Potential step study of electrooxidation of methanol in 1-butyl-3-methylimidazolium tetrafluoroborate

Abstract

A potential step method was used to characterize the electrooxidation of methanol on a chemically modified electrode in an ionic liquid solvent. Two major findings were reported from this study. Firstly, the oxidation was dominant 2.2s after the potential step. Before that, the double layer charging and adsorption were dominant. Therefore, there should be a waiting time of a few seconds if a methanol sensor is developed with a potential step method. Secondly, the oxidation of methanol on the electrode was diffusion controlled. The concentration of methanol affected the diffusion. The diffusion constant D0 was 8.37×10−17m2/s when the concentration was lower than 0.5M and was 2.66×10−13m2/s when the concentration was higher than 1.0M. This suggests that the methanol concentration should be kept higher than a threshold in an ionic liquid based fuel cell.