Etching engineering on controllable synthesis of etched N-doped hierarchical porous carbon toward efficient oxygen reduction reaction in zinc–air batteries

Abstract

Low-cost, high-performance oxygen reduction reaction (ORR) catalysts greatly determine the practical application of advanced energy storage and conversion systems, including fuel cells and metal–air batteries. Precise design and controllable preparation of cutting-edge ORR catalysts demonstrate much meaningful to their electrochemical performance. Herein, etching engineering is applied on polypyrrole-derived carbon to controllably prepare etched N-doped hierarchical porous carbon (ENHPC–t, t means etching time) by using ammonia as an etching source. By systematical characterization and analysis, we find altering etching time exerts a profound effect on the morphology, structure, and composition of ENHPC–t. In spite of relatively lower defect density than the counterparts, the obtained ENHPC–5 with unique hierarchical porous structure, much larger specific surface area, and more optimized N configurations, display significantly improved ORR performance in both basic and acid media. When constructed as a cathode catalyst for zinc–air batteries, it also presents competitive performance to commercial Pt/C catalysts. Undoubtedly, our adopted etching strategy provides good guidance on a controllable synthesis of low-price but high-performance carbon-based ORR catalysts.