Facile Exposure of P‐Co/Co(OH) ₂ Heterointerfaces for Enhanced Activity and Stability in Alkaline Hydrogen Evolution Reaction

Abstract Hydroxyl desorption process has recently attained a significant attention due to its sluggish kinetic for the alkaline water electrolysis. Previous research primarily focuses on its effect on the hydrogen evolution reaction (HER) activity, with less attention paid to durability. Herein, alleviated hydroxyl adsorption at P‐Co/Co(OH) 2 heterointerface is demonstrated as an effective strategy for the enhancement of durability. Theoretical calculations, electrochemical tests, and in situ infrared spectra reveal that the exposed heterointerface weakens the hydroxyl adsorption, which accelerates the water dissociation, and optimization of the hydrogen adsorption. As expected, P‐Co/Co(OH) 2 exhibits excellent alkaline HER performance with a low overpotential of 36.7 mV at 10 mA cm −2 and robust durability, maintaining a retention rate of 97.1% current density after 55 h. This is much superior to Co@Co(OH) 2 , which needs an overpotential of 217.6 mV at 10 mA cm −2 and a retention rate of only 59.1% after the same durability test. When paired with a high‐performance state‐of‐the‐art anode, the electrolyzer requires only 2.03 V to drive a current density of 200 mA cm −2 and can maintain stable output for 350 h, highlighting the promising practical applications of P‐Co/Co(OH) 2 in water electrolysis.