibits better cycle stability and higher rate discharge capacity, compared with the bare S/CCB electrode. The improved performance is largely due to the introduction of Ni(OH)2 surface modification, which can effectively suppress the "shuttle effect" of polysulfides, resulting in enhanced cycling life and higher capacity.

The development of environment-friendly electrode materials is highly desired for the clean and sustainable Li-ion batteries (LIBs) system. Organic cathode materials that involve conducting polymers, organic carbonyl/sulfur compounds are expected to be promising candidates for future LIBs with a concept of “green and sustainable”. However, their battery performances are relatively worse than that of inorganic counterparts due to their low electronic conductivity and unwanted dissolution reactions occurring in electrolytes. Aimed to alter their performances, we herein focuses on the preparation of upgraded organic materials by chemical engineering of graphene oxide (GO) and the systematic study of their electrochemical performance as positive electrodes for LIBs. The obtained decarboxylated GO and carbonylated/hydroxylated GO electrodes show significantly enhanced electrochemical performance compared with that of the GO electrode. Our results demonstrate that the manipulation of oxygen functional groups on GO is an effective strategy to greatly improve the Li storage property of GO-based materials for advanced LIBs cathodes.

Due to the rational design, the Co(OH)₂@S/CCB electrode exhibits enhanced electrochemical performances compared with the bare S/CCB electrode.

A high-flux thin film composite (TFC) hollow fiber nanofiltration (NF) membrane was fabricated using a barrier layer of polypiperazine amide synthesized via interfacial polymerization (IP) on a previously prepared dual-layer (PES/PVDF) hollow fiber substrate, which was synthesized via the two-step TIPS/NIPS method. The permeability of the TFC membrane was smaller by an order of magnitude than that of the substrate, which was due to the formation of a thick barrier layer. The structure of the barrier layer was controlled via the addition of cyclic ethers (dioxane, oxolane and trioxane). By increasing the polarity of cyclic ethers, the thickness of the barrier layer and the dense layer was reduced due to the piperazine concentration in the organic phase. Comparing with oxolane and trioxane, the addition of dioxane resulted in a narrower pore size as that of the conventional IP process, which was ascribed to the narrow IP reaction zone via the immiscibility of interface. With the addition of dioxane up to 2 wt%, the barrier layer became thinner, the pure water flux of the resultant membrane was improved and the dextran rejection was maintained. The novel hollow fiber NF membrane has a permeability of 16.6 L m−2 h−1 bar−1, a MWCO of 330 Da and a tensile strength of 10.3 MPa. This membrane had a higher rejection of total organic carbon and a lower rejection of total dissolved solids of the secondary effluent from a petrochemical industry plant, which proves the potential of this membrane in municipal, agricultural and industrial wastewater treatment.

Abstract Hyperbolic metamaterials (HMMs) have emerged as a burgeoning field of research over the past few years as their dispersion can be easily engineered in different spectral regions using various material combinations. Even though HMMs have comparatively low optical loss due to a single resonance, the noble‐metal‐based HMMs are limited by their strong energy dissipation in metallic layers at visible frequencies. Here, the fabrication of noble‐metal‐free reconfigurable HMMs for visible photonic applications is experimentally demonstrated. The low‐loss and active HMMs are realized by combining titanium nitride (TiN) and stibnite (Sb 2 S 3 ) as the phase change material. A reconfigurable plasmonic biosensor platform based on active Sb 2 S 3 –TiN HMMs is proposed, and it is shown that significant improvement in sensitivity is possible for small molecule detection at low concentrations. In addition, a plasmonic apta‐biosensor based on a hybrid platform of graphene and Sb 2 S 3 –TiN HMM is developed and the detection and real‐time binding of thrombin concentration as low as 1 × 10 −15 m are demonstrated. A biosensor operating in the visible range has several advantages including the availability of sources and detectors in this region, and ease of operation particularly for point‐of‐care applications.

Abstract Insertion‐type anode materials with beneficial micro‐ and nanostructures are proved to be promising for high‐performance electrochemical metal ion storage. In this work, heterostructured TiO 2 shperes with tunable interiors and shells are controllably fabricated through newly proposed programs, resulting in enhanced pseudocapacitive response as well as favorable Na + storage kinetics and performances. In addition, reasonably designed nanosheets in the extrinsic shells are also able to reduce the excess space generated by hierarchical structure, thus improving the packing density of TiO 2 shperes. Lastly, detailed density functional theory calculations with regard to sodium intercalation and diffusion in TiO 2 crystal units are also employed, further proving the significance of the surface‐controlled pseudocapacitive Na + storage mechanism. The structure design strategies and experimental results demonstrated in this work are meaningful for electrode material preparation with high rate performance and volume energy density.

