On-line mass spectroscopy applied to electroreduction of nitrite and nitrate ions at porous Pt electrode in sulfuric acid solutions

On-line mass spectroscopy was applied to detect volatile products of the electroreduction of NO−2 and NO−3 at Pt in 0.5M H2SO4. It provided important information, particularly on the transient behavior. Nitrite is reduced stepwise to NO (at 0.6–1 V, rhe), N2O (0.2–0.8 V) and N2 (0.1–0.6 V) in the potential ranges indicated. On the other hand, nitrate reduction takes place at much lower potentials (E <0.4 V), simultaneously yielding N2O and N2 but no NO, and terminated at prolonged polarization time.