Search

Electrocatalysts play a vital role to overcome the slow kinetics of the oxygen evolution reaction (OER). Herein, we developed iron-doped (Fe-doped) NiCoO 2 nanoplates with NaCl-type structure as an efficient electrocatalyst to speed up OER. NiCoO 2 nanoplates doping with different concentration of Fe were optimized. Specifically, the catalytic properties of 10 mol% Fe-doped NiCoO 2 (denoted as FNC0.1) showed outstanding OER catalytic activity, with an overpotential of 302 mV and a low Tafel slope of 42 mV dec −1 at 10 mA cm −2 in 0.1 M KOH. More importantly, the activity of FNC0.1 was only about 3% loss after 10 h of stability measurements at 1.53 V vs. RHE. The dramatically enhanced OER performance of the FNC0.1 might derive from the synergistic interplay of Co, Ni and Fe, a certain level of amorphization and easily hydroxylation after doping Fe. This work demonstrated that doping Fe would be beneficial to improve the OER activities and the stabilities of the catalysts.

Liquid-phase exfoliation is an effective method to fabricate thin nanosheet materials with layered structure. In this paper, we successfully synthesized NH 4 Co 0.4 Ni 0.6 PO 4 ·H 2 O nanosheets with the thickness of about tens of nanometers through liquid-phase exfoliation under ultrasonication. Specifically, the formamide solution was chosen as the exfoliation solvent due to it is capable of entering the interlayer of bulk materials and rapidly swelling between layers. Electrochemistry tests revealed that the optimized exfoliation time was 4 days. The asymmetric battery type energy storage device AC//NH 4 Co 0.4 Ni 0.6 PO 4 ·H 2 O nanosheets showed an energy density of 10.8 Wh kg −1 at the power density of 703.1 W kg −1 . More importantly, the long-term cycle stability measurements demonstrated that NH 4 Co 0.4 Ni 0.6 PO 4 ·H 2 O nanosheets after exfoliation had an ultra-long cycling life that still retained 102.3% of specific capacitance even 10000 continuous charge/discharge cycles.

The development of efficient and stable non-noble-metal electrocatalytic materials for the oxygen evolution reaction (OER) is a huge and important challenge at present. Herein, we report the prominent enhancement of OER activity via doping vanadium into CoFe-based layered double hydroxide (LDH) electrocatalysts. Electrochemical characterization shows that the Co2Fe0.5V0.5 LDH grown on carbon papers (CPs) has an enormous electrochemical surface area (ECSA) and exhibits the smallest overpotential of 242 mV at 10 mA cm-2, which only requires a small Tafel slope of 41.4 mV dec-1 in 1 M KOH solution. The X-ray photoelectron spectroscopy (XPS) peak position of Co, Fe and O moves slightly to higher binding energy, elucidating the improved covalency of the metal-oxygen bond after V doping. DFT+U simulation indicates that the outstanding electrocatalytic activity of Co2Fe0.5V0.5 could be ascribed to the increased metal-oxygen covalency in LDH after V element doping, and facilitates the charge-transfer from oxygen to the metal. This finely tuned strategy by V doping into the CoFe-based LDH matrix can adjust the covalency of metal-oxygen bridges and enhance its electrocatalytic activity for the OER. In this work, we also present a general method to study various highly efficient metal hydroxide catalysts for the OER.

Developing non-noble metal-based electrocatalysts with high catalytic activity is an urgent task for overall electrocatalytic water decomposition. In this study, carbon-incorporated porous honeycomb NiCoFe phosphide (labelled NiCoFeP/C) was successfully developed from a metal–organic framework (MOF) precursor for the first time. Benefitting from a unique structure and compositional advantages, NiCoFeP/C exhibits excellent bifunctional electrocatalytic activity for the oxygen evolution reaction/hydrogen evolution reaction (OER/HER) in alkaline solution, showing low OER and HER overpotentials of 270 and 149 mV at 10 mA cm−2, respectively. This work successfully developed a MOF-derived novel multi-component transition metal phosphide with a unique structure, which shed some light on the development of promising catalysts for the OER/HER.

Carbon-incorporated NiO/Co3O4 concave surface microcubes (denoted as NCMC) are successfully developed from a precursor of Ni3[Co(CN)6]2 for the first time. The NCMC exhibits excellent electrocatalytic activity for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in potassium hydroxide solution, affording a current density of 10 mA cm-2 at 169.5 mV for the HER and 290 mV for the OER, respectively. This communication describes a rational design of MOF-derived mixed metal oxides as electrocatalysts for overall water splitting, promoting the further development of MOF materials in the field of energy conversion.

