Influence of pH condition on colloidal suspension of exfoliated graphene oxide by electrostatic repulsion

► Graphene nanosheets were prepared by a zwitterions amino acid intermediate from graphite oxide. ► 11-aminoundecanoic acid was protonated to intercalate molecules into the graphene oxide to achieve ion exchange. ► The d002-spacing of the graphite oxide greatly increased from 0.330 nm to 0.415 nm after 11-aminoundecanoic acid treatment.