Activating Catalytic Inert Basal Plane of Molybdenum Disulfide to Optimize Hydrogen Evolution Activity via Defect Doping and Strain Engineering

Molybdenum disulfide (MoS2) is a promising alternative hydrogen evolution reaction (HER) catalyst to high-cost platinum (Pt) due to its large surface area, low cost, easy preparation, and earth abundance. The HER efficiency of MoS2 remains low because only the edge S-sites are active for the HER. In this work, two practical strategies, heteroatom doping (Rh, Pd, and Ag) and strain engineering, are proposed to activate the inert in-plane S-site for the HER. The density functional theory calculations demonstrate that doping MoS2 with heteroatom can trigger the HER activity of the S atoms next to the doping atoms, with a negative hydrogen adsorption free energy (ΔGH*0). The negative ΔGH*0 can be further significantly optimized by a small compressive strain. Therefore, the combination of heteroatom doping and a small compressive strain can yield an ideal value of hydrogen-binding free energy (ΔGH*0 = 0 eV) for HER. These results highlight an innovative avenue to optimize the HER performance of MoS2.