Noncovalent Interaction with Graphene Oxide: The Crucial Role of Oxidative Debris

Graphene oxide (GO) is a very promising material because it is easy to process, water-soluble, and chemically versatile due to the presence of oxygenated groups on its surface. GO has been used in different areas such as electronics, biosensing, and environmental remediation. To design efficient materials, especially for biosensing and for remediating pollutants, the knowledge of surface noncovalent interaction and functionalization is crucial. Recently, it has been suggested revisions on the structural models of GO because the presence of highly oxidized polyaromatic carboxylated fragments (oxidative debris) on the GO surfaces. These debris are produced during acid treatments commonly employed in GO synthesis and purification. Here we applied chemical analysis, bioassays, and atomistic simulations to study the influence of oxidative debris on the noncovalent interaction of GO sheets with an important organic pollutant (e.g., 1-nitropyrene). GO samples without oxidative debris were found to be 75% more effective to adsorb 1-nitropyrene than samples with debris. Our results suggest that small (∼1 nm) oxidative debris are responsible for preventing adsorption sites on GO surfaces from being reached by potentially adsorbate molecules.