Revealing the active sites for the electrocatalytic CO2 reduction in Co single atom catalysts using operando XAS

Transition metal-nitrogen-doped carbons (TM-N-C) are promising catalysts for key electrochemical processes like CO2 reduction (CO2RR). These catalysts incorporate nitrogen into a carbon matrix, forming binding sites for metal species, considered the active sites for CO2RR. Among TM-N-Cs, Ni-N-C is extensively studied for reducing CO2 to CO, demonstrating the highest selectivity and significant current density. Co-N-C also shows potential, but its selectivity varies widely, from 20% to 100%, indicating more complex dynamics involving multiple Co species. Our recent work with Cu-based catalysts for CO2RR highlighted how performance can be optimized through pulsed reactions, steering the catalyst structure toward specific species. We propose a similar strategy for Co-N-C, yet an operando study with high time resolution is essential to understand local structural transformations, clarify the roles of different Co species, and guide the design of a novel pulsed reaction approach.