High pyridine nitrogen regulates the d-band center in single atom iron electrocatalyst for promoted oxygen reduction

Abstract

The design and development of a high pyridine nitrogen anchored Fe single atom (Fe SA) catalyst for efficient oxygen reduction reaction (ORR) are extremely urgent but still ambiguous. In this effort, we proposed a high-temperature pyrolysis strategy coupled with the pre-coordination of active sites to construct the N-doped carbon (NC) nanobox embedded with Fe SA moiety. Expectantly, the well-regulated FeSA@NC electrocatalyst delivered superior electrochemical ORR activity, evidenced by a promoted half-wave potential of 0.928 V and a decent limiting current density of 6.01 mA/cm2 in 0.1 M KOH solution. Beyond that, the resulting FeSA@NC product afforded a large peak power density of 267 mW/cm2 and satisfactory long-term stability. The theoretical calculation revealed that the increased pyridine nitrogen helps to promote the capture of more electrons at the Fe active site, thus optimizing the d-band center of the catalyst, and reasonably regulating the adsorption energy barrier of *OH species on the catalyst surface, both contributing to the boosted ORR performance. More importantly, this designed preparation strategy can be easily extended to the constructions of other transition metals (e.g., Co, Ni, Cu)-based SA catalysts, thus presenting a universal synthesis method for other similar SA catalyst systems in the future.