Monoclinic bismuth vanadate (BiVO4) is a promising semiconductor for photoelectrochemical water splitting. Here, we developed a facile fabrication of BiVO4 double layer photoanode on the fluorine-doped tin oxide substrate by electrodeposition. The BiVO4 double layer photoanode is composed by a dense BiVO4 film as the inner layer and a nanoporous BiVO4 film as the outer layer. Compared to the BiVO4 single layer photoanode, the optimized BiVO4 double layer photoanode produced a much higher photocurrent of 1.15 mA/cm2 at 0.6 V vs. Ag/AgCl under AM 1.5G (100 mW/cm2) illumination. The results of the photoelectric conversion kinetics for different samples revealed that the charge separation and oxidation kinetics efficiencies for the BiVO4 double layer are 47.2% and 51.6% at 0.6 V vs. Ag/AgCl, while the values for BiVO4 single layer are 32.3% and 35.8%, respectively. The improved photoelectrochemical performance for BiVO4 double layer is mainly ascribed to the decrease of defect state at the interface after inserting a dense BiVO4 as an inner layer to prevent the recombination of photogenerated electron-hole pairs.

The surface roughness, weight of phosphating film and wettability of magnesium alloy substrates after abrasion and phosphating treatment were investigated in this work. The interfacial bonding and corrosion properties of a magnesium-based fibre metal laminate (MgFML) were analysed. The results showed that the wettability of the magnesium alloy was greatly influenced by the surface roughness, and the rough surface possessed a larger surface energy and better wettability. The surface energy and wettability of the magnesium alloy were significantly improved by the phosphating treatment. After phosphating for 5 min, a phosphating film with a double-layer structure was formed on the magnesium substrate, and the weight of the phosphating film and the surface energy reached their maximum values. The surface energies of the phosphated substrate after abrasion with #120 and #3000 grit abrasive papers were 84.31 mJ/m 2 and 83.65 mJ/m 2 , respectively. The wettability of the phosphated magnesium was significantly better than the abraded magnesium. The phosphated AZ31B sheet had a better corrosion resistance than the abraded AZ31B sheet within short times. The corrosion resistance of the magnesium alloy was greatly increased by being composited with glass fibre/epoxy prepregs.

This work intends to clarify the different effects of sodium salts and organic solvents on the morphology of Ti-supported TiO2 nanomaterials. Titanates were chosen as the precursor to synthesis TiO2 nanomaterials and the morphology controlled synthesis of titanates plays an important role in optimizing the morphology and properties of TiO2 nanostructures. Based on our experiments, titanate nanotubes with thick tube walls (8–10 nm on one side) were obtained in alkaline aqueous solution. The addition of NaCl can lead to the formation of titanate nanosheets, while the addition of NaF or NaBr has no obvious effect on the formation of nanosheets and nanotubes were still obtained. Organic solvents can dramatically influence the morphology and mass loading of titanate on Ti foils. Ethylene glycol can lead to the nanotubes aggregating together to form network structures, while ethanol helps to produce nanosheets. The corresponding possible growth mechanism was preliminarily proposed. The photoelectrochemical performances of titanate-derived TiO2 were investigated, and found that TiO2 nanosheets prepared with NaCl have the best photoelectrochemical performance compared with others. This work provides basis for further study on controlling the morphology and properties of titanate as well as TiO2 nanomaterials on Ti foils. Keywords: Titanate, TiO2, Hydrothermal, Morphology, Growth mechanism

Porous carbon and metal oxides/sulfides prepared by using metal-organic frameworks (MOFs) as the precursors have been widely applied to the realm of supercapacitors. However, employing MOF-derived metal phosphides as positive and negative electrode materials for supercapacitors has scarcely been reported thus far. Herein, two types of MOFs are used as the precursors to prepare CoP and FeP4 nanocubes through a two-step controllable heat treatment process. Due to the advantages of composition and structure, the specific capacitances of FeP4 and CoP nanocubes reach 345 and 600 F g-1 at the current density of 1 A g-1 , respectively. Moreover, a quasi-solid-state asymmetric supercapacitor is assembled based on charge matching principle by employing CoP and FeP4 nanocubes as the positive and negative electrodes, respectively, which exhibits a high energy density of 46.38 Wh kg-1 at the power density of 695 W kg-1 . Furthermore, a solar-charging power system is assembled by combining the quasi-solid-state asymmetric supercapacitor and monocrystalline silicon plates, substantiating that the device can power the toy electric fan. This work paves a practical way toward the rational design of quasi-solid-state asymmetry supercapacitors systems affording favorable energy density and long lifespan.

In this paper, the UV–Vis photocatalytic degradation of methylene blue (MB) by copper tungstate (CuWO4) has been studied in neutral aqueous heterogeneous suspensions CuWO4 nanochains and nanoparticles were synthesized via solvothermal method. CuWO4 was evaluated regarding a photocatalytic degradation of organic dyes, which is highly important to decontaminate water. Our results demonstrate that the CuWO4 nanoparticles have a better photocatalytic degradation performance than nanochains, and the nanoparticles with 86% of MB degradation is obtained after 90 min UV–Vis irradiation. Further, the MB degradation process follows Langmuir–Hinshelwood mechanism first order kinetics, in the process of MB degradation, O2− and ·OH acted as the main reactive species. This work provides an overall strategy for further study on the catalysts for photo degradation of organic pollutant.

