Sum frequency generation (SFG) vibrational spectroscopy and contact angle measurements of an ionic liquid, 1-butyl-3-methylimidazolium dicyanamide [BMIM][DCA] at solid-liquid interfaces are reported. Bare solid single-crystal barium fluoride (BaF2) (111) surface, monolayer graphene-coated BaF2 (111) surface and a bilayer graphene-coated BaF2 (111) surface were used as the solid substrates. The SFG results show that only [DCA]- are observed at the BaF2 (111) surface, while both [BMIM]+ and [DCA]- are detected on the graphene coated BaF2 (111) surface. [DCA]- anions are attracted to the positively charged BaF2 (111) surface and occupy the first layer at the solid-liquid interface. The graphene coating shielded the charged crystal surface and allowed both cations and anions to exist at the interface. Furthermore, increase in the contact angle of BaF2 surface after graphene layers deposition suggests that the graphene coating lowers the surface energy. 

Sum frequency generation spectroscopy study of an ionic liquid at a graphene-BaF<sub>2</sub> (111) interface

247th National Meeting (2014)

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Sum frequency generation spectroscopy study of an ionic liquid at a graphene-BaF2 (111) interface

Sum frequency generation spectroscopy study of an ionic liquid at a graphene-BaF₂ (111) interface