Controlled synthesis of M doped Co3O4 (M = Ce, Ni and Fe) on Ni foam as robust electrocatalyst for oxygen evolution reaction and urea oxidation reaction

Electrocatalytic water splitting has become one of the most promising and effective ways to solve energy crises and environmental pollution.In this work, a series of M-doped Co3O4 materials with foreign ions (M = Ce, Ni and Fe) were grown on a Ni foam substrate through classical hydrothermal and calcination methods.It is worth noting that not all doping of foreign ions can promote the electrocatalytic performance of intrinsic materials.The Ce-doped Co3O4 material shows excellent oxidation properties of water (overpotential of 320 mV at 50 mA cm-2) and urea (potential of 1.39 V at 50 mA cm-2).However, the doping of Ni reduces the water oxidation performance of the intrinsic material (overpotential of 410 mV@ 50 mA cm-2), and the doping of Fe reduces the urea oxidation performance of the inherent material (potential of 1.45 V@ 50 mA cm-2).A series of experimental results indicate that the improved activity of the Ce-Co3O4 electrode is attributed to faster electron transport capacity, higher exposure to active sites, and improved conductivity due to doping of Ce. It is noteworthy that the doping of these ions does alter the rate-determination step for the water oxidation reaction. The stability test demonstrated that the current density of water oxidation and urea oxidation of the catalyst had no significant attenuation after a long electrocatalytic activity test. This work provides a new idea for improving the electrocatalytic activity of catalysts by a doping strategy.