Clarifying the effects of oxygenated groups on cobalt-nitrogen-carbon catalysts for H 2 O 2 electrosynthesis

Abstract The incorporation of oxygen functional groups (OFGs) into cobalt-nitrogen-carbon (CoNC) catalysts is widely regarded as a promising strategy for enhancing hydrogen peroxide (H2O2) electrosynthesis via the two-electron oxygen reduction reaction (2e− ORR). However, the roles and effects of OFGs in CoNC catalysts on H2O2 electrosynthesis, especially on the actual production, remain unclear. Herein, we conducted a comprehensive investigation into a series of typical CoNC catalysts with or without OFGs for H2O2 electrosynthesis. Contrary to the traditional insight, our finding demonstrates that the incorporation of OFGs into CoNC leads to a notable decline in actual H2O2 productivity. Remarkably, this phenomenon occurs across diverse oxidizing agents and CoNC catalysts, indicating its generality. Mechanistic investigations reveal that the OFGs regulate the surface chemical states and interfacial hydrophobicities of CoNC, resulting in hindered O2 diffusion, thus harming H2O2 productivity. This study not only clarifies the complex role of OFGs in CoNC catalysts for H2O2 electro-synthesis but also promotes their more extensive application in the field of electrocatalyst development.