Aqueous asymmetric supercapacitors (ASCs) with a wide voltage window can effectively improve energy storage capacity of energy storage devices. Zeolitic imidazolate framework-67 (ZIF-67) was used as a precursor to prepare nanoporous carbon (NC), and K

Because of the potential application in photoelectrochemical cells for water splitting, the synthesis of BiFeO3 (BFO) is receiving increasing attention. A simple, low-cost drop-casting route was used to synthesize Ti ions doped BiFeO3 thin films and the effects of the Ti ions doping on their crystal structure, morphology, and photoelectrocatalytic activity had been studied. X-ray diffraction results of Ti-BFO films showed that the doping of Ti ions lead to the distortion of crystal structure. Photoelectrochemical measurements indicated that the photoelectrocatalytic activities of BFO film doped with 5 % Ti ions showed the best performance. The UV–Vis absorption spectra of Ti-BFO films showed that the absorption wavelength of BFO doped with 5 % Ti had obvious shift and the band gap decreased. From the results of Mott–Schottky (M–S) plots, we calculated the positions of valence band (VB) and conduction band (CB) for Ti-BFO film. The outcomes showed that the band gap structure of BFO samples doped with 5 % Ti had more positive CB and more negative VB. The calculated photogenic charge carrier concentrations of BFO and Ti (0.05)-BFO were 5.07 × 1019 and 6.32 × 1019 cm−3, respectively. The reduced band gap and increased photogenic charge carrier concentration are the major factors contributing to the enhancement of photoelectrocatalytic performances of Ti-BFO films.

Amorphous nanomaterials have been regarded as extremely promising electrode materials for battery-like energy storage device (BESD) due to their atomic disorder, homogeneous and metastable properties, etc. Here, an amorphous NiCo layered double hydroxide (NiCo LDH) with different morphologies is synthesized for the first time by a green, economical and practicable ultrahigh voltage electrophoretic deposition method (EPD), constructing a 3D architecture with high specific surface area as the positive electrode for energy storage. The obtained amorphous NiCo LDH nanosheets/CFP electrode exhibits a high specific capacitance of 347 mF cm −3 and a good retention of 88.3% after 10000 cycles. Moreover, an asymmetric BESD based on the amorphous NiCo LDH/CFP and commercial activated carbon (AC) offers an energy density of 41.67 W h cm −3 at the power density of 0.5 kW cm −3 and excellent cycle life (only 0.3% deterioration of its initial specific capacitance after 10000 cycles). The good performance of amorphous NiCo LDH nanosheets in capacitance is ascribed to the high inner charge storage and efficient ion transportation. This research provides a new method to control the morphologies of amorphous nanomaterials by EPD technique in the future.

Free end torsion was carried out on extruded Mg alloy AZ31. Subsequently, tension or compression was implemented on pretorsion specimens. The microstructures of samples with 100 and 200° of pretorsion reveal that no obvious change has occurred; however, samples with 300 and 400° of pretorsion show that there are extensive twins. Compressive yield stress of pretorsion samples increases with increasing pretorsion angle. However, their tensile yield stress exhibits practically the same value with extruded samples. Consequently, yield asymmetry ratio increases from 0.55 of extruded sample to 0.84 of sample with 400° of pretorsion. Both textures rotated around the radial axis by free end torsion, and different deformation mechanisms of compression and tension deformation result in decrease in yield asymmetry.

The design and fabrication of sustainable and efficient electrocatalyst for water splitting are crucial for rechargeable metal-air batteries and regenerative fuel cells. In this report, a highly stable and active NiCo-selenide electrocatalyst was successfully prepared by a facile two-step solvothermal approach. In 0.1 M KOH alkaline electrolyte solution, the novel NiCo-selenide electrocatalyst afforded the current density of 10 mA cm−2 at a lower overpotential of 393 mV, a smaller Tafel slope of ~89 mV dec−1 and better stability, compared with NiCo-based oxide and sulfide.

CuWO 4 films with feature particle sizes of 100–200 nm and thickness up to 700–900 nm on fluorine-doped tin oxide (FTO) substrates were prepared by hydrothermal synthesis. The prepared CuWO 4 films were treated in hydrogen atmosphere at constant temperature 300 °C for different annealing time and used for photoelectrochemical (PEC) water oxidation. Compared with pristine CuWO 4 film, the optimized hydrogen-treated CuWO 4 film presented three times enhanced photocurrent density of 0.75 mA/cm 2 at 1.2 V vs. Ag/AgCl in 0.1 M Na 2 SO 4 solution under the illumination. The donor density of hydrogenated CuWO 4 film determined by Mott–Schottky analysis was improved one order of magnitude as well. The enhanced photoelectrochemical activity could be attributed to the formation of oxygen vacancies after hydrogen treatment, which facilitated the charge transport and collection.

