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Despite the broad catalytic relevance of metal–support interfaces, controlling their chemical nature, the interfacial contact perimeter (exposed to reactants), and consequently, their contributions to overall catalytic reactivity, remains challenging, as the nanoparticle and support characteristics are interdependent when catalysts are prepared by impregnation. Here, we decoupled both characteristics by using a raspberry-colloid-templating strategy that yields partially embedded PdAu nanoparticles within well-defined SiO2or TiO2supports, thereby increasing the metal–support interfacial contact compared to nonembedded catalysts that we prepared by attaching the same nanoparticles onto support surfaces. Between nonembedded PdAu/SiO2and PdAu/TiO2, we identified a support effect resulting in a 1.4-fold higher activity of PdAu/TiO2than PdAu/SiO2for benzaldehyde hydrogenation. Notably, partial nanoparticle embedding in the TiO2raspberry-colloid-templated support increased the metal–support interfacial perimeter and consequently, the number of Au/TiO2interfacial sites by 5.4-fold, which further enhanced the activity of PdAu/TiO2by an additional 4.1-fold. Theoretical calculations and in situ surface-sensitive desorption analyses reveal facile benzaldehyde binding at the Au/TiO2interface and at Pd ensembles on the nanoparticle surface, explaining the connection between the number of Au/TiO2interfacial sites (via the metal–support interfacial perimeter) and catalytic activity. Our results demonstrate partial nanoparticle embedding as a synthetic strategy to produce thermocatalytically stable catalysts and increase the number of catalytically active Au/TiO2interfacial sites to augment catalytic contributions arising from metal–support interfaces.
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Identification of active sites on supported metal catalysts with carbon nanotube hydrogen highways
Abstract Catalysts consisting of metal particles supported on reducible oxides exhibit promising activity and selectivity for a variety of current and emerging industrial processes. Enhanced catalytic activity can arise from direct contact between the support and the metal or from metal-induced promoter effects on the oxide. Discovering the source of enhanced catalytic activity and selectivity is challenging, with conflicting arguments often presented based on indirect evidence. Here, we separate the metal from the support by a controlled distance while maintaining the ability to promote defects via the use of carbon nanotube hydrogen highways. As illustrative cases, we use this approach to show that the selective transformation of furfural to methylfuran over Pd/TiO2occurs at the Pd-TiO2interface while anisole conversion to phenol and cresol over Cu/TiO2is facilitated by exposed Ti3+cations on the support. This approach can be used to clarify many conflicting arguments in the literature.
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- PAR ID:
- 10154321
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 9
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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