Titration for Basal Plane versus Edge Plane Surface on Graphitic Carbons by Adsorption

By using three model graphitic carbon materials, a simple technique for measuring the basal plane surface area and edge plane surface area of graphitic carbon materials is proposed. The technique involves adsorption of CO₂, which has a high selectivity toward edge plane sites, at 1 atm and room temperature. It can also be used to measure active sites for carbon gasification reactions because the edge surface area is responsible for gasification whereas the basal plane has only a negligible contribution. The proposed method could be extended to other crystalline materials and nongraphitic carbon materials. For the purpose of understanding the different adsorption abilities of SO₂ and CO₂ on different faces of graphite, a semiempirical molecular orbital (MO) calculation was made. The results of MO calculations show that it can be used to qualitatively predict the adsorption capacity.