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The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH 4 , SB). In this paper, a flower shaped Co 2 FeO 4 catalyst with high catalytic performance was selected from a series of Co x M 3-x O 4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance. The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH 4 , SB). In this paper, a flower shaped Co 2 FeO 4 catalyst with high catalytic performance was selected from a series of Co x M 3-x O 4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance. [Display omitted] • Flower-like Co 2 FeO 4 showed the best catalytic performance. • The "D-band center" and "valence -band center" of Co 2 MO 4 were studied. • Composition and electronic control improve the catalytic performance of Co 2 MO 4. • The adsorption configuration of H 2 O on the Co 2 MO 4 (311) surface was studied. [ABSTRACT FROM AUTHOR]

Compared with traditional water electrolysis, electrolysis of seawater has larger resources and a brighter future. However, seawater contains more elements that have greater corrosive effects on electrodes; especially chloride ions (seawater contains more chloride ions) have the greatest impact. The existence of the corrosion problem creates greater difficulties in electrolyzing seawater, further limiting the efficiency of the electrocatalyst for electrolysis of seawater. In this paper, we report a Mn-doped Ni 2 P/Cu 3 P as an environmentally friendly monofunctional electrode for seawater electrolysis, which was made by a simple hydrothermal phosphatization operation method. The experimental results show that Mn-doped Ni 2 P/Cu 3 P presents overpotential of only 161 mV for oxygen evolution reaction (OER) at iR compensation of 90 and a current density of 10 mA cm−2. It has a small Tafel slope (25.15 mV dec−1) and a large capacitance (9.58 mF cm−2 on 1 × 1 nickel foam), which exceeds most reported oxygen evolution activities of non-precious metal-based electrocatalysts for electrolysis of alkaline seawater. The performance of Ni 2 P/Cu 3 P was probably significantly enhanced due to Mn doping by some characterization means. Through Density functional theory (DFT) analysis, it is known that the doping of Mn gives a large enhancement in the adsorption energy of water when Ni 2 P/Cu 3 P is electrolyzed with seawater. This paper provides train of thought for the exploration of excellent electrocatalysts for electrolysis of alkaline seawater. The experimental results show that Mn-dopedNi 2 P/Cu 3 P present overpotential of only 161 mV at i-R compensation of 90 for oxygen evolution reaction in alkaline seawater. [Display omitted] • Mn-doped Ni 2 P/Cu 3 P electrodes was synthesized for the first time through hydrothermal processes. • The overpotential of Mn-doped Ni 2 P/Cu 3 P electrode is only 161 mV at 10 mA cm−2 for OER. • The doping of Mn gives a large enhancement in the adsorption energy of water. [ABSTRACT FROM AUTHOR]

Electrolysis of water for production of hydrogen has become one of the most fascinating methods to relieve the energy crisis and environmental pollution. In this paper, a series of M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials was in situ grown on Ni foam through a two-step hydrothermal process, and the synthesized Co–NiS/Mo 2 S 3 material present excellent hydrogen evolution reaction (HER) properties. Under an alkaline condition of 1 M KOH, Co–NiS/Mo 2 S 3 requires only overpotential of 142 mV to achieve a current density of 10 mA cm−2, and using Co–NiS/Mo 2 S 3 as both cathode and anode, only the potential of 1.574 V is required to drive a current density of 50 mA cm−2, with a relatively good durability over 15 h. Density functional theory (DFT) analysis show that the ΔG H* of Co–NiS is closer to 0 and its density of states near the Fermi energy level is higher, suggesting that Co–NiS improves the electrical conductivity of Co–NiS/Mo 2 S 3 and plays a significant catalytic action. This work proposes novel insights for the future exploration of novel sulfur-based composite electrocatalysts with excellent HER performance. In this paper, a series of M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials was in situ grown on Ni foam by a two-step hydrothermal method, and the synthesized Co–NiS/Mo 2 S 3 material present excellent hydrogen evolution reaction (HER) properties. [Display omitted] • M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials were successfully synthesized by hydrothermal processes. • Co–NiS/Mo 2 S 3 electrode shows excellent catalysis in the cathode reaction of water and water electrolysis. • Co–NiS/Mo 2 S 3 requires only overpotential of 142 mV to achieve a current density of 10 mA cm−2. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is considered as a green and efficient way of hydrogen production. How to promote the performance of electrode and develop stable non-precious metal catalysts has caused extensive research. One of the effective strategies is combining two or more catalytic materials to build heterogeneous structures. In this paper, a series of Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 heterostructured materials were synthesized to in-situ grow Ni 3 S 2 /Ni 3 Sn 2 S 2 on Ni foam with a 3D porous structure by modulating the substance ratio of elemental cobalt and elemental sulfur through a one-step hydrothermal process. The materials have superior oxygen evolution reaction (OER) properties and urea oxidation reaction (UOR) performance. Under an alkaline electrolyte of 1 M KOH, for OER, Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 only requires overpotential of 251 mV to obtain a current density of 10 mA cm−2. In an alkaline solution of 1 M KOH +0.5 M urea, for UOR, only the potential of 1.326 V was demanded for the catalyst to reach a current density of 50 mA cm−2, but its stability over 15 h was average. Density Functional Theory (DFT) analyses suggest that Co–Ni 3 S 2 has better metallic properties and promote the dynamics in catalysis. This study put forward a new thought for future research on nickel-tin binary metal sulfide hybrid electrocatalysts with excellent freshwater, seawater and urea oxidation properties. In this paper, a series of Co x -Ni 3 S 2 /Ni 3 Sn 2 S 2 materials was in situ grown on Ni foam by a one-step hydrothermal method, and the synthesized Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 material present excellent water and urea oxidation properties. [Display omitted] • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 materials were successfully synthesized by hydrothermal processes. • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 electrode shows excellent catalysis in the cathode reaction of water and urea. • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 requires only potential of 1.326 V to achieve a current density of 50 mA cm−2 for UOR. [ABSTRACT FROM AUTHOR]

