Mechanism for hydrogen evolution from water splitting based on a MoS/WSe heterojunction photocatalyst: a first-principle study.

In this study, density functional theory and hybrid functional theory are used to calculate the work function and energy band structure of MoS and WSe, as well as the binding energy, work function, energy band structure, density of states, charge density difference, energy band alignment, Bader charge, and H adsorption free energy of MoS/WSe. The difference in work function led to the formation of a built-in electric field from WSe to MoS, and the energy band alignment indicated that the redox reactions were located on the MoS and WSe semiconductors, respectively. The binding energy of MoS and WSe indicated that the thermodynamic properties of the heterogeneous structure were stable. MoS and WSe gathered electrons and holes, respectively, and redistributed them under the action of the built-in electric field. The photogenerated electrons and holes were enriched on the surface of WSe and MoS, which greatly improved the efficiency of hydrogen production by photocatalytic water splitting.