Decoupling Protection and Doping Unlocks Asymmetric Zn Single Atoms for Efficient Oxygen Reduction

Precise manipulation of the coordination environment in single-atom catalysts is crucial yet challenging for boosting oxygen reduction reaction (ORR) performance. Here we present a sacrificial-guided etching strategy to activate intrinsically passive d¹⁰ Zn centers in single-atom catalysts, wherein Bi(NO₃)₃-mediated protection preserves ZnN₄ coordination by mitigating excessive etching, while NaCl-driven Cl doping imparts a remote electron-withdrawing effect, concertedly modulating the electronic structure of the Zn centers. This decoupling strategy, which assigns protection and doping to distinct species, unlocks asymmetric Zn single atoms with dual precision over coordination number and dopant configuration. The resulting catalyst achieves an exceptional ORR half-wave potential of 0.916 V, surpassing commercial Pt/C, and delivers a record peak power density of 258 mW cm^-2 with outstanding cycling stability exceeding 450 h in zinc-air batteries. Integrated theoretical and in situ spectroscopic analyses reveal that Cl incorporation disrupts the symmetric ZnN₄ electronic structure, optimizes the d-band center, and alters unoccupied orbital hybridization, thereby accelerating O₂ protonation and boosting the overall catalytic activity. This work establishes a well-defined strategy for the precise construction of single-atom metal centers, providing insights into the development of high-performance non-precious metal electrocatalysts.