Using the WIEN2k code, first-principles simulations of ZrXH 3 (X = Zn, Cd) hydride perovskites are performed to determine their hydrogen storage properties. The purpose of this study is to investigate their structural, optoelectronic, hydrogen storage, mechanical and thermoelectric properties. The structural analysis demonstrates their stability through the heat of formation along with desorption temperature and shows that these compositions belong to the orthorhombic space group Cmcm (no.63). The band structure and density of states are estimated for electronic characteristics, indicating the metallic nature of both compositions. Analysis of elastic properties such as elastic constants, Pugh's ratio, bulk modulus, Poisson's ratio, and anisotropy factor are explored to determine the mechanical stability of these compositions and demonstrate their suitability as a transport medium in hydrogen storage systems even at higher pressure. To study the optical behavior of the perovskites under consideration for hydrogen storage applications, the dielectric parameters, dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function are studied. The present paper represents the initial theoretical effort toward future exploration of these materials for hydrogen storage applications. [Display omitted] Using the WIEN2k code, first-principles simulations of ZrXH 3 (X = Zn, Cd) hydride perovskites are performed to determine their hydrogen storage properties. The purpose of this study is to investigate their structural, optoelectronic, hydrogen storage, mechanical and thermoelectric properties. The structural analysis demonstrates their stability through the heat of formation along with desorption temperature and shows that these compositions belong to the orthorhombic space group Cmcm (no.63). The band structure and density of states are estimated for electronic characteristics, indicating the metallic nature of both compositions. Analysis of elastic properties such as elastic constants, Pugh's ratio, bulk modulus, Poisson's ratio, and anisotropy factor are explored to determine the mechanical stability of these compositions and demonstrate their suitability as a transport medium in hydrogen storage systems even at higher pressure. To study the optical behavior of the perovskites under consideration for hydrogen storage applications, the dielectric parameters, dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function are studied. The present paper represents the initial theoretical effort toward future exploration of these materials for hydrogen storage applications. • Stability of ZrXH 3 (X = Zn, Cd) hydride perovskites is confirmed by Enthalpy of formation. • ZrXH 3 (X = Zn, Cd) hydride perovskites have high value of decomposition temperature. • The gravimetric hydrogen storage capacities comes out to be 1.89 % and 1.46 % respectively. • Metallic behavior is reveled by electronic structure of these hydrides. [ABSTRACT FROM AUTHOR]

