Search

The creation of considerably effective electrocatalysts to reduce overpotentials is essential for speeding up the sluggish oxygen evolution reaction (OER) processes, which is imperatively required for the practical exploitation of electrochemical water-splitting. Herein, we prepared a unique composite structure, uniformly spherical Ni-MOF decorated with NiMoO 4 nanorods on Ni foam (NF), and assessed its performance toward oxygen evolution reaction. The synergistic effect between NiMoO 4 and Ni-MOF remarkably promoted the OER intrinsic activity. Moreover, introducing NiMoO 4 endowed the composite structure with enhanced electrical conductivity and exposed more active sites. The NiMoO 4 /Ni-MOF/NF electrode exhibited exceptional electrocatalytic activity in 1.0 M KOH aqueous solution, with a low overpotential of 218 mV to drive the current density of 10 mA cm−2 and a low Tafel slope (67.75 mV dec−1), surpassing the benchmark RuO 2. The presented strategy opens a promising candidate for preparing novel non-precious metal OER electrocatalysts derived from MOF materials for sustainable energy applications. [Display omitted] • The composite exhibits OER activity with an overpotential of 218 mV at 10 mA cm−2. • The introduction of NiMoO 4 enhanced the electrical conductivity of the composite. • Uniform active sites and high porosity for pristine Ni-MOF were retained. • The superior OER activity was due to more active sites and the heterostructure. [ABSTRACT FROM AUTHOR]

● A facile sol-gel method is first proposed to synthesize NASICON-type Li 2 Zn 2 (MoO 4) 3 and Li 2 Cu 2 (MoO 4) 3. ● Rietveld refinement indicated the structure evolution in Cu-doped Li 2 Zn 2−x Cu x (MoO 4) 3. ● The Li 2 Zn 2 (MoO 4) 3 and Li 2 Cu 2 (MoO 4) 3 electrode display excellent lithium storage performance. ● In-situ XRD confirmed the existence of mesophase Li 4 MoO 5 in Li 2 M 2 (MoO 4) 3 (M=Zn, Cu) during the initial lithium insertion. NASICON (Na superionic conductor) type electrode materials are known for their wide range of electrochemical potentials, high ionic conductivity, and most importantly their structural and thermal stabilities. Li 2 M 2 (MoO 4) 3 (M=Zn, Cu), belonging to molybdenum-based NASICON family, are successfully synthesized by simple sol-gel method. The structure evolution caused by the substitution of Zn2+ by Cu2+ within Li 2 Zn 2- x Cu x (MoO 4) 3 (0 ≤ x ≤ 2) has been investigated. Rietveld refinement results reveals that the priority order of copper atoms replacing zinc atoms in Li 2 Zn 2 (MoO 4) 3. Furthermore, both Li 2 Zn 2 (MoO 4) 3 and Li 2 Cu 2 (MoO 4) 3 electrodes deliver excellent electrochemical performance, and high reversible capacities of 864 mAh g−1 and 747 mAh g−1 can be acquired at a current density of 0.1 A g−1, respectively. In addition, the in-operando X-ray diffraction measurements indicate the formation of cubic mesophase Li 4 MoO 5 both in Li 2 Zn 2 (MoO 4) 3 and Li 2 Cu 2 (MoO 4) 3 during the initial lithium insertion, which irreversibly converts into the amorphous phases on further discharge at subsequent discharge and charge process. [ABSTRACT FROM AUTHOR]

