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Probing the electric double-layer capacitance in Keggin-type polyoxometalate ionic liquid gated graphene transistor

Abstract

A variety of device applications have been proposed using polyoxometalate-based ionic liquid. However, the assembly of large polyoxometalate ions on surfaces and the associated interfacial properties are not well understood, particularly since it involves the role of steric effects and stronger ion-ion interactions. In this work, graphene transistors gated with a polyoxometalate-based ionic liquid are probed with in-situ Raman spectroscopy and charge transport studies. The ionic liquid comprises of Cu-substituted lacunary Keggin anions, [PW11O39Cu]5-, which are surrounded by tetraoctyl ammonium cations, (C32H68N)+. Application of gate voltage causes these ions to assemble at the interface with graphene which results in a shift of the Fermi level of graphene monolayer grown on copper foil. The shift is determined by the quantum capacitance Cq of graphene in series with the electric-double layer capacitance. Estimates of the electric-double layer thickness, spatial density of the ions and temporal rate of assembly of the electric double-layer are obtained. This work provides insights in microscopic understanding of the electric double-layer formation at the graphene interface.

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Publication details

The article was received on 11 Apr 2018, accepted on 09 Jun 2018 and first published on 13 Jun 2018


Article type: Paper
DOI: 10.1039/C8CP02307G
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    Probing the electric double-layer capacitance in Keggin-type polyoxometalate ionic liquid gated graphene transistor

    L. George, S. K, R. R. Gangavarapu and M. Jaiswal, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP02307G

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