Enhancing hydrogen evolution on the basal plane of transition metal dichacolgenide van der Waals heterostructures

Recent years have seen a surge in the use of low-dimensional transition metal dichacolgenides, such as MoS2, as catalysts for the electrochemical hydrogen evolution reaction. In particular, sulfur vacancies in MoS2 can activate the inert basal plane, but that requires an unrealistically high defect concentration (~9%) to achieve optimal activity. In this work, we demonstrate by first-principles calculations that assembling van der Waals heterostructures can enhance the catalytic activity of MoS2 with low concentrations of sulfur vacancies. We integrate MoS2 with various two-dimensional nanostructures, including graphene, h-BN, phosphorene, transition metal dichacolgenides, MXenes, and their derivatives, aiming to fine-tune the free energy of atomic hydrogen adsorption. Remarkably, an optimal free energy can be achieved for a low sulfur vacancy concentration of ~2.5% in the MoS2/MXene-OH heterostructure, as well as high porosity and tunability. These results demonstrate the potential of combining two-dimensional van der Waals assembly with defect engineering for efficient hydrogen production