While foreign pundits have alternatively blamed and praised the Chinese government’s handling of the COVID-19 virus, little is known about how citizens within China understand this performance. This article considers how satisfied Chinese citizens are with their government’s performance during the COVID-19 pandemic. It first considers the impact of authoritarian control, political culture, and/or actual government performance on citizen satisfaction. Then, it tests the consequences of satisfaction and specifically whether citizen satisfaction leads to greater trust. Analyzing data from the first post-COVID survey of its kind (n = 19,816) conducted from April 22 to 28 April 2020, the authors find that Chinese citizens have an overall high level of satisfaction, but that this satisfaction drops with each lower level of government. Further, authoritarian control, political culture, and awareness of government performance all contribute to citizen satisfaction and this in turn, has enhanced public support for the Chinese government.

The epidemic of COVID-19 has aroused people's particular attention to biosafety. A growing number of disinfection products have been consumed during this period. However, the flaw of disinfection has not received enough attention, especially in water treatment processes. While cutting down the quantity of microorganisms, disinfection processes exert a considerable selection effect on bacteria and thus reshape the microbial community structure to a great extent, causing the problem of disinfection-residual-bacteria (DRB). These systematic and profound changes could lead to the shift in regrowth potential, bio fouling potential, as well as antibiotic resistance level and might cause a series of potential risks. In this review, we collected and summarized the data from the literature in recent 10 years about the microbial community structure shifting of natural water or wastewater in full-scale treatment plants caused by disinfection. Based on these data, typical DRB with the most reporting frequency after disinfection by chlorine-containing disinfectants, ozone disinfection, and ultraviolet disinfection were identified and summarized, which were the bacteria with a relative abundance of over 5% in the residual bacteria community and the bacteria with an increasing rate of relative abundance over 100% after disinfection. Furthermore, the phylogenic relationship and potential risks of these typical DRB were also analyzed. Twelve out of fifteen typical DRB genera contain pathogenic strains, and many were reported of great secretion ability. Pseudomonas and Acinetobacter possess multiple disinfection resistance and could be considered as model bacteria in future studies of disinfection. We also discussed the growth, secretion, and antibiotic resistance characteristics of DRB, as well as possible control strategies. The DRB phenomenon is not limited to water treatment but also exists in the air and solid disinfection processes, which need more attention and more profound research, especially in the period of COVID-19.

In this work, corrosion inhibition of steel caused by imidazoline derivative in the presence of sulfate-reducing bacteria (SRB) with organic carbon starvation was investigated in CO2-saturated seawater. Results demonstrate that the corrosion is inhibited by SRB with a high initial count in the absence of organic carbon but it is accelerated when the initial SRB counts decrease. The maximum value of corrosion rate caused by SRB is (0.179 ± 0.003) mm/y. The inhibition efficiency of imidazoline derivative is improved with a value of 76.2% after 14 days of testing when the initial SRB is 107 cells/mL.

Membrane fouling is currently a significant constraint on reverse osmosis (RO) processes, and little is known about the fouling characteristics in winter. In this paper, RO membranes operating in winter were autopsied to explore the foulant composition. Both organic and inorganic foulant contents showed a decreasing trend from the front-most model to the end-most model, and organics were the main foulant, accounting for 93.90 %–95.24 % of the RO membrane surface deposits. Al, Ca, Mg, Na and K were dominant inorganic scalants, and the deposition amount of Al on the membrane surface reached up to 18.45 mg/m2, although the concentration of Al in RO feed water was as low as only 38.21 μg/L. Organic fouling was more severe than biofouling. The predominant bacteria in water and on the membrane of different positions differed significantly. The relative abundance of Actinobacteriota, Actinobacteria, Mycobacteriaceae, and Mycobacterium on the front-most membrane at the phylum, class, family, and genus levels accounted for approximately 73 %. The percentage of Proteobacteria on the end-most membrane at the phylum level was 85.85 %. This study helps to elucidate the composition of membrane fouling under low temperatures in winter and provides a reference for pretreatment and chemical cleaning.

The inefficiency of nitrogen removal in pyrite autotrophic denitrification (PAD) and the low efficiency of PO43−-P removal in sulfur autotrophic denitrification (SAD) limit their potential for engineering applications. This study examined the use of pyrite and sulfur coupled autotrophic denitrification (PSAD) in batch and column experiments to remove NO3−-N and PO43−-P from sewage. The effluent concentration of NO3−-N was 0.32 ± 0.11 mg/L, with an average Total nitrogen (TN) removal efficiency of 99.14%. The highest PO43−-P removal efficiency was 100% on day 18. There was a significant correlation between pH and the efficiency of PO43−-P removal. Thiobacillus, Thiomonas and Thermomonas were found to be dominant at the bacterial genus level in PSAD. Additionally, the abundance of Thermomonas in the PSAD was greater than that observed in the SAD reactor. This result indirectly indicates that the PSAD system has more advantages in reducing N2O.

