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Niefind F, Mao Q, Nayir N, Kowalik M, Ahn JJ, Winchester AJ, Dong C, Maniyara RA, Robinson JA, van Duin ACT, Pookpanratana S. Watching (De)Intercalation of 2D Metals in Epitaxial Graphene: Insight into the Role of Defects. Small 2024; 20:e2306554. [PMID: 37919862 DOI: 10.1002/smll.202306554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/06/2023] [Indexed: 11/04/2023]
Abstract
Intercalation forms heterostructures, and over 25 elements and compounds are intercalated into graphene, but the mechanism for this process is not well understood. Here, the de-intercalation of 2D Ag and Ga metals sandwiched between bilayer graphene and SiC are followed using photoemission electron microscopy (PEEM) and atomistic-scale reactive molecular dynamics simulations. By PEEM, de-intercalation "windows" (or defects) are observed in both systems, but the processes follow distinctly different dynamics. Reversible de- and re-intercalation of Ag is observed through a circular defect where the intercalation velocity front is 0.5 nm s-1 ± 0.2 nm s.-1 In contrast, the de-intercalation of Ga is irreversible with faster kinetics that are influenced by the non-circular shape of the defect. Molecular dynamics simulations support these pronounced differences and complexities between the two Ag and Ga systems. In the de-intercalating Ga model, Ga atoms first pile up between graphene layers until ultimately moving to the graphene surface. The simulations, supported by density functional theory, indicate that the Ga atoms exhibit larger binding strength to graphene, which agrees with the faster and irreversible diffusion kinetics observed. Thus, both the thermophysical properties of the metal intercalant and its interaction with defective graphene play a key role in intercalation.
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Affiliation(s)
- Falk Niefind
- Nanoscale Device Characterization Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD, 20742, USA
| | - Qian Mao
- Department of Mechanical Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Nadire Nayir
- Department of Mechanical Engineering, Pennsylvania State University, University Park, PA, 16802, USA
- Department of Physics, Karamanoglu Mehmetbey University, Karaman, 70000, Turkey
| | - Malgorzata Kowalik
- Department of Mechanical Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Jung-Joon Ahn
- Nanoscale Device Characterization Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
- Department of Physics, Georgetown University, Washington, DC, 20057, USA
| | - Andrew J Winchester
- Nanoscale Device Characterization Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
- Institute for Soft Matter, Georgetown University, Washington, DC, 20057, USA
| | - Chengye Dong
- Department of Materials Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Rinu A Maniyara
- Department of Materials Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Joshua A Robinson
- Department of Materials Science & Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Adri C T van Duin
- Department of Mechanical Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Sujitra Pookpanratana
- Nanoscale Device Characterization Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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