Vanadium‐Doped Heterogeneous Bimetallic Phosphides Derived from Layered Double Hydroxides for Saline Water Splitting

Abstract The development of energy‐ and time‐saving synthetic methods to prepare bifunctional and high stability catalysts are vital for overall water splitting. Here, V‐doped nickel‐iron hydroxide precursor by etching NiFe foam (NFF) at room temperature with dual chloride solution (“NaCl‐VCl3”), is obtained then phosphating to obtain V‐Ni 2 P‐FeP/NFF as efficient bifunctional (oxygen/hydrogen exchange reaction, OER/HER) electrocatalysts, denoted as NFF(V, Na)‐P. The NFF(V, Na)‐P requires only 185 and 117 mV overpotentials to reach 10 mA cm −2 for OER and HER. When used as a catalyst for water splitting in a full cell, it can be stably sustained for more than 1000 h in alkaline brine electrolysis at both current densities of 100 and 500 mA cm −2 . In situ Raman analyses and density functional theory (DFT) show that the V‐doping‐induced surface remodeling generates hydroxyl oxides as the true catalytic active centers, which not only enhances the reaction kinetics, but also reduces the free energy change in the rate‐determining step. This work provides a cost‐effective substrate self‐derivation method to convert commercial NFF into a powerful catalyst for electrolytic brine, offering a unique route to the development of efficient electrocatalysts for saline water splitting.