AVS 62nd International Symposium & Exhibition
    Surface Science Tuesday Sessions
       Session SS+AS+EN-TuM

Paper SS+AS+EN-TuM4
Tracking Site-Specific C-C Coupling of Formaldehyde Molecules on Rutile TiO2(110)

Tuesday, October 20, 2015, 9:00 am, Room 113

Session: Mechanistic Insight of Surface Reactions: Catalysis, ALD, etc. - I
Presenter: Zhenrong Zhang, Baylor University
Authors: Z. Zhang, Baylor University
K. Zhu, Baylor University
Y. Xia, Baylor University
M. Tang, Southern Illinois University Carbondale
Z.-T. Wang, Pacific Northwest National Laboratory
I. Lyubinetsky, Pacific Northwest National Laboratory
Q. Ge, Southern Illinois University Carbondale
Z. Dohnálek, Pacific Northwest National Laboratory
K. Park, Baylor University
Correspondent: Click to Email
We report the direct visualization of molecular coupling of the smallest aldehyde, formaldehyde, on reduced rutile TiO2(110) surfaces using scanning tunneling microscope (STM). Images from the same area at viable temperatures (75 ~ 170 K) show that formaldehyde preferably adsorbs to bridging-bonded oxygen vacancy (VO) defect site. VO-bound formaldehyde couples with Ti-bound CH2O form a diolate species, which stays stable at room temperature. In addition, two VO-bound formaldehyde molecules can couple and form Ti-bound species, which desorbs above ~215 K. This coupling reaction heals both the VO sites indicating formation and desorption of ethylene. We also directly observed the diffusion of methylene groups to nearby empty VO sites formed upon dissociation of the C-O bond in VO-bound formaldehyde, which suggests that the ethylene formation is via coupling of the methylene groups.