Computational screening of oxygen and sulfur decorated MXene supported transitions metal single-atom catalysts for hydrogen evolution reaction

Herein, we systematically performed the comparative analysis of 24 transition metals single-atom catalysts (SACs) supported on MXene (Mo₂CT₂; T = O or S) surface for hydrogen evolution reaction (HER) and investigated their electronic structures, geometries, stabilities, selectivity, and catalytic activities by using first-principles calculations. The molecular dynamics and thermal stabilities of MXene (Mo₂CO₂ and Mo₂CS₂) monolayers were first investigated by using AIMD simulations and phonon dispersion spectra. Based on the Volmer-Heyrovsky pathway, TM/Mo₂CO₂ (TM = Ti, V, Cr, Co, Mo, Tc, Ru) and TM/Mo₂CS₂(TM = Cr, Mn, Fe, Zn, Tc, Ru, W, Pt) SACs exhibited good catalytic performance for HER and their ΔG_H* values are close to the optimum value (ΔG_H* → 0). The calculated ΔG_H* values of Ti/Mo₂CO₂, Mo/Mo₂CO₂, Tc/Mo₂CO₂, Ru/Mo₂CO₂, Zn/Mo₂CS₂, W/Mo₂CS₂, Cr/Mo₂CS_2, and Pt/Mo₂CS₂ are equal or better than Pt (111) catalyst, making them active and selective catalysts for HER. Moreover, Mo/Mo₂CO₂ and Pt/Mo₂CS₂ catalysts exhibited outstanding catalytic performance towards HER much better than the Pt (111) catalyst. Therefore, the present investigation would provide a useful guideline for experimentalists to design MXene-based transition metals SACs for HER and other electrochemical applications.