Influencia del pretratamiento en los nanocompuestos de CeO2 y Au/CeO2 para mejorar la creación de defectos superficiales que permitan modificar la interbanda óptica

Abstract

Cerium oxide as a material within heterogeneous catalysis remains a relevant research topic due to its redox behavior, directly related to the presence of oxygen vacancies (Vo-) which are responsible for ceria’s high oxygen storage capacity. CeO2 also have been employed as a support for active noble metal particles; in particular, supported gold catalyst has been proposed as a candidate to be used in different reactions such as CO oxidation, catalytic combustion of hydrocarbons, WGS reaction, among others. Despite its relevance, few works have a detailed understanding of the pretreatment effect on these catalysts. For this reason, in this work, we study the in situ behavior of CeO2 and Au/CeO2 during different pretreatments in temperature and atmosphere by Raman and Diffuse reflectance UV-Vis. These techniques allow us to follow in real-time the surface changes of Au nanoparticles and CeO2. We demonstrate a direct correlation lattice structural defects of CeO2 with modifications formed by electronic states in the optical interband and, the deposition of Au nanoparticles on the surface of CeO2 allows to improve the properties formed by the electronic states between the valence band and the conduction band by increasing more than twice the structural defects compared to CeO2 alone.