• A multidimensional nanosheets/nanowires P-Co 3 O 4 electrode for Zn-ion batteries and supercapacitors was constructed. • The conductivity and interface reaction activity of Co 3 O 4 were improved by phosphating to obtain enhanced specific capacity. • The assembled P-Co 3 O 4 //Zn exhibited a specific capacity of 119.4 mAh g−1 and a capacity retention of 111% after 5000 cycles. Here, a surface phosphating Co 3 O 4 electrode materials with multidimensional nanostructure and oxygen-deficient have been fabricated and applied to aqueous Zn-ion batteries and asymmetric supercapacitors. The multidimensional nanostructure is beneficial to the full contact between active materials and electrolyte. Moreover, the oxygen vacancies can enhance electrical conductivity and further increases the concentration of active sites, consequently accelerating their interface reaction activity and kinetics. Therefore, the combination of structural and compositional advantages endows the P-Co 3 O 4 nanosheets/nanowires electrode a specific capacity of 244.9 mAh g−1 at 4 A g−1. Furthermore, the assembled P-Co 3 O 4 //Zn battery showed fascinating electrochemical performance, including a high specific capacity of 119.4 mAh g−1 at 1 A g−1 and a high energy density of 193.7 Wh kg−1 at a power density of 1.6 kW kg−1 and excellent stability of 111% capacity retention after 5000 cycles. The assembled P-Co 3 O 4 //AC ASC device also achieved an energy density of 24.87 Wh kg−1 and excellent cycle stability. Outstanding performance advantages make it possible for P-Co 3 O 4 electrode to be applied in the fields of new energy storage devices and wearable electronic devices. [ABSTRACT FROM AUTHOR]

Halide perovskite quantum dots have attracted considerable research interest as excellent candidate for photonic and optoelectronic applications due to their unique optoelectronic properties. Stability is prerequisite and therefore is of critical importance. Here we demonstrate highly stable luminescent CsPbBr 3 quantum dots (QDs) can be achieved in different glass matrices via the high temperature melting process and melt-quench method. The microstructure of CsPbBr 3 QDs glass as well as their optical properties are systematically characterized by microscopic techniques and time-resolved spectroscopic techniques. We conclude the surface passivation is the key aspect for the high stability and high luminescence by embedding the quantum dots in the glass matrix. This study provides technical method to form highly stable luminescent solid devices and detailed physical understanding which is critical for the practical applications. • Luminescence in CsPbBr 3 QDs glass were study. • CsPbBr 3 QDs precipitated in 3 kinds of glass matrices. • Exciton recombination is confirmed as the dominant radiative mechanism. • the QDs glass could be flexibly fabricated into various device. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the effects of stress aging treatment on the microstructure, mechanical properties and corrosion behavior of Al-Zn-Mg-Cu alloy. The alloys were subjected to SAT and stress-free aging treatment (SFAT) at 175 °C under different aging stress and aging time conditions. Various analytical techniques, including scanning electron microscopy (SEM), electron back-scatter diffraction (EBSD), transmission electron microscopy (TEM), slow strain rate tensile, X-ray Diffraction (XRD) and potentiodynamic polarization, were employed to obtain results. The findings demonstrate heightened strength, improved corrosion resistance under SAT conditions in contrast to SFAT. The alloys subjected to SAT exhibit higher strength compared to SFAT, attributed to the diffusion of stress-induced dislocations and extensive nucleation of matrix precipitates. Furthermore, the presence of large-sized and discontinuous grain boundary precipitates impedes the anodic dissolution of grain boundaries and the expansion of stress corrosion, contributing to the enhanced corrosion resistance of the alloy. • The strength of the alloys showed an increasing and then decreasing trend with increasing applied stress, the correct application of SAT can improve the strength of alloys. • SAT results in lower I corr values compared to SFAT. S100 exhibits a larger capacitance arc in the Nyquist plots, indicative of superior corrosion resistance. • SAT improves the mechanical properties of the alloy. Applied stress facilitates dislocation diffusion and aggregation, creating additional nucleation sites that promote the nucleation and growth of precipitated phases. • SAT improves the corrosion resistance of the alloy. Applying aging stress beyond a specific threshold and extending the aging time both facilitated Gbps growth and widened the PFZ. Thereby enhancing the alloy's corrosion resistance. [ABSTRACT FROM AUTHOR]

