Crystallization of NiCo MOF-74 on a Porous NiO Film as an Anode for the Urea/H2O2 Fuel Cell

NiCo-MOF-74 crystallized directly on the surface of porous NiO (p-NiO) film using a solvothermal method is proposed as an effective electrocatalyst for the anode in direct urea fuel cells. A nickel-to-cobalt ratio of 4:1 was found to show optimum catalytic activity toward urea oxidation with significant current enhancement in comparison to other electrodes, including Ni foil and p-NiO. At optimized conditions in an electrolyte solution of 3.0 M KOH and 1.0 M urea, a current density of around 110 mA cm-2 with a maximum power density of 4131 mu W cm-2 can be produced. This is ascribed to the increase of the active surface area over conventional nickel-based anodes, providing an abundance of active sites for urea oxidation. Excellent stability and reproducibility over 15 h application in a direct urea fuel cell was obtained with cell voltage of similar to 0.6 V. Powder X-ray diffraction shows the crystalline MOF film remains intact after chronoamperometry tests, and after fuel cell application, illustrating applicability in real devices.

Automated summary

This study proposes NiCo-MOF-74 synthesized directly on the surface of porous NiO film as an efficient electrocatalyst for the anode in direct urea fuel cells. The nickel-to-cobalt ratio of 4:1 exhibits the best catalytic activity towards urea oxidation, resulting in significant current enhancement compared to other electrodes. At optimized conditions, a current density of approximately 110 mA cm-2 and a maximum power density of 4131 mu W cm-2 can be achieved in an electrolyte solution of 3.0 M KOH and 1.0 M urea. The increased active surface area of the nickel-based anodes contributes to an abundance of active sites for urea oxidation, leading to excellent stability and reproducibility over 15 hours of application in a direct urea fuel cell.