Ultrathin carbon nanomesh enriched with highly exposed para-position ZnN2 moiety for effective oxygen electroreduction.

Atomically dispersed Zn-based catalysts with a fully filled Zn2+ 3d10 electronic configuration display exceptional stability for the oxygen reduction reaction (ORR), but their catalytic activity is inferior. Herein, an unsaturated two‑nitrogen coordinated Zn single-atom (ZnN2) anchored on carbon catalyst with highly exposed active sites (denoted as H-ZnN/C) is fabricated via a thermal etching combined with ultrasonic exfoliation strategy. Thermal etching by molten KI salt creates nitrogen defects to form an unsaturated nitrogen coordination structure within para-position ZnN2 moiety, while ultrasonic treatment exfoliates the carbon layers to form ultrathin carbon nanomesh with a thickness ∼4.3 nm. The experiments and density functional theory calculations reveal that the para-position ZnN2 moiety can induce electron redistribution of Zn from eg to t2g orbitals, downshifting the d-band center of Zn, thereby facilitating *OH intermediate desorption. Benefiting from the highly exposed para-position ZnN2, H-ZnN/C delivers a half-wave potential (E1/2) up to 0.88 V, maintains E1/2 with negligible shift after 10,000 cycles, and resists poisoning by methanol, SCN- and S2-, all exceeding the performance of commercial Pt/C catalysts. This work provides a new prospect for rational design of high-performance and robustness ORR electrocatalysts.