Effect of Graphite Oxidation on the Yield and Quality of Graphene Synthesized By Supercritical Exfoliation and Its Application in Photocatalytic Degradation of Methylene Blue

After fullerene and nanotubes, graphene is a new allotrope of carbon. thisattractive nanomaterial can be produced by different methods. in this work,we have used the less common approach for preparation of graphene. thistechnique is based on the utilization of supercritical fluid. ethanol was usedas the solvent for exfoliation of pristine graphite, at the temperature of 400oc and pressure of 40 mpa. in addition, supercritical ethanol was used toreduce and exfoliate graphite oxide. ft-ir spectra indicate that reductionand exfoliation of graphite oxide can be done in supercritical ethanol,simultaneously. effect of graphite oxidation on the yield and quality ofgraphene was investigated and results showed that oxidation of graphite canimprove the yield of supercritical process from 12.5% to 26.8%, but ramanspectra revealed that quality of graphene samples produced by graphiteoxide is lower than neat graphite. moreover, the impacts of initial graphiteconcentration and sonication power on the exfoliation yield were studied.finally, hybrid structure of graphene and titanium dioxide nanoparticleswere prepared by ultrasonic method and used for photocatalytic degradationof methylene blue dye pollutant. results revealed that titanium dioxidenanoparticles show better photocatalytic performance in presence ofgraphene sheets.