Highly Exposed Discrete Co Atoms Anchored in Ultrathin Porous N, P-Codoped Carbon Nanosheet for Efficient Oxygen Electrocatalysis and Rechargeable Aqueous/Solid-State Zn-Air Batteries

Single atom catalysts (SACs) exhibit desirable catalytic properties in key renewable energy reactions and devices. However, rational design of SACs and boost their performances for oxygen electrocatalysis and rechargeable Zn-Air batteries (ZABs) are still crucial yet challenging. Herein, single Co stoms anchored in ultrathin N, P-codoped porous carbon nanosheet (CoSA/NPC) were prepared by in situ confinement pyrolysis strategy. The ultrathin nanosheet structure provide ideal platform for high exposure of the generated Co active sites and extremely shortening the electron transport pathways. Both experimental and theoretical results demonstrate that the N/P coordinated Co sites enables optimized charge distribution and facilitates oxygen intermediates adsorption/desorption. Such CoSA/NPC catalyst exhibits high oxygen reduction reaction (ORR) activity with a half-wave potential (E1/2) of 0.87 V and oxygen evolution reaction (OER) property with a low potential of 1.67 V at 10 mA cm−2. As the air electrode in ZABs, it demonstrates high peak power density of 204.3 mW cm-2 and excellent long-term stability in aqueous ZABs. It also reveals superior flexibility and stability in solid-state ZABs. Thus, CoSA/NPC is a promising bifunctional electrocatalyst for practical applications in aqueous and flexible solid-state ZABs.