Journal
ACS CATALYSIS
Volume 10, Issue 5, Pages 3084-3093Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acscatal.9b04840
Keywords
single-atom catalysis; CO oxidation; Langmuir-Hinshelwood; microkinetics modeling; first-principles
Categories
Funding
- NSFC [21771029, 11811530631, 21573034, 21373036, 21103015]
- Chinese Scholarship Council [201706060254]
- Special Academic Partner GCR Program from King Abdullah University of Science and Technology (KAUST)
- EU-2020 Advanced Project [670173]
- High Performance Computing Center at the Dalian University of Technology
- National Supercomputing Center in Guangzhou, China
- Supercomputing Center at KAUST
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Although substantial advances have been made in a few reactions of industrial significance over single-atom catalysts (SACs), the origin of the superior catalytic performance, the nature of the active sites, and the reaction pathways are still the subject of debate. Even for CO oxidation over SACs on nonreducible substrates, the understanding is limited. We investigated the performance of Pd atoms monodispersed on graphene (PdGr) in CO oxidation. Combining first-principles-based thermodynamics calculations and microkinetics modeling, we showed that the positively charged PdGr can exhibit a rather high low-temperature activity in CO oxidation. Under reaction conditions, the Pd atom binds strongly with 02, acting as the reactive species to convert CO. A comparison of the conversion rates of steps along different potential reaction pathways provides direct evidence that CO oxidation mainly proceeds through revised Langmuir-Hinshelwood pathways, and the dissociation of the peroxide intermediate (O-O-C=O) is the rate limiting step. The predicted catalytic performance was attributed to the specific electronic structure of PdGr with the positively charged Pd on graphene monovacancy exposing sp-type frontier states. We expect these findings to help in understanding the performance of SACs and to guide the design and fabrication of SACs with superior catalytic performance.
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