Interstitial Doping Promotes the Hydrogen Evolution Activity of the CrI3 Monolayer

In recent years, the communities of condensed matter physics, materials, and chemistry have extensively focused on two-dimensional materials and single-atom catalysis. Our study investigates the potential of a single-atom catalyst comprising a 2D material CrI3 monolayer with an interstitial atom. It is found that inter-stitial atoms, namely, V, Co, Mo, and W, significantly reduce Delta GH values, which are lower than those of the pure CrI3 monolayer. Notably, the Delta GH value of the system with an interstitial Mo atom is 0.03 eV, which is comparable to Pt-based materials. We conclude that the weak interaction between H and interstitial atoms effectively enhances the hydrogen evolution reaction (HER) performance. Moreover, we observe that the weak interaction between H and the active atom in the pure system hampers the boost in HER performance. Our work presents a new understanding of the relationship between HER performance and geometric and electronic structures. It can stimulate further theoretical work and provide reference information for experimental research.