Electrocatalytic reduction of nitrate and nitrite at Nafion-coated electrodes in concentrated sodium hydroxide solution

Abstract

The electrochemical reduction of nitrate ions in alkaline solution has been studied using various cathode materials and is the basis for a patent describing the conversion of nitrate into hydroxide ion in carbonate solutions. Recently, Taniguchi et al. have reported that certain well studied transition metal cyclic amine complexes, namely Co(III)-cyclam and Ni(II)-cyclam where cyclam is 1,4,8,11-tetraazacyclotetradecane, efficiently electrocatalyze the reduction of nitrate and nitrite to hydroxylamine at mercury electrodes. Here the authors report that the metal cyclam catalyst can be incorporated into a Nafion film electrode, and that the reduction of nitrate and nitrite proceeds efficiently at these electrodes in concentrated NaOH solution. Nafion is a perfluoroalkanesulfonated cation exchange material that has been widely used to immobilize redox couples at electrode surfaces, including electrocatalysis species.