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

Abstract 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 Ni 5 P 4 clusters on NiCo 2 O 4 (achieving Ni 5 P 4 @NiCo 2 O 4 ) by a phosphating process of NiO clusters on NiCo 2 O 4 . Acting as a high‐efficiency electrode for alkaline water electrolysis, the Ni 5 P 4 @NiCo 2 O 4 can efficiently and preferentially convert H 2 O to H 2 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 NiCo 2 O 4 species exhibit a higher ability to electrolyze water into H* intermediate and then Ni 5 P 4 clusters facilitate the subsequent desorption of the H 2 products. Profiting from the promoted kinetic steps, the Ni 5 P 4 @NiCo 2 O 4 electrocatalyst is promising for scalable alkaline hydrogen production.