INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
Photoelectrochemical Behavior of Alizarin Modified TiO2 Films
YÉSICA DI IORIO; HERNÁN B. RODRÍGUEZ; ENRIQUE SAN ROMÁN; MARÍA ALEJANDRA GRELA
JOURNAL OF PHYSICAL CHEMISTRY C
AMER CHEMICAL SOC
Año: 2010 vol. 114 p. 11515 - 11515
Photocurrent voltage curves obtained under visible light excitation of alizarin molecules chemisorbed to nanoporous TiO2 films show both anodic and cathodic currents. The potential at which the sign reversal occurs depends on the electrolyte pH, the presence of acceptors, and the dye coverage, but as a general rule, it occurs at potentials ca. 600-700 mV more positive than the flat band potential. Negative photocurrents are accounted by efficient electron discharge to the electrolyte mediated by the ligand. Cathodic photocurrents are only observed at pH values higher than ca. 4.0 and go through a maximum at intermediate alizarin loadings. This phenomenon is ascribed to the progressive reparation of surface states by alizarin which hampers carrier transport through the TiO2 matrix and decreases electron discharge to the electrolyte solution.