Improved noncovalent functionaliztion and aqueous dispersibility of graphene via removing carbonaceous adsorbates

• Aqueous dispersion of graphene with improved concentration was prepared.
• Base wash of graphene oxide removes carbonaceous adsorbates.
• Elimination of carbonaceous adsorbates facilitates noncovalent functionalization.

Colloidal suspension of graphene with improved concentration was prepared via efficient noncovalent functionalization with a large aromatic stabilizer (sodium perylenetetracarboxylate). A mechanism is proposed that preliminary base wash of graphene oxide for removing carbonaceous adsorbates effectively promotes the adsorption of stabilizer onto graphene via π–π interaction, which ultimately prevents graphene sheets from re-stacking through electrostatic repulsion. Ultraviolet–visible spectroscopy results disclose stabilizer was successfully anchored onto graphene sheets because redshift of characteristic peaks was observed as reduction time elongated. Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy reveals oxygen-containing groups were substantially removed through base wash and subsequent reduction. This result provides underlying understanding of stabilizing graphene which is helpful for improving efficiency of preparing graphene dispersions and fabrication of electronics and composites.