Electrodeposition of cobalt-iron bimetal phosphide on Ni foam as a bifunctional electrocatalyst for efficient overall water splitting

To solve environmental pollution and energy crisis, it is essential to design an efficient, economical, and stable bifunctional electrocatalyst for water splitting to produce renewable energy sources H2 and O2. In this study, low-crystallinity and microspherical CoFe-P/NF catalyst synthesized by potentiostat electrodeposition on a foam nickel substrate had an excellent hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and water splitting performance. In 1 M KOH solution, the CoFe-P/NF required the overpotentials of 45 mV for HER and 287 mV for OER in order to create a current density of 10 mA cm-2. Furthermore, the Tafel slope for HER and OER was measured as 35.4 and 43.2 mV dec-1, respectively. Serving as the bifunctional catalysts, the CoFe-P/NF electrode couple displays a low voltage of only 1.58 V at 10 mA cm-2 with an excellent long-term stability. Such remarkably properties of the CoFe-P/NF are attributed to the crystalline-amorphous phase structure, the synergistic effect of Co, Fe and P, and rapid separation of bubbles from the electrode surface. In summary, this study provides a new method for developing cost-effective catalyst towards green hydrogen production via water splitting.