Vapor‐Depositing Single‐Atom Iron Catalysts on Porous Carbon Nanosheets for Enhanced Oxygen Reduction

ABSTRACT Single‐atom Fe catalysts (Fe–SACs) are recognized as the effective alternative to platinum‐based counterparts for the oxygen reduction reaction (ORR). Maximizing availability efficiency of active sites is of great significance for Fe–SACs in practical application. Herein, an efficient chemical vapor deposition route is developed to generate Fe–SACs on porous carbon nanosheets for ORR. Metal‐organic framework (ZIF‐8) is converted into highly porous and N,S‐co‐doped carbon nanosheets as Fe–SACs support. Ferrocene is sublimated and deposited on carbon nanosheet support to generate isolated single‐atomic Fe sites. Spectral and microscopic investigations confirm that Fe elements in Fe–SACs are highly dispersed in carbon support and coordinated asymmetrically with nitrogen and sulfur atoms in Fe–N 3 S 1 configuration. The optimized Fe–SACs achieve outstanding alkaline ORR activity with a half‐wave potential of 0.91 V vs. RHE. After 10 000 cycles, the half‐wave potential only shows 16 mV decays. Furthermore, the rechargeable zinc–air batteries assembled with Fe–SACs as the air electrode can show a peak power density of 213 mW cm −2 and retain a stable voltage plateau over 10 000 charge–discharge cycles. This work affords an efficient strategy for preparing highly exposed Fe–SACs for energy‐related applications.