ORIENTATION DEPENDENCE OF PHOTOCHEMICAL-REACTIONS ON TIO2 SURFACES

The photochemistry of oriented rutile surfaces has been examined using the photoreduction of Ag+ to Ag metal from an aqueous solution onto t he TiO2 surfaces. The photochemical reaction rates and quantum yields of rutile films were found to be a function of the orientation of the rutile surface. The (100) and (110) rutile orientations have lower pho toreduction rates than the (101), (111), and (001). This dependence of the photochemical reaction rates on film surface orientation is obser ved over a range of light intensities, illumination wavelengths, and f ilm thicknesses. Atomic force microscopy has been used to characterize the morphologies of the film surfaces and the photoreduced Ag at thes e surfaces. Several properties of rutile! such as the surface morpholo gy, surface chemistry, space charge phenomena, and charge transport, a re discussed in relation to their possible contributions to the orient ation dependence of the photochemistry on the rutile films.