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The effect of oxygen vacancies on the binding interactions of NH(3) with rutile TiO(2)(110)-1 × 1.
MedLine Citation:
PMID:  23034737     Owner:  NLM     Status:  Publisher    
A series of NH(3) temperature-programmed desorption (TPD) spectra were taken after dosing NH(3) at 70 K on rutile TiO(2)(110)-1 × 1 surfaces with oxygen vacancy (V(O)) concentrations of ∼0% (p-TiO(2)) and 5% (r-TiO(2)), respectively, to study the effect of V(O)s on the desorption energy of NH(3) as a function of coverage, θ. Our results show that in the zero coverage limit, the desorption energy of NH(3) on r-TiO(2) is 115 kJ mol(-1), which is 10 kJ mol(-1) less than that on p-TiO(2). The desorption energy from the Ti(4+) sites decreases with increasing θ due to repulsive NH(3)-NH(3) interactions and approaches ∼55 kJ mol(-1) upon the saturation of Ti(4+) sites (θ = 1 monolayer, ML) on both p- and r-TiO(2). The absolute monolayer saturation coverage is determined to be about 10% smaller on r-TiO(2) than that on p-TiO(2). Additionally, the trailing edges of the NH(3) TPD spectra on the hydroxylated TiO(2)(110) (h-TiO(2)) appear to be the same as that on r-TiO(2) while those on oxidized TiO(2)(110) (o-TiO(2)) shift to higher temperatures. We present a detailed analysis of the results and reconcile the observed differences based on the repulsive adsorbate-adsorbate dipole interactions between neighboring NH(3) molecules and the surface charge associated with the presence of V(O)s.
Boseong Kim; Zhenjun Li; Bruce D Kay; Zdenek Dohnálek; Yu Kwon Kim
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-4
Journal Detail:
Title:  Physical chemistry chemical physics : PCCP     Volume:  -     ISSN:  1463-9084     ISO Abbreviation:  Phys Chem Chem Phys     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100888160     Medline TA:  Phys Chem Chem Phys     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Department of Energy Systems Research and Department of Chemistry, Ajou University, Suwon 443-749, South Korea.
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