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A facile and scalable strategy is developed to fabricate three dimensional core-shell Fe 2 O 3 @ carbon/carbon cloth structure by simple hydrothermal route as binder-free lithium-ion battery anode. In the unique structure, carbon coated Fe 2 O 3 nanorods uniformly disperse on carbon cloth which forms the conductive carbon network. The hierarchical porous Fe 2 O 3 nanorods in situ grown on the carbon cloth can effectively shorten the transfer paths of lithium ions and reduce the contact resistance. The carbon coating significantly inhibits pulverization of active materials during the repeated Li-ion insertion/extraction, as well as the direct exposure of Fe 2 O 3 to the electrolyte. Benefiting from the structural integrity and flexibility, the nanocomposites used as binder-free anode for lithium-ion batteries, demonstrate high reversible capacity and excellent cyclability. Moreover, this kind of material represents an alternative promising candidate for flexible, cost-effective, and binder-free energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flower-like C-ZnO microspheres assembly from nanoneedles were prepared using carbon spheres as templates. • C-ZnO nanoneedle is single crystal with exposed nonpolar {1010} facets. • Doping ZnO with C results in the production of oxygen vacancies. • Flower-like C-ZnO microspheres exhibited high photoreactivity and excellent stability towards MO degradation. In this work, carbon spheres (CSs) derived from glucose by simple eco-friendly process were used to create a multiphase environment for precipitation reaction to obtain flower-like C-doped ZnO (C-ZnO) nanoneedles assembly. It was found that the presence of carbon spheres can affect the crystal orientation and morphology of ZnO. When the additive amount of carbon spheres was 13 wt%, one-dimensional (1D) needle-like single crystal C-doped ZnO were obtained, which exposed with higher proportion of nonpolar {1010} facets (51%) than that of pristine ZnO (46%), and C-Zn and C-O-Zn bonds were formed. Compared with pristine ZnO prepared by direct precipitation method (ZnO-DPM) without carbon spheres, carbon doped ZnO exhibited higher light absorption ability and smaller band gap width due to the formation of surface defects. The photocatalytic degradation rate of methyl orange over 13 %C-ZnO was 99.98% for 3 h under the irradiation of UV lamp (15 W), almost 1.3 times higher than that of pristine ZnO-DPM. Even after repeating use for 3 times, the degradation rate of methyl orange can be kept as high as 99%. The present study offers a new preparation method for high photoreactive ZnO with exposed nonpolar {1010} facets by precipitation reaction. [ABSTRACT FROM AUTHOR]

Highlights: [•] A bioactive coating was produced on porous Ti surface by an amendatory chemical method. [•] The structure of coating consisted of three layers: Ti substrate, intermediate layer and the outer surface. [•] The coating cross-sectional showed a compositional gradient from the intermediate layer toward the outer surface. [•] The coating exhibits a high ability to form apatite because of the hydroxyl functionalized surface with numerous Ca ions. [ABSTRACT FROM AUTHOR]

Abstract: Pd2+-doped ZnO nanotetrapods were prepared and studied for the humidity detection application. The humidity sensors developed were featured by combination of a quartz crystal microbalance (QCM) as a transducer and Pd2+-doped ZnO nanotetrapods as a sensing element. The ZnO nanotetrapods were synthesized by evaporating highly pure zinc pellets (99.999%) at 900°C in air and PdCl2 was doped on by traditional solution mixing process. Then the mixed solution distributed onto the electrode surfaces of the quartz crystal at room temperature. Pd2+-doped ZnO nanotetrapods were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results indicated that the response of the sensors varied with the different dosage PdCl2. Linear regression algorithm was used for evincing the highly linear behavior of the Pd2+-doped ZnO nanotetrapods sensor. In this humidity sensing system, the Pd2+-doped ZnO nanotetrapods sensing material coated on the gold electrode of QCM showed good sensitivity (∼74.24324Hz/%RH (relative humidity)), reproducibility, linearity (R 2 =−0.98834), short response and recovery time (less than 5s). [Copyright &y& Elsevier]

Abstract: The ZnO nanowires have been prepared and studied as the sensing element for the detection of ammonia. The ZnO nanowires were first synthesized by evaporating high purity zinc pellets at 900°C and then distributed onto the electrode surfaces of quartz crystals at room temperatures. Gas sensitive properties of ZnO nanowires layer were studied in terms of the quartz crystal microbalance (QCM) at room temperature. It is found that the obtained response of the sensors varied with the thickness of the ZnO nanowires layer. ZnO nanowires showed high sensitivity to ammonia in the range of 40–1000ppm. The response time of the sensor was as fast as ∼5s at any concentration (40–1000ppm) of ammonia gas. The ZnO nanowires-coated sensors have a good frequency stability and reproducibility. All results demonstrated that the ZnO nanowire was a potential gas sensing material for practical use. [Copyright &y& Elsevier]