Enhancing charge separation and collection in semiconducting photoelectrodes is a key issue in the area of photoelectrochemical applications. Herein, we report that the photoelectrochemical performance of BiFeO3 nanoparticles can be significantly enhanced by treatment with hydrogen atmosphere at elevated temperature for different time periods. Compared with pristine BiFeO3 nanoparticles, the hydrogen-treated BiFeO3 nanoparticles showed substantial improvement of intrinsic features from structural, optical and electronic aspects. These hydrogen-treated BiFeO3 nanoparticles exhibit an unexpected red shift, which was attributed to the formation of sub-band-gap states between the conduction and valence bands, resulting from oxygen vacancies due to the hydrogen treatment. However, the highly concentrated defects in BiFeO3 nanoparticles can act as charge annihilation centers, which is not conducive to the separation of photo-generated carriers. The hydrogen-treated BiFeO3 prepared at 300 °C for 15 min exhibited optimal photoelectrochemical performance. More than three times higher photocurrent density was achieved compared with pristine BiFeO3, demonstrating its potential in practical application.

Thin films of two copper-based metal vanadates (CuV2O6 and Cu2V2O7) were synthesized by a facile drop-casting method. The primary photoelectrochemical (PEC) and physical properties of these two materials including photocurrent response, band gap, flat band potential, incident photon to current conversion efficiency, chemical stability, and oxygen evolution faradaic efficiency were researched. The photocurrent density of CuV2O6 and Cu2V2O7 films at 1.23 V vs RHE in 0.1 M sodium borate buffer solution was about 25 and 35 μA/cm2, respectively. At 1.58 V vs RHE, however, the photocurrent density reached approximately 220 and 120 μA/cm2, respectively. Although the photocurrents observed for these two materials at 1.23 V vs RHE were relatively low, the photocurrents were much higher when tested with sodium sulfite as a hole scavenger. Suitable oxygen evolution catalysts are therefore expected to improve the PEC performance of these materials.

Previous work demonstrates that Fe2O3 is a promising negative electrode material. Its biochemical performance is strongly influenced by the morphology. Hence, Fe2O3 with nanoparticles, nanosheets and nanorods morphologies are synthesized by hydrothermal method respectively. The relationship between morphology and electrochemical property, particularly in terms of specific capacitance and rate capability are investigated. Detail cyclic voltammetry analysis reveals that the relative contributions of surface capacitive and inner intercalation capacitance change with the morphology. Different contribution of surface relative to inner charge storage leads to different specific capacitance and rate capability. Additionally, Fe2O3 nanosheets delivers a remarkable specific capacitance of 279.9 F g−1 (419.8 mF cm−2) at the scan rate of 5 mV s−1 ascribing to the inner intercalation effect. Moreover, electrochemical tests in neutral and alkaline solution show that the capacitive behavior of Fe2O3 is closely related to the potential window and different electrolyte leads to different contribution of surface relative to inner charge storage. These studies should be useful for elucidating the mechanism and morphological effects on charge storage for Fe2O3-based electrode and provide a direction to enhance its capacitance.

A self-assembled MoSe2 nanolayers/reduced graphene oxide (MoSe2/rGO) foam was prepared using a hydrothermal method. The samples were systematically investigated by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy. Electrochemical performances were evaluated in two-electrode cells versus metallic lithium. It is demonstrated that the obtained MoSe2/rGO nanocomposites show three-dimensional architecture and excellent electrochemical performance as anode materials for Li-ion batteries. The specific capacity of MoSe2/rGO anode can reach up to 650 mAh g−1 at a current rate of 0.1C in the voltage range 0.01–3.0 V (vs. Li/Li+), which is higher than the theoretical capacity of MoSe2 (422 mAh g−1). Additionally, the fabricated half cells have shown good rate capability and long cycling stability with 10.9% capacity loss after 600 cycles under a current density of 0.5C. The excellent performance of the synthesized MoSe2/rGO is attributed to its unique nanostructure, including nanolayered MoSe2, highly conductive rGO networks and mechanically stable 3D architecture.

Dimensionality and rational design of electrode architectures play a crucial role in determining materials' fundamental properties and the electrochemical performance of supercapacitor. For a proof-of-concept, Ni–Co layered double hydroxides (LDH), NiCo2O4 and NiCo2S4 nanosheets supported on carbon fiber paper (CFP) substrate are prepared by simple hydrothermal methods in this work. When tested as the pseudo-capacitor positive electrode, the self-support nanosheets on CFP demonstrate good performance and rate capability as well as excellent cycling life, which contributes to the unique hierarchical nanosheets structure supported on 3D conductive CFP substrate with open permeable channels, facilitating electrolyte penetration and ensuring more efficient ion diffusion and faster electron transport. The asymmetric supercapacitor based on pseudocapacitance of both electrodes is further first realized by using NiCo2S4 nanosheets and FeOOH nanorods as positive and negative materials, respectively. The obtained device can deliver a maximum power density of 8.6 kW kg−1 and energy density of 45.9 Wh kg−1 and even after 10000 reversible cycles at a cell voltage of 1.6 V in aqueous electrolyte, there still retained 86.4% of its initial capacitance.

