Genuine Active Species Generated from Fe3N Nanotube by Synergistic CoNi Doping for Boosted Oxygen Evolution Catalysis

The surface reconstruction of oxygen evolution reaction (OER) catalysts has been proven favorable for enhancing its catalytic activity. However, what is the active site and how to promote the active species generation remain unclear and are still under debate. Here, the in situ synthesis of CoNi incorporated Fe3N nanotubes (CoNi–Fe3N) on the iron foil through the anodization/electrodeposition/nitridation process for use of boosted OER catalysis is reported. The synergistic CoNi doping induces the lattice expansion and up shifts the d‐band center of Fe3N, which enhances the adsorption of hydroxyl groups from electrolyte during the OER catalysis, facilitating the generation of active CoNi–FeOOH on the Fe3N nanotube surface. As a result of this OER‐conditioned surface reconstruction, the optimized catalyst requires an overpotential of only 285 mV at a current density of 10 mA cm−2 with a Tafel slope of 34 mV dec−1, outperforming commercial RuO2 catalysts. Density functional theory (DFT) calculations further reveal that the Ni site in CoNi–FeOOH modulates the adsorption of OER intermediates and delivers a lower overpotential than those from Fe and Co sites, serving as the optimal active site for excellent OER performance. CoNi incorporated Fe3N nanotubes (CoNi–Fe3N) are in situ grown on iron foil. During oxygen evolution reaction (OER) catalysis, the lattice distortion and upshifted d‐band center enable facilitated reconstruction of CoNi–Fe3N toward active CoNi–FeOOH, in which the Ni site is the genuine active site with optimal adsorption for oxygenated intermediates. This work supplies a new insight into developing high‐efficiency OER catalysts through adjusting dynamic self‐reconstruction.