Atomically Resolved Elucidation of the Electrochemical Covalent Molecular Grafting Mechanism of Single Layer Graphene

Raluca I. Gearba, Minjung Kim, Kory M. Mueller, Peter A. Veneman, Kayoung Lee, Bradley J. Holliday, Calvin K. Chan, James R. Chelikowsky, Emanuel Tutuc, Keith J. Stevenson

    Research output: Contribution to journalArticlepeer-review

    8 Citations (Scopus)

    Abstract

    Engineering graphene at the atomic level via chemical doping, substrate interactions or lateral confinement opens up avenues for precise tuning of its electronic and magnetic properties. Chemical doping by covalent modification routes using electrochemical tools offers rich opportunities that are yet to be fully explored. The key to controlling graphene's physicochemical properties requires a detailed atomistic understanding of the geometry and mechanism of the covalent attachment process. By employing diaryliodonium salts instead of the commonly used diazonium salts, precise molecular grafting onto epitaxial graphene is achieved. Using atomically resolved imaging via scanning tunneling microscopy it is shown that for single layer, high quality, low defect graphene, the functionalization process is controlled by kinetics rather than thermodynamics in accord with Marcus–Gerisher theory. The predominance of the preferential pairwise attachment of molecular grafts specifically on the same graphene sublattice gives rise to ferromagnetic properties previously observed in nitrophenyl modified graphene. Furthermore, p-type doping has been quantified by electrical measurements and angle resolved photoelectron spectroscopy. Overall this electrochemical route for precise covalent functionalization of single layer graphene is general and can be straightforwardly extended to other 2D few-layer confined materials such as transition metal chalcogenides.

    Original languageEnglish
    Article number1600196
    JournalAdvanced Materials Interfaces
    Volume3
    Issue number16
    DOIs
    Publication statusPublished - 19 Aug 2016

    Keywords

    • angle resolved photoelectron spectroscopy
    • electronic properties in graphene
    • graphene covalent functionalization
    • scanning tunneling microscopy

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