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.