Thanks to the “one belt one road” initiative, the international logistics of Western China has made a huge development. However, the shortage of top international logistics talents prevents its further progress. This paper induces the demand types of talents and analyzes it by using the gray forecast model respectively from the qualitative and quantitative aspect. Aiming at the demand, a double-three-spiral talent training model is built, which include school-government optimizing schooling resources; joint practice platforms of school-enterprise; government-enterprise perfecting the mechanism. With perfecting three-year graduate education system, internalizing knowledge, externalizing capability, and improving themselves, the quality of talents training is finally improved.

We demonstrate the fabrication of ultra-fine hierarchical NiO@MnO2 core–shell nanosheet arrays on carbon fiber paper via a facile and two-step hydrothermal method as the electrode for supercapacitors. Owing to the unique hierarchical core–shell heterostructured nanosheet array configuration and synergetic contribution from the NiO core and MnO2 shell, the as-prepared hybrid nanosheet arrays exhibited a high specific capacitance of 494.8 F g−1 and good rate capability, which are better than those of the obtained individual component of the NiO nanosheets. More importantly, the asymmetric supercapacitor, composed of NiO@MnO2 core–shell nanosheet arrays as the positive electrode and activated carbon as the negative electrode delivers a specific capacitance of 86.3 F g−1 and reaches up to an energy density of 30.6 W h kg−1 and power density of 400 W kg−1. The improved performance of the NiO@MnO2 core–shell nanosheet arrays demonstrates that rational design of electrode structure is an effective way to fabricate a high-performance electrode for supercapacitors.

Single-crystalline anatase TiO2 nanobelts with a dominant surface of the {101} facet were hydrogenated and used as substrates of platinum for methanol oxidation reaction (MOR). The hydrogenated TiO2 anatase{101} supporting Pt exhibits a 228% increase of current density for methanol oxidation compared with the same system without hydrogenation under dark conditions. The synergetic interactions of hydrogenated anatase{101} with the Pt cluster were investigated through first principles calculations, and found that the hydrogenation shifts the conduction band minimum to the Fermi level of pristine TiO2, and reduces the activation barrier for methanol dissociation considerably. Thus, this work provides an experimental and theoretical basis for developing non-carbon substrates with high electro-catalytic activity toward MOR.

The reaction mechanism of CO oxidation catalyzed by several Pt3M (M = Pt, Ni, Mo, Ru, Pd, Rh) clusters has been investigated with density functional theory calculations in the present work. The reaction prefers to proceed via Langmuir–Hinshelwood mechanism. The calculated barriers for the reactions mediated by bimetallic clusters are comparable with that catalyzed by monometallic Pt4 cluster. According to thermodynamics and kinetics results, CO oxidation can take place readily without thermal activation and the O2 scission to form OCOO* is the rate-determining-step. Pt3Mo exhibits superior catalytic activity for CO oxidation among all those investigated clusters and good adsorption for O2. The different performance of those bimetallic clusters for CO oxidation is scrutinized with aid of molecular orbital and natural bond orbital population analysis.

The reaction mechanism of O2 dissociation on PtxRuyMz (M = Fe, Ni, Cu, Mo, Sn, x + y + z = 4, x ≥ 1, y ≥ 1) alloy catalysts have been investigated with density functional theory calculations in this work. For bare alloy clusters, bimetallic clusters are more stable than the ternary alloy clusters. The geometries of the PtxRuyMz–O2 system, O–O bond stretching frequency and electronic-structure details have been investigated. The energies of O2 adsorption on PtRu clusters are slightly higher than those on PtxRuyMz clusters, and the more charge transfer to O2 from the metal cluster, the higher O2 the adsorption energy obtains. The reaction barriers show that the catalytic performance of trimetallic clusters are better than those of bimetallic clusters, and Pt2RuM clusters exhibit superior catalytic activity for O2 dissociation. The different performance of these alloy clusters for O2 dissociation is scrutinised with aid of molecular orbital and natural bond orbital population analysis.

A density functional theory (DFT) based method in conjunction with the projector augmented wave and pseudopotential methods have been applied to investigate the adsorption of Pt4 and Pt3Ni on the anatase TiO2 (1 0 1) surface. Two stable Pt3Ni adsorptions with considerable adsorption energies on the anatase TiO2 (1 0 1) surface were identified. Analysis of the partial density (PDOS) of states and Bader charge suggest that the electronic structure of Pt is modified by Ni due to the electron transfer from Ni to Pt atoms in the Pt3Ni clusters. The 2cO (3cO)-PtNi-5cTi conformation of the adsorbed Pt3Ni on the anatase TiO2 (1 0 1) surface provides a more feasible model for electron injection through the Pt3Ni/TiO2 interface. The reactivity of Pt3Ni/TiO2 is superior to Pt4/TiO2 and effectively manifests itself in the eased decomposition of O H bonds derived by methanol and alleviative CO adsorption.

