Chemisorption of CO on Au/TiO_x/Pt(111) Model Catalysts with Different Stoichiometry and Defectivity

Authors: Artiglia, Luca; Rizzi, Gian Andrea; Sedona, Francesco; Agnoli, Stefano; Granozzi, Gaetano

Source: Journal of Nanoscience and Nanotechnology, Volume 8, Number 7, July 2008 , pp. 3595-3602(8)

Publisher: American Scientific Publishers

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Abstract:

Au/TiO_x/Pt(111) model catalysts were prepared starting from well characterized TiO_x/Pt(111) ultrathin films, according to an established procedure consisting in a reactive evaporation of Ti, subsequent thermal treatment in O₂ or in UHV, and final deposition of submonolayer quantities of Au. Temperature Programmed Desorption measurements were performed to compare the interaction of CO in the case of two reduced TiO_x/Pt(111) substrates (indicated as w-TiO_x and w′-TiO_x, being the former characterized by an ordered array of defects that can act as template for the deposition of a stable array of Au nanoparticles), with the case of a stoichiometric rect′-TiO₂/Pt(111) substrate. It was found that in all cases CO is molecularly adsorbed and two different desorption peaks are detected: one at ≈140 K corresponding to CO desorption from less active adsorption sites (terraces) of the Au nanoparticles and one at ≈200 K corresponding to CO desorption from Au nanoparticles step sites. After annealing at 770 K, the high temperature CO desorption peak is still present in the case of the defective reduced w-TiO_x phase, supporting the good templating and stabilizing effect of such phase. On the rect′-TiO₂ stoichiometric phase, the CO uptake decreases after annealing but only to a minor extent.

Keywords: CO CHEMISORPTION; AU NANOPARTICLES; TITANIA TEMPLATES; ULTRATHIN FILMS; TPD; MODEL CATALYST

Document Type: Research article

DOI: http://dx.doi.org/10.1166/jnn.2008.386

Publication date: 2008-07-01

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