Pyridinic-N Regulated Electron Injection to Modulate *OH Adsorption at Fe–N–C Sites for an Efficient Oxygen Reduction Reaction
Qiaoling Xu, Jin‐Song Hu, Huiying Yao, Jie Lei, Chunhui Zhou, Lei Zhang, Huan Pang
Abstract
To enhance the efficiency of oxygen reduction reaction (ORR) catalysts, precise control over the adsorption/desorption energy barriers of oxygen intermediates at atomically dispersed Fe–N–C sites is essential yet challenging. Addressing this, we employed a pyrolysis approach using a nitrogen-containing polymer to fabricate Fe single-atom (SA) catalysts embedded in a pyridinic-N enriched carbon matrix. This synthesis strategy yielded Fe SAs that demonstrated a superior electrochemical ORR performance, evidenced by an impressive half-wave potential of 0.941 V and a high limiting current density of 5.72 mA/cm 2 . Moreover, when applied in homemade Zn–air batteries, this premier catalyst exhibited exceptional specific capacity (720 mAh/g Zn ), peak power density (253 mW/cm 2 ), and notable long-term stability. Theoretical insights revealed that the increased pyridinic-N content in the catalyst facilitated efficient electron transfer from N atoms to the Fe active sites, thus fine-tuning the d-band center and effectively controlling the adsorption energy barrier of *OH species. These mechanisms synergistically improve the ORR performance. Crucially, this fabrication method shows promise for adaptation to other transition metal-based SAs, including Co, Ni, and Cu, potentially establishing a versatile synthesis route for developing atomically dispersed catalyst systems in future applications.