Hydrogen energy is one of promising non-polluting and renewable energy sources. In this paper, we present a first principal study of hydrogen storage in pure C 60 fullerene cage and Stone-Wales (SW) defective C 60 cages using density functional theory (DFT) with applying both the exchange functional B3LYP and the dispersion correction wb97xd at 6–31+g(d,2p) basis set. In addition, the counterpoise correction is applied, and the basis set superposition error is calculated. The calculations underscore that the hydrogenation binding energy of C 60 cages occurs through an endothermal process for C 60 H in with a hydrogen binding energy of 0.09 eV and through an exothermal process for C 60 H out , C 60 SW 66 H out , and C 60 SW 65 H out , cages with hydrogen binding energies of −2.17 eV, −2.96 eV, and −2.20 eV, respectively. Remarkably, for the first time, the intermediate hydrogen binding energy is found inside C 60 SW 66 H in fullerene, and C 60 SW 65 H in fullerene cages with energies of −0.26 eV and −0.81 eV, respectively. The hydrogen adsorption inside the cavity of C 60 SW 66 fullerene cage is thermodynamically possible below 289.8 K and entire pressure range considered. Our results highlight, for the first time, that the endohedral cavity of C 60 SW 66 is a promising new medium for hydrogen storage due to its binding energies (−0.26 eV) and its hydrogen storage weight percentage (5.3%) that are close to the optimal conditions specified by DOE for commercial use. In addition, this study opens up a new discovery of Stone-Wales defective C 60 fullerene for further endohedral cavity applications. • New insight into endohedral cavity of Stone Wales C 60 SW 66 is reported. • For the first time, a new promising medium for hydrogen storage inside cavity of C 60 SW 66 is proved. • Binding energies of −0.26 eV and hydrogen storage weight percentage up to 5.3% are achieved inside the cavity of C 60 SW 66. • This study opens a new discovery of the SW defective C 60 fullerene for further endohedral cavity applications. [ABSTRACT FROM AUTHOR]

In this paper, a new design principle for bimetallic catalysts is proposed by combining strongly adsorbed atoms (SAA) with weakly adsorbed atoms (WAA) where the SAA and WAA are classified by the free adsorption energy of oxygen-containing intermediates on the metal atom. And the ORR performances of the bimetallic catalysts designed by the method are compared with the common single metal atom catalysts. The method is successfully confirmed as the overpotential of the Mn-based bimetallic catalysts decreases from 0.63 V in G-MnN 4 to as low as 0.33 V, and that of the Fe-based bimetallic catalysts decreases from 0.76 V in G-FeN 4 to 0.23 V. In addition, the correlation between adsorption free energy and adsorption bond length is revealed for the first time, and the optimal adsorption bond length is determined. Finally, the adsorption energy of O 2 is plotted versus the free adsorption energy of three oxygen-containing intermediates for the first time, and a suitable adsorption energy of O 2 is found to be -1.4∼-1.0 eV. These findings provide a new perspective for the design of high-performance bimetallic catalysts. • Catalysts obtained by combining strongly adsorbed atoms with weakly adsorbed atoms show superior performance. • Correlation between adsorption free energy and adsorption bond length is revealed for the first time. • Adsorption energy of O 2 can be used as a descriptor of ORR performance. • ORR performance is related to the energy difference of hybridization between metal atom and adsorbed species. [ABSTRACT FROM AUTHOR]

The efficient hydrogen-production through the Aluminum-water reaction has become a prominent subject of interest. The impediment encountered in the reaction can be effectively alleviated by Aluminum-based alloy. In this study, density functional theory (DFT) was utilized to explore the mechanism of water decomposition stage on the surface of aluminum and gallium alloy (AGA). Through surface reaction calculations of 12 stable AGA configurations, it was gradually revealed that the optimal alloy ratio was gallium-to-aluminum at 3.5:1. Analysis of the density of states (DOS) indicated that the presence of gallium amplified the activity of surface aluminum. Moreover, frontier orbital theory and charge density maps confirmed that, due to the weak interaction between Ga and ions, the presence of H 2 inhibited Ga passivation, thereby enhancing the reactivity of AGA. This paper provided valuable insights into the surface reaction mechanisms of AGA using DFT, offering theoretical support for hydrogen production processes. • Density functional theory investigated the early stages of AGA-water reaction. • Modeling AGA (Ga proportions 73.8%–81.2%) yields 12 stable configurations. • Ga:Al = 3.5:1 exhibits highest energies for O 2 , H 2 O, and co-adsorption. • Ga enhances AGA's catalytic activity, shown in DOS graphs comparisons. • AGA plays dual roles in surface hydrogen dynamics. [ABSTRACT FROM AUTHOR]

