Microwave assisted covalent functionalization of ionic liquids on reduced graphene oxide

Abstract

Physical properties of graphene-related materials can be tuned by doing chemical modifications in its structure through covalent and non-covalent functionalization. Covalent functionalization of ionic salts on rGO structures changes it's optical and electronic properties. In this work, pyrrolidone and imidazolium-based ionic liquids namely N-methyl-2pyrrolidone hydrogensulfate (H-NMP+.HSO4-), 1-butyl-3-methyl imidazoliumtetrafluoroborate (BMIM BF4), 1-butyl-3-methyl imidazoliumtrifluoroacetate (BMIM TFA) and 1-butyl-3-methyl imidazoliummethylsulfate (BMIM MeSO4) were covalently functionalized on reduced graphene oxide through microwave assisted process. Presence of (002) peak in the XRD pattern indicates the reduction of GO and fluorination of rGO prepared by functionalzation with BMIM BF4 was confirmed by a peak (001) appeared at 2θ of 12.730. Red shift of π-π* and blue shift of n-π* transitions in UV-Vis spectrum were due to chemical modification in rGO sheets through IL functionalization. The peaks corresponding to IL were observed in FTIR spectra of synthesized samples. The increase in ID/IG ratio in micro-Raman analysis shows more sp3 bonds were formed during IL functionalization.