Semiconductor Based Interfacial Electron Transfer Reactivity: Decoupling Kineticsfrom pH Dependent Band Energetics in a Dye-Sensitized Titanium Dioxide/Aqueous Solution System

摘要

Hexaphosphonation of Ru(bpy)3(2+) provides a basis for surface attachment tonanocrystalline TiO2 in film (electrode) or colloidal form and for subsequent retention of the molecule over an extraordinarily wide pH range. Visible excitation of the surface attached complex leads to rapid injection of an electron into the semiconductor. Return electron transfer, monitored by transient absorbance spectroscopy, is biphasic with a slow component that can be reversibly eliminated by adjusting the potential of the dark electrode to a value close to the conduction band edge (E sub CB). Evaluation of the fast component yields a