The novel S-scheme heterostructure shows its superiority in photocatalysis due to its high efficiency of charge transfer. In this paper, we compared the mechanical, electronic, optical and transport properties of two different contact modes of heterostructure structures of MoSe 2 /Janus PtSSe and their applications in photocatalytic water splitting through density functional theory. The results show that the charge transfer of MoSe 2 /SePtS heterostructures occurs between layers. On the contrary, the charge separation of MoSe 2 /SPtSe heterostructures is significant, and there are internal electric fields and suitable band arrangements at the interface from MoSe 2 to SPtSe direction, forming S-scheme photocatalysts. Compared with the MoSe 2 /SePtS heterostructure, the MoSe 2 /SPtSe heterostructure has higher carrier mobility. Furthermore, the MoSe 2 /SPtSe heterostructure has good light absorption in the visible range, and the solar-to-hydrogen (STH) efficiency is as high as 7.97%. Gibbs free energy calculation shows that the overpotential η OER = 1.63 V (pH = 0) decreases to η OER = 1.11 V(pH = 7) with the increase of pH value. We expect that our results can provide valuable insights into the rational design of efficient heterostructure in photocatalytic water splitting systems. [Display omitted] • MoSe 2 /SPtSe heterostructure with high carrier mobility. • The existence of charge transfer in the MoSe 2 /SPtSe heterostructure is advantageous. • MoSe 2 /SPtSe heterostructure is a S-scheme photocatalyst for water splitting. • The ηOER of MoSe 2 /SPtSe heterojunction decreased with the increase of pH. • MoSe 2 /SPtSe heterostructure has ultra-high STH efficiency (7.79%). [ABSTRACT FROM AUTHOR]

In this paper, based on the first-principle calculations of hybrid density functional theory, the MoSTe/g-GeC of the Z-scheme heterostructure is constructed. The stability, electronic properties, optical absorption properties, and photocatalytic mechanism of the heterostructure is investigated. The band structure of MoSTe/g-GeC heterostructure is staggered, and the bandgap is 0.47 eV. The built-in electric field from g-GeC to MoSTe, with a size of 1.03 eV. The optical absorption coefficient of MoSTe/g-GeC heterostructures is significantly higher than that of MoSTe and g-GeC layer. When pH ranges from 0 to 7, the reduction reaction occurs in g-GeC layer, and the oxidation reaction occurs in the MoSTe layer. In the MoSTe/g-GeC heterostructure under different stresses, the band structure is arranged in a staggered manner. Importantly, under tensile strain, the bandgap of MoSTe/g-GeC heterostructure can be changed from the indirect into a direct bandgap. The bandgap of heterostructure decreases under the strain. In addition, the analysis of the photocatalytic mechanism shows that the redox reaction of the MoSTe/g-GeC heterostructure occurs on the layer with strong redox ability, and their light absorption ability is significantly enhanced compared to single-layers, which effectively improves the photocatalytic properties. It's a potential high-efficiency photocatalytic materials for direct Z-scheme heterostructure. In this paper, the stability, electronic properties, optical absorption properties, and photocatalytic mechanism of the MoSTe/g-GeC heterostructure is systematically studied. The results show that the heterostructure is a direct z-scheme heterostructure, and the photocatalytic performance is better than that of MoSTe and GeC monolayers. [Display omitted] • MoSTe/g-GeC heterostructure is a direct Z-scheme heterostructure, which is suitable for photocatalytic water splitting. • MoSTe/g-GeC heterostructure has excellent absorption coefficient (9.8 × 104 cm−1) in the visible and ultraviolet ranges. • The bandgap of MoSTe/g-GeC heterostructure can change from indirect bandgap to direct bandgap under partial strain. [ABSTRACT FROM AUTHOR]

Sustainable and energy-efficient ammonia production requires facile nitrogen reduction for hydrogen preservation and inorganic fertilizers. A nitrogen reduction apparatus with optimal stability, selectivity, and activity for ambient temperatures and pressure is needed to catalyze ammonia synthesis. This paper describes the investigation of using transition metal carbonitrides as catalyst to reduce molecular nitrogen electrochemically to NH 3 at room temperature and atmospheric pressure. Density functional theory calculations determine the competition among associative, dissociative, and Mars-van Krevelen mechanisms where in most cases the Mars-van Krevelen is a more favorable reaction pathway. VCN and NbCN are the best candidates for ammonia production via the Mars-van Krevelen mechanism at low onset potentials of −0.52 V and −0.53 V vs reversible hydrogen electrode on the (100) facets. These carbonitrides are predicted to favor nitrogen reduction reaction rather than hydrogen evolution reaction. [Display omitted] [ABSTRACT FROM AUTHOR]

