Figure 7.

Antioxidant mechanisms and example application. A: Overview of relevant antioxidant mechanisms (UV absorption, iron binding, ^·OH adduct formation on sp²–carbon sites; electron transfer, and hydrogen donation). This study shows that the primary antioxidant activity for graphene-based materials is against ^·OH and is associated with pristine sp²-carbon domains. Hydrogen donation activity is limited by the low population of phenolic OH, which are found on edge but not basal sites. B: Example application of graphene-based oxidation protection. TiO₂-mediated photocatalytic destruction of Rhodamine B dye in the presence and absence of graphene-based materials when exposed to 365 nm long-wavelength UV. Addition of GO (final concentration 20 ppm) in suspension slightly inhibits dye destruction. Encapsulation of TiO₂ in graphene nanosacks (0.1 mg mL⁻¹ nanosacks with ~80 wt% TiO₂ and ~20 wt% rGO) significantly inhibits dye oxidation. ROS produced at TiO₂ surfaces are scavenged by internal rGO surfaces prior to release and dye oxidation.