CuCo2O4@Zr6O8-MOF Composite: A Trifunctional Electrocatalyst (HER/OER/UOR) for Energy-Saving Hydrogen Production and Urea Oxidation.

The urea oxidation reaction (UOR) has recently emerged as a promising alternative to the oxygen evolution reaction (OER) due to its favorable thermodynamics, offering an efficient route for low-energy hydrogen production while simultaneously enabling the treatment of urea-rich wastewater. In this work, a heterogeneous electrocatalyst composed of CuCo2O4 nanosheets integrated with Zr6O8-MOF nanostructures on nickel foam (CuCo2O4@Zr6O8-MOF/NF) was successfully synthesized and evaluated for the hydrogen evolution reaction (HER), OER, and UOR. The optimized composite exhibits enhanced electrocatalytic activity with overpotentials of 31 and 175 mV for HER, 220 and 390 mV for OER, and UOR potentials of 1.29 and 1.42 V (vs RHE) at current densities of 10 and 100 mA cm-2, respectively. The improved performance is mainly attributed to the MOF-derived architecture, which regulates the dispersion of CuCo2O4 and prevents agglomeration, thereby increasing the accessible active surface area. Electrochemical water and urea electrolysis in a two-electrode configuration further confirm the advantage of the hybrid system, showing lower cell voltages compared to conventional water splitting.