• WC-Co composite powder is synthesized by employing successive liquid methanol. • Carbon nanolayers loaded on the intermediates prevent particle aggregation of WC-Co. • WC-Co composite powder with clean surface is no need for washing with water or acid. • WC-Co composite powder possesses controllable carbon content. Tungsten carbide-cobalt (WC-Co) mixtures is the most critical material for cemented carbide. However, traditional preparation methods by using various carbon sources (e. g. carbon black, glucose, methane, carbon monoxide) cause severe carbon deposition. Consequently, traditional WC-Co mixtures exhibits uncontrollable carbon content. To address the challenge, we investigate the in-situ synthesis of WC-Co mixtures by supplying successive liquid methanol as a carbon source and nitrogen gas as a diluent. The as-prepared WC-Co mixture possesses clean surface and controllable carbon content, which are no need for removing excess carbon deposition by washing with water. The carbon nanolayers derived from methanol cracking gas appear on the surface of the intermediates, which can effectively prevent particle aggregation, efficiently increase the intimate contact probability of WC particles and Co particles, and greatly reduce the appearance of excess carbon deposition during subsequent carbonization processes. The present study offers insights on employing quantitative methanol cracking gas as reductive and carbonaceous atmosphere to mediate carbon content in the WC-Co composite powder, which presents a more economical and efficient pathway for large-scale synthesis of high-quality WC-Co mixtures with clean surface and controllable carbon content. [ABSTRACT FROM AUTHOR]

ZrN and TiNiN nanolayers are alternately deposited on silicon substrate by magnetron sputtering. A series of ZrN/TiNiN nano-multilayer films with different Ni contents are prepared by varying the Ni:Ti volume ratio of the targets. The effects of Ni content on the microstructures and mechanical properties of ZrN/TiNiN nano-multilayer films are studied by X-ray diffractometer (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and nanoindentation instrument. The results show that with the increase of Ni content, the crystallization degree of ZrN phase first increases and then decreases. Besides, the hardness, elastic modulus and toughness of the films also increase first and then decrease with Ni content increasing. When Ni:Ti= 1:24, the ZrN/TiNiN nano-multilayer films obtain the highest hardness, elastic modulus and fracture toughness, which are 23.2 GPa, 317.8 GPa and 2.29 MPa·m1/2, respectively. This is mainly attributed to the best columnar crystal growth of the ZrN/TiNiN nano-multilayer film. The TiNiN layer changes into face centered cubic structure under the template of ZrN layer, and grows in coherent epitaxy with ZrN layer. ● A series of ZrN/TiNiN nano-multilayer films with different Ni contents are prepared by magnetron sputtering. ● When Ni:Ti= 1:24, the ZrN/TiNiN nano-multilayer films simultaneously obtain the highest hardness and fracture toughness. ● The high hardness and toughness are due to that the TiNiN layer grows in coherent epitaxy under the ZrN layer template. [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries (LSBs) have attracted widespread attention because of their advantages such as high discharge capacity and high energy density. Although LSBs have good development potential, there are still many obstacles, such as poor conductivity, volume expansion etc., especially shuttle effect which seriously limit the application of LSBs. To restrain the shuttle effect, we proposed a novel Co 3 O 4 /ZnO dodecahedral heterojunction as a separator blocking layer which was derived form ZIF-67/ZIF-8 bimetallic MOF. Since the bimetallic oxide heterojunction contains more abundant oxygen vacancies, it has better adsorption and catalytic performances than monometallic oxides. Co 3 O 4 /ZnO coated on the PE separator can effectively block the lithium polysulfides (LiPSs) shuttle due to its good adsorption ability, furthermore, the catalytic effect will accelerate the reaction of LiPSs and improve the electrochemical performances. Consequently, the initial discharge specific capacity of the Co 3 O 4 /ZnO modified separator battery at 0.5 C rate reaches up to 875.5 mAh g−1 when the cathode sulfur areal density is 3 mg cm−2, and still keep 500.9 mAh g−1 after 400 long cycles. Even when the cathode sulfur areal density is 5 mg cm−2, it still shows good cycle stability. • Co 3 O 4 /ZnO dodecahedral heterojunction is derived from ZIF-67/ZIF-8 bimetallic MOF. • Co 3 O 4 /ZnO heterojunction is used as a separator coating material for Li-S battery. • Co 3 O 4 /ZnO heterojunction show excellent absorption and catalytic effect for polysulfides. [ABSTRACT FROM AUTHOR]

