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Two-dimensional (2D) van der Waals (vdW) heterostructures have attracted much attention due to their unique properties in photocatalysis, electronics, and energy storage. This work comprehensively analyzed the electronic properties and photocatalytic efficiency properties of 2D vdW MoS2/Hf2CO2 heterostructure by first-principles calculations and molecular dynamics simulation. An ideal band gap of 1.44 eV was found for visible light absorption. Meanwhile, a high solar-to-hydrogen efficiency of 17.14% is obtained from the calculated band-edge positions, and a high power conversion efficiency of 13.84% is also confirmed by spectroscopy limited maximum efficiency simulation. We estimate the time scale for electron–hole transfer and recombination times using a combination of non-adiabatic molecular dynamics and time-dependent density functional theory. A suitable e-h recombination time of 1.86 ns and electron (hole) transfer time of 331 (978) fs are obtained in the 2D MoS2/Hf2CO2 heterostructure, which is expected to ensure high photocatalytic efficiency. Therefore, the constructed MoS2/Hf2CO2 heterostructures provide a new example for the prediction of high-performance nano optoelectronic devices. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) van der Waals (vdW) heterostructures have attracted much attention due to their unique properties in photocatalysis, electronics, and energy storage. This work comprehensively analyzed the electronic properties and photocatalytic efficiency properties of 2D vdW MoS2/Hf2CO2 heterostructure by first-principles calculations and molecular dynamics simulation. An ideal band gap of 1.44 eV was found for visible light absorption. Meanwhile, a high solar-to-hydrogen efficiency of 17.14% is obtained from the calculated band-edge positions, and a high power conversion efficiency of 13.84% is also confirmed by spectroscopy limited maximum efficiency simulation. We estimate the time scale for electron–hole transfer and recombination times using a combination of non-adiabatic molecular dynamics and time-dependent density functional theory. A suitable e-h recombination time of 1.86 ns and electron (hole) transfer time of 331 (978) fs are obtained in the 2D MoS2/Hf2CO2 heterostructure, which is expected to ensure high photocatalytic efficiency. Therefore, the constructed MoS2/Hf2CO2 heterostructures provide a new example for the prediction of high-performance nano optoelectronic devices. [ABSTRACT FROM AUTHOR]

The fabricated VS 4 /Ni 3 S 2 /NF NBs was prepared by self-templated strategy, with exposed abundant hetero-interfaces and high active disulfide (S 2 2-) sites. The density functional theory revealed the reversible conversion catalysis mechanism of bridge S 2 2- during HER process, jointly promoting the HER performance. [Display omitted] • A novel VS 4 nanoparticle decorated Ni 3 S 2 nanobelt array was synthesized via one-step organic ligand-assisted solvothermal method. • The abundant disulfide (S 2 2-) moieties grafted on the hetero-interfaces of VS 4 /Ni 3 S 2 led to strong electronic interaction and promote the chemisorption of H-containing intermediates. • The density functional theory reveals the reversible conversion catalysis mechanism about disulfide (S 2 2-) sites during HER process. • The findings provide fresh insights for developing potential polysulfides as high-performance hydrogen-evolving electrocatalysts from water splitting. Elaborate and rational design of cost-effective and high-efficiency non-noble metal electrocatalysts for pushing forward the sustainable hydrogen fuel production is of great significance. Herein, a novel VS 4 nanoparticle decorated Ni 3 S 2 nanobelt array in-situ grown on nickel foam (VS 4 /Ni 3 S 2 /NF NBs) was prepared by a self-templated synthesis strategy. Benefitting from the unique nanobelt array structure, abundant highly active bridge S 2 2- sites and strong electronic interaction between VS 4 and Ni 3 S 2 on the heterointerface, the integrated VS 4 /Ni 3 S 2 /NF NBs exhibited excellent electrocatalytic hydrogen evolution activity and robust stability. The density functional theory (DFT) further revealed the reversible conversion catalysis mechanism of bridging S 2 2- sites in VS 4 /Ni 3 S 2 /NF NBs during HER process. Notably, bidentate bridging S S bonds as the predominant catalytically active centers can spontaneously open once H adsorbed its surface, leading to the aggregation of negative charges on S atoms and thus facilitating the generation of H* intermediates, and spontaneously close when H* desorption is going to form H 2. Our work provides fresh insights for developing potential polysulfides as high-performance hydrogen-evolving electrocatalysts for prospective clean energy production from water splitting. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) are expected to be an effective solution for energy storage to be applied to various electronic devices due to their cost-effective performance and similar working principles to lithium-ion batteries (LIBs). However, the electrochemical performances of SIBs are currently hindered by the challenges posed by the large size and slow diffusion kinetics of Na+. Chalcogenide heterojunctions have great potential in SIBs anode materials. Therefore, this study presents a MoSSe heterojunction with a three-dimensional flower-like spherical structure. This heterojunction exhibits enhanced Na+ adsorption and storage capabilities, a high rate of Na+ diffusion, and improved structural stability. These excellent structures and characteristics are highly beneficial for Na+ storage, demonstrating superior stability, and large capacity. Consequently, the designed MoSSe exhibits long cycling stability at 5.0 A g−1 (195.2 mAh g−1 after 2000 cycles) and exceptional capacity at 0.1 A g−1 (413.1 mAh g−1). This work demonstrates that heterojunctions can become excellent electrode materials for SIBs to achieve stable sodium energy storage. [Display omitted] • The 3D flower spheres MoSSe heterojunction improves the electronic conductivity. • The MoSSe possesses a good cyclability over 2000 cycles with a capacity of 195.2 mAh/g at 5.0 A/g. • The MoSSe shows high-rate performance of 181.2 mAh/g at 5.0 A/g. [ABSTRACT FROM AUTHOR]

The schematic diagram of MoSe 2 /NiSe‖Na 3 V 2 (PO 4) 3 /C full-cell, and the schematic diagram of charge–discharge process is shown in the Figure. [Display omitted] • The 3D flower spheres MoSe 2 /NiSe heterojunction can effectively alleviate the volume expansion during sodiation/desodiation process. • The DFT calculation results reveal the charge transfer mechanism between MoSe 2 and NiSe. • The MoSe 2 /NiSe possesses a good cyclability over 3000 cycles with a capacity of 172 mAh/g at 5.0 A/g. • The full cell with Na3V2(PO4)3/C cathode shows high-rate performance of 276 mAh/g at 2.0 A/g. Due to the large size of Na+ and the slow redox kinetics, the energy storage performance of sodium ion batteries (SIBs) is far from satisfactory. Heterojunction with layered structure has great potential in advanced material of SIBs. Herein, the 3D flower spheres MoSe 2 /NiSe heterostructure with fast dynamic properties was proposed, which shows enhancement in the adsorption and storage capacity of Na+ with a low migration energy barrier. Unique structure design can further effectively alleviate the volume expansion during sodiation/desodiation process. Furthermore, the DFT calculation results reveal the charge transfer mechanism between NiSe and MoSe 2 , as well as improved intrinsic electric structure of MoSe 2 /NiSe. In consequence, the designed MoSe 2 /NiSe possesses a good cyclability over 3000 cycles with a capacity of 172 mAh/g at 5.0 A/g, and the full cell with Na3V2(PO4)3/C cathode shows high-rate performance of 276 mAh/g at 2.0 A/g, which solidly proves the feasibility of the designed MoSe 2 /NiSe anode in the practical application. This work shows that the heterojunction can achieve long-lasting sodium electrochemistry and expand to other energy storage fields. [ABSTRACT FROM AUTHOR]