Bifunctional enhancement via geometry and electronic effects of Co-Nx sites enables durable ORR catalysts in Zn-air battery

Non-precious metal catalysts have emerged as the leading candidate to replace platinum-based catalysts due to their cost-effectiveness. However, the sluggish oxygen reduction kinetics and inadequate durability limit their application in zinc-air battery technology. Herein, we demonstrate a facile strategy to construct a hierarchical architecture of N-doping γ-graphyne-supported carbon nanotubes encapsulating cobalt nanoparticles (Co@N-CNT/N-GY). This unique structure prevents the aggregation and exfoliation of nanoparticles, thereby enhancing the catalysts durability. Synchrotron radiation absorption spectroscopy confirms the presence of Co-N x coordination in Co@N-CNT/N-GY, which contributes to promote the oxygen reduction reaction. Density-functional theory calculations further reveal that nitrogen doping in carbon nanotubes induces substantial charge redistribution among adjacent carbon atoms, facilitating the formation of the OOH* intermediate and lowering the overall Gibbs free energy barrier. Moreover, the open-pore architecture of N-doping γ-graphyne promotes the rapid diffusion of dissolved oxygen and creates abundant gas-liquid-solid interfaces, thereby boosting the Oxidation-reduction reaction (ORR) kinetics. As a result, the Co@N-CNT/N-GY catalyst delivers a high specific capacity (723 mAh g −1 ) and excellent power density (135.86 mW cm −2 ) when employed in a zinc-air battery. This study provides valuable insights for designing the γ-graphyne-supported non-precious metal ORR electrocatalyst with high activity and durability.