Interface engineering of heterogeneous transition metal chalcogenides for electrocatalytic hydrogen evolution.

MoS 2 and MoSe 2 are recognized as promising electrocatalysts for the hydrogen evolution reaction (HER), but the active sites are mainly located on the edge, limiting their electrochemical efficiency. Here we have introduced the 2H-1T' interface structures in MoSSe and MoS 2 -MoSe 2 heterostructures to enhance the HER activity in the basal planes by using the density functional theory (DFT) calculations. The structural stability and electronic properties of different 2H-1T' interface structures are investigated and the HER activities are evaluated by using the H adsorption free energy (Δ G H ). The H adsorption free energy along the interface boundaries is very close to zero, and the optimal sites for the HER are the S or Se atoms, which are bonded with three Mo atoms and located in the center of a hexagonal ring composed of three Mo atoms and three halogen atoms. Our study provides a different approach to activate the basal planes and efficiently improve the electrochemical HER performance of transition metal dichalcogenide materials.