[Display omitted] • Doping of transition metal (Sc, Ti, V, Cr, Mn, Fe, Co and Ni) atoms in α and β phase arsenene is studied. • Adsorption of SF 6 decomposition gases on pristine and Sc doped arsenene is comprehensively investigated. • Sc dopant can adjust the interactions between arsenene monolayer and different gases. • Sensor properties of pristine and Sc doped arsenene are analyzed. • Sc doped arsenene can be applied as SF 6 decomposition gases sensor or adsorbent. Arsenene has two stable allotropes, phosphorene-like puckered structure (α-As) and phosphorene-like buckled structure (β-As), showing potential prospects in gas sensing. In this work, we systematically investigate the pristine and metal-atom-doped arsenene as potential adsorbate candidates of three SF 6 decomposition products (SO 2 , SOF 2 and SO 2 F 2) based on first-principles theory. Our results reveal pristine arsenene, α-As and β-As, has poor detecting performance due to the relatively weak interaction toward gas molecules. After introducing transition metal dopants (TM = Sc, Ti, V, Cr, Mn, Fe, Co and Ni) on arsenene, Sc doped systems show the strongest structural stability. Analysis results of adsorption energies and electronic properties indicate that Sc doped α-As monolayer possesses quite strong adsorption behaviors towards SO 2 and SOF 2 , while the similar strong adsorption behaviors are found in Sc doped β-As for the three gases, which makes it possible to develop monolayer arsenene-based adsorbent to remove the polluted gases in SF 6 insulation devices. Therefore, our research shows that Sc doped arsenene is a novel potential adsorbate material that can be used to evaluate SF 6 insulation devices' working status. [ABSTRACT FROM AUTHOR]

[Display omitted] • Au single atoms-modified In 2 O 3 PNSs were prepared. • The Au 1 /In 2 O 3 sensor showed improved CO sensing performance. • The sensitization effects of Au single atoms on In 2 O 3 were discussed. The growing concern on environmental issues has stimulated intensive research interest on the gas sensors based on metal oxide semiconductor (MOS) due to their superiority in monitoring gaseous pollutants. In this context, developing advanced MOS sensors that can realize fast and selective detection of various flammable and harmful gases is of greatly desired, but still remains challenging. Here, we propose an Au single-atom sensitization strategy to boost the CO sensing performance of In 2 O 3. To expound it, Au single atom catalyst (Au 1) was prepared from an iced photochemical reduction method and then modified on In 2 O 3 porous nanospheres (PNSs) to obtain the hybrid Au 1 /In 2 O 3 gas sensing material. Benefiting from the outstanding spillover and catalytic effects of Au 1 , the best Au 1 /In 2 O 3 -2 show superior CO sensing performances to the bare In 2 O 3 counterpart, especially of lower optimal working temperature (OWT: 360 °C vs 380 °C), higher sensitivity (0.032/ppm vs 0.003/ppm to 10–100 ppm CO), and faster response/recovery speed (2/10 s vs 47/205 s). Besides, the Au 1 /In 2 O 3 -2 sensor also shows good selectivity and stability. These features make the present Au 1 /In 2 O 3 PNS a promising candidate for fabricating high-performance CO sensor. Our research demonstrates that surface functionalization with single-atom metal catalyst is a promising strategy to develop advanced MOS sensor. [ABSTRACT FROM AUTHOR]

Abstract: Zinc oxide (ZnO) nanofibers were synthesized by atom layer deposition (ALD) using polyvinylpyrrolidone (PVP) fibers as template. It was found that the morphologies of ZnO nanofibers were the same as PVP nanofibers. By annealing treatment, the different morphologies of ZnO nanofibers could be formed with the decomposition of PVP nanofibers which were characterized by means of transmission electron microscopy (TEM) and room temperature Raman spectra. The crystal and the optical properties can be also improved. The photocatalytic activities of the as-growth ZnO samples were evaluated in the photocatalytic degradations of aqueous solutions of methyl orange at room temperature. ZnO nanofibers showed higher photocatalytic activity due to more surface-to-volume ratio. [Copyright &y& Elsevier]

