Tailoring structural properties of carbon via implanting optimal co nanoparticles in n‐rich carbon cages toward high‐efficiency oxygen electrocatalysis for rechargeable zn‐air batteries

Abstract Rational construction of carbon‐based materials with high‐efficiency bifunctionality and low cost as the substitute of precious metal catalyst shows a highly practical value for rechargeable Zn‐air batteries (ZABs) yet it still remains challenging. Herein, this study employs a simple mixing‐calcination strategy to fabricate a high‐performance bifunctional composite catalyst composed of N‐doped graphitic carbon encapsulating Co nanoparticles (Co@NrC). Benefiting from the core‐shell architectural and compositional advantages of favorable electronic configuration, more exposed active sites, sufficient electric conductivity, rich defects, and excellent charge transport, the optimal Co@NrC hybrid (Co@NrC‐0.3) presents outstanding catalytic activity and stability toward oxygen‐related electrochemical reactions (oxygen reduction and evolution reactions, i.e., ORR and OER), with a low potential gap of 0.766 V. Besides, the rechargeable liquid ZAB assembled with this hybrid electrocatalyst delivers a high peak power density of 168 mW cm−2, a small initial discharge‐charge potential gap of 0.45 V at 10 mA cm−2, and a good rate performance. Furthermore, a relatively large power density of 108 mW cm−2 is also obtained with the Co@NrC‐0.3‐based flexible solid‐state ZAB, which can well power LED lights. Such work offers insights in developing excellent bifunctional electrocatalysts for both OER and ORR and highlights their potential applications in metal‐air batteries and other energy‐conversion/storage devices.