Investigation of the effects metallic concentration and P-doping on newly designed P-doped CoMoOTe2 nanostructures as bifunctional electrocatalyst for hydrogen and oxygen evolution reactions

Developments of new bimetallic chalcogenides with rich active sites is highly desirable for overall water splitting. In this work, phosphorus-doped, metal oxide integrated cobalt molybdenum telluride (P–CoMoOTe₂) is newly designed by optimizing Co to Mo ratios and P doping amounts. The optimal P–CoMoOTe₂ exhibits better electrochemical performances for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The overpotential of 147 and 310 mV at 10 mA/cm² as well as the Tafel slopes of 115.6 and 79.3 mV dec⁻¹ are respectively obtained for HER and OER. This optimal P–CoMoOTe₂ also shows higher electrochemical surface area than those of cobalt molybdenum layered double hydroxide and cobalt molybdenum telluride. In the long-term stability test, the optimal P–CoMoOTe₂ retained 6 % and 80% of its initial current density after 48 h of continuous testing for HER and OER, respectively. Furthermore, the catalyst demonstrated good stability over 120 h. Finally, the two-electrode configuration based on the optimal P–CoMoOTe₂ electrodes requires only 1.68 V to achieve 10 mA cm⁻². This configuration also delivers the current density retention of 60% in 1.0 M KOH after 48 h. The higher electronic conductivity, richer active sites and therefore better electrochemical performance in HER and OER for P–CoMoOTe₂ are verified to be facilitated with optimized metallic concentrations and P doping amounts.