Electrochemically Driven Covalent Functionalization of Graphene from Fluorinated Aryl Iodonium Salts
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
- Department of Biochemistry &, Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
Chemical functionalization is required to adapt graphene’s properties to many applications. However, most covalent functionalization schemes are spontaneous or defect driven and are not suitable for applications requiring directed assembly of molecules on graphene substrates. In this study, we demonstrate the electrochemically driven covalent bonding of trifluoromethylphenylene (CF3Ph) onto epitaxial graphene. Submonolayer and full monolayer chemisorption was demonstrated by varying the duration of the electrochemical driving potential. A 10× increase in the CF3Ph density was obtained by varying the duration of the graphene electrochemical potential by 4×. A maximum closed-pack density of 1 × 1014 molecules·cm–2 was observed. Chemical, electronic, and defect states of CF3Ph–graphene were studied by photoemission spectroscopy, spatially resolved Raman spectroscopy, and water contact angle measurement. Covalent attachment rehybridized some of the delocalized graphene sp2 orbitals to localized sp3 states. Increased water contact angles and work functions were observed for increasing CF3Ph functionalization densities, which is consistent with increasing concentration and orientation of fluorine on the graphene surfaces. Control over the relative spontaneity (reaction rate) of covalent graphene functionalization is an important first step to the practical realization of directed molecular assembly on graphene.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Understanding Charge Separation and Transfer at Interfaces in Energy Materials (CST)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- DOE Contract Number:
- SC0001091
- OSTI ID:
- 1382298
- Journal Information:
- Journal of Physical Chemistry. C, Vol. 117, Issue 23; Related Information: CST partners with University of Texas at Austin (lead); Sandia National Laboratories; ISSN 1932-7447
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
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