Enhancing the hydrogen evolution reaction by non-precious transition metal (Non-metal) atom doping in defective MoSi2N4 monolayer

Highlights: • The HER performance of the MoSi₂N₄ monolayer with non-noble metal (non-metal) doping. • The O, P, Fe and Nb doped MoSi₂N₄ present a near-zero ΔG_H. • The "states filling" model well explains the novel HER activities. • The energy level of the first unoccupied states modulates the hydrogen binding strength. Two-dimensional (2D) hydrogen evolution reaction (HER) electrocatalysts have attracted great attention due to their unique electronic properties and high activities. Recently, a new 2D monolayer material of MoSi₂N₄ has been successfully synthesized and its semiconducting property and excellent ambient stability have also been demonstrated (Science 2020, 369, 670). Here, a systematic screening of catalysts for HER among N- and Si-defective MoSi₂N₄-supported single non-precious transition metal (TM) and non-metal (NM) atom catalysts is performed by means of density functional theory (DFT) calculations. Interestingly, the single O/P/Fe/Nb atom doped N-(Si-) defective MoSi₂N₄ monolayer were found to possess excellent HER performance presenting a near-zero ΔG_H, which is comparable to or even better than the state-of-the-art Pt-based materials. Moreover, the novel HER activities of some TM doped structures were explained by the "states filling" model. The energy level of the first available unoccupied states for accommodating hydrogen drops after the introduction of TM atom, which modulates the hydrogen binding strength. This work opens the door for the application of MoSi₂N₄ monolayer and other related 2D materials in the field of energy conversion.