Electronic Structure and Crystalline Phase Dual Modulation via Anion-Cation Co-doping for Boosting Oxygen Evolution with Long-Term Stability Under Large Current Density.

Designing a state-of-the-art nonprecious oxygen evolution reaction (OER) electrocatalyst with ultralong stability under high current density (≥100 h under 1000 mA cm) is greatly desirable for the viable electrolysis of water. The synthesis of nanostructure catalysts is an effective method for improving the OER performance, but nanostructure-based catalysts are easily destroyed by mechanical force via the vigorous oxygen gas evolution process at a high current density. Herein, we present a facile strategy of N-anion and Fe-cation dual doping to construct a three-dimensional self-supported nickel selenide film-based catalyst via a one-step chemical vapor deposition process. The film exhibits outstanding OER activity with a small Tafel slope of 34.86 mV dec and an overpotential of 267 mV at 100 mA cm in 1 M KOH media. Impressively, the film-based catalyst can maintain this excellent catalytic activity over 100 h, even when operated at a high current density of 1 A cm, thus exhibiting the best reported OER stability under high current density so far. Further studies reveal that anion-cation co-doping can simultaneously modulate the electronic state and phase structure of nickel selenide, thereby promoting the in situ formation and transformation of oxygen-vacancy-rich amorphous OER active species and resulting in the superior OER performance of the film-based catalyst.