ABSTRACT
As it is well known, metal nanoparticles distributed on a TiO2 surface can improve dramatically the reaction rate and selectivity of reaction in gas sensing. In this work, we studied the Pt particles embedded on crystalline TiO2 nanopowders used as a semiconductor gas sensor. We prepared a wide set of TiO2 samples grown at different temperatures and with different nominal Pt concentrations using the impregnation method. The aim of this study was to analyze the Pt distribution on the TiO2 surface as well as the possible epitaxial relationships between the metal nanoparticles and the semiconductor oxide support. We used high-resolution electron microscopy (HRTEM) to study Pt nanoparticle morphology. The HRTEM images were compared with computer simulations to confirm the results obtained. In this way we used the EMS software package to create the image simulations. Our supercell files were created using INDEM, a homemade program developed in CEMES laboratories, which allowed us to build epitaxial structures between two different materials. Good epitaxial relationships were found for platinum nanoparticles smaller than 3 nm in diameter, which adopted a cuboctahedral morphology.
