Characterization
UV-vis absorption and/or transmission spectra were obtained using a Shimadzu UV 1601 spectrophotometer. The spectra were taken from the reaction mixture (diluted by a factor of 30) at different times. The dispersion/aggregation state of CCG sheets in water was monitored by measuring their average particle size using a Malvern Zetasizer Nano-ZS particle analyser. Note that the particle size measurement on this instrument is based on the assumption that the particles are spherical, so the instrument is unable to give the absolute sizes of graphene sheets. Nevertheless, the measurements obtained provide a means of monitoring dispersion stability. Attenuated total reflectance FT-IR spectra of free-standing films prepared by vacuum filtration were recorded on a Nicolet AVATAR 360 FTIR spectrometer with a Smart OMNI Sampler with a germanium crystal. AFM images were