Abstract In this work, we employ density functional theory simulations to investigate possible spin polarization of CeO 2 -(111) surface and its impact on the interactions between a ceria support and Pt nanoparticles. With a Gaussian type orbital basis, our simulations suggest that the CeO 2 -(111) surface exhibits a robust surface spin polarization due to the internal charge transfer between atomic Ce and O layers. In turn, it can lower the surface oxygen vacancy formation energy and enhance the oxide reducibility. We show that the inclusion of spin polarization can significantly reduce the major activation barrier in the proposed reaction pathway of CO oxidation on ceria-supported Pt nanoparticles. For metal-support interactions, surface spin polarization enhances the bonding between Pt nanoparticles and ceria surface oxygen, while CO adsorption on Pt nanoparticles weakens the interfacial interaction regardless of spin polarization. However, the stable surface spin polarization can only be found in the simulations based on the Gaussian type orbital basis. Given the potential importance in the design of future high-performance catalysts, our present study suggests a pressing need to examine the surface ferromagnetism of transition metal oxides in both experiment and theory.
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Atomic level fluxional behavior and activity of CeO2-supported Pt catalysts for CO oxidation
Reducible oxides are widely used catalyst supports that can increase oxidation reaction rates by transferring lattice oxygen at the metal-support interface. There are many outstanding questions regarding the atomic-scale dynamic meta-stability (i.e., fluxional behavior) of the interface during catalysis. Here, we employ aberration-corrected
- Award ID(s):
- 1604971
- NSF-PAR ID:
- 10307505
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract In this work, we compare the CO oxidation performance of Pt single atom catalysts (SACs) prepared via two methods: (1) conventional wet chemical synthesis (strong electrostatic adsorption–SEA) with calcination at 350 °C in air; and (2) high temperature vapor phase synthesis (atom trapping–AT) with calcination in air at 800 °C leading to ionic Pt being trapped on the CeO 2 in a thermally stable form. As-synthesized, both SACs are inactive for low temperature (<150 °C) CO oxidation. After treatment in CO at 275 °C, both catalysts show enhanced reactivity. Despite similar Pt metal particle size, the AT catalyst is significantly more active, with onset of CO oxidation near room temperature. A combination of near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and CO temperature-programmed reduction (CO-TPR) shows that the high reactivity at low temperatures can be related to the improved reducibility of lattice oxygen on the CeO 2 support.more » « less
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Abstract Co2C, an emerging catalyst for the conversion of syngas to oxygenates, shows support‐sensitive behavior that has not yet been fully explained. Here, we characterize Co catalysts modified with ZnO atomic layer deposition on SiO2, carbon, CeO2, and Al2O3supports. We find that under syngas conditions, ZnO‐promoted Co transforms into Co2C on SiO2, carbon, and CeO2, but not on Al2O3. Moreover, the support affects the extent of carburization: while the SiO2‐supported catalyst carburizes completely, carbon‐ and CeO2‐supported catalysts show incomplete conversion of Co to Co2C. These three catalysts also exhibit different oxygenate selectivities. In contrast, the modified Al2O3‐supported catalyst retains the Fischer‐Tropsch catalytic properties of metallic Co. By depositing increasing amounts of Al2O3by ALD on the SiO2support, decreasing Co2C formation and oxygenate selectivity occurs.
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