Unexpected electrochemical oxidation of urea on a new NiCuGO composite catalyst

The NiCuGO composite catalyst for urea electrooxidation was prepared using the electrodeposition method. Prepared material has shown ipA of 5.88 mA cm−2 at 514 mV during CV scan and 10 mA cm−2 at 693 mV during LSV in 0.15 M urea in 1 M KOH solution. The reaction mechanism was examined during bulk electrolysis with the periodic sampling and reaction products analysis. We found that the reaction efficiency was higher for our catalyst, with lower clamping voltages with respect to pure nickel. However, analysis with IC has shown that UOR using a NiCuGO electrode has led to a higher content of NO2− ions. The presence of this type of by-product in wastewater is a major environmental threat, which is why further research is needed for catalyst optimisation. It also shows that the widely agreed mechanism of UOR with Ni-based catalysts leading to N2, CO2, and H2O is not accurate in some cases and how crucial product analysis is for the catalyst evaluation.