Semiconductor heterostructures based on transition metal dichalcogenides provide a broad platform to research two-dimensional nanomaterials and design atomically thin devices for fundamental and applied interests. The MoS 2 /WS 2 heterostructure was prepared on SiO 2 /Si substrate by chemical vapor deposition (CVD) in our research. And the optical properties of the heterostructure was characterized by Raman and photoluminescence (PL) spectroscopy. The similar 2 orders of magnitude decrease of PL intensity in MoS 2 /WS 2 heterostructures was tested, which is attribute to the electrical and optical modulation effects are connected with the interfacial charge transfer between MoS 2 and WS 2 films. Using MoS 2 /WS 2 heterostructure as channel material of the phototransistor, we demonstrated over 50 folds enhanced photoresponsivity of multilayer MoS 2 field-effect transistor. The results indicate that the MoS 2 /WS 2 films can be a promising heterostructure material to enhance the photoresponse characteristics of MoS 2 -based phototransistors. [ABSTRACT FROM AUTHOR]

AlGaAs materials are used in a variety of cutting-edge devices and the band gap states after the surface oxidization is found with Fermi level pinning. With first-principle calculations, we explore the formation of gap states during the initial stage of native-oxide growth on Al 0.5 Ga 0.5 As (001) surface. The results indicate that oxygen adsorption at the bridge sites of Al (Ga)-As satisfies the bond saturation and doesn't lead to any effect on the surface gap states. The breaking of As-As dimer results in the defect states in band gap with Fermi level pining due to the replacement of oxygen. In the oxidization process, it is found that the As-As dimer is very easy to be broken. In addition, the defect states in band gap maybe disappear after the full oxidization of surface with the elimination of unsaturated As on surface. With these gap states, some absorption peaks are found to appear in the range of 0–1 eV in the absorption spectra. [ABSTRACT FROM AUTHOR]

[Display omitted] • It was demonstrated that the MOF (ZIF-8) could facilitate the gas-sensitive performances of WO 3 nanofibers on the repeatability and recovery capability. • Toward SF 6 decomposition products, the temperature-dependent and time-dependent in-situ DRIFT spectra of the nanofibers were firstly employed to reveal the sensitive mechanism. • The results of in-situ DRIFT experiments were consistent with those of gas-sensitive tests, and it has verified the catalytic effect of ZIF-8. • The method used in this work can be extended to other target gases, providing the guidance for the synthesis of the novel gas-sensitive materials. SF 6 decomposition products are of significance to the diagnosis of gas insulated switchgear (GIS) equipment. Amounts of previous literature have employed a series of advanced materials to detect these characteristic products (H 2 S, SO 2 , SO 2 F 2 and SOF 2). However, the development of the gas-sensitive mechanism is seriously lagging behind the gas-sensitive materials. This work has synthesized the MOF-modification WO 3 nanofibers (NFs) via electrospinning, and further investigated its sensitivity toward four gas analytes. With the assistance of in-situ diffuse reflectance infrared Fourier transform (DRIFT) spectra, the sulfites and sulfates sourced from the SO 2 adsorption was regarded as the essence of the material poisoning. At the particular bands, the in-situ experiments have indicated the composites performed larger absorbance intensity and better recovery capability than the pristine WO 3 , which were consistent with the results of gas-sensing experiments. This work provides the guidance for improving the performance of nanomaterials toward SF 6 decomposition products by MOF doping. [ABSTRACT FROM AUTHOR]

The tube-brush-like ZnO nanostructures were synthesized by hydrothermal method using electrospinning polyvinylpyrrolidone (PVP) nanofibers as templates. The photocatalytic activity of as-grown samples was investigated by photo-degradation of Rhodamine B (RhB). The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV/visible absorption spectroscopy (UV–vis) and photoluminescence (PL) spectroscopy. It was found that the morphologies of the prepared ZnO were tube-brush-like nanostructures. With the grown time increasing, the crystal and the optical properties were improved. In the photocatalytic experiment, the tube-brush-like ZnO nanostructures photocatalytic activity was enhanced the degradation of RhB was up to 98% after 2 h of irradiation. The tube-brush-like ZnO nanostructures showed higher photocatalytic activity because of the special surface morphology. [ABSTRACT FROM AUTHOR]

Abstract: To overcome the limitations of the conventional inhibition method for mechanism study, here we developed a combined CLSM technique as an alternative approach to evaluate and explain the antibacterial process of nanostructure at single cell level. Three different nanostructures (dumbbell-shaped ZnO, rod-shaped ZnO and ZnO/Ag composites) were examined here as a model system. Their antibacterial processes against Escherichia coli (E. coli) were quantitatively studied in detail. According to the obtained time-dependent mean fluorescence intensity (MFI) decay dynamics, an interesting two-step cellular disruption process was observed and discussed for the first time. The combined CLSM technique described here is superior to standard growth method for they can provide a more detailed and reliable description of cell–nanostructure interactions. [Copyright &y& Elsevier]

