Engineering g-C3N4 composited Fe-UIO-66 to in situ generate robust single-atom Fe sites for high-performance PEMFC and Zn–air battery

Abstract

Developing an efficient and robust electrocatalyst for the sluggish oxygen reduction reaction (ORR) in PEMFC is imperatively desirable and challenging. This study presents a feasible route of co-carbonization of the Fe-loaded UIO-66/g-C₃N₄ hybrid to access an efficient mesoporous carbon (MC) encapsulated Fe–N ensemble (denoted as Fe–N/MC catalyst). The co-presence of g-C₃N₄ served as a significant binary functionality during the synthesized route. One way is affording the N species covalency with Fe atoms to generate the Fe–N active sites and the other way is by offering carbon precursors to yield mesoporosity within the carbon matrix. Beneficial to these enriched Fe–N species, improved conductivity, hierarchical porosity, etc.; this novel Fe–N/MC catalyst presents significantly improved ORR activity and stability as the cathode in the membrane electrode assembly (MEA). Specifically, a high and stable peak power density of 1.15 W cm⁻² with a minor decay (ca. 21.8%) of power density after a long period of discharge is achieved. This work may offer a facile strategy to develop non-precious metal-based catalysts assembled in a cathode for both PEMFC and metal–air batteries with high performance and improved stability.