The catalysts for oxygen reduction reaction (ORR) are of great significance to the development of electrochemical energy systems. In this paper, the ORR catalytic performance of Mn–Ni dual-metal doped N-coordinated graphene is studied by density functional theory (DFT). The results show that the catalysts with dual-metal active sites are more stable than that with single metal site, and all catalysts show certain catalytic activity. The reaction pathway analyses of catalysts with two different adsorption configurations of O 2 show that when O 2 is adsorbed on two metal sites, OOH will automatically split into OH and O. When O 2 is adsorbed on Mn site alone, the other site does not participate in the adsorption of oxygen-containing intermediates. The thermodynamic calculation results show that the catalytic performance is mainly influenced by the adsorption strength of O, which is controlled by the number of active sites involved in the adsorption, bond length and the number of transferred electrons at the active sites. The G-MnNiN 6 -3 shows the best catalytic performance with an overpotential of 0.453 V and a reaction energy barrier of 0.19 eV. The results of this study highlight the potential application of Mn–Ni dual-metal doped N-coordinated graphene as a highly efficient non-precious catalyst. • The ORR catalytic performance of Mn–Ni dual-metal doped N-coordinated graphene is studied for the first time. • The adsorption of O 2 can be classified into single adsorption and co-adsorption on bimetallic catalyst. • The catalytic performance is most affected by the adsorption strength of O. • The best catalyst shows the overpotential of 0.453 V and a reaction energy barrier of 0.19 eV. [ABSTRACT FROM AUTHOR]

Hydrogen production from water splitting is a popular subject at present. Therefore, we design the hBNC/Janus MoSSe heterojunctions for hydrogen evolution of photocatalytic water splitting. This investigation is based on the density functional theory. The results indicate that the band alignments of the hBNC/Janus MoSSe heterojunctions are typical type-II. According to the direction of built-in electric field in the heterojunction, we confirm that the hBNC/Janus MoSSe is the direct Z-scheme heterojunction. In addition, the electron mobility and optical absorption coefficient are improved in the hBNC/Janus MoSSe heterojunctions. The hBNC/SeMoS has higher reduction reaction overpotential (χ H2 = 3.34 eV) than it (χ H2 = 3.06 eV) in the hBNC/SMoSe, while the oxidation reaction overpotential (χ O2 = 0.07 eV) in the hBNC/SMoSe is higher than it (χ O2 = -0.06 eV) in hBNC/SeMoS. Furthermore, the change of Gibbs free energy under the external potential which is provided by the photoexcited carriers with the light irradiation confirms that the hydrogen evolution reaction is exothermic and could react spontaneously. This work indicates that the hBNC/Janus MoSSe heterojunctions have the potential in hydrogen production of photocatalytic water splitting. [Display omitted] • This paper confirms that the hBNC/Janus MoSSe is the direct Z-scheme heterojunction. • The electron mobility is enhanced in the hBNC/Janus MoSSe heterojunctions. • The optical absorption coefficient is also improved. • The hBNC/Janus MoSSe can spontaneously complete HER. [ABSTRACT FROM AUTHOR]

Electrolysis of water and splitting of urea to produce hydrogen are identified as one of the most attractive approach to reduce environmental pollution. However, this approach is both promising and challenging. In the paper, the NiFeZr LDH material was in situ grown on Ni foam through a one-step hydrothermal process. The electrochemistry activity of the NiFeZr LDH electrode was investigated by two probe reactions, one for the oxidation of urea and the other for the oxidation of water. It is worth mentioning that whether it is the oxidation reaction of urea (potential of 1.42 V @ 10 mA cm−2) or water (overpotential of 350 mV @ 10 mA cm−2), the doping of Zr improves the catalytic activity of the material. What is worth mentioning that the oxidation of urea does significantly decrease energy consumption compared to the oxidation of water. However, experiments show that the catalytic active sites are different in the two reactions. We speculate that iron is the active site for the oxidation of water, while zirconium is the active site for the oxidation of urea. Experiments demonstrate that the promoted performance is assigned to the exposure of the centre site, the rapid charge transfer rate and the improved electron configuration. Density functional theory analysis indicates that this NiFeZr LDH electrode presents optimal adsorption energy for urea, which improves the catalytic activity of the material. The NiFeZr LDH material present superior electrocatalytic performance for water oxidation reaction (Overpotential of 350 mV@10 mAcm−2) and urea oxidation reaction (potential of 1.42 V@10 mAcm−2). [Display omitted] • NiFeZr LDH nanoarrays were prepared by typical hydrothermal processes. • The NiFeZr LDH presents an improved activity with small overpotentials of 350 mV for water oxidation. • The NiFeZr LDH presents an improved activity with potentials of 1.42 V for urea oxidation. [ABSTRACT FROM AUTHOR]

