Concave Structural Carbon Co‐Doped with Iron Atom Pairs and Nitrogen as Ultra‐High Performance Catalyst Toward Oxygen Reduction

Abstract

AbstractIt is crucial to rationally design and synthesize atomic‐scale transition metal‐doped carbon catalysts with high electrocatalytic activity to achieve a high‐efficient oxygen reduction reaction (ORR). Herein, an electrocatalyst comprised of Fe–Fe dual atom pairs and N‐doped concave carbon are reported (N‐CC@Fe DA) that achieves ultrahigh electrocatalytic ORR activity. The catalyst is prepared by a gaseous doping approach, with zeolitic imidazolate framework‐8 (ZIF‐8) as the carbon framework precursor and cyclopentadienyliron dicarbonyl dimer as the Fe–Fe atom pair precursor. The catalyst exhibits high cathodic ORR catalytic performance in an alkaline Zn/air battery and proton exchange membrane fuel cell (PEMFC), yielding peak power densities of 241 mW cm−2 and 724 mW cm−2, respectively, compared to 127 mW cm−2 and 1.20 W cm−2 with conventional Pt/C catalysts as cathodes. The presence of Fe atom pairs coordinate with N atoms is revealed by X‐ray photoelectron spectroscopy (XPS) and X‐ray absorption spectroscopy (XAS) analysis, and Density Functional Theory (DFT) calculation results show that the Fe–Fe pair structure is beneficial for adsorbing oxygen molecules, activating the O─O bond, and desorbing OH* intermediates formed during oxygen reduction, resulting in a more efficient oxygen reaction. The findings may provide a new pathway for preparing ultra‐high‐performance doped carbon catalysts with Fe–Fe atom pair structures.