High energy and efficient solar charging stations using electrochemical capacitors (ECs) are a promising portable power source for the future. In this work, two kinds of metal-organic framework (MOF) derivatives, NiO/Co3 O4 microcubes and Fe2 O3 microleaves, are prepared via thermal treatment and assembled into electrochemical capacitors, which deliver a relatively high specific energy density of 46 Wh kg-1 at 690 W kg-1 . In addition, a solar-charging power system consisting of the electrochemical capacitors and monocrystalline silicon plates is fabricated and a motor fan or 25 LEDs for 5 and 30 min, respectively, is powered. This work not only adds two novel materials to the growing categories of MOF-derived advanced materials, but also successfully achieves an efficient solar-ECs system for the first time based on all MOF derivatives, which has a certain reference for developing efficient solar-charge systems.

Density functional theory based calculations have been employed to investigate structures and properties of coupled tetragonal pyramid (CTP) Pt 7 based Pt (7 − x ) Ni x ( x = 1, 2, 3) bimetallic clusters, and the reaction mechanism of methanol dehydrogenation to CO on Pt 7 and PtNi bimetallic clusters. The models chosen to catalyze the methanol are Pt 7 (CTP, quintet) cluster and Pt 5 Ni 2 (I) cluster (two Pt atoms in the bottom of Pt 7 (CTP) are replaced by Ni atoms) which is the most stable structure among all the isomers of Pt (7 − x ) Ni x ( x = 1, 2, 3). The methanol dehydrogenation on Pt 7 (CTP) cluster preferentially proceeds along the pathway of CH 3 OH → CH 2 OH → CH 2 O → CHO → CO, while on Pt 5 Ni 2 (І) the pathway of CH 3 OH → CH 3 O → CH 2 O → CHO → CO is more favorable. In addition, the complete dehydrogenation product of methanol, CO, can more easily dissociate from Pt 5 Ni 2 (I) than that on Pt 7 . Electronic configuration analysis shows that charge transfer from Ni to Pt and results in increase of the electron density in Pt 5d orbitals. Moreover, the density of states (DOS) at Fermi level of clusters reduces gradually as the increase of the doped Ni atoms and this improves the catalytic activity for methanol decomposition.

In this paper we synthesize well aligned Ni–Co sulfide nanowire arrays (NWAs) with a Ni–Co molar ratio of 1 : 1 on 3D nickel foam by a facile two-step hydrothermal method. Owing to the low electronegativity of sulfur, Ni–Co sulfide NWAs exhibit a more flexible structure and much higher conductivity compared with Ni–Co oxide NWAs when used as active materials in supercapacitors. The electrochemistry tests show that these self-supported electrodes are able to deliver ultrahigh specific capacitance (2415 F g−1 and 1176 F g−1 at a current density of 2.5 mA cm−2 and 30 mA cm−2, respectively), together with a considerable areal capacitance (6.0 F cm−2 and 2.94 F cm−2 at a current density of 2.5 mA cm−2 and 30 mA cm−2, respectively), and good rate capability. More importantly, the asymmetric supercapacitor, composed of Ni–Co sulfide NWAs as the positive electrode and activated carbon as the negative electrode, reaches up to an energy density of 25 W h kg−1 and a power density of 3.57 kW kg−1 under a cell voltage of 1.8 V. Furthermore, the two assembled supercapacitors in series can power a 3 mm diameter red (2.0 V, 20 mA) round light-emitting diode (LED) indicator for more than 30 minutes after charging separately for a total time of 6 min. The superior electrochemistry capacity demonstrates that the self-standing Ni–Co sulfide nanowire arrays are promising for high-performance supercapacitor applications.

We report the synthesis of mesoporous alumina by a template method and its applications as a new solid phase extraction adsorbent with abamectin and ivermectin as the target analytes by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Chromatographic separation was conducted on a C18 column using a gradient mobile phase consisting of methanol (solvent A) and 0.2% formic acid in a 5 mmol L−1 ammonium acetate buffer (solvent B) at a flow rate of 0.3 mL min−1. The linearity of the calibration curves was excellent and yielded correlation coefficients (r2 = 0.9990–0.9999) in a range of 0.02–0.50 mg L−1. Samples were spiked with known quantities of the analytes at three different concentration levels (0.05, 0.10 and 0.20 mg L−1), and the recoveries were in the range of 87.3–104.5% with the relative standard deviation (RSD) values ranging between 0.53% and 5.8%. The limits of detections and limits of quantization were 0.16 ng g−1 and 0.53 ng g−1, respectively. These results indicated that mesoporous alumina has enormous potential as a novel solid phase extraction adsorbent material in the food security field.

CoNiO nanowire arrays loaded on TiO2 nanotubes (CoNiO/TiO2NTs) are synthesized by a hydrothermal method and used firstly as an anode material for lithium-ion batteries. The morphology, structure and composition of the composite are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The EDS patterns display the atomic ratio of Co to Ni is 0.41:0.59 with accuracy of more than 99%. SEM images show that the diameters of these nanowires range from 10 to 40 nm and the average length approximately 1 μm. Electrochemical characterizations are performed in a three-electrode system to determine the capacity, cyclic stability and to investigate the reaction mechanism. As an anode material for lithium-ion batteries, the CoNiO/TiO2NTs nanocomposite delivers a high areal capacity of 362 μAh cm−2 (1097 mAh g−1, 0.33 mg cm−2) after 40 discharge/charge cycles at a current density of 0.2 mA cm−2 (about 606 mA g−1). EIS results show that addition of Ni to the CoO could increase the conductivity of the composite significantly and improve the kinetic behavior during discharge–charge process. The present finding provides a kind of nanostructure fabrication that might be applied in supercapacitor and solar cells, etc.