As a fascinating approach for sustainable NH 3 production, the electrocatalytic nitrogen reduction reaction (NRR) is still hampered by low Faraday efficiency due to high energy required for inert N N triple bond activation and competitive hydrogen evolution reaction (HER). In this paper, we propose a method to increase the NRR catalytic activity by constructing bimetallic sites on boron nitride (BN) monolayer. In order to approach the efficient NRR region, the metal-based linear-scaling relationship between adsorbed intermediates is broken by synergistic effects between the bimetallic active sites. TiRu-BN was identified as an effective NRR electrocatalyst with low limiting potential (−0.28 V) and superior selectivity after systematic evaluation of the thermal stability, electrochemical stability, activity, and selectivity of 36 homo- and heteronuclear diatomic catalyst candidates. Analysis on the origin of high performance shows the screened high-performance diatomic catalyst is located in the region of moderate linear-scaling relationship breaking of intermediates. Breaking the linear scale relationship to the most significant extend does not imply the most improved catalytic activity. This work not only provides experimentally synthesizable exceptional NRR electrocatalyst candidates, but also provides theoretical guidance for practical application of efficient NRR electrocatalyst. [Display omitted] • Metal dimers anchored on defective BN monolayers for NRR investigated. • TiRu-BN was identified as high performance NRR electrocatalyst. • Synergistic effect of dual metal site breaks scaling relationship of intermediates. • High-performance catalyst shows the moderate scaling relationship breaking. [ABSTRACT FROM AUTHOR]

ZnO/CuInS 2 composites were synthesized by using electrospun ZnO chain structures as a template, along with InCl 3 , CuCl 2 , and thiourea as sources of indium, copper, and sulphur, respectively. The ZnO/CuInS 2 core-shell structure enhances light absorption and carrier transport efficiency. Moreover, ZnO/CuInS 2 exhibits superior light absorption and photocatalytic hydrogen production performance compared to ZnO, with a peak hydrogen production of 4188.24 μmol g−1. The arrangement of energy levels within the ZnO/CuInS 2 heterojunction is the crucial factor in enhancing photocatalytic properties. Increased electrons distribution near the interface facilitates the transport performance of charge carriers, which accelerates hydrogen production kinetics at the interface, and promotes greater participation of photogenerated electrons and holes in catalytic reactions. Combined with the application of density functional theory, the computational analyses of work function and differential charge support this assertion. This paper introduces a fresh method for creating innovative photocatalysts and grasping the reaction mechanism involved in photocatalytic hydrogen generation. The ZnO/CuInS 2 heterojunction, encompassing CuInS 2 nanosheets surrounding ZnO nanofibers, displayed exceptional hydrogen production capacity. The most remarkable hydrogen production achievement was 4188.25 μmol g−1 in 6 h, a value more than 623.7 times superior to that of pure ZnO. The disparity in charge density highlighted the presence of significant charge transfer at the interface of ZnO/CuInS 2. This reinforces the fact that the ZnO/CuInS 2 construction and interface charge transfer are crucial in elevating its photohydrogen production capabilities. [Display omitted] • ZnO/CuInS 2 was synthesized by the electrospinning method. • The hydrogen production of heterojunction reached 4188.25 μmol g−1 in 6 h. • The mechanism was analyzed by DFT calculation. [ABSTRACT FROM AUTHOR]

As a promising candidate for accident-tolerant fuel (ATF) cladding materials, FeCrAl alloys are susceptible to hydrogen embrittlement (HE) under high-temperature radioactive water environments. Understanding the HE mechanism of FeCrAl is crucial, and studying H 2 dissociative adsorption can provide valuable insights since it is the first step in the HE processes. In this paper, we investigated the H 2 dissociative adsorption on Fe (110) and FeCrAl (110) surfaces using first-principles calculations based on Density Functional Theory (DFT). Our results indicate that the decomposition of H 2 molecules on FeCrAl (110) surfaces is significantly affected by surface elemental effects compared to Fe (110) surfaces. Specifically, Al atoms weaken both the H 2 decomposition and the H binding strength of Al-containing sites. Cr atoms decrease the decomposition tendency of H 2 in certain configurations, but Cr aggregation enhances the binding strength of H atoms on Cr-containing sites. The mechanism underlying the Al/Cr weakening effects on H 2 decomposition is due to the charge deficiency through alloying. Our findings have generalized implications for studying the interactions between iron-based alloys and hydrogen in various applications such as hydrogen storage, transportation, and prevention. • The strength of H 2 –Fe/Cr/Al interactions follow the order: H 2 –Al < H 2 –Cr < H 2 –Fe. • Al atoms have strong weakening effect on H 2 dissociation compared to Fe. • Cr atoms have slight weakening effect on H 2 dissociation compared to Fe. • The Cr aggregation can enhance H 2 –Cr interaction & H binding strength. • The weakening effects of Al & Cr on H 2 dissociation are caused by the charge deficit of Al & Cr after alloying with Fe. [ABSTRACT FROM AUTHOR]

