Co–P/Fe3O4 composite film on nickel foam prepared by one-step electrodeposition for efficient overall water splitting

Abstract

The design and construction of heterogeneous interface is an effective strategy to enhance the performance of non-precious metal catalysts for electrolytic water splitting. Herein, a facile nanostructure of porous cobalt phosphide/ferroferric oxide (Co–P/Fe3O4) composite film on nickel foam (Co–P/Fe3O4@NF) is designed and prepared by a one-step electrodeposition. The abundant heterogeneous interface of Co–P/Fe3O4 produces and exposes highly active catalytic sites. Meanwhile, the appropriate interaction between cobalt phosphide and Fe3O4 and the close contact between Co–P/Fe3O4 film and NF promote rapid electron transfer in catalytic process. Due to the catalyst being well-designed, the self-supported Co–P/Fe3O4@NF bifunctional electrodes exhibit outstanding performances with only needing overpotentials of 132.8 mV and 343.0 mV for hydrogen evolution reaction and oxygen evolution reaction, respectively, to drive 20 mA cm−2 in 1.0 M KOH. Additionally, the alkaline electrolyzer assembled by Co–P/Fe3O4@NF can achieve 10 mA cm−2 at a low cell voltage of 1.686 V. Even better, the electrolyzer can operate continuously over 40 h with nearly 100% Faraday efficiency and can also be powered by commercial solar cells in general outdoor environments.