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Title: Elucidation of Active Sites for the Reaction of Ethanol on TiO 2 /Au(111)

Abstract

Obtaining a molecular-level understanding of the reaction of alcohols with heterogeneous model catalysts is critical for improving industrial catalytic processes, such as the production of H 2 from alcohols. Gold has been shown to be an excellent oxidation catalyst once oxygen is added to it. The use of reducible oxides provides a source of oxygen on Au(111) for the reaction of ethanol, which is easily regenerated in the presence of an oxygen background. In this work, ethanol operates as a probe molecule to investigate the role of Au(111), TiO 2 nanoparticles, and TiO 2/Au interfacial surface sites on the catalytic properties of TiO 2/Au(111). Ultrahigh vacuum temperature-programmed desorption (TPD) studies with ethanol/Au(111) elucidate previously unreported adsorption sites for ethanol. Ethanol molecularly adsorbs to Au terrace sites, step edges, and undercoordinated kink sites with adsorption energies of -51.7, -55.8, and -65.1 kJ/mol, respectively. In a TPD coverage study of ethanol on TiO 2/Au(111) indicates ethanol undergoes dissociative adsorption to form H*(a) and CH 3CH 2O*(a) on the inverse model catalyst surface. The desorption temperature of low coverages of ethanol from TiO2/Au(111) (Tdes ≈ 235 K) is at an intermediate temperature between the desorption temperatures from bulk Au(111) and TiO 2(110), indicatingmore » both Au and TiO 2 play a role in the adsorption of ethanol. Both low-temperature adsorption and high-temperature reactions are studied and indicate that ethanol-derived products such as acetaldehyde and ethylene desorb from TiO 2/Au(111) at ~500 K. Here, we report the identification of catalytically active sites on TiO 2/Au(111) as interfacial sites between the oxide and Au(111) surface through the use of temperature-programmed desorption and infrared reflection absorption spectroscopy.« less

Authors:
 [1];  [1];  [2];  [1];  [1];  [1];  [1];  [3];  [2]; ORCiD logo [1]
  1. James Madison Univ., Harrisonburg, VA (United States). Dept. of Chemistry and Biochemistry
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Dept. of Chemistry
  3. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1372450
Report Number(s):
BNL-114048-2017-JA
Journal ID: ISSN 1932-7447; R&D Project: CO040; KC0302010
Grant/Contract Number:
SC00112704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 14; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Boyle, David T., Wilke, Jeremy A., Palomino, Robert M., Lam, Vivian H., Schlosser, Daniel A., Andahazy, Wil J., Stopak, Cameron Z., Stacchiola, Dario J., Rodriguez, Jose A., and Baber, Ashleigh E.. Elucidation of Active Sites for the Reaction of Ethanol on TiO 2 /Au(111). United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.6b11764.
Boyle, David T., Wilke, Jeremy A., Palomino, Robert M., Lam, Vivian H., Schlosser, Daniel A., Andahazy, Wil J., Stopak, Cameron Z., Stacchiola, Dario J., Rodriguez, Jose A., & Baber, Ashleigh E.. Elucidation of Active Sites for the Reaction of Ethanol on TiO 2 /Au(111). United States. doi:10.1021/acs.jpcc.6b11764.
Boyle, David T., Wilke, Jeremy A., Palomino, Robert M., Lam, Vivian H., Schlosser, Daniel A., Andahazy, Wil J., Stopak, Cameron Z., Stacchiola, Dario J., Rodriguez, Jose A., and Baber, Ashleigh E.. Fri . "Elucidation of Active Sites for the Reaction of Ethanol on TiO 2 /Au(111)". United States. doi:10.1021/acs.jpcc.6b11764. https://www.osti.gov/servlets/purl/1372450.
@article{osti_1372450,
title = {Elucidation of Active Sites for the Reaction of Ethanol on TiO 2 /Au(111)},
author = {Boyle, David T. and Wilke, Jeremy A. and Palomino, Robert M. and Lam, Vivian H. and Schlosser, Daniel A. and Andahazy, Wil J. and Stopak, Cameron Z. and Stacchiola, Dario J. and Rodriguez, Jose A. and Baber, Ashleigh E.},
abstractNote = {Obtaining a molecular-level understanding of the reaction of alcohols with heterogeneous model catalysts is critical for improving industrial catalytic processes, such as the production of H2 from alcohols. Gold has been shown to be an excellent oxidation catalyst once oxygen is added to it. The use of reducible oxides provides a source of oxygen on Au(111) for the reaction of ethanol, which is easily regenerated in the presence of an oxygen background. In this work, ethanol operates as a probe molecule to investigate the role of Au(111), TiO2 nanoparticles, and TiO2/Au interfacial surface sites on the catalytic properties of TiO2/Au(111). Ultrahigh vacuum temperature-programmed desorption (TPD) studies with ethanol/Au(111) elucidate previously unreported adsorption sites for ethanol. Ethanol molecularly adsorbs to Au terrace sites, step edges, and undercoordinated kink sites with adsorption energies of -51.7, -55.8, and -65.1 kJ/mol, respectively. In a TPD coverage study of ethanol on TiO2/Au(111) indicates ethanol undergoes dissociative adsorption to form H*(a) and CH3CH2O*(a) on the inverse model catalyst surface. The desorption temperature of low coverages of ethanol from TiO2/Au(111) (Tdes ≈ 235 K) is at an intermediate temperature between the desorption temperatures from bulk Au(111) and TiO2(110), indicating both Au and TiO2 play a role in the adsorption of ethanol. Both low-temperature adsorption and high-temperature reactions are studied and indicate that ethanol-derived products such as acetaldehyde and ethylene desorb from TiO2/Au(111) at ~500 K. Here, we report the identification of catalytically active sites on TiO2/Au(111) as interfacial sites between the oxide and Au(111) surface through the use of temperature-programmed desorption and infrared reflection absorption spectroscopy.},
doi = {10.1021/acs.jpcc.6b11764},
journal = {Journal of Physical Chemistry. C},
number = 14,
volume = 121,
place = {United States},
year = {Fri Mar 17 00:00:00 EDT 2017},
month = {Fri Mar 17 00:00:00 EDT 2017}
}

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  • Au(111) does not bind CO and O 2 well. The deposition of small nanoparticles of MgO, CeO 2, and TiO 2 on Au(111) produces excellent catalysts for CO oxidation at room temperature. In an inverse oxide/metal configuration there is a strong enhancement of the oxide–metal interactions, and the inverse catalysts are more active than conventional Au/MgO(001), Au/CeO 2(111), and Au/TiO 2(110) catalysts. An identical trend was seen after comparing the CO oxidation activity of TiO2/Au and Au/TiO 2 powder catalysts. In the model systems, the activity increased following the sequence: MgO/Au(111) < CeO 2/Au(111) < TiO 2/Au(111). Ambient pressure X-raymore » photoelectron spectroscopy (AP-XPS) was used to elucidate the role of the titania–gold interface in inverse TiO 2/Au(111) model catalysts during CO oxidation. Stable surface intermediates such as CO(ads), CO 3 2–(ads), and OH(ads) were identified under reaction conditions. CO 3 2–(ads) and OH(ads) behaved as spectators. The concentration of CO(ad) initially increased and then decreased with increasing TiO 2 coverage, demonstrating a clear role of the Ti–Au interface and the size of the TiO 2 nanostructures in the catalytic process. Overall, our results show an enhancement in the strength of the oxide–metal interactions when working with inverse oxide/metal configurations, a phenomenon that can be utilized for the design of efficient catalysts useful for green and sustainable chemistry.« less
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