Two-dimensional material rhenium disulfide (ReS 2) has attracted much attention recently as a potential electrochemical catalyst for the Hydrogen Evolution Reaction (HER). The ReS 2 monolayer is found to be catalytically inert. The challenge lies in activating the ReS 2 monolayer to increase HER output. One of the approaches to this lies in depositing small metal clusters on the monolayer. This paper examines the formation and stability of small metal clusters on 1T distorted ReS 2 monolayer using dispersion-corrected Density Functional Theory. Four different kinds of transition metal clusters, viz. Au, Pt, Mo, and Cr are investigated for geometry and binding on the ReS 2 monolayer. HER activity of each type of ReS 2 -supported metal cluster is investigated based on computed free energy. The HER mechanism was investigated for clusters with optimal activity, and it was found that while the ReS 2 monolayer follows the Volmer-Heyrovsky route, for the transition metal cluster decorated ReS 2 , the Volmer-Tafel route is more probable. • ReS 2 basal plane is catalytically inert; therefore, surface activation is required. • ReS 2 monolayer decorated with small clusters of Au, Pt, Mo and Cr are stable. • ReS 2 supported Au, Pt and Mo clusters are HER active, especially Au3, Pt4 and Mo5, but Cr clusters are not. • The clusters on ReS 2 follow a Tafel mechanism, with lower activation barriers than pure ReS 2. [ABSTRACT FROM AUTHOR]

Hydrogen production by urea electrolysis is a green, energy conservation and environment protection method. Compared with traditional water electrolysis for hydrogen production, it not only saves costs and energy consumption, but also can treat urea wastewater to purify the environment. In this paper, the sea urchin-like nanoneedles (M (M = Cr, Mo and W)–FeCo 2 P/NF) arrays with different doping elements M (M = Cr, Mo and W) were prepared by hydrothermal method and moderate temperature phosphating method. It is proved that the doping of different elements in the same group cooperates to adjust the electronic structure of Co 2 P, thereby increasing the electrochemical active area and improving the active site. What is noteworthy is that Mo–FeCo 2 P/NF material only needs potential of 1.305 V and overpotential of 232 mV to drive 50 mA cm−2 for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). The Mo–FeCo 2 P/NF (±) electrolyser can drive a current density of 10 mA cm−2 at a potential of 1.471 V, and is stable for at least 12 h in urea electrolysis. The density functional theory (DFT) demonstrates that Mo–FeCo 2 P/NF electrode has a moderate Gibbs free energy (G H∗) of H adsorption. This work put forward a new strategy for improving the activity and stability of transition metal phosphides by doping strategy for urea electrolysis. The Mo–FeCo 2 P/NF (±) electrolyser cell for only 1.471 V to provide current density of 10 mA cm−2, which is one of the best electrochemistry performances reported up to now. [Display omitted] • Mo, Fe co-doped Co 2 P electrodes was synthesized for the first time through hydrothermal processes. • This Mo–FeCo 2 P nanoarrays exhibits enhanced activity of the urea splitting (cell voltage of 1.471 V @10 mA cm−2). • DFT show that the Mo–FeCo 2 P material exhibits the minimum Gibbs free energy. [ABSTRACT FROM AUTHOR]

The dehydrogenation enthalpy, a crucial thermodynamic parameter, determines the difficulty of hydrogen desorption in V–Ti–Cr–Fe alloy, but it is unaffordable to predict and modify the dehydrogenation enthalpy and investigate the synergistic effects of structural and chemical parameters relying on conventional experimental methods. In this paper, an extreme gradient boosting (Xgboost) model with feature selection is developed, which can obtain a relative error under 15% in prediction on most of the data. Moreover, the genetic algorithm is utilized for optimizing alloy composition having suitable dehydrogenation enthalpy. The accuracy of prediction and optimization is demonstrated by the subsequent experimental validation, where the error between calculation and experiment is within 4.5%. Density function theory (DFT) is used to analyze the key features provided by machine learning, with results suggesting that the volumes, valence electrons, and bulk module factors have a significant impact. This research supplies an efficient way of using machine learning to predict and optimize the dehydrogenation enthalpy. In addition, DFT calculation also validates the feature importance outputted by machine learning and reveals the principle of feature effects at the microscopic aspect. • ML models predict precisely the dehydrogenation enthalpy of V–Ti–Cr–Fe alloy. • Properties calculation optimized by GA have good agreement with experiments. • Explanation of volume, electron and module factors affecting enthalpy using DFT. [ABSTRACT FROM AUTHOR]

