Harnessing Pyridinic N Vacancy Defect in Microporous Structures to Induce the Pre‐Adsorption of Oxygen and Boost Oxygen Reduction Reaction Kinetics

Abstract

Abstract Defect structures within the carbon matrix play a crucial role in enhancing the oxygen reduction reaction (ORR) activity of Fe single atom and nitrogen‐doped catalysts (Fe‐N‐C SACs). However, overlooking the O 2 pre‐adsorption process induced by defective structures hampers the precise identification of active sites and the investigation of the reaction mechanism in Fe‐N‐C SACs. Hence, we report a Fe SAC with abundant pyridinic N vacancy defects in microporous structures (Fe‐N v ‐C SAC) and propose a synergistic effect between pyridinic N vacancy defects and O 2 molecules that promotes the kinetics of ORR. The developed Fe‐N v ‐C SAC demonstrates exceptional ORR performance, exhibiting superior mass activity and turnover frequency compared to conventional Fe‐N‐C SACs. The in situ Fourier transform infrared spectroscopy (FTIR) and theoretical calculations indicate that pyridinic N vacancy defects in microporous structures facilitate pre‐adsorption of O 2 molecules results in the d‐band centers of central Fe atoms shifting away from the fermi level. This shift weakens the adsorption strength of *OH species, thereby facilitating the kinetic process of ORR. This work addresses a critical gap in the field of electrocatalysis by providing the experimental validation of pre‐adsorption of O 2 molecules on Fe single‐atom catalysts, a phenomenon previously only speculated through theoretical calculations.