Breaking Charge Symmetry in Co-Zn Dual‑Atom Catalyst With Axial Sulfur Coordination for Efficient Oxygen Reduction Reaction.

Dual-atom catalysts (DACs) represent an emerging and promising paradigm in electrocatalysis. Nevertheless, their symmetric electron density distribution hampers the polarization and subsequent scission of the O─O bond. In this work, a Co-Zn DAC with axial sulfur coordination (Co─Zn@SNC) was constructed via a molecular-cage encapsulation method. The as-synthesized catalyst demonstrated outstanding oxygen reduction reaction (ORR) activity across a wide pH range, with half-wave potentials of 0.902 V in 0.1 M KOH, 0.817 V in 0.1 M PBS, and 0.809 V in 0.1 M HClO4. Theoretical calculations revealed that the axially coordinated S not only modulated the orbital and electronic structure of the Co active center but also collaborated with the nearby Zn site to induce an asymmetric charge distribution within the Co-N4, thereby shifting the catalytic activity closer to the peak of the Sabatier volcano plot. The zinc-air battery (ZAB) and microbial fuel cell (MFC) assembled with the Co─Zn@SNC cathode exhibited peak power densities of 166.36 mW cm-2 and 1.505 W m-2, respectively, as well as good stability. The present work provided fundamental insights into the precise regulation and underlying mechanism of DACs, offering a viable strategy for the rational design of advanced electrocatalysts for energy storage and conversion applications.