The reaction mechanism and kinetics of H2O2 production on graphene modified by oxygen functional groups: the effect of an aqueous environment†

Abstract

Carbon-based materials incorporated with oxygen functional groups (OFGs-Gr) exhibit outstanding electrocatalytic performance for hydrogen peroxide (H₂O₂) production via the two-electron oxygen reduction reaction (2e⁻ ORR). Currently, the nature of the active functional group and the underlying reaction mechanism are still under debate. Herein, we constructed the OFGs-Gr structures and systematically investigated the effect of the aqueous environment (including pH and electrode potential) on the catalyst performance in combination with ab initio molecular dynamics (AIMD). The carboxyl group (COOH-Gr structure) plays a key role in the neutral solution environment. The water molecules on COOH-Gr effectively modified the interaction of the C sites with OOH. The adsorption strength of OOH increases with increasing pH, resulting in an ether group (dopant-Gr in the C–O–C structure), maintaining excellent properties in alkaline media. Furthermore, our calculations demonstrate that the selectivity of H₂O₂ generation for dopant-Gr is increased by an elevated electrode potential, while the selectivity for COOH-Gr is decreased. These findings provide a dynamic perspective that elucidates that both pH and electrode potential synergistically influence the catalytic properties for H₂O₂ synthesis.