Experimental Investigation of Potential Oscillations during the Electrocatalytic Oxidation of Urea on Ni Catalyst in Alkaline Medium

For the first time, potential oscillations are observed during the electrochemical oxidation of urea on Ni catalyst in alkaline medium. Electrochemical measurements, in combination with in situ time-resolved surface enhanced Raman (SER) spectroscopy studies, revealed that the potential oscillations might be caused by the periodic reduction and oxidation of the electrochemically active NiOOH catalyst to its inactive Ni(OH)(2) state and vice versa. Cyclic voltammetry and rotating disc electrode voltammetry suggests that mass transfer of urea to the double layer region due to local convection caused by oxygen evolution reaction does not play a role in the potential oscillation mechanism.