High-performance bifunctional Cr-doped cobalt phosphide for low-cost water electrolysis

Developing a bifunctional catalyst that combines low cost and high performance for water electrolysis remains an unsolved challenge. In this study, a Cr-doped transition metal-based electrocatalytic material is synthesized on a stainless steel mesh substrate. The obtained Cr 0.2 -CoP/SS catalyst exhibits an overpotential of only 98 mV for the hydrogen evolution reaction (HER) at 10 mA cm −2 in alkaline electrolyte, and exhibits an overpotential of 254 mV for the oxygen evolution reaction (OER); in acidic electrolyte, the HER overpotential at 10 mA cm −2 is as low as 118 mV, and it demonstrates excellent stability. Furthermore, when Cr 0.2 -CoP/SS is used in traditional overall water splitting systems, the required voltage at 10 mA cm −2 is as low as 1.56 V. Theoretical studies show that Cr doping reduces the Gibbs free energy of hydrogen adsorption and narrows the bandgap to zero, which enhances catalytic activity and structural stability.