Boron doped partially wrapped hierarchical porous carbon materials towards oxygen reduction reaction

Abstract

Heteroatom-doped metal-free materials have been widely investigated as promising oxygen reduction electrocatalysts because of their cheapness, high activity and environmental friendliness. Herein, a convenient strategy to exploit the volatility of zinc-based MOF (ZIF-8) is cleverly presented in this work, and then ZIF-8 is successfully wrapped with melamine and boric acid as a template to form highly B and N doped metal-free partially wrapped hierarchical porous carbon materials (BN/MPC). The developed BN/MPC catalyst has good catalytic activity for ORR in alkaline electrolytes (Eonset = 0.96 V vs. RHE, E1/2 = 0.78 V vs. RHE) and outstanding long-term stability (retain = 95.7 %). Delightfully, the extraordinary performance is attributed to the structural and compositional features of BN/MPC, including large surface area (937.7 m2 g−1), hierarchical porous structure, B and N co-doping. The electron spin resonance (ESR) can confirm the electron-deficient nature of element B in BN/MPC, proper binding to OH* which in turn facilitates the adsorption of O2 and improves the ORR performance. The as-prepared BN/MPC cathode catalysts exhibits a power density of 105.4 mW cm−2 and a specific capacity of 770 mAh gZn−1 after forming a zinc-air batteries.