Active and Stable Nickel‐Based Electrocatalysts Based on the ZnO:Ni System for Water Oxidation in Alkaline Media

Abstract

AbstractThe synthesis of monodisperse, surfactant‐free, Ni‐substituted ZnO nanocrystallites (ZnO:Ni) by the mild solvolysis of heterobimetallic Ni4−xZnxO4 cubane‐like precursors (x=1–3) in benzylamine is reported. Ni4−xZnxO4 was grafted by electrophoretic deposition onto fluorine‐doped tin oxide glass substrates and used as an active and stable working electrode for water oxidation. Upon the application of a voltage at the electrodes, the ZnO:Ni precatalyst leads to an active composite material that can oxidize water (>15 h) with an increasing catalytic current. In contrast, the performance of homometallic NiO reference materials decreases rapidly over time and is surpassed by the composite from the ZnO:Ni precatalyst in terms of both stability and activity. Extensive characterization of the as‐prepared and activated ZnO:Ni precatalyst by using hard X‐ray photoelectron spectroscopy revealed that the excellent performance of the electrode material is because of the formation of a unique self‐supported turbostratically disordered mixture of γ‐NiOOH/α‐Ni(OH)2‐like phases from the rapid dissolution of ZnII in the ZnO:Ni precatalyst into the electrolyte during activation.