Co single atoms and Co nanoparticle relay electrocatalyst for rechargeable zinc air batteries

The commercialization of rechargeable zinc air batteries (ZABs) requires the discovery of high-performance, low-cost and durable bifunctional oxygen electrocatalysts. In this work, we report nitrogen doped carbon nano/microtubes confined metallic cobalt nanoparticles and single atoms ([email protected]/[email protected]) as robust oxygen electrocatalyst for rechargeable ZABs. [email protected]/[email protected] exhibits 18 times better ORR performance than [email protected] ascribed to the relay catalysis by Co-SAs and Co-NPs via O2→H2O2→H2O pathway. Experimental and theoretical investigations reveal that Co-SAs are capable of efficient oxygen reduction to H2O2, which is further reduced to H2O by Co-NPs due to its higher oxophilicity. Besides, due to the formed microtubes, the overpotential at 100 mA cm−2 in OER catalysis is lowered by 130 mV for [email protected]/[email protected] than [email protected] The power density of the assembled rechargeable ZAB is 155 mW cm−2 for [email protected]/[email protected] outperforming the noble-metal counterpart (Pt/CB-IrO2: 71 mW cm−2). Furthermore, a superior stability with inappreciable increment in voltage gap for 300 h is achieved. [email protected]/[email protected] also performs its high potential in the practical application with a maximum battery performance of 120 mW cm−2 sustained for 17 h in all-solid-state ZABs test.