A Bifunctional Electrocatalyst of Flower-Like Cr-Doped CoP/Fe2P Microsphere for Efficient Overall Water Splitting

Abstract Developing efficient, low-price non-noble metal-based electrocatalysts for overall water splitting in alkaline medium remains a formidable challenge. In our work, Cr-doped CoP/Fe2P (Cr-CoP/Fe2P) flower-like microsphere was synthesized through a simple hydrothermal and phosphating process. The resulting Cr-CoP/Fe2P electrocatalyst shows significantly enhanced oxygen evolution reaction performance (262 mV @ 10 mA cm-2) and has a satisfactory hydrogen evolution reaction performance (114 mV @ 10 mA cm-2), coupled with favorable stability in an alkaline medium. Furthermore, when assembling Cr-CoP/Fe2P into an electrolytic cell, the two-electrode system can provide a current density of 10 mA cm-2 at a voltage of 1.61 V. At high current density, the performance of the electrolytic cell composed of Cr-CoP/Fe2P is superior to that of noble metal catalyst electrode pair. Electronic structure analysis and various characterizations confirm that Cr doping and the formation of CoP/Fe2P heterogeneous interfaces redistribute the electron densities of the active sites, enlarge the specific surface area, and enhance the aerophobicity of the catalysts, thereby improving the electrocatalytic property. This work provides a referable method for engineering highly efficient and stable non-noble polymetallic phosphides, which serve as bifunctional electrocatalyst for overall water splitting.