A 3D electrode of core@shell branched nanowire TiN@Ni_0.27Co_2.73O₄ arrays for enhanced oxygen evolution reaction

The combination of highly active materials with judicious nanostructures is crucial to develop high-performance electrocatalysts for oxygen evolution reaction (OER), which involves sluggish multistep electron transfer processes. Herein, TiN nanowire arrays are used as conductive trunks to support active Ni-doped Co₃O₄ (Ni_0.27Co_2.73O₄) nanosheets to construct a binder-free three-dimensional (3D) electrode for OER. In the core@shell configuration, the TiN nanowire arrays possess a single-crystal-like structure favoring charge migration and the ultrathin Ni_0.27Co_2.73O₄ nanosheets have a mesoporous structure providing more active sites. The hierarchically branched morphology, high conductivity and large surface area can be achieved simultaneously by the optimization in composition and nanostructure, which contributes to excellent electrochemical performances. The TiN@Ni_0.27Co_2.73O₄ electrode shows much better OER activity than the Ni-doped Co₃O₄ nanosheets deposited on planar Ti substrate and low conductive TiO₂ nanowire arrays.