Addition of methyl viologen (MV2+) enhances the anodic currents observed for TiO2 suspensions under illumination by trapping of photogenerated electrons with formation of MV+·. The magnitude of the photocurrent depends upon the relative location of the semiconductor Fermi level and Eredox of the MV2+/MV+· couple. The location of the Fermi level in the anatase powders was estimated as -0.05 V vs. NHE (pH 0) based on the observed variation of photocurrent with pH. The shift in the quasi-Fermi level with light intensity is also discussed.
ASJC Scopus subject areas
- Colloid and Surface Chemistry