Variable-temperature scanning tunneling microscopy and dispersion-corrected density functional theory were employed to study the interaction of 1,3-propanediol with reduced TiO2(110) surfaces. We find that at 300 K, 1,3-propanediol molecules dissociate via O-H bond scission of one of the OH groups on bridge-bonded oxygen (Ob) vacancy (VO) defects forming pairs of monoalkoxide (Ob-(CH2)3-OH) and bridge-bonded bonded hydroxyl (HOb) species. The OH group of the monoalkoxide species is bound to the adjacent 5-coordinated Ti4+ (Ti5c) sites. The Ob-(CH2)3-OH species are observed to rotate around their Ob anchor, switching the position of the OH between the two adjacent Ti5c rows. The rotating species are found to assist cross-Ob row HOb hydrogen transfer. The OH group of the monoalkoxide species is further observed to dissociate forming a bidentate type dioxo (Ob-(CH2) 3-OTi5c) species and an additional HOb. The reversible interconversion between the mono and dioxo species illustrates the attainment of a dynamic equilibrium between these conjugate acid/base pairs.
ASJC Scopus subject areas
- Materials Science(all)
- Physical and Theoretical Chemistry