Activating MoS2 basal planes for hydrogen evolution through the As doping and strain

As a non-precious catalyst for the electrochemical hydrogen evolution reaction (HER), the two-dimensional MoS₂ has been widely studied. To activate the MoS₂ inert basal plane to enable optimal activity, high defect concentration of sulfur vacancies is needed. Herein, based on the first-principles calculations we demonstrate that the HER of MoS₂ can be greatly enhanced by As doping and biaxial strain. We show that the As-doping sites are new catalytic sites and the bonding of H can be greatly enhanced. Moreover, the relative hydrogen adsorption free energy ($\mathrm{\Delta }\mathrm{\Delta }{\mathrm{G}}_{\mathrm{H}}$) can be further manipulated by the strain effect, which efficiently adjusts the catalytic activity. With the synergy of the biaxial strain (2%–3%) and the uniform doping of the As atoms (3.125% concentration), the $\mathrm{\Delta }\mathrm{\Delta }{\mathrm{G}}_{\mathrm{H}}$ can be modulated to zero. Our findings provide a way to achieve the high intrinsic HER activity among molybdenum-sulfide-based catalysts.