New Insight on Hydrogen Evolution Reaction Activity of MoP₂ from Theoretical Perspective

Abstract

We systematically investigated the hydrogen evolution reaction (HER) of six facets of MoP 2 based on the periodic density functional theory (DFT). The calculated values of Gibbs free energy of hydrogen adsorption ( Δ G H ) indicated that the (111) facet has a good HER activity for a large range of hydrogen coverages. The zigzagged patterns before 75% hydrogen coverage suggest a facilitation among Mo1, P1 and Mo2 sites, which are attributed to repeat occupancy sites of H atoms. From ab initial atomistic thermodynamics analysis of hydrogen coverage, we gained that the most stable coverage of hydrogen is 18.75% at 1 atm H 2 and 298 K. Finally, the doping effects on HER activity were investigated and found that catalytic performance can be improved by substituting P with an S or N atom, as well as substituting the Mo atom with an Fe atom, respectively. We hope this work can provide new insights on further understanding of HER for MoP 2 and give instructions for the experimental design and synthesis of transition metal phosphides (TMPs)-based high-performance catalysts.

Keywords

• hydrogen evolution reaction
• periodic density functional theory
• hydrogen coverage
• catalytic performance
• MoP₂