Trace Ni Doping Reduces Electron Transfer in Co-Carbon Catalysts for Oxygen Reduction

Designing nonprecious electrocatalysts that simultaneously exhibit optimal intrinsic activity and rapid mass transfer capabilities for the oxygen reduction reaction (ORR) is an area of intense research but remains a significant challenge. To overcome this challenge, a hybrid composite consisting of trace Ni doped Co nanoparticles uniformly embedded within hierarchically structured macro-/meso-/microporous N-doped carbon polyhedra (HOMC) has been rationally designed. The theoretical analyses reveal that incorporating trace Ni reduces electron transfer from cobalt species to HOMC, promoting the desorption of *OH at the C/N site. As anticipated, the DNi-Co@HOMC demonstrates exceptional ORR performance, achieving a half-wave potential of 0.917 V (vs RHE), outperforming most transition metal-embedded carbon catalysts reported so far. Notably, employing the DNi-Co@HOMC catalyst as the air electrode in a zinc–air battery yields a higher open-circuit voltage (1.459 V) and power density (105.58 mW cm–2) than those achieved by the commercial Pt/C + IrO2 catalyst. These findings are anticipated to drive the advancement of advanced nonprecious catalysts for energy storage and conversion technologies.