Titanium (Ti) and its alloys have great application potential. However, their relatively poor surface hardness, wear resistance, corrosion resistance, and biological activity greatly limit their effectiveness in practical applications. As a surface treatment method, the micro-arc oxidation (MAO) process has attracted much attention because it does not require expensive production equipment and is simple to operate. This paper discussed and summarized the mechanism of micro-arc oxidation and some classic models, which require development to provide better understanding and guidance for future research. Subsequently, the influencing factors of the formation of the micro-arc oxidation coating during micro-arc oxidation process were analyzed in detail. In addition, common applications of micro-arc oxidation coatings, including biomedical applications, wear resistance, corrosion resistance properties, and decoration, were summarized independently. Finally, existing problems and future prospects of the titanium alloy micro-arc oxidation process were discussed to facilitate the wide application of titanium alloy MAO process. [ABSTRACT FROM AUTHOR]

Because of its high theoretical specific capacity, lithium-sulfur batteries are regarded as one of the most promising secondary batteries. However, there are still a series of problems, which seriously affect the commercial application of lithium-sulfur batteries. Therefore, a magnetic porous carbon material was developed in this work for the modification of lithium-sulfur battery separators, which may reduce the shuttle effect of polysulfides and increase its electrochemical performances. The solvothermal preparation of Ni-Zn bimetallic MOF precursors was followed by a high-temperature carbonization in nitrogen environment to sublimate Zn ions and produce porous structures, achieving Ni@C(Zn) composite. In order to improve the electrochemical performances of lithium-sulfur batteries, the Ni@C(Zn) composite was coated on one side of the polyethylene (PE) separator. Ni@C(Zn) composite displays good physisorption and chemisorption properties, and it can also operate as a secondary current collector to promote the usage of active materials as well as inhibiting shuttle effect of polysulfides. By using Ni@C(Zn) coated PE separator, the initial discharge specific capacity of lithium sulfur battery is as high as 1278.6 mAh g−1 at a current density of 0.05 C when the S cathode is loaded with 3 mg cm−2 active materials. Furthermore, the discharge specific capacity in the first cycle at 0.5 C is 749.4 mAh g−1, which remains at 461 mAh g−1 after 500 long cycles, and the capacity retention rate is as high as 61.5%. Even when the S loading is as high as 5 mg cm−2, it can still experience a stable cycle of 100 cycles at 0.2 C. • Ni@C(Zn) composite was derived by bimetallic Ni-Zn MOFs. • Ni@C(Zn) composite was used as separator modification layer of lithium sulfur battery. • larger specific surface area and higher porosity can better block the shuttle of polysulfides. • Ni@C(Zn) composites have good catalytic effect which can promote the redox conversion of polysulfides. [ABSTRACT FROM AUTHOR]

