Electrical Double Layer of Supported Atomically Thin Materials

Sun Sang Kwon, Jonghyun Choi, Mohammad Heiranian, Yerim Kim, Won Jun Chang, Peter M. Knapp, Michael Cai Wang, Jin Myung Kim, Narayana R. Aluru, Won Il Park, Sung Woo Nam

Research output: Contribution to journalArticle

Abstract

The electrical double layer (EDL), consisting of two parallel layers of opposite charges, is foundational to many interfacial phenomena and unique in atomically thin materials. An important but unanswered question is how the "transparency" of atomically thin materials to their substrates influences the formation of the EDL. Here, we report that the EDL of graphene is directly affected by the surface energy of the underlying substrates. Cyclic voltammetry and electrochemical impedance spectroscopy measurements demonstrate that graphene on hydrophobic substrates exhibits an anomalously low EDL capacitance, much lower than what was previously measured for highly oriented pyrolytic graphite, suggesting disturbance of the EDL ("disordered EDL") formation due to the substrate-induced hydrophobicity to graphene. Similarly, electrostatic gating using EDL of graphene field-effect transistors shows much lower transconductance levels or even no gating for graphene on hydrophobic substrates, further supporting our hypothesis. Molecular dynamics simulations show that the EDL structure of graphene on a hydrophobic substrate is disordered, caused by the disruption of water dipole assemblies. Our study advances understanding of EDL in atomically thin limit.

Original languageEnglish (US)
Pages (from-to)4588-4593
Number of pages6
JournalNano letters
Volume19
Issue number7
DOIs
StatePublished - Jul 10 2019

Keywords

  • 2D materials
  • electrical double layer
  • graphene
  • surface energy

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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  • Cite this

    Kwon, S. S., Choi, J., Heiranian, M., Kim, Y., Chang, W. J., Knapp, P. M., Wang, M. C., Kim, J. M., Aluru, N. R., Park, W. I., & Nam, S. W. (2019). Electrical Double Layer of Supported Atomically Thin Materials. Nano letters, 19(7), 4588-4593. https://doi.org/10.1021/acs.nanolett.9b01563