Towards the Effect of Pt<sup>0</sup>/Pt<sup>δ+</sup> and Ce<sup>3+</sup> Species at the Surface of CeO<sub>2</sub> Crystals: Understanding the Nature of the Interactions under CO Oxidation Conditions
Laís Reis Borges, Anderson G. M. da Silva, Adriano H. Braga, Liane M. Rossi, Marco Aurélio Suller Garcia, Pedro Vidinha
Abstract
Abstract We synthesized CeO 2 nanowires and nanocubes showing {110}+{100} and {100} surfaces predominantly, respectively, once the different surface energies play a crucial role in the behavior of Ce 4+ /Ce 3+ reversibility. We found out that Pt/CeO 2 nanowires presented more Ce 3+ content, oxygen vacancies, and atomically dispersed Pt, indicating a stronger Pt−Ce interaction. In contrast, the Pt/CeO 2 nanocubes presented a higher contribution of Pt δ+ species, suggesting a well‐controlled Pt particle size (∼1 nm) and significant interaction with ceria, with oxygen species more available at the surface. Thus, we suggest that the ceria‘s different surface energies may lead to different Pt distributions of species over the supports. H 2 ‐reduction treatment led to changes in Pt structure that showed a better catalysis performance for the Pt/CeO 2 nanowires essentially, supported by XPS and CO‐DRIFTS. Nevertheless, this step did not cause improved activity to the point of overcoming the nanocubes‐based catalyst, and the reasons were fully discussed. Herein, we propose that catalysts′ performance depends on a complex combination of several materials′ characteristics. These features may lead to different reaction pathways depending on the pre‐treatment of the samples.