Because of its high theoretical specific capacity, lithium-sulfur batteries are regarded as one of the most promising secondary batteries. However, there are still a series of problems, which seriously affect the commercial application of lithium-sulfur batteries. Therefore, a magnetic porous carbon material was developed in this work for the modification of lithium-sulfur battery separators, which may reduce the shuttle effect of polysulfides and increase its electrochemical performances. The solvothermal preparation of Ni-Zn bimetallic MOF precursors was followed by a high-temperature carbonization in nitrogen environment to sublimate Zn ions and produce porous structures, achieving Ni@C(Zn) composite. In order to improve the electrochemical performances of lithium-sulfur batteries, the Ni@C(Zn) composite was coated on one side of the polyethylene (PE) separator. Ni@C(Zn) composite displays good physisorption and chemisorption properties, and it can also operate as a secondary current collector to promote the usage of active materials as well as inhibiting shuttle effect of polysulfides. By using Ni@C(Zn) coated PE separator, the initial discharge specific capacity of lithium sulfur battery is as high as 1278.6 mAh g−1 at a current density of 0.05 C when the S cathode is loaded with 3 mg cm−2 active materials. Furthermore, the discharge specific capacity in the first cycle at 0.5 C is 749.4 mAh g−1, which remains at 461 mAh g−1 after 500 long cycles, and the capacity retention rate is as high as 61.5%. Even when the S loading is as high as 5 mg cm−2, it can still experience a stable cycle of 100 cycles at 0.2 C. • Ni@C(Zn) composite was derived by bimetallic Ni-Zn MOFs. • Ni@C(Zn) composite was used as separator modification layer of lithium sulfur battery. • larger specific surface area and higher porosity can better block the shuttle of polysulfides. • Ni@C(Zn) composites have good catalytic effect which can promote the redox conversion of polysulfides. [ABSTRACT FROM AUTHOR]

Due to the increasing demand of new energy vehicles and large-scale power grids for high energy density devices, lithium-sulfur batteries (LSBs) have attracted more and more researchers' attention stemming from their advantages of high theoretical specific capacity, low cost of active substances and environmental friendliness. However, there are still some intractable problems hindering the commercialization of LSBs, among which the most serious problem is "shuttle effect" of polysulfides. For the purpose of solving this problem, this paper prepared hollow structure molybdenum sulfide/cobalt sulfide mixed with amorphous carbon (MoS 2 /Co 9 S 8 /C) (HMCC) nanoparticles using ZIF-67 as the precursor and coated on the side of ordinary PE separator facing the positive electrode by a simple scraper coating process. The combination of MoS 2 and Co 9 S 8 bimetallic sulfides can not only adsorb and catalyze the rapid transformation of intermediates, but also effectively conduct lithium ions mainly because of the exposure of many active sites of layered MoS 2 in the outermost layer. In addition, a small amount of carbon inside can enhance electrical conductivity of the coating, increasing the utilization of active substances, and the stable hollow structure can act as a "transfer station", greatly inhibiting the large amount of polysulfides to run off. The dual advantages of structure and composition make the modified separator have excellent performance in different current densities. Reversible specific capacities of 930.4 mAh g−1 and 690.7 mAh g−1 are released at 0.5 C and 1 C, and capacity retention of 72 % and 64 % after 500 and 600 cycles, respectively. In addition, due to the rapid conduction of lithium ions, the growth of lithium dendrites is greatly inhibited, which maintains the high safety of the battery. This provides a new research direction for the application of other new bimetallic sulfides in the separator modification of LSBs. • A hollow bimetallic sulfide composite MoS 2 /Co 9 S 8 /C is derived from ZIF-67. • MoS 2 /Co 9 S 8 /C is used as a separator coating layer for lithium polysulfides. • The hollow MoS 2 /Co 9 S 8 /C show both physical confinement and catalytic effect on lithium polysulfides. [ABSTRACT FROM AUTHOR]

