Synergizing Single-Atom and Carbon-Encapsulated Nanoparticles of Fe for Efficient Oxygen Reduction and Durable Zn-Air Batteries

Overcoming the sluggish kinetics of the oxygen reduction reaction(ORR)remains a critical challenge for Zn-air batteries. Fe-N/C catalysts have emerged as promising alternatives to precious Pt-based materials. Herein, we report the design and synthesis of carbon-encapsulated Fe nanoparticles decorated Fe-N/C(denoted as Fe-NPs@Fe-N/C) via controlled pyrolysis. The Fe-NPs@Fe-N/C catalyst exhibits excellent ORR performance in alkaline media with a half-wave potential (E-1/2) of 0.893V(RHE). The strategic integration of carbon-encapsulated Fe nanoparticles substantially improves the catalytic activity of Fe-N/C catalysts. The Fe-NPs@Fe-N/Cas the Zn-air battery cathode delivers an impressive peak power density of 175.7mW cm(-2 )and excellent stability over 500 h, surpassing the Pt/C benchmarks. Density functional theory calculations reveal that the carbon-encapsulated Fe nanoparticles facilitate electron transfer to the catalytic site by modulating the d-bandcenter, there by boosting the ORR activity. This research paves the way for future design strategies integrating nanoparticles and single atoms for efficient electrocatalysis.