In this paper we investigate the nature of hydrogen diffusion in substoichiometric TiC using simulations. Specifically, we examine how well connected the carbon structural vacancies are in TiC x using percolation theory and how many structural carbon vacancies are connected to the surface of TiC x. This provides direct insight into the number of sites available for hydrogen storage and the interconnected nature of the carbon vacancy network. We also compute the binding energies and migration energies of hydrogen in TiC x using density functional theory. This is conducted over a range of carbon concentrations from nearly stoichiometric TiC to Ti 2 C and includes the differences in vacancy ordering. We find that the migration energy of hydrogen in TiC x generally decreases with carbon loss and is associated with the tetrahedral interstices near them but that the binding energy of hydrogen to TiC x is independent of carbon concentration. Furthermore, we show that this migration path can occur through the tetrahedral interstices, which is influenced by local carbon concentration. These results also demonstrate the vacancy ordered R 3 ¯ m Ti 2 C structure does not possess any more superior ability to store or transport hydrogen than the F d 3 ¯ m Ti 2 C structure. • Hydrogen insertion in TiC x should occur for carbon concentrations below TiC 0.7. • The energy barriers for hydrogen diffusion drop with carbon concentration. • Hydrogen diffusion occurs from carbon vacancy to tetrahedral interstice. • It is easier to diffuse hydrogen into ordered F d 3 ¯ m Ti 2 C than R 3 ¯ m Ti 2 C. [ABSTRACT FROM AUTHOR]

The perovskite-type hydride compounds are potential candidate materials in the field of hydrogen storage. This paper presents a systematical study of XTiH 3 (X = K, Rb, Cs) using density functional theory. The analysis of formation energy, elastic properties and phonon dispersion curves indicate that all the studied materials are thermodynamically, mechanically and dynamically stable. By analyzing the B/G ratio, it is determined that these compounds are brittle materials. The electronic properties reveal that the XTiH 3 compounds exhibit semi-metallic characteristics. The charge transfer characteristics of these compounds were analyzed using Bader partial charges. Moreover, the thermodynamic characteristics of these compounds were investigated and the dependence of their free energy, entropy and heat capacity on the temperature were analyzed. Finally, the gravimetric hydrogen storage capacities of KTiH 3 , RbTiH 3 and CsTiH 3 were calculated to be 3.36, 2.22 and 1.65 wt%, respectively. The hydrogen desorption temperatures of KTiH 3 , RbTiH 3 and CsTiH 3 were found to be 209 K, 161 K and 107 K, respectively. To our knowledge, this study represents the very first investigation of XTiH 3 compounds and offers valuable references to this hydrogen storage material. [Display omitted] • XTiH 3 (X = K, Rb, Cs) perovskite have been investigated using first-principles. • XTiH 3 perovskite exhibit thermodynamic, mechanical and dynamical stability. • The gravimetric hydrogen storage capacity is found to be 3.36 wt% for KTiH 3. [ABSTRACT FROM AUTHOR]

Seawater is one of the richest hydrogen sources around our environment, so it has a lot of advantages to decompose and produce hydrogen. However, considering that chloride ions in seawater have a strong corrosive action on the electrode. Therefore, the design and exploration of highly effective and antiseptic oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) electrocatalysts were studied. It's worth noting that Cu 2 S@Ni 3 S 2 /NF is engaged as a difunctional electrode in this study, which drives a current density of 10 mA cm−2 with requiring overpotentials of only 78 mV and 170 mV, and highlights its significant selectivity of OER and HER. The results show that the increased activity of Cu 2 S@Ni 3 S 2 /NF electrode can be assigned to the synergistic catalysis of (211) and (110) crystal faces, as well as the transfer and the increase of the number of active sites caused by lattice defects. The results of density functional theory show that Cu 2 S material has optimal free energy of the adsorbed states for H, indicating that the introduction of Cu 2 S promotes the kinetics of the reaction. The introduction of Ni 3 S 2 material greatly improves the conductivity of Cu 2 S@Ni 3 S 2 /NF electrode. This paper proposes novel insights into the exploration of environmentally friendly and corrosion resistant difunctional catalysts for seawater splitting. Cu 2 S@Ni 3 S 2 /NF is used as a difunctional catalyst in this study, which provides a current density of 10 mA cm−2 with required overpotentials of only 130 mV and 170 mV, and highlights its significant selectivity of OER and HER. [Display omitted] • Cu 2 S@Ni 3 S 2 electrodes was synthesized for the first time through hydrothermal processes. • The overpotential of Cu 2 S@Ni 3 S 2 electrode is only 130 m V at 100 mA cm−2 for OER. • Density functional theory analysis demonstrates that the Ni 3 S 2 material presents optimal free energy for H. [ABSTRACT FROM AUTHOR]