Does Doping Always Increase Activity? Theoretical Insights into Non-metallic Doping Engineering of Corrugated Graphene.

Abstract

Conventional wisdom suggests that pristine graphene (Gr) is chemically inactive and that doping is an effective strategy to enhance its catalytic activity. Nevertheless, experimental evidence has demonstrated that non-metallic element (e.g., N, P, and S) doping of Gr significantly suppresses overall hydrogenation activity, yet the underlying mechanism remains to be elucidated. The present study investigates H₂ activation on P- and S-doped corrugated Gr using density functional theory calculations. The results show that the H₂ dissociation barriers on doped corrugated Gr are higher than those on undoped corrugated Gr, thus providing a plausible rationalization of the experimental observations. Importantly, the incorporation of non-metallic elements is found to exert a geometrical and electronic effect on Gr, signified by an increased distance and a decreased difference in the p_z band center between dissociation sites, which is deleterious to the stabilization of transition states in H₂ activation. This study provides theoretical insights for the design of efficient metal-free catalysts for hydrogenation via non-metallic doping engineering.