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Tungsten coatings have unique properties such as high melting points and hardness and are widely used in the nuclear fusion and aviation fields. In experiments, compared to pure Na2WO4 molten salt, electrolysis with Na2WO4–WO3 molten salt results in a lower deposition voltage. Herein, an investigation combining experimental and computational approaches was conducted, involving molecular dynamics simulations with deep learning, high-temperature in situ Raman spectroscopy and activation strain model analysis. The results indicated that the molten salt system's behaviour, influenced by migration and polarization effects, led to increased formation of Na2W2O7 in the Na2WO4–WO3 molten salt, which has a lower decomposition voltage and subsequently accelerated the cathodic deposition of tungsten. We analyzed the mechanism of the effect of the electric field on the Na2W2O7 structure based on the bond strength and electron density. This research provides crucial theoretical support for the effect of electric field on tungsten in molten salt and demonstrates the feasibility of using machine learning-based DPMD methods in simulating tungsten-containing molten salt systems. [ABSTRACT FROM AUTHOR]

Tungsten trioxide has attracted extensive attention for photocatalytic applications owing to its unique structure and intrinsic merits; however, the small specific surface area and rapid electron–hole recombination still limit its adsorption and photocatalytic efficiency. Herein, WO3·0.33H2O/g-C3N4 nanocomposite photocatalysts were designed and constructed using a facile low temperature hydrothermal method. The interaction between 1D WO3·0.33H2O nanorods and 2D g-C3N4 nanosheets produces a heterojunction with enhanced adsorption and photocatalytic degradation performance towards methylene blue pollutant. It is found that the synergistic effect of the surface charge and specific surface area significantly enhances the adsorption capacity which can be up to 23 times higher than that of WO3·0.33H2O, and the optimal photocatalytic activity is 3.67 and 1.70 times higher than that of pristine WO3·0.33H2O and g-C3N4, respectively. [ABSTRACT FROM AUTHOR]

A strategy that visible-light responsive zeolitic-imidazolate-framework-67 (ZIF-67) encapsulates noble-metal sensitized semiconductors, ZnO@M (M = Au, Pt, and Ag) to fabricate composite catalysts for photoelectrochemical (PEC) water splitting is proposed. The obtained ZnO@M@ZIF-67 catalysts have good catalytic performance, particularly, the ZnO@Au@ZIF-67 exhibits quite improved photoconversion efficiency and photocurrent density, superior to most of the reported photoelectrode catalysts. This can be attributed to the wider solar spectra harvesting capability originating from visible-light responsive ZIF-67 and UV-light active ZnO. Simultaneously, their integration enables interfacial electrons in the ZIF-67 shell to easily transfer to the ZnO@Au core, providing good electron–hole separation. In addition, the porous ZIF-67 as a protective shell ensures structural robustness, while maintaining fast ion or gas bubble diffusion through its pores, accounting for stable and excellent PEC performance. [ABSTRACT FROM AUTHOR]

A hybrid model that combines first principles calculations and thermodynamic evaluation was developed to describe the thermal stability of a nanocrystalline solid solution with weak segregation. The dependence of the solute segregation behavior on the electronic structure, solute concentration, grain size and temperature was demonstrated, using the nanocrystalline Cu–Zn system as an example. The modeling results show that the segregation energy changes with the solute concentration in a form of nonmonotonic function. The change in the total Gibbs free energy indicates that at a constant solute concentration and a given temperature, a nanocrystalline structure can remain stable when the initial grain size is controlled in a critical range. In experiments, dense nanocrystalline Cu–Zn alloy bulk was prepared, and a series of annealing experiments were performed to examine the thermal stability of the nanograins. The experimental measurements confirmed the model predictions that with a certain solute concentration, a state of steady nanograin growth can be achieved at high temperatures when the initial grain size is controlled in a critical range. The present work proposes that in weak solute segregation systems, the nanograin structure can be kept thermally stable by adjusting the solute concentration and initial grain size. [ABSTRACT FROM AUTHOR]

CoAl-based layered-double-hydroxide@zeolitic-imidazolate-framework-67 (LDH@ZIF-67) was fabricated via a hydrothermal synthesis of LDH film on Ni substrate followed by the in situ growth of ZIF-67. Its derivatives, MMO@Co3O4, spinelle@C and LDH@CoS with hierarchical structures were obtained by the subsequent oxidation, carbonization and sulfurization of LDH@ZIF-67, respectively, which exhibit distinct specific capacitances of 692, 781 and 1205 F g−1 at a discharge current density of 1 A g−1. Interestingly, these derivatives retained hierarchical structures with large surface area, which ensures that the majority of exposed active species can participate in the charge–discharge process and thus effectively contribute to total capacitances. The synergistic effect from fast electronic transfer reduces reversible ion accumulation at the interface, which imparts LDH@ZIF-67 derivatives improved electrochemical activities, in contrast to conventional bulk MOF derivatives. In addition, it was found that the combination of the remarkable electrical conductivity of sulfides (compared with their oxide counterparts) and the strong electronic coupling between LDH and CoS can facilitate fast electron transfer. As a result, LDH@CoS exhibits an excellent specific energy of 44.5 W h kg−1 at a current density of 20 A g−1, as well as good capacitance retention of 88.5% after 2000 cycles. This work thus demonstrates a feasible strategy for the design and fabrication of LDH@MOF derived composites as SCs components, which is applicable in constructing other novel electrode materials with hierarchical structures for applications in energy storage systems. [ABSTRACT FROM AUTHOR]

Tungsten coatings have unique properties such as high melting points and hardness and are widely used in the nuclear fusion and aviation fields. In experiments, compared to pure Na 2 WO 4 molten salt, electrolysis with Na 2 WO 4 -WO 3 molten salt results in a lower deposition voltage. Herein, an investigation combining experimental and computational approaches was conducted, involving molecular dynamics simulations with deep learning, high-temperature in situ Raman spectroscopy and activation strain model analysis. The results indicated that the molten salt system's behaviour, influenced by migration and polarization effects, led to increased formation of Na 2 W 2 O 7 in the Na 2 WO 4 -WO 3 molten salt, which has a lower decomposition voltage and subsequently accelerated the cathodic deposition of tungsten. We analyzed the mechanism of the effect of the electric field on the Na 2 W 2 O 7 structure based on the bond strength and electron density. This research provides crucial theoretical support for the effect of electric field on tungsten in molten salt and demonstrates the feasibility of using machine learning-based DPMD methods in simulating tungsten-containing molten salt systems.