Site effects in the adsorption of carbon monoxide on real 1.8 nm Pt nanoparticles: An Infrared investigation in time and temperature

A study using in situ Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy has targeted carbon monoxide (CO) adsorption on the standard platinum (Pt) reference catalyst EuroPt-1. Reduced and non-reduced EuroPt-1 were analyzed in an infrared (IR) chamber which allowed the control of the CO atmosphere from temperatures ranging from -30 to 300 degrees C. The complex spectra of CO linearly adsorbed on highly dispersed Pt have been analyzed by using a combination of Fourier self-deconvolution and curve fitting. The linear-CO spectrum is composed of three main bands at 2096, 2083 and 2072 cm(-1). These were attributed to the three different adsorption sites - faces, edges and corners - of the 55-atom cuboctahedron Pt particles. The adsorption site competition was followed as a function of the temperature and it was demonstrated that these sites were never completely covered with CO. Furthermore, non-reduced EuroPt-1 presented reversible oxygen binding at low temperature in competition with CO. At 300 C, CO mainly occupied corner sites and a comparable state was approached for both catalysts by the removal of the oxygen from these corner sites. (C) 2013 Elsevier B.V. All rights reserved.