Gap channel carbon layer coated bimetallic CoFe phosphate as a bifunctional electrocatalyst for overall water splitting

Designing efficient non-precious electrocatalysts to facilitate overall water splitting is crucial and highly desirable, but remains challenging. Herein, a carbon-coated bimetallic CoFe phosphate (Co7Fe3–P/C) electrocatalyst is synthesized via simple gel-sol, pyrolysis and phosphating process. Co7Fe3–P/C exhibits excellent activity with low overpotential of 194 and 260 mV to achieve a current density of 10 mA cm−2 in alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. With Co7Fe3–P/C as two-electrode for overall water splitting, only a low cell voltage of 1.76 V and 1.88 V is required to achieve a current density of 100 mA cm−2 and 500 mA cm−2, which outperform that of the commercial Pt/C–RuO2 couple and reported CoFe alloy materials, showing the promising potential application in the industrial water electrolysis. The superior activity of overall water splitting over carbon-coated bimetallic CoFe phosphate electrocatalyst is attributed to the excellent mass transfer by gap channel of carbon layer, charge enhancement effect by phosphating and in-situ oxidization into its corresponding amorphous (oxy)hydroxides (CoOOH and FeOOH).