Probing the interaction of ionic liquids with graphene using surface‐enhanced Raman spectroscopy

Abstract

We report an in situ measurement of the interaction of an imidazolium-based room temperature ionic liquid with both pure silver and a graphene-over-silver electrode under an applied electrochemical potential. At a negative applied potential, overall signal intensity increased indicating enhanced ionic liquid concentration at both silver and graphene electrodes. Vibrational modes associated with the imidazolium ring exhibited greater intensity enhancements and larger peak shifts compared with the anion indicating that the cation adsorbs with the ring and alkyl chain parallel to the electrode surface for both silver and graphene. In contrast to the silver, the surface enhanced Raman spectra of the ionic liquid near graphene showed shifts in the cation peaks even at no applied potential because of the strong π-π interaction between the ionic liquid and the graphene. Furthermore, the intensity of the graphene peak decreased in the presence of ionic liquid possibly due to the interaction between the ionic liquid and graphene. These results illustrate the effectiveness of surface-enhanced Raman spectroscopy to investigate electrolyte interactions with graphene at the liquid/electrode interface.

Graphene Meets Ionic Liquids: Fermi Level Engineering via Electrostatic Forces

“…Upon deposition of neat ILs, additional peaks located between 1300 cm –1 and 1575 cm –1 appear in the Raman spectrum (Figure S1, Supporting Information). These additional peaks are associated with the imidazolium ring and aliphatic chain vibrations of the C n MIM + cation . These assignments were validated by performing Raman measurements on the bulk ionic liquid sample for C 4 MIM-BF 4 (Figure S2, Supporting Information) and indicate that there is no/limited convolution with the native bands of graphene.…”

“…These additional peaks are associated with the imidazolium ring and aliphatic chain vibrations of the C n MIM + cation. 37 These assignments were validated by performing Raman measurements on the bulk ionic liquid sample for C 4 MIM-BF 4 (Figure S2, Supporting Information) and indicate that there is no/limited convolution with the native bands of graphene. The most interesting feature of the Raman spectra obtained after deposition of ILs, however, is the shift of both Pos(G) and Pos(2D) to lower wavenumbers relative to the pristine (unfunctionalized) graphene.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

“…Mahurin and co‐workers probed the interaction of ionic liquids with graphene using SERS. They found, in contrast to silver, the SERS of the ionic liquid near graphene showed shifts in the cation peaks even at zero applied potential because of the strong π‐π interaction between the ionic liquid and the graphene . Roy et al applied Raman imaging and stress quantification to self‐assembled graphene oxide fiber “Latin Letters.” This article demonstrates the significance of morphology in stress distribution across the self‐assembled and “smart‐integrable” GOF “Latin letters.” Wang and co‐workers presented a systematic Raman study of twisted tetralayer graphene (t(2 + 2)LG), under excitation of two laser lines.…”

“…They found, in contrast to silver, the SERS of the ionic liquid near graphene showed shifts in the cation peaks even at zero applied potential because of the strong π-π interaction between the ionic liquid and the graphene. [78] Roy et al applied Raman imaging and stress quantification to self-assembled graphene oxide fiber "Latin Letters." This article demonstrates the significance of morphology in stress distribution across the self-assembled and "smart-integrable" GOF "Latin letters."…”

Síntesis de grafeno 3D

“…El grafeno puede ser funcionalizado mediante distintas técnicas, una de ellas consiste en el agregado de líquidos iónicos (IL). 109 En este caso, la plataforma Además, la relación de intensidades de las bandas principales del grafeno (I 2D /I G ) se modificó respecto a la plataforma GNif, como ocurre cuando existen analitos adsorbidos sobre su superficie, pasando de 6.5 a 3.3. Cabe destacar que se realizó el análisis sobre zonas con configuración "rotada-H" ya que, como se demostró en la sección anterior, presentan mayor sensibilidad.…”