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

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/Fe 2 P (Cr-CoP/Fe 2 P) flower-like microsphere was synthesized through a simple hydrothermal and phosphating process. The resulting Cr-CoP/Fe 2 P 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/Fe 2 P 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/Fe 2 P 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/Fe 2 P 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.