In-situ growth of hierarchical CuO@Cu3P heterostructures with transferable active centers on copper foam substrates as bifunctional electrocatalysts for overall water splitting in alkaline media

Abstract

To fulfill the growing demand for green H 2 fuels, low-cost, efficient, and stable bifunctional electrocatalysts must be developed. Herein, a hierarchical CuO@Cu 3 P/CF nanowire core-shell heterostructure with transferable active centers was developed for a bifunctional electrocatalyst with high activity. In this system, the transfer of electrochemically active centers between Cu 3 P and CuO is used to facilitate the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), respectively. Particularly, Cu 3 P acts as the active center for HER, while the active center shifts to CuO for OER reaction, and Cu 3 P acts as a co-catalyst to improve the conductivity of the system. Benefit from superhydrophilicity's high electrochemical surface area and synergistic effect of CuO core and Cu 3 P shell, and CuO@Cu 3 P/CF shown significant catalytic activity for hydrogen or oxygen evolution, requiring low overpotentials of 144 and 267 mV to achieve a current density of 10 mA cm −2 . In addition, the assembled CuO@Cu 3 P/CF-based electrolyzer exhibit excellent overall water splitting performance with a low operating voltage of 1.75 V at 10 mA cm −2 and a negligible decrease in catalytic activity. This gives encouraging evidence for the utility of our catalysts in application areas. • CuO@Cu 3 P/CF was successfully synthesized via growth-oxidation-phosphidation procedure. • Nanostructured substrate integrated growth ensured good mechanical bonding between CuO@Cu 3 P and CF. • The rough surface and stacked nanosheets make it easy for liquids to penetrate between the nanosheets. • The OER active site is derived from Cu III produced from Cu II after the cathodic oxidation reaction.