Synergistic Interplay of Fe and Co Single‐Atom Sites Spatially Separated on g‐C ₃ N ₄ for Enhanced Electrochemical Performance in Li‐O

ABSTRACT

Developing single‐atom catalysts (SACs) with efficient atomic usage and well‐defined coordination environments is pivotal for addressing limitations in redox kinetics and durability in lithium‐oxygen (Li‐O ₂ ) batteries. Herein, an efficient yet broadly applicable ball‐milling followed by pyrolysis approach for the synthesis of bi‐metal Fe, Co SACs supported on a graphitic carbon nitride (g‐C ₃ N ₄ ) matrix is proposed. The synthesis involves a top‐down approach, where Fe and Co metals are atomized and stabilized on g‐C ₃ N ₄ support, facilitating uniform distribution of isolated metal atoms while inhibiting aggregation. This approach promotes the formation of coexisting Fe‐N ₄ and Co‐N ₄ single‐atom sites anchored on distinct triazine units within g‐C ₃ N ₄ , where the Co‐N ₄ sites serve primarily as electronic modulators of the Fe‐centred active sites. The electronic interplay between the Co and Fe‐N ₄ sites within the g‐C ₃ N ₄ framework modulates the local electronic structure and optimizes the adsorption energetics of LiO ₂ intermediates, thereby accelerating both the oxygen reduction reaction and oxygen evolution reaction. As a result, the resulting catalysts deliver enhanced discharge capacity, lower overpotential, and prolonged cycling stability in Li‐O ₂ batteries. Overall, this work provides new insights into bi‐metal synergistic catalysis on g‐C ₃ N ₄ and highlights the critical role of active‐site engineering in governing Li‐O ₂ battery performance.