Because of the potential for application in photoelectrochemical cells for water splitting, the synthesis of nanostructured BiVO4 is receiving increasing attention. Here we report a simple new drop-casting method for the first time to synthesize un-doped and doped bismuth vanadate (BiVO4) nanoflake array films. Synthesis parameters such as the amount of polyethylene glycol 600 (PEG-600) and the precursor solution drying time are investigated to optimize the films for photoelectrochemical water oxidation. The BiVO4 films consisting of nanoflakes with an average thickness of 20 nm and length of 2 μm were synthesized from a precursor solution containing Bi3+, V3+ and PEG-600 with a Bi:V: PEG-600 volume ratio of 2:2:1, dried at 135 °C for 55 min. Photoelectrochemical measurements show that the BiVO4 nanoflake array films have higher photoelectrochemical activity than the BiVO4 nanoparticle films. Additionally, the nanoflake arrays were tested after incorporating W and Mo to enhance the photoelectrochemical activity. The 2% W, 6% Mo co-doped BiVO4 nanoflake array films demonstrate the best photoelectrochemical activity with photocurrent densities about 2 times higher than the un-doped BiVO4 nanoflake films and greater than the photocurrents of individually Mo doped or W doped BiVO4 films. The origin of enhanced photoelectrochemical activity for the co-doped film may be due to the improved conductivity through the BiVO4 or slightly enhanced water oxidation kinetics.

A new 3D V2O5@PPy network built from numerous ultrathin, flexible and single-crystalline nanoribbons was successfully fabricated by a combined hydrothermal, freeze-drying and nanocasting process. Such a unique network can not only provide a high surface area for enhancement of electrolyte/electrode interactions, and reduce the diffusion length of ions, but also efficiently maintain the high electrical conductivity. As a result, this network exhibits high capacitance, excellent rate capability and good charge–discharge stability for energy storage. An asymmetric supercapacitor based on a 3D V2O5@PPy network as the cathode material further delivers high energy density and high power density. We expect that our work presents an efficient approach to design and produce various 3D architectures built from nanoribbons or nanosheets for energy storage and other applications.

Various two-dimensional (2D) materials have recently attracted great attention owing to their unique properties and wide application potential in electronics, catalysis, energy storage, and conversion. However, large-scale production of ultrathin sheets and functional nanosheets remains a scientific and engineering challenge. Here we demonstrate an efficient approach for large-scale production of V2O5 nanosheets having a thickness of 4 nm and utilization as building blocks for constructing 3D architectures via a freeze-drying process. The resulting highly flexible V2O5 structures possess a surface area of 133 m(2) g(-1), ultrathin walls, and multilevel pores. Such unique features are favorable for providing easy access of the electrolyte to the structure when they are used as a supercapacitor electrode, and they also provide a large electroactive surface that advantageous in energy storage applications. As a consequence, a high specific capacitance of 451 F g(-1) is achieved in a neutral aqueous Na2SO4 electrolyte as the 3D architectures are utilized for energy storage. Remarkably, the capacitance retention after 4000 cycles is more than 90%, and the energy density is up to 107 W·h·kg(-1) at a high power density of 9.4 kW kg(-1).

3D SnO2 nanoflowers on Ti foil have been synthesized by a simple hydrothermal method without using any surfactant or catalyst. The synthesized 3D SnO2 nanostructures are characterized by X-ray diffraction, field emission scanning electron microscopy and X-ray photoelectron spectroscopy. The FESEM results showed that the nanoflower consists of multiple nanopetals of width ∼5 nm and each SnO2 nanoflower is ∼3 μm in diameter. The time-dependent morphology evolution of SnO2 nanoflowers was studied in detail, and a possible growth mechanism was proposed. In addition, high dispersed Ni nanoparticles was loaded on SnO2 nanoflowers applied in supercapacitor. The electrochemical properties of the 3D Ni/SnO2 nanoflowers were investigated by a series of electrochemical tests.

In this paper, we report the fabrication and characterization of PPy sensitized ZnO nanorod arrays (PPy/ZnO NRs), and its use as a photo-electrode for efficient photo-electrochemical splitting of water under solar light. PPy/ZnO NRs were synthesized on a large scale on indium tin oxide (ITO) by a simple two-step method. UV–vis spectrum showed that PPy/ZnO NRs had strong absorption in nearly the visible light spectrum. FTIR results indicated that there might be a strong interaction between PPy and ZnO with the valence bond of C3O3Zn. The photo-electrochemical measurements of PPy/ZnO NRs exhibited extreme optimal photocurrent up to 0.68 mA/cm2. The results implied that PPy/ZnO NRs offerred improved light absorption, increased photocurrent generation due to the effective charge separation in PPy and ZnO NRs, and enhanced oxidized H2O kinetics because of the synergistic effect of PPy and ZnO NRs.

