Balancing Edge Defects and Graphitization in a Pt-Fe/Carbon Electrocatalyst for High-Power-Density and Durable Flow Seawater-Al/Acid Hybrid Fuel Cells and Zn-Air Batteries.

Overcoming the trade-off between the graphitization of the carbon substrate and enhanced electronic metal-support interaction (EMSI) and intrinsic activity of Pt-C catalysts remains a major challenge for ensuring the durable operation of energy conversion devices. This article presents a hybrid catalyst consisting of PtFe nanoparticles and single Pt and Fe atoms supported on N-doped carbon (PtFe NPs @PtFe SAs -N-C), which exhibits improved activities in hydrogen evolution and oxygen reduction reactions (HER and ORR, respectively) and has excellent durability owing to the high graphitization, rich edge defects, and porosity of the carbon in PtFe NPs @PtFe SAs -N-C, as well as strong EMSI between the PtFe nanoparticles and edge-defective carbon embedded with Pt and Fe atoms. According to theoretical calculations, the strong EMSI optimizes the H* adsorption-desorption and facilitates the adsorption OOH*, accelerating the HER and ORR processes. A novel flow seawater-Al/acid hybrid fuel cell using the PtFe NPs @PtFe SAs -N-C cathode can serve as a high-efficiency energy conversion device that delivers a high power density of 109.5 mW cm -2 while producing H 2 at a significantly high rate of 271.6 L m -2 h -1 . Moreover, PtFe NPs @PtFe SAs -N-C exhibits a remarkable performance (high power density of 298.0 mW cm -2 and long-term durability of 1000 h) in a flow Zn-air battery.