Adsorption of Catechol on TiO2 Rutile (100): A Density Functional Theory Investigation

We have used DFT calculations to investigate the binding of catechol, one of the smallest sensitizing chromophores, to the rutile TiO 2 (100) surface. On the clean surface, we find that monodentate adsorption is favored over molecular adsorption. An oxygen defective site strongly favors the fully dissociative bidentate adsorption, which is otherwise found not to be stable. Regardless of the protonation form of catechol, however, occupied molecular states are introduced into the band gap of rutile (100). The lowest unoccupied levels are localized exclusively on the substrate.