Effect of Ambient Gas Pressure on the Thermal Exfoliation of Graphite Oxide: Tuning the Number of Graphene Sheets

We have investigated the effect of ambient gas pressure (Argon) used during thermal exfoliation of graphite oxide on the number of graphene sheets in the resulting graphene. The ambience gas Ar pressures used are 80, 25, 1 atmosphere and 10-3 as well as 10-5 torr. We have found curious result that the number of graphene sheets in exfoliated graphene stack is dependent on the applied pressure for exfoliation of graphite oxide (GO). By lowering the exfoliation pressure, the numbers of sheets get reduced. The numbers of sheets in exfoliated graphene stack have been determined by Lorentzian fit of their respective 002 peak of XRD profile. The numbers of sheets have also been confirmed with high resolution transmission electron microscopy (HRTEM). The numbers of sheets in exfoliated graphene stack samples have been found to be 28, 12, 8, 5 and 3 at 80 atm, 25 atm, 1 atm, 10-3 torr and 10-5 torr pressures respectively. The results of present investigation suggest a simple but effective method for synthesizing graphene with a specific number of sheets.