Mechanism of surface dehydration of anatase (TiO2)

Abstract

A comparative study of the dehydration of the (001) and (111) surfaces of TiO2 (anatase) has been made starting from a master equation and introducing suitable transition probabilities. From the experimental data considered, relative to sample Degussa P25 of Munuera and co-workers, it is concluded that the (111) face is the most likely to be exposed. The detailed mechanism of dehydration is analyzed and an estimate of the values of activation energies and frequency factors is presented. This analysis makes it clear that the surface migration of protons plays an important role during the dehydration process. Also the influence on the degree of surface hydration, the dehydration rate, and the numbers of certain ionic groups on the surface exerted by the temperature rate in a linear heating program and by initial surface coverage are discussed.