Elementary Steps of the Oxygen Reduction Reaction on Nitrogen-Doped Graphene Revealed by Raman Spectroelectrochemistry

Nitrogen-doped graphene (N-doped graphene) is a promising material for electrochemical applications, particularly as a catalyst in the oxygen reduction reaction (ORR). Despite numerous studies, the detailed mechanism of ORR on N-doped graphene remains unresolved. This study utilizes spectroelectrochemical Raman (SEC-Raman) spectroscopy to investigate the elementary steps of the ORR on graphene doped with pyridinic and graphitic nitrogen configurations. A comprehensive Raman spectral analysis reveals the evolution of adsorbed species and active sites during the reaction, suggesting an unconventional pathway involving outer-sphere electron transfer and unique adsorption dynamics. These insights clarify the interplay between nitrogen configurations and catalytic performance, offering a deeper understanding of the structure-activity relationship in N-doped graphene. The findings pave the way for improved design and optimization of metal-free ORR electrocatalysts.