We have studied the adsorption of a variety of aromatic organic molecules on TiO2 rutile (110) and anatase (101) surfaces using a combination of STM, photoemission spectroscopy, and accompanying DFT calculations performed by collaborators.
Catechol / TiO2 is a model system for dye sensitized solar cell. In this talk, I am going to talk about the adsorpion of catechol on both rutile TiO2(110) and anatase TiO2(101) surfaces. We found that the electronic structure of catecholate on TiO2 is correlated to its bonding configuration. The molecule switches back-and-forth between different configurations via facile transfer of hydrogen transfer to and from the TiO2 surface. Hydrogen also plays a key role in the diffusion of catecholates, the product via catechol adsorption, across the surface.
The adsorption of aniline (C6H5NH2) and azobenzene (C6H5N=NH5C6) has been also investigated with the goal to understand the role TiO2 plays in the catalytic synthesis of nitroaromatics.  In this talk, I will also demonstrate that both molecules form the same superstructure on rutile (110) as well as anatase (101) surfaces, suggesting that TiO2 is instrumental in cleaving the N=N double bond of azobenzene.