Dispersed Co–N 4 Sites on N‐Doped Porous Carbon for High‐Performance pH‐Universal ORR Catalyst

Developing cost‐effective, highly active, wide‐pH oxygen reduction reaction (ORR) electrocatalysts remains a critical challenge for replacing platinum‐group‐metal benchmarks in emerging electrochemical energy systems. In this work, we report a facile approach to synthesize single‐atom‐type catalyst Co 1 @N 4 ‐C catalyst using renewable bacterial cellulose (BC) as the carbon source. BC’s intrinsic 3D nanofibrous structure greatly suppresses active moiety agglomeration during thermal conversion, yielding uniformly dispersed Co–N4 sites in hierarchically porous carbon with excellent ORR activity under alkaline, acidic, and neutral conditions. Specifically, the catalyst delivers half‐wave potentials of 0.83, 0.84, and 0.687 V (vs. RHE) in alkaline, acidic, and neutral media, respectively, values that are comparable to or even surpass those of commercial Pt/C. In addition, Co 1 @N 4 ‐C exhibits superior electrochemical durability, retaining 97.7%, 95.2%, and 94.1% of the initial current density after 11 000 cycles in alkaline, acidic, and neutral electrolytes, respectively. Furthermore, when integrated as the air‐cathode catalyst in a zinc–air battery, the device delivers a peak power density of 122 and 125 mW cm −2 under alkaline and neutral conditions, respectively, together with excellent cycling stability, underscoring the practical promise of this catalyst for real‐world energy conversion devices.