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).