Electrooxidation of ammonia and simple amines at titanium electrodes modified with a mixture of ruthenium and titanium dioxides

Electrooxidation of ammonia at the Ti/TiO2/RuO2 electrode was investigated using voltammetry, coulometry, 14N NMR, potentiometry with a nitrate ISE, and numerical simulation. The major product of electrooxidation was elementary nitrogen. Nitrate was a minor product. NH4 is not electroactive at the oxide electrode. Since protons are formed in the course of the electrode reaction, incoming ammonia is transformed to NH4, and therefore the flux of ammonia to the electrode surface is strongly depressed in solutions containing no excess of hydroxide ion. Amines were electrooxidized to a variety of compounds. Both ammonia and amines strongly adsorb on the electrode surface. Height of the anodic voltammetric peaks of both ammonia and simple amines was found to be linearly dependent on substrate concentration in a wide millimolar range.