Breaking Structural Symmetry of Atomically Dispersed Co Sites for Boosting Oxygen Reduction

Abstract Breaking structural symmetry is regarded as an efficient strategy for modulating the electronic structure of single‐atom catalysts (SACs), but achieving precise modulation through SACs symmetry breaking for better catalysis remains challenging. Herein, this work proposes a comprehensive integration of theoretical predictions and experimental validation, demonstrating the rational modulation of the coordination environment in traditional Co‐N 4 sites to break their structural symmetry for boosting their oxygen reduction reaction (ORR) activity. Four Co‐SACs models with Co‐N 4 , Co‐N 3 C, Co‐N 2 C 2 , and Co‐N 3 ‐Nv moieties are first constructed by theoretical calculations, which validate that the asymmetric Co‐N 3 C exhibits a moderate adsorption energy of OOH * in comparison with those of Co‐N 4 , Co‐N 2 C 2 , and Co‐N 3 ‐Nv models, respectively. And, the Co SAC ‐N 3 C/NC and Co SAC ‐N 4 /NC are precisely prepared by directly controlling the pyrolysis temperature without secondary treatment. In situ Fourier transform infrared and Raman spectroscopy further reveal that the bonding of OOH * intermediate on Co SAC ‐N 3 C/NC is strengthened compared to Co SAC ‐N 4 /NC. As such, Co SAC ‐N 3 C/NC demonstrates outstanding ORR activity with a half‐wave potential of 0.9 V and fast kinetics. Zinc‐air batteries assembled with Co SAC ‐N 3 C/NC as air cathode exhibit a high‐power density (310.2 mW cm −2 ) and superior cycling stability (1400 cycles). This work elucidates the critical role of breaking the structural symmetry of SACs for better catalysis.