Journal
CHEMCATCHEM
Volume 13, Issue 5, Pages 1340-1354Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/cctc.202001621
Keywords
ceria; platinum species; oxygen vacancies; CO oxidation
Categories
Funding
- FAPESP [2015/14905-0]
- SHELL Brazil through the 'Research Centre for Gas Innovation - RCGI' (FAPESP) [2014/50279-4]
- ANP (Brazil's National Oil, Natural Gas, and Biofuels Agency)
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Different surface energies of CeO2 nanowires and nanocubes affect the Pt distribution and interaction, leading to varying catalytic performance. The H-2-reduction treatment improves the catalysis of Pt/CeO2 nanowires, but does not surpass the nanocubes-based catalyst, highlighting the complex combination of material characteristics in determining catalyst performance.
We synthesized CeO2 nanowires and nanocubes showing {110}+{100} and {100} surfaces predominantly, respectively, once the different surface energies play a crucial role in the behavior of Ce4+/Ce3+ reversibility. We found out that Pt/CeO2 nanowires presented more Ce3+ content, oxygen vacancies, and atomically dispersed Pt, indicating a stronger Pt-Ce interaction. In contrast, the Pt/CeO2 nanocubes presented a higher contribution of Pt delta+ species, suggesting a well-controlled Pt particle size (similar to 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/CeO2 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.
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