Electrochemical behavior of nitromethane and its influence on the electro-oxidation of formic acid: an on-line MS study

Abstract

The electrochemical behavior, including both oxidation and reduction, of nitromethane at a porous platinum electrode in sulfuric acid solution was studied using differential electrochemical mass spectroscopy (DEMS). It was found that under these conditions nitromethane can be oxidized to CO 2 and NO x in reactions involving only adsorbed species. Below 0.4 V/RHE nitromethane is reduced, as shown by the cathodic current density in the cyclic voltammogram and a simultaneous decrease in the ion currents associated with CH 3NO 2. The presence of nitromethane catalyzed the bulk oxidation of formic acid in the low potential range below 0.8 V/RHE. In contrast, at potentials above 0.8 V/RHE, the oxidation of formic acid was inhibited by nitromethane. These effects were studied for various concentrations of nitromethane ranging from 0.01 to 1 M. In contrast with formic acid, the oxidation of methanol on platinum in acid solution was inhibited by the presence of nitromethane. The electrochemical behavior of nitromethane on platinum in acid is compared with that of acetonitrile. Both compounds are catalytically active towards the oxidation of formic acid. Possible explanations for the catalytic action of nitromethane are discussed.