Catalytic activity for hydrogen evolution reaction of Janus monolayer MoXTe (X=S, Se)

At present, the precious metal Pt is a common catalyst for large-scale hydrogen evolution reaction (HER) production of hydrogen, but due to its high price and scarcity, finding an innovative catalyst has become the key to electrocatalytic hydrogen evolution. Here, the HER electrocatalytic activity of Janus MoXTe (X = S, Se) monolayers was investigated through first-principles calculations. Mo vacancy, X vacancy and Te vacancy were introduced into 2H, 1T, and 1T’ phase respectively and their stability was studied. The results show that the introduction of vacancy can improve the electrocatalytic hydrogen evolution performance. Particularly, the Gibbs free energies (ΔGH) of Te vacancy of 2H phase MoSTe and MoSeTe are close to zero (ΔGH = 0.03, −0.05 eV, respectively), and has the highest exchange current density. We further find that the conductivity of 2H phase MoSTe and MoSeTe is enhanced after introducing Te vacancy. In details, H get 1.86 and 1.43 e on VTe in 2H phase MoSTe and MoSeTe. The bond between S and H is more stable, H is better adsorbed on the catalyst, and the performance is improved. Our research provides a strategy for designing MoXTe monolayer electrocatalysts, which are predicted to be employed in HER catalysts with low cost and high performance.