AVS 58th Annual International Symposium and Exhibition
    Surface Science Division Wednesday Sessions
       Session SS-WeA

Paper SS-WeA10
Adsorption of Carbon Dioxide on Rutile TiO2(110): A Scanning Tunneling Microscopy Study

Wednesday, November 2, 2011, 5:00 pm, Room 107

Session: Adsorption & Reactions on Oxide Surfaces
Presenter: Xiao Lin, Pacific Northwest National Laboratory
Authors: X. Lin, Pacific Northwest National Laboratory
B.D. Kay, Pacific Northwest National Laboratory
Z.T. Wang, Pacific Northwest National Laboratory
I. Lyubinetsky, Pacific Northwest National Laboratory
Z. Dohnalek, Pacific Northwest National Laboratory
Correspondent: Click to Email
Understanding the fundamental aspects of CO2 adsorption and reaction on well-characterized oxide surfaces is critical in providing fundamental understanding on how to control catalytic carbon sequestration and CO2 conversion to fuels. A model oxide surface, rutile TiO2(110) is used to investigate the adsorption properties of CO2 using scanning tunneling microscopy (STM). STM images obtained before and after in-situ doses of CO2 at 50 K reveal that the CO2 molecules preferentially bind in bridge-bonded oxygen vacancy (VO) defect sites. We show that electron injection from the STM tip can induce CO2 reduction to CO and VO annihilation. After the saturation of VO’s, CO2 molecules preferentially adsorb on five-fold coordinated Ti sites, where they remain mobile even at 50 K. The mobile CO2 molecules may be corralled by other immobile species such as CO. The contrast observed in the STM images suggests that the distribution of mobile CO2 molecules tracks the distribution of the subsurface charge as demonstrated by the CO2 induced standing wave patterns along the Ti rows. The adsorption behavior of CO2 on hydroxylated TiO2 surfaces will also be presented.