Ultrathin B, N co-doped porous carbon nanosheets derived from intumescent flame retardant for rechargeable Zn-air battery

Engineering highly efficient and robust porous carbon materials for the oxygen reduction and oxygen evolution reactions (ORR/OER) remains a great challenge for boosting the practical application of metal-air batteries. Herein, we report a carbonization-etching approach to achieve ultrathin B, N co-doped porous carbon nanosheets (BN–PCN) with hierarchically porous structure and large specific surface area (966.46 m2 g−1) using intumescent flame retardant (IFR) system. Owing to its unique structural features, the BN-PCN delivers high electrocatalytic ORR activity with a comparable half-wave potential of 0.84 V and superior stability to those of commercial Pt/C. Moreover, the BN-PCN exhibits a smaller overpotential for OER in comparison with singly doped counterparts, suggesting that the structural properties of BN-PCN play important roles in imparting the electrocatalytic activities of ORR and OER. Furthermore, BN-PCN-driven Zn-air battery demonstrates excellent power density (193.6 mW cm−2) and high energy efficiency. This study offers a promising avenue for designing multiple heteroatom-doped porous carbon materials for clean energy conversion and storage applications.