Orbital Modulation with P Doping Improves Acid and Alkaline Hydrogen Evolution Reaction of MoS2

There has been great interest in developing and designing economical, stable and highly active electrocatalysts for the hydrogen evolution reaction (HER) via water splitting in an aqueous solution at different pH values. Transition-metal dichalcogenides (TMDCs), e.g., MoS2, are identified to be promising catalysts for the HER due to the limited active sites at their edges, while the large basal plane of MoS2 is inert and shows poor performance in electrocatalytic hydrogen production. We theoretically propose orbital modulation to improve the HER performance of the basal plane of MoS2 through non-metal P doping. The substitutional doping of P provides empty 3p(z) orbitals, perpendicular to the basal plane, can enhance the hydrogen adsorption for acid HER and can promote water dissociation for alkaline HER, which creates significant active sites and enhances the electronic conductivity as well. In addition, 3P-doped MoS2 exhibits excellent HER catalytic activity with ideal free energy at acid media and low reaction-barrier energy in alkaline media. Thus, the doping of P could significantly boost the HER activity of MoS2 in such conditions. Our study suggests an effective strategy to tune HER catalytic activity of MoS2 through orbital engineering, which should also be feasible for other TMDC-based electrocatalysts.