Voltammetric and spectroelectrochemical results are presented for the one-electron reduction of n-heptylviologen dibromide on clean and silanemodified, tin oxide, and on indium tin oxide metallized-plastic optically transparent electrodes (MPOTE). The amount of n-heptylviologen dibromide reduced and the rate of coloration due to the formation of the cation-radical film can strongly be influenced by the state of the electrode surface. The initial 200-500 msec of viologen deposition are not mass transport controlled. Calculations for the amount of viologen deposited vary, depending on whether a spectrophotometric or coulometric estimated is used. Spectrophotometric data indicate that the amount of viologen deposited in the first 200 msec of chronoamperometric reduction from a concentrated viologen solution is ca. 10-14 monolayers and is increased at least 60% by the addition of a monolayer of the silane modifier to the electrode surface. In the case of the metallized plastic films, the increase in coloration rate may be attributed to the presence of nonpolar surface groups present at the surface of the conductive film.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry