Antioxidant chemistry of graphene-based materials and its role in oxidation protection technology

Abstract

Two-dimensional nanomaterials have potential as a new class of antioxidants that combine physical barrier function with ultrahigh surface area for free radical scavenging. This work presents the first measurements of the chemical reactivities of graphene-based materials toward a set of model free radicals and reactive oxygen species using electron paramagnetic resonance spectroscopy (EPR) and sacrificial dye protection assays. Graphene-based materials are shown to protect a variety of molecular targets from oxidation by these species, and to be highly effective as hydroxyl-radical scavengers. When hydroxyl radical is produced photolytically, the overall antioxidant effect is a combination of preventative antioxidant activity (UV absorption) and ·OH radical scavenging. Few-layer graphene is more active than monolayer graphene oxide, despite its lower surface area, which indicates that the primary scavenging sites are associated with the sp2-carbon network rather than oxygen-containing functional groups. To explain this trend, we propose that GO is a weak hydrogen donor, due to the non-phenolic nature of most OH groups on GO, which reside at basal sp3-carbon sites that do not allow for radical resonance stabilization following hydrogen donation. As an example application of graphene antioxidant behavior, we show that encapsulation of TiO2 nanoparticles in graphene nanosacks reduces undesired photo-oxidative damage to nearby organic target molecules, which suggests graphene encapsulation as a new approach to managing adverse environmental or health impacts of redox-active nanomaterials.

The synergistic mechanism of thermally reduced graphene oxide and antioxidant in improving the thermo-oxidative stability of polypropylene

“…Those studies suggested that both physical and chemical adsorption can occur when free radicals approach to the graphene surface. The radical scavenging activity of graphene-based materials towards hydroxyl, superoