Unique electron-feeding mechanism in CoN₃O for enhanced acidic oxygen reduction

Co-centered single-atom catalysts (SACs) have emerged as an increasingly promising non-platinum group candidate for acidic oxygen reduction reaction (ORR) due to their balanced activity and stability. However, the intrinsic ORR activity of present Co-centered SACs remains far below the commercial Pt/C. Herein, a CoN₃O-structured SAC is successfully fabricated by a gas-phase strategy and achieves a peak power density of 492.6 mW cm⁻² under the 1.0 bar H₂/air condition, demonstrating its excellent application potential in practical fuel cells. Unique electron-feeding mechanism is revealed to account for the remarkably enhanced ORR activity inner CoN₃O SAC. It is indicated that the electron interaction inner active site governed by both electronegativity in σ bond and d-p back-feeding in π bond reaches balance at CoN₃O, thus optimized adsorption of oxygen-containing intermediates. Our work provides multiple insights into the orbital scale laws for higher-performance PGM-free ORR catalysts.