Hydroxylamine Oxidation on Polycrystalline Gold Electrodes in Aqueous Electrolytes: Quantitative On-Line Mass...

Herein, a method is presented that allows quantitative determination of faradaic efficiencies for dinitrogen (N₂ ) generation during the electrochemical oxidation of hydroxylamine (NH₂ OH), $$ , on a polycrystalline gold Au(poly) disk electrode in aqueous electrolytes over a wide pH range. This tactic involves the use of an impinging jet electrolyte configuration incorporating a gas porous ring connected in turn to a mass spectrometer. The actual amount of N₂ generated at the Au(poly) disk was assayed using the oxidation of hydrazine (N₂ H₄ ) in aqueous phosphate buffer (pH 7). This redox process yields N₂ as the only product, allowing a direct correlation to be established between the changes in the partial pressures of N₂ and the current flowing through the disk electrode. An analysis of the data collected revealed a strong dependence of $$ both on pH and the applied potential. Although values of $$ as high as 20 to 30 % were found in acid and neutral media over a narrow potential region, those in alkaline solution were far smaller in the entire potential range examined.