Highly ordered TiO 2 nanotube arrays (TiO 2 NTs) evenly modified by Ni–Cu nanoparticles were successfully prepared by potential step method. Their morphologies, structures, and alloy composition were characterized by FESEM, XRD and EDS, respectively. The as-prepared Ni–Cu/TiO 2 NTs electrodes were employed for non-enzymatic glucose detection in alkaline electrolyte and showed better electro-catalytic activity compared with Ni/TiO 2 NTs and Cu/TiO 2 NTs electrodes. Factors that affected the electrocatalysis of the electrodes were examined and optimized. Consequently, a sensitive amperometric electrode of glucose was achieved under 0.6 V vs. Ag/AgCl with a high sensitivity (1590.9 μA mM −1 cm −2 ), low detection limit (5 μM) and wide linear range from 10 μM to 3.2 mM ( R 2 = 0.993). Furthermore, the oxidable species such as ascorbic acid and uric acid showed no significant interference in determination of glucose. The experiment results revealed a very good reproducibility and high stability for the proposed Ni–Cu/TiO 2 NTs electrodes.

Three-dimensional (3D) interconnected metal alloy nanostructures possess superior catalytic performance owing to their advantageous characteristics, including improved catalytic activity, corrosion resistance, and stability. Hierarchically structured Ni-Cu alloys composed of 3D network-like microscopic branches with nanoscopic dendritic feelers on each branch were crafted by a facile and efficient hydrogen evolution-assisted electrodeposition approach. They were subsequently exploited for methanol electrooxidation in alkaline media. Among three hierarchically structured Ni-Cu alloys with different Ni/Cu ratios (Ni0.25Cu0.75, Ni0.50Cu0.50, and Ni0.75Cu0.25), the Ni0.75Cu0.25 electrode exhibited the fastest electrochemical response and highest electrocatalytic activity toward methanol oxidation. The markedly enhanced performance of Ni0.75Cu0.25 eletrocatalyst can be attributed to its alloyed structure with the proper Ni/Cu ratio and a large number of active sites on the surface of hierarchical structures.

SnO2@carbon-doping TiO2 nanotube arrays (SnO2@C-TiO2NTs) were synthesized by hydrothermal method and evaluated for lithium ion insertion and photoelectrochemical activity. The composite electrode prepared for 5 h as anode materials for lithium-ion batteries exhibited much improved electrochemical performance due to the aligned pore structure and the synergistic effect of the electrode. A capacity of 142 μA h cm−2 can be obtained after 50 discharge/charge cycles at a high current density of 200 μA cm−2. Moreover, UV–vis results of the sample showed stronger absorption intensity in the range of 200–800 nm compared with bare TiO2NTs. The composite electrode displayed the maximum photocurrent density of 1.80 mA cm−2. This is attributed to the heterojunction formed at the interface between SnO2 and TiO2NTs resulting the enhance charge separation efficiency. Eletrochemical impendence spectroscopy (EIS) also shows that SnO2@C-TiO2 NTs has a noticeably lower charge-transfer resistance.

Deformation behaviour of a hot extruded Mg–3Al–1Zn alloy subjected to uniaxial compression at room temperature was investigated. Microstructure evolution showed that the amount of lenticular shaped extension twins increased with the increase in true strain when it was lower than ∼4% but decreased when it was higher than ∼4%. Previous studies indicated that detwinning occurred. However, we have demonstrated in the present paper that no detwinning occurred, but a process of twin growth and coalescence, leading to an analogous detwinning phenomenon observed in the optical micrographs because most of the matrixes were consumed. A strong texture evolution occurred in this process, and the reorientation produced by strong twinning was mainly responsible for strain hardening when compressed along the extrusion direction.

We develop a facile hydrothermal synthesis method to fabricate mesoporous Ni–Co oxides nanowire arrays on ordered TiO2 nanotubes (Ni–Co oxides NWs@TiO2NTs) as a high-capacity pseudocapacitor material. The composite electrode presented the highest specific capacitance of 2353 F g−1 at a charge and discharge current density of 2.5 A g−1 with excellent cycling ability, retaining 95% of the maximum capacitance after 3000 cycles. Even at a high current density of 50 A g−1, the electrode exhibited a specific capacitance of up to 2173 F g−1. In addition, the testing of a (Ni–Co oxides NWs@TiO2NTs)//(Ni–Co oxides NWs@TiO2NTs) symmetric cell yielded a specific capacitance of up to 144 F g−1 at a current density of 4 A g−1. The much improved capacity and cycling stability may be attributed to the superior conductivity and the aligned structure of the Ni–Co oxides NWs and the TiO2NTs substrate, which can improve electron/ion transport and enhance the kinetics of the redox reactions.