Nanometric Ni5P4 Clusters Nested on NiCo2O4 for Efficient Hydrogen Production via Alkaline Water Electrolysis

A number of non‐noble catalysts are developed for hydrogen production via acidic water electrolysis. Nevertheless, for the more economical alkaline hydrogen generation, the restricted kinetics of the water dissociation Volmer step along with its following proton recombination Tafel step for these non‐noble electrocatalysts generally lead to sluggish hydrogen‐production process. Here, a facile method is designed to nest nanometric Ni5P4 clusters on NiCo2O4 (achieving Ni5P4@NiCo2O4) by a phosphating process of NiO clusters on NiCo2O4. Acting as a high‐efficiency electrode for alkaline water electrolysis, the Ni5P4@NiCo2O4 can efficiently and preferentially convert H2O to H2 with a low overpotential of 27 mV at 10 mA cm−2 and the Tafel slope of 27 mV dec−1, which are comparable to the results for platinum and superior than those of the state‐of‐the‐art platinum‐free electrocatalysts. Density functional theory calculations confirm that NiCo2O4 species exhibit a higher ability to electrolyze water into H* intermediate and then Ni5P4 clusters facilitate the subsequent desorption of the H2 products. Profiting from the promoted kinetic steps, the Ni5P4@NiCo2O4 electrocatalyst is promising for scalable alkaline hydrogen production. Nanometric Ni5P4 clusters nested on NiCo2O4 for highly efficient electrochemical hydrogen production are first demonstrated. Owing to the largely reduced energy barriers of both Volmer step and Tafel step, the as‐achieved Ni5P4@NiCo2O4 electrocatalyst exhibits a high hydrogen evolution reaction activity under alkaline conditions, which is highly comparable to that of Pt and outperforms many reported non‐noble electrocatalysts.