Uncovering Dynamic Edge-Sites in Atomic Co-N-C Electrocatalyst for Selective Hydrogen Peroxide Production

Understanding the nature of single-atom catalytic sites and identifying their spectroscopic fingerprints are essential prerequisites for the rational design of target catalysts. Here, we apply correlated in situ X-ray absorption and infrared spectroscopy to probe the edge-site-specific chemistry of Co-N-C electrocatalyst during the oxygen reduction reaction (ORR) operation. The unique edge-hosted architecture affords single-atom Co site remarkable structural flexibility with adapted dynamic oxo adsorption and valence state shuttling between Co(2-delta)+ and Co2+, in contrast to the rigid in-plane embedded Co-1-N-x counterpart. Theoretical calculations demonstrate that the synergistic interplay of in situ reconstructed Co-1-N-2-oxo with peripheral oxygen groups gives a rise to the near-optimal adsorption of *OOH intermediate and substantially increases the activation barrier for its dissociation, accounting for a robust acidic ORR activity and 2e(-) selectivity for H2O2 production.

Automated summary

Understanding the nature and spectroscopic fingerprints of single-atom catalytic sites is crucial for designing target catalysts. In this study, in situ X-ray absorption and infrared spectroscopy were used to investigate the edge-site-specific chemistry of Co-N-C electrocatalyst during the oxygen reduction reaction. The unique edge-hosted architecture allows for remarkable structural flexibility of single-atom Co site, resulting in dynamic oxo adsorption and valence state changes. Theoretical calculations show that the in situ reconstructed Co-1-N-2-oxo and peripheral oxygen groups synergistically enhance the adsorption of *OOH intermediate and increase the activation barrier for its dissociation, leading to robust acidic ORR activity and 2e(-) selectivity for H2O2 production.