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

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.