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 μW 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 ∼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.

Highly oriented microporous nickel oxide films were prepared through the simple and fast anodization of nickel foils at 30 V, followed by calcination at 400 °C. Low concentrations of ammonium chloride and potassium hydroxide solutions, which were dispersed in ethylene glycol, were used as electrolytes. Microporous dimensions and large surface areas of the films were obtained by using both electrolytes. The ammonium chloride system provided a highly oriented microporous structure with excellent distribution of pores at the surface of nickel foil. On the contrary, it was not uniform in the potassium hydroxide system. Furthermore, cyclic voltammetry of the microporous films in alkaline solutions containing urea showed the highest oxidation currents at the nickel oxide films prepared in the ammonium chloride system. This nickel oxide film also showed excellent stability of the current responses, indicating that the method has potential to be applied in electrode preparation, especially urea oxidation.

No abstract

Boron-doped diamond (BDD) was modified with copper and gold particles by using an electrodeposition technique to improve its catalytic effect on CO2 reduction in a flow system.

No abstract