Heterostructured V-Doped Ni 2 P/Ni 12 P 5 Electrocatalysts for Hydrogen Evolution in Anion Exchange Membrane Water Electrolyzers.

Regulating the electronic structure and intrinsic activity of catalysts' active sites with optimal hydrogen intermediates adsorption is crucial to enhancing the hydrogen evolution reaction (HER) in alkaline media. Herein, a heterostructured V-doped Ni 2 P/Ni 12 P 5 (V-Ni 2 P/Ni 12 P 5 ) electrocatalyst is  fabricated through a hydrothermal treatment and controllable phosphidation process. In comparison with pure-phase V-Ni 2 P, in/ex situ characterizations and theoretical calculations reveal a redistribution of electrons and active sites in V-Ni 2 P/Ni 12 P 5 due to the V doping and heterointerfaces effect. The strong coupling between Ni 2 P and Ni 12 P 5 at the interface leads to an increased electron density at interfacial Ni sites while depleting at P sites, with V-doping further promoting the electron accumulation at Ni sites. This is accompanied by the change of active sites from the anionic P sites to the interfacial Ni-V bridge sites in V-Ni 2 P/Ni 12 P 5 . Benefiting from the interface electronic structure, increased number of active sites, and optimized H-adsorption energy, the V-Ni 2 P/Ni 12 P 5 exhibits an overpotential of 62 mV to deliver 10 mA cm -2 and excellent long-term stability for HER. The V-Ni 2 P/Ni 12 P 5 catalyst is applied for anion exchange membrane water electrolysis to deliver superior performance with a current density of 500 mA cm -2 at a cell voltage of 1.79 V and excellent durability.