Abstract: Vertically aligned ZnO nanowires (NWs) can be reconstructed on large scales by a solvent-evaporation-induced method. The morphologies of the nanowires are regulated by changing the concentration of the solution. Possible mechanism, which the compressive residual stresses and wires/wires self-attraction can be responsible for the surface reconstruction, is addressed. Furthermore, we compare the structural properties of ZnO nanowires before and after reconstructed. [ABSTRACT FROM AUTHOR]

Single Cr atom supported on defective boron nitride nanotubes was designed as a single atom catalyst (SAC) for N 2 O reduction reaction by CO. The stepwise mechanism of N 2 O + CO reaction and catalytic performance of the SAC were studied. • Single atom catalyst on BNNT was theoretically designed for N 2 O reduction by CO. • Single Cr atom exhibits excellent activity, and is less susceptible to poisoning. • The reaction is more likely to follow the stepwise mechanism. • BNNT and Cr atom play as the electron reservoir and bridge in reaction respectively. The removal of harmful N 2 O and CO in one step has attracted extensive research interest. Here, we studied the feasibility of N 2 O + CO reaction on single atom catalysts (SACs) supported on defective boron nitride nanotube (BNNT) by means of density functional theory (DFT) calculations. The Cr single atom catalyst which can avoid catalyst poisoning was screened from five low-price transition metal atoms (Ti, Cr, Mn, Fe, and Co) based on the adsorption strength of reactant and product on catalyst. The stepwise mechanism was considered which reveals the reaction path involves N 2 O decomposition, CO oxidation and CO 2 desorption. The rate-limiting step is CO 2 desorption with the desorption barrier of 0.42 eV. Along the reaction path, optimized structures and electronic property analyses indicate Cr atom acts as bridge to transfer electron due to its 3d orbital, which plays an important role in activation of N 2 O and CO molecules. Meanwhile, BNNT support with high redox stability acts as electron reservoir, withdrawing or donating electron, to facilitate the whole reaction. Therefore, Cr/BNNT is proposed to be a promising and highly efficient catalyst for eliminating environmentally unfriendly N 2 O and CO gases simultaneously. [ABSTRACT FROM AUTHOR]

• Stone-Wales defects can upgrade the SO 2 -sensing performance of arsenene. • It is highly appreciated because point defects especially Stone-Wales defect generate much easier on arsenene than other common 2D material. • Most of gas sensor based on 2D material have a slow recovery. • The external electric field can greatly adjust the SO 2 -sensing performance on arsenene with Stone-Wales defects. • This makes it possible to substantially accelerate the recovery of the arsenene with Stone-Wales defects. • Both biaxial strain and external electric field can further enhance the SO 2 -sensing performance of arsenene with Stone-Wales defects. Reported here is a first-principle study of the adsorption of four SF 6 decomposition products on pristine arsenene and arsenene with Stone-Wales defects (SW). The results revealed that pristine arsenene exhibited high sensitivity and selectivity to SO 2 , and Stone-Wales defects enhanced the SO 2 -sensing performance. The presence of ambient O 2 , H 2 O, and SF 6 only slightly affected the adsorption on both pristine and SW arsenene. We also investigated the effect of biaxial strain and an external electric field on the SO 2 detection of SW arsenene. The SO 2 adsorption strength on SW arsenene was drastically enhanced or weakened, depending on the direction of the electric field, which is desirable for realizing the ultra-sensitive adsorption and desorption of SO 2. [ABSTRACT FROM AUTHOR]

• High selectivity and sensitivity of GeP monolayer to nitrogen oxides. • The variation of work function change can be used to distinguish NO 2 and NO. • Compressive strain improve sensitivity of GeP to NO 2 without raising recovery time. • Applied negative electric field can greatly enhance response of GeP monolayer to NO 2. The sensing properties of GeP monolayer to small gas molecule (CO, CO 2 , O 2 , H 2 O, NH 3 , NO and NO 2) have been investigated by performing first-principle calculations. Based on calculated adsorption distance, adsorption energy and charge transfer, we find that GeP monolayer is the most sensitive to NO 2 and NO molecules, and all gas molecules act as acceptors to gain electrons from GeP monolayer. The adsorption energy of NO 2 is smaller than that of NO molecule, which implies that NO 2 is more easily desorbed from GeP. And different work function changes also indicate the possibility to identify NO 2 and NO in an oxygen-free environment. Moreover, we apply uniaxial and biaxial strains to GeP monolayer and find that a small biaxial compressive strain can effectively enhance the sensitivity of work function type sensor based GeP to NO 2 molecule without increasing recovery time. We also discuss the effect of external vertical electric field on the adsorption performance of NO 2 molecule. The negative electric field can significantly increase the adsorption strength, charge transfer and work function change of NO 2 -GeP system. Our results indicate that GeP monolayer is a potential candidate for NO 2 gas sensor. [ABSTRACT FROM AUTHOR]