Reduction Mechanism of Nitrate on Titanium

Abstract

Reduction mechanism of nitrate ion on titanium electrode was investigated using electrochemical method. Cathodic polarization curve of titanium was measured in nitric acid with different concentrations of ions （H^＋，NO₃^－，HNO₂）. Reduction mechanism of nitrate ion on titanium was investigated from Tafel slope and reaction order of each ions. It was considered that reduction of titanium oxide was involved in reduction mechanism of nitrate ion on titanium, and reduction mechanism was suggested as follows.
NO₃^－ ⇄ NO_3ad^－      （QE）
TiO₂ + H⁺ + e^－ ⇄ TiOOH      （QE）
NO_3ad^－ + TiOOH → (NO₃^－－TiOOH)_ad     （RDS）
(NO₃^－ － TiOOH)_ad + H⁺ + e^－ → NO_2ad^－ + TiO₂ + H₂O