Bifunctional atomic iron-based catalyst for oxygen electrode reactions

• Published in: Journal of catalysis 2019-10, Vol.378, p.353-362
• Main Authors: Bai, Lu, Duan, Zhiyao, Wen, Xudong, Guan, Jingqi
• Format: Article
• Language: English
• Subjects: Density-functional theory; FeN4-moiety; Oxygen evolution reaction; Oxygen reduction reaction; Single-site catalysis
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2019.09.009

A single-site iron- and nitrogen-codoped graphene catalyst shows excellent OER and ORR performance with an overpotential of 275 mV at 10 mA cm−2 and a half-wave potential of 0.90 V vs. RHE in 0.1 M KOH solution, respectively. [Display omitted] •Atomically dispersed iron was embedded onto nitrogen-doped graphene.•Fe@NG shows OER with low overpotential of 194 mV at 10 mA cm−2 in 1.0 M KOH.•Fe@NG shows OER with low overpotential (275 mV at 10 mA cm−2) in 0.1 M KOH.•Fe@NG shows ORR performance with E1/2 of ∼0.9 V vs RHE in 0.1 M KOH.•The overpotential-determining step is the OO coupling step. Development of high-efficiency atomic transition metal catalysts for oxygen electrode reactions is attractive for regenerative energy conversion and storage technologies. Here we report a facile approach to fabricate an atomic iron- and nitrogen-codoped graphene catalyst with high content of iron (up to 1.5 wt%). The atomic iron-based catalyst on glassy carbon electrodes displays low overpotential (194 mV and 275 mV) reported at 10 mA cm−2 in 1.0 M KOH and 0.1 M KOH solutions for the oxygen evolution reaction (OER), respectively. In addition, the atomic iron-based composite electrocatalyst exhibits a high half-wave potential of 0.90 V vs. RHE for the oxygen reduction reaction (ORR) in 0.1 M KOH, and a combined ORR and OER potential gap of 0.605 V. Structural characterization and theoretical calculations demonstrate that the efficient active sites for OER and ORR should be FeN4-moiety embedded into the graphene, on which the overpotential-determining step is the OO coupling step.