NiCo 2 O 4 nanosheets grown on current collectors as binder-free electrodes for hydrogen production via urea electrolysis

Abstract As a novel solid hydrogen carrier, urea (CO(NH 2 ) 2 ) has shown great promise in hydrogen production, hydrogen storage and transportation. Mesoporous NiCo 2 O 4 nanosheets were synthesized on current collectors and evaluated as binder free electrodes for hydrogen production via urea electrolysis. The as-grown NiCo 2 O 4 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 NiCo 2 O 4 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 NiCo 2 O 4 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.