Adsorption and interaction of CO2 on rutile TiO2(110) surfaces: a combined UHV-FTIRS and theoretical simulation study. Issue 37 (27th August 2015) - Cao, Yunjun
Abstract : P-polarized RAIR spectra of CO2 adsorbed on reduced rutile TiO2 (110) surfaces as a function of CO2 dosage and adsorption temperature. The incidence plane is along (a) the [001] azimuth and (b) the [11̄0] azimuth respectively. Abstract : CO2 adsorption and interaction on rutile TiO2 (110) surfaces was studied by UHV-FTIRS combined with theoretical simulations. With increasing CO2 exposure, CO2 adsorbs in succession at the oxygen vacancy (Vo) sites, on the five-coordinated Ti cation (Ti5c ) sites and the bridging oxygen (Obr ) sites at low temperature. The coupling has occurred between neighboring CO2 adsorbed on Ti5c sites from rather low CO2 coverage (∼0.5 ML), leading the ν 3 (OCO) asymmetric stretching vibrations to split into two absorption bands in IR spectra. Two kinds of coupled geometries of adjacent CO2 on Ti5c sites are determined by theoretical simulations. For the higher CO2 coverage (∼1.5 ML), the horizontal adsorption configuration along the [11̄0] azimuth of CO2 adsorbed on Obr sites is identified for the first time using polarization- and azimuth-resolved RAIRS in experiments. The significant deviation of CO2 from the top of Obr sites demonstrates the strong coupling between CO2 adsorbed on Obr and Ti5c sites.