Phosphorus‐Doping‐Induced Optimization of Atomic Hydrogen Binding Energy in MoSe ₂ under High Coverage for Efficient Electrocatalytic Hydrogen Evolution Reactions

Abstract

Abstract Self‐standing two‐dimensional P‐doped molybdenum diselenide (MoSe 2 ) nanosheets were synthesized on carbon fiber paper (CFP) (P‐doped MoSe 2 /CFP) using a hydrothermal reaction followed by phosphorization and were subsequently used as a high‐efficiency hydrogen evolution reaction (HER) electrocatalyst. Nanosheet aggregation was remarkably inhibited, and numerous active sites were exposed. The H adsorption and desorption capacities of MoSe 2 were optimized by doping P atoms in the MoSe 2 lattice. Electrochemical testing indicated that the overpotential ( η 50 ) required by P‐doped MoSe 2 /CFP was only 186 mV, which was much lower than that of the as‐prepared MoSe 2 /CFP (237 mV). The Tafel slope of P‐doped MoSe 2 /CFP was 54.3 mV ⋅ dec −1 , which was remarkably lower than that of the as‐prepared MoSe 2 /CFP (79.8 mV ⋅ dec −1 ). The Gibbs energy of the H atoms adsorbed on P‐doped MoSe 2 (ΔG H* ) reached the lowest value (0.202 eV) when the hydrogen coverage ( θ H ) was 75 %. For MoSe 2 , the lowest ΔG H* value was 0.296 eV when θ H was 25 %. The adsorption and desorption of H atoms at the active sites of P‐doped MoSe 2 occurred easier than at the active sites of MoSe 2 . Moreover, the P doping effect facilitated the formation of more H ads species during the Volmer reaction and substantially accelerated the kinetics of the HER.