Interaction of Formaldehyde with the Rutile TiO ₂ (110) Surface: A Combined Experimental and Theoretical Study

Journal Article · Thu Jun 16 00:00:00 EDT 2016 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/acs.jpcc.6b03689· OSTI ID:1324912

Yu, Xiaojuan; Zhang, Zhenrong; Yang, Chengwu; Bebensee, Fabian; Heissler, Stefan; Nefedov, Alexei; Tang, Miru; Ge, Qingfeng; Chen, Long; Kay, Bruce D.; Dohnálek, Zdenek; Wang, Yuemin; Wöll, Christof

The adsorption and reaction of formaldehyde (CH₂O) on the oxidized rutile TiO₂(110) surface were studied by temperature programmed desorption (TPD), scanning tunneling microscopy (STM), infrared reflection-absorption spectroscopy (IRRAS) and density functional theory (DFT) calculations. The experimental and theoretical data reveal the presence of various species depending on the temperature and coverage. After formaldehyde adsorption on TiO₂(110) at 65 K, the multilayer CH₂O was detected, which desorbs completely upon heating to 120 K. The isolated CH₂O monomer was identified after submonolayer adsorption at low temperatures (45-65 K), in which CH₂O is bound to the surface Ti5c sites via σ-donation and adopts a tilted geometry. With heating to higher temperatures the CH₂O monomers remain stable up to 70 K and then undergo coupling reactions to form paraformaldehyde (polyoxymethylene, POM) at the Ti_5c rows. The POM chain is oriented primarily along the [001] direction in a slightly disordered configuration. POM becomes the predominant species at 120 K and is decomposed releasing CH₂O at about 250 K. In addition, dioxymethylene (DOM) was detected as minority species formed via reaction of Ti_5c-bound CH₂O with both neighboring O_2c along the [1-10] direction and oxygen adatoms (Oad) at Ti_5c sites along [001] on the oxidized TiO₂(110) surface.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1324912
• Report Number(s): PNNL-SA-116863; 48287; 48368; KC0302010
• Journal Information: Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 23 Vol. 120; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

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