| AVS 54th International Symposium | |
| Surface Science | Wednesday Sessions |
| Session SS1-WeM |
| Session: | Oxide Surface Reactivity |
| Presenter: | P.R. McGill, The University of Auckland, New Zealand |
| Authors: | P.R. McGill, The University of Auckland, New Zealand H. Idriss, The University of Auckland, New Zealand |
| Correspondent: | Click to Email |
Formamide is a compound of considerable interest, owing to its ability to yield nucleobases during photoreaction over TiO2 in both aqueous1 and ultrahigh vacuum conditions.2 The mechanisms for this synthesis have been postulated to involve the generation and subsequent decomposition of HCN polymers on the surface. While a number of experimental studies have investigated formamide and HCN adsorption to the surfaces of TiO2,2,3,4 computational work has focused on their interaction with metal surfaces.5 In this study, a series of periodic DFT calculations are conducted on formamide and HCN adsorption to the (110) and (011) bulk terminated surfaces of rutile TiO2, employing plane wave basis sets and the PBE exchange correlation functional. Dissociative adsorption appears favoured for formamide on both investigated surfaces; the formamide molecule binding in a bridging manner across two surface Ti sites analogous to that of formic acid on the rutile TiO2 (110) surface. Molecular adsorption through the carbonyl oxygen's interaction with the surface Ti is also found to be energetically favourable, though to a lesser extent. No stable interaction mode is observed for molecular adsorption through the N atom to the surface Ti species, in agreement with IR studies3 conducted on formamide over polycrystalline TiO2. HCN was found to strongly preference toward molecular adsorption in an orientation perpendicular to the surface, with the nitrogen binding to a surface Ti. Dissociative adsorption is found to be less favourable than molecular adsorption, with dissociative adsorption through the C atom yielding a greater stability than through the N atom. Adsorption modes parallel to the surface (which are reported on metal surfaces5) do not appear to represent energy minima, and convert back to perpendicular configurations on geometry optimisation.
1 Saladino, R., Cresti, C., Costanzo, G. DiMauro, E. (2004) Curr.Org.Chem. 8, 1425.
2 Senanayake, S.D., Idriss, H. (2006) Pro. Nat. Acad. Sci. USA. 103, 1194.
3 Wu, W.C., Liao, LF, Chuang, C.C., Lin, J.L. (2000) J.Catal. 195, 416.
4 Raskó, J., Bánsági, T., Solymosi, F. (2002) Phys.Chem.Chem.Phys. 4, 3509.
5 Oliva, C., van den Berg, C., Niemantsverdriet, J.W.H., Curulla-Ferre, D. (2007) J. Catal. 245, 436.