Porous TiO₂/Co₉S₈ core-branch nanosheet arrays with high electrocatalytic activity for a hydrogen evolution reaction

Exploring new non-noble metallic catalysts with highly efficient and stable catalytic performance toward a hydrogen evolution reaction (HER) is a major requirement in the field of electrochemical water splitting. In this study, we report a facile strategy to synthesize a three-dimensional (3D) porous TiO₂/Co₉S₈ core-branch nanosheet arrays on Ni foam with superior HER catalytic activity. The hierarchically 3D porous architecture not only provides rich active sites, but also enables fast electron transport and easy electrolyte permeation. Consequently, the TiO₂/Co₉S₈ core-branch nanosheet arrays achieve a remarkably low overpotential of 150 mV at 10 mA cm^-2, small Tafel slope of 71 mV Dec^-1 and outstanding long-term stability for the HER reaction. The elaborate design should provide a new strategy to controllably synthesize porous and rational nanostructured materials as a prominent electrocatalyst for water splitting applications.