Vacancy-assisted diffusion of alkoxy species on rutile TiO2(110)

Using scanning tunneling microscopy (STM) and density functional theory simulations, we have studied the diffusion of alkoxy species formed by the dissociation of alcohols on bridge-bonded oxygen (BBO) vacancies (BBOV's) on TiO2(110). At elevated temperatures (400K) the sequential isothermal STM images show that mobile BBOV's mediate the diffusion of alkoxy species by providing space for alkyl-group-bearing BBO atom to diffuse into. The experimental findings are further supported by simulations that find that BBOV diffusion is the rate limiting step in the overall diffusion mechanism.