Designing oxygen-doped Fe-N-C oxygen reduction catalysts for proton- and anion-exchange-membrane fuel cells

Tailoring the local environment and electronic structure of the active center of M-N-C catalysts is a promising route to improve the performance of catalysts. Herein, we design and controllably synthesize an O-doped O-FeN4C-O catalyst and identify its local structure, which contains two kinds of oxygen doping, i.e., axial-oxygen doping and second-coordination-shell oxygen doping of FeN4 species. Density functional theory calculations reveal that the synergy of the two kinds of oxygen doping optimizes electronic structure and therefore boosts oxygen reaction reduction (ORR) performance. Consequently, the O-FeN4C-O exhibits excellent ORR activities in both acidic and alkaline conditions. Importantly, the O-FeN4C-O-based proton- and anion-exchange membrane fuel cells deliver ultra-high peak power densities of 0.88 and 1.24 W cm−2, which ranked among the top performers of non-precious-metal ORR catalysts-based fuel cells. This work paves a new avenue for designing M-N4-X (X = P, S, etc.) catalysts with tunable electronic structures for different electrocatalysis, including carbon dioxide and nitrogen reduction and oxygen and hydrogen evolution.