Combined DFT and kinetic Monte Carlo study of a bridging-spillover mechanism on fluorine-decorated graphene
| Autor: | Hongbo Wang, Gang Chen, Jinxiang Liu, Haiying Liu, Jing-Hua Guo |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Hydrogen Graphene General Physics and Astronomy chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences law.invention Catalysis Adsorption chemistry law Chemical physics Fluorine Cluster (physics) Kinetic Monte Carlo Physical and Theoretical Chemistry 0210 nano-technology Carbon |
| Zdroj: | Physical chemistry chemical physics : PCCP. 23(3) |
| ISSN: | 1463-9084 |
| Popis: | In this work, combining first-principles calculations with kinetic Monte Carlo (KMC) simulations, we constructed an irregular carbon bridge on the graphene surface and explored the process of H migration from the Pt catalyst to carbon bridge, and further migration to the graphene surface. The calculated reaction diagrams show that the hydrogen atoms can easily migrate from the Pt cluster to the carbon bridge with a low barrier of 0.22-0.86 eV, and KMC simulations indicate that the migration reactions can take place at intermediate temperatures (91.9-329.5 K). Our research clarified the role of the carbon bridge: (1) the close combination of Pt clusters and carbon bridges reduces H2 adsorption enthalpy, which facilitates the spillover of H atoms from the Pt cluster to the carbon bridges and (2) the unsaturated carbon atoms on the carbon bridges have radical character and tend to bind radical H atoms. The subsequent study shows that the F atoms decorated on graphene can greatly reduce the migration barrier of H atoms from the carbon bridge to graphene. With F atoms decorated, the carbon atoms are in an electron-deficient state, which have a strong ability to bind the hydrogen atoms, and it promotes the migration of H atoms to the graphene surface. The migration barrier and reaction temperature are reduced to 0.72 eV and 279 K, respectively. |
| Databáze: | OpenAIRE |
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