Hierarchical three-dimensional framework interface assembled from oxygen-doped cobalt phosphide layer-shelled metal nanowires for efficient electrocatalytic water splitting

A novel hierarchical electrocatalyst of oxygen-doped cobalt phosphide layer-shelled copper nanowires vertically attached on surface of three-dimensional framework was fabricated through a simple and cost-effective approach. Such unique architecture was demonstrated to produce significant defects and modulated surface chemistry with rich-electroactive sites, adjusted adsorption energy, and enhanced surface area owning abundant channels for diffusion process. The catalyst achieved low overpotentials of 101 and 270 mV to acquire current response of 10 mA cm⁻² towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline, respectively. Rapid kinetics were also obtained with low Tafel slopes of 69.4 mV dec^-1 for HER and 74.4 mV dec^-1 for OER. A practical electrolyzer of the electrocatalyst for water splitting exhibited small cell voltages of 1.54 and 1.71 V at 10 and 50 mA cm^-2, respectively, along with excellent stability, which are superior to those of a similar device based on RuO₂-C + Pt-C.