Synergistically Tuning Water and Hydrogen Binding Abilities Over Co₄N by Cr Doping for Exceptional Alkaline Hydrogen Evolution Electrocatalysis

Abstract Searching for highly efficient and cost‐effective electrocatalysts toward the hydrogen evolution reaction (HER) in alkaline electrolyte is highly desirable for the development of alkaline water splitting, but still remains a significant challenge. Herein, the rational design of Cr‐doped Co₄N nanorod arrays grown on carbon cloth (Cr–Co₄N/CC) that can efficiently catalyze the HER in alkaline media is reported. It displays outstanding performance, with the exceptionally small overpotential of 21 mV to obtain the current density of 10 mA cm⁻² and good stability in 1.0 m KOH, which is even better than the commercial Pt/C electrocatalyst, and much lower than most of the reported transition metal nitride‐based and other non‐noble metal‐based electrocatalysts toward the alkaline HER. Density functional theory (DFT) calculations and experimental results reveal that the Cr atoms not only act as oxophilic sites for boosting water adsorption and dissociation, but also modulate the electronic structure of Co₄N to endow optimized hydrogen binding abilities on Co atoms, thereby leading to accelerating both the alkaline Volmer and Heyrovsky reaction kinetics. In addition, this strategy can be extended to other metals (such as Mo, Mn, and Fe) doped Co₄N electrocatalysts, thus may open up a new avenue for the rational design of highly efficient transition metal nitride‐based HER catalysts and beyond.