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Title: High Activity of Au/K/TiO 2(110) for CO Oxidation: Alkali-Metal-Enhanced Dispersion of Au and Bonding of CO

Abstract

In this paper, images from scanning tunneling microscopy show high mobility for potassium (K) on an oxidized TiO 2(110) surface. At low coverages, the alkali metal occupies mainly terrace sites of the o-TiO 2(110) system. The results of X-ray photoelectron spectroscopy indicate that K is fully ionized. The electron transferred from K to the titania affects the reactivity of this oxide, favoring the dispersion of Au particles on the terraces of the o-TiO 2(110) surface. When small coverages of K and Au are present on the o-TiO 2(110) system, only a few K–Au pairs are formed and the alkali metal affects Au chemisorption mainly through the oxide interactions. Addition of K to Au/o-TiO 2(110) enhances the reactivity of the system, opening new reaction paths for the adsorption and oxidation of carbon monoxide. CO can undergo disproportionation (2CO → C ads + CO 2,ads) on K/o-TiO 2(110) and Au/K/o-TiO 2(110) surfaces. The Au–KO x interface binds CO much better than plain Au–TiO 2, increasing the surface coverage of CO and facilitating its oxidation. Kinetic tests show that K promotes CO oxidation on Au/TiO 2. Finally, turnover frequencies of 2.1 and 10.8 molecules (Au site) -1 s –1 were calculated for oxidationmore » of CO on Au/o-TiO 2(110) and Au/K/o-TiO 2(110) catalysts, respectively.« less

Authors:
ORCiD logo [1];  [1];  [2]; ORCiD logo [1]; ORCiD logo [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Dept.
  2. Central Univ. of Venezuela, Caracas (Venezuela)
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1430849
Report Number(s):
BNL-203369-2018-JAAM
Journal ID: ISSN 1932-7447; TRN: US1802626
Grant/Contract Number:  
SC0012704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 122; Journal Issue: 8; 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

Rodriguez, Jose A., Grinter, David C., Ramirez, Pedro J., Stacchiola, Dario J., and Senanayake, Sanjaya. High Activity of Au/K/TiO2(110) for CO Oxidation: Alkali-Metal-Enhanced Dispersion of Au and Bonding of CO. United States: N. p., 2018. Web. doi:10.1021/acs.jpcc.7b11771.
Rodriguez, Jose A., Grinter, David C., Ramirez, Pedro J., Stacchiola, Dario J., & Senanayake, Sanjaya. High Activity of Au/K/TiO2(110) for CO Oxidation: Alkali-Metal-Enhanced Dispersion of Au and Bonding of CO. United States. doi:10.1021/acs.jpcc.7b11771.
Rodriguez, Jose A., Grinter, David C., Ramirez, Pedro J., Stacchiola, Dario J., and Senanayake, Sanjaya. Wed . "High Activity of Au/K/TiO2(110) for CO Oxidation: Alkali-Metal-Enhanced Dispersion of Au and Bonding of CO". United States. doi:10.1021/acs.jpcc.7b11771. https://www.osti.gov/servlets/purl/1430849.
@article{osti_1430849,
title = {High Activity of Au/K/TiO2(110) for CO Oxidation: Alkali-Metal-Enhanced Dispersion of Au and Bonding of CO},
author = {Rodriguez, Jose A. and Grinter, David C. and Ramirez, Pedro J. and Stacchiola, Dario J. and Senanayake, Sanjaya},
abstractNote = {In this paper, images from scanning tunneling microscopy show high mobility for potassium (K) on an oxidized TiO2(110) surface. At low coverages, the alkali metal occupies mainly terrace sites of the o-TiO2(110) system. The results of X-ray photoelectron spectroscopy indicate that K is fully ionized. The electron transferred from K to the titania affects the reactivity of this oxide, favoring the dispersion of Au particles on the terraces of the o-TiO2(110) surface. When small coverages of K and Au are present on the o-TiO2(110) system, only a few K–Au pairs are formed and the alkali metal affects Au chemisorption mainly through the oxide interactions. Addition of K to Au/o-TiO2(110) enhances the reactivity of the system, opening new reaction paths for the adsorption and oxidation of carbon monoxide. CO can undergo disproportionation (2CO → Cads + CO2,ads) on K/o-TiO2(110) and Au/K/o-TiO2(110) surfaces. The Au–KOx interface binds CO much better than plain Au–TiO2, increasing the surface coverage of CO and facilitating its oxidation. Kinetic tests show that K promotes CO oxidation on Au/TiO2. Finally, turnover frequencies of 2.1 and 10.8 molecules (Au site)-1 s–1 were calculated for oxidation of CO on Au/o-TiO2(110) and Au/K/o-TiO2(110) catalysts, respectively.},
doi = {10.1021/acs.jpcc.7b11771},
journal = {Journal of Physical Chemistry. C},
issn = {1932-7447},
number = 8,
volume = 122,
place = {United States},
year = {2018},
month = {2}
}

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Figures / Tables:

Figure 1 Figure 1: STM images of (a) as-prepared h-TiO2(110) and (b) oxidised o-TiO2(110). (20 × 10 nm2, V = +1.74 V, I = 0.1 nA)

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