The NiCr/Al nanomultilayered films with different Al thicknesses (t Al) were prepared by magnetron sputtering. The structural evolution of the Al nanolayer with the increase in t Al was investigated. When the Al layer thickness changed from 1.2 nm to 2.4 nm, the Al layer could keep the co-epitaxial growth with the adjacent NiCr layer. Accordingly, the crystallization degree improved. When the Al layer thickness changed from 2.4 nm to 3.0 nm, the transformation from the coherent to incoherent interfaces took place between the NiCr and Al layers. Meanwhile, the co-epitaxial growth with the adjacent NiCr nanocrystallites was destroyed, the crystallinity and the grain size decreased, leading to the increase of the resistivity under the combined effects of the grain boundary scattering and interface scattering. The interfacial evolution of NiCr/Al nanomultilayered films was closely related to the changes of electrical properties. When the Al layer thickness changed from 3.0 nm to 3.6 nm, the surface quality of the film was improved, which effectively reduced the scattering of defects and vacancies during the electron transport, resulting in the decrease of the resistivity of the NiCr/Al nanomultilayered film. [Display omitted] • Al films inserted NiCr nanolayers with different thickness were synthesized. • The microstructure structure of NiCr was damaged with insertion of Al nanolayers. • The resistivity was renewedly increased with the change of interface structure. • The resistivity later deteriorates with the improvement of the surface quality. [ABSTRACT FROM AUTHOR]

Heterojunction has been considered to be one of the most effective methods for efficient hydrogen evolution reaction by photocatalytic water splitting. In this work, nanostructured Cu 7 S 4 /MnIn 2 S 4 heterojunction was successfully fabricated via a simple two-step method, which was much simpler than most heterojunction synthesis. Firstly, Cu 7 S 4 nanoparticles were synthesized by oil bath stirring, and then the Cu 7 S 4 /MnIn 2 S 4 heterojunctions were synthesized by the hydrothermal method. The prepared Cu 7 S 4 /MnIn 2 S 4 composite exhibited significantly improved hydrogen evolution activity with a rate of 13.81 μmol h−1 (10 mg catalyst), which was approximately 18 times higher than that of pristine MnIn 2 S 4. This result could be attributed to the construction of p-n heterojunction for promoting the separation of photogenerated charge carriers and inhibiting their recombination. Possible electron transfer mechanism was proposed by the related characterization. This work will inspire the simple fabrication of nano-heterojunctions in the future. [Display omitted] A facile and effective method was developed to fabricate nanostructured Cu 7 S 4 /MnIn 2 S 4 p-n heterojunction via oil bath mixing and hydrothermal methods by using p-type Cu 7 S 4 and n-type MnIn 2 S 4 nanoparticles, which exhibited significantly improved hydrogen evolution activity and stability. The construction of p-n heterojunction inhibits the recombination of carriers and holes. • The heterojunction was prepared by a simple oil bath mixing and hydrothermal method. • Photocatalytic hydrogen evolution rate reached 13.81 μmol h−1 (10 mg catalyst). • Cu 7 S 4 /MnIn 2 S 4 is a typical p-n heterojunction, which was successfully fabricated for the first time. The function of p-n junction and the mechanism were also discussed in detail. [ABSTRACT FROM AUTHOR]

• Urchin-like Nb 2 O 5 @N-C microspheres are prepared by two simple steps. • Polydopamine was served as carbon and nitrogen source. • Nb 2 O 5 @N-C microspheres exhibit outstanding rate and cyclic performances. [Display omitted] Orthorhombic Nb 2 O 5 is a promising material for the anodes of lithium-ion batteries (LIBs) owing to its pseudocapacitive features, stability, and safety. However, the practical applications for Nb 2 O 5 are limited due to its poor electrical conductivity. In this work, three-dimensional (3D) urchin-like microspheres coated with N-doped carbon were synthesized by hydrothermal synthesis and then polymerized in dopamine. When evaluated as anode for LIBs, the 3D urchin-like Nb 2 O 5 @N-C composites exhibited excellent high-rate capability (146 mAh g−1 at 20 C) and stability (78 mAh g−1 at 10 C after 2900 cycles). The remarkable electrochemical performance of the Nb 2 O 5 @N-C composites was ascribed to their unique structure and the N-doped carbon coating, which prevents the electrode from structural damage, mitigates volume expansion during the charge/discharge process, and enhances the conductance of the active material. [ABSTRACT FROM AUTHOR]