Insights into the CeO2 facet-depended performance of propane oxidation over Pt-CeO2 catalysts

Propane (C3H8) is one of the gases hardest to convert in vehicles’ exhausts, which largely affects the emission control ability of after-treatment systems. In this paper, we take Pt-CeO2 catalysts as an example to investigate the supports’ facet-depended propane oxidation performance. Four types of CeO2 materials with different morphologies (nano-lamella, nano-cube, nano-polyhedron and nano-rod) were synthesized and were found to expose different dominating facets. Consequently, the nano-lamellar CeO2, mainly exposed (1 1 0) facet, delivered the best catalytic activity among various Pt-CeO2 catalysts. The ageing and reduction pretreatments tuned the amount of oxygen vacancies and Pt size/Pt charge which remarkably affected the performances of Pt-CeO2 catalysts. Based on the experiments and DFT calculations, it was concluded that oxygen on CeO2 (1 0 0) surface was easily removed in reduction atmosphere leading to electron-rich Pt formed on oxygen absent (1 0 0) surface, while on CeO2 (1 1 0) surface abundant oxygen vacancies were generated during reduction pretreatment and additional surface lattice oxygen contributed to form electron-deficient Pt kept in small cluster size. This research will help us to develop more efficient exhaust catalysts through a deep understanding of the electronic interactions between the metal and active surface of supports.