The development of electrode materials for Sodium-Ion Batteries (SIBs) has received more and more attention. Among them, vanadium sulfide, as a member of the transition metal sulfide family, owns the characteristics of rich electrochemical activity, high theoretical capacity and adjustable spatial structure. However, the complicated synthetic process, poor rate capability and intricate redox mechanism of vanadium sulfides make them less competitive for commercial use. In this work, a facile approach based on the ball-milling technique followed by adjusted annealing temperature is introduced to fabricate large-scale vanadium sulfides. This general phase-controlled method can bring three different crystal types of V 5 S 8 , V 3 S 4 and V 3 S 5 . With homogeneous covering of super P and Carbon Nano Tubes (CNTs), a conductive network that favors the Na ions/electrons transport in the vanadium sulfides-based electrodes can be fabricated. The V 5 S 8 exhibits the best performance in SIBs with specific capacity of 918 mAh g -1 at 0.1 A g -1 (100 cycles). Moreover, V 5 S 8 electrode also exhibits an ultra-rate capability of 333 mAh g -1 at 50 A g -1 after cycling lifespan (4000 loops). The extremely high pseudo-capacitance characteristics of V 5 S 8 is significant during the SIBs discharge/charge. Additionally, the V 5 S 8 anode also shows the high energy density of 165 Wh kg -1 in SIBs full cell. The form of vanadium sulfide V 5 S 8 possesses connected conductive network and enhanced electrical conductivity, showing the ultra-long cycling at ultra-high rate for SIBs. • The vanadium sulfides are fabricated by phase-controlled approach. • The exquisite architecture owns the enhanced conductivity and connected conductive networks. • The V 5 S 8 exhibits superior performance for SIBs half/full batteries. • The short and connected ion/electron transportation of V 5 S 8 is responsible for boosted kinetics.

The effects of particle shape (angularity α and sphericity S), physical properties (shear modulus Gp and Poisson’s ratio νp) and particle size distribution (uniformity coefficient Cu) on the small-strain stiffness Gmax were investigated via the discrete element method (DEM) in this study. The Gmax values were obtained by DEM simulations of drained triaxial tests. Microscopic analysis indicates that Gmax uniquely depends on two microscale variants, i.e., the mechanical coordination number CNm and contact stiffness between particles. The particle shape effect was only related to CNm. The contact stiffness can be represented by the values of Gp and Cu. Accordingly, an empirical expression composed of CNm, Gp and Cu that can predict the Gmax of granular materials with different particle properties (e.g., particle size distribution, particle shape, and fabric effect) was proposed. The accuracy of the expression has been verified by comparing the data with previous studies.

Co-ferrite films were deposited on SiO2 single-crystal substrates. The as-deposited films were amorphous. The crystallization required an annealing at 700 °C or higher. Magnetic properties were found to be strongly dependent on annealing temperature, annealing duration, and film thickness. A small film thickness can restrict the formation of large particles. A coercivity as high as 9.3 kOe was achieved in the 50 nm film after annealing at 900 °C for 15 min deposited on (100)-SiO2 substrate. The high coercivity was associated with a nanostructure, lattice strain, and larger Raman shift with a relatively sharp peak.

We present a simple technique for manipulating and assembling one-dimensional (1D) CuO nanorods. Our technique exploits the optical trapping ability of line optical tweezers to trap, manipulate and rotate nanorods without physical contact. With this simple and versatile method, nanorods can be readily arranged into interesting configurations. The optical lin et weezers could also be used to manipulate an individual nanorod across two conducting electrodes. This work demonstrates the potential of optical manipulation and assembly of 1D nanostructures into useful nanoelectronics devices. M This article features online multimedia enhancements (Some figures in this article are in colour only in the electronic version)

The effect of catalysts on ZnO nanowire growth was investigated by comparing the performances of Au, Pt, and Ag nanoparticles. Additional control of growth was achieved by implementing a substrate temperature of either 800 °C with a ZnO/graphite powder source or 500 °C with a Zn powder source. At 800 °C, the vapor−liquid−solid mechanism plays a very important role when the Au and Pt nanoparticles are in the liquid phase. On the other hand, nanowires can also be grown on solid nanoparticles, that is, oxidized Ag at 800 °C and nanoscale cracks, that is, Pt at 500 °C, where, the vapor−solid is the only possible mechanism. At 500 °C, the vapor−liquid mechanism still dominates even though Au and Ag appear to be liquid, which is a result of high Zn vapor pressure.