In Situ X-Ray Diffraction Study of Urea Electrolysis on Nickel Catalysts

In situ X-ray diffraction (XRD) technique combined with electrochemical analysis was used for investigating the structural changes of nickel hydroxide catalysts in alkaline media and to provide a better understanding of the reaction mechanism of urea electrooxidation for applications in hydrogen production, fuel cells, and sensors. The evolution of XRD patterns reveals Ni(OH)2 is electrochemically oxidized to NiOOH at cell voltages from 1.2 to 1.6 V. The generated NiOOH reacts with urea and thus is reduced back to Ni(OH)2, while urea is concurrently oxidized. The technique can be extended to other electrochemical systems (alkaline rechargeable batteries, supercapacitors, and fuel cells).