NiCo2O4 nanosheets grown on current collectors as binder-free electrodes for hydrogen production via urea electrolysis

As a novel solid hydrogen carrier, urea (CO(NH2)2) has shown great promise in hydrogen production, hydrogen storage and transportation. Mesoporous NiCo2O4 nanosheets were synthesized on current collectors and evaluated as binder free electrodes for hydrogen production via urea electrolysis. The as-grown NiCo2O4 nanosheet electrodes with 0.6 mg cm−2 catalyst loading exhibit ca. 80 mV decreasing in the onset potential of urea oxidation in alkaline solution comparing to those of bulk nickel hydroxide modified electrodes. The NiCo2O4 nanosheet electrodes also improved the urea oxidation current density by at least 28 times at a constant potential of 0.50 V vs. Hg/HgO compared to that of bulk Ni(OH)2 electrodes. The enhanced electrocatalytic performances of the binder free NiCo2O4 nanosheet electrodes may bring new opportunities for the scale-up of the urea electrolysis technology, which will benefit energy and environmental issues, such as urea-rich wastewater treatment, hydrogen production, and fuel cells.