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Updated: Jul 19, 2025
Raman and IR Spectroelectrochemical Methods as Tools to Analyze Conjugated Organic Compounds
Published on: October 12, 2018
Dynamic Study of Intercalation/Deintercalation of Ionic Liquids in Multilayer Graphene Using an Alternating Current
Zhi Cai1, Haley Weinstein2, Indu Aravind3
1Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089, United States.
Abstract:
We report Raman spectra and infrared (IR) imaging collected during the intercalation-deintercalation half cycles in a multilayer graphene (MLG) device (∼100 layers) operating at 0.2-10 Hz. The device consists of a MLG/alumina membrane/copper stack, in which the alumina membrane is filled with ionic liquid [DEME][TFSI], forming an electrochemical cell. Upon the application of a positive voltage, the TFSI- anions intercalate into the interstitial spaces in the MLG. The incident laser light is modulated using an optical chopper wheel that is synchronized with (and delayed with respect to) a 0.2-10 Hz alternating current (AC) voltage signal. Raman spectra taken just 200 ms apart show the emergence and disappearance of the intercalated G band mode at around 1610 cm-1. By integration of over hundreds of cycles, a significant Raman signal can be obtained. The intercalation/deintercalation is also monitored with thermal imaging via voltage-induced changes in the carrier density, complex dielectric function ε(ω), and thermal emissivity of the device.
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