Tri-functional Ir-doped MnNiO catalyst drives hydrogen production via urea-assisted water splitting

Urea oxidation is an important process for hydrogen production using living catalysts with nickel components. In this study, iridium-doped manganese nickel oxide was prepared with a reflux procedure on carbon black (Ir@MnNiO/C) at 120 ℃ for 24 h and was annealed in an air atmosphere at 500 ℃ for 2 h. The chemical composition and morphology of Ir@MnNiO/C was investigated by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The electrocatalytic activity with Ir@MnNiO/C catalysts for urea oxidation in alkaline KOH with urea electrolyte confirmed that Ir@MnNiO/C exhibited a significant redox capacity and a superior charge-transfer conversion. This catalyst showed enhanced urea oxidation and oxygen evolution reaction values, with potentials of 1.42 V and 1.27 V (vs. Ag/AgCl) at a current density of 10 mA cm⁻², respectively. Ir@MnNiO/C as both the cathode and anode required cell voltages of 2.0 V and 1.86 V, respectively, at 10 mA cm⁻² to function as a full cell electrolyzer for water and urea splitting in alkaline electrolytes. In the field of renewable energy generation, these findings provide an effective framework for useful and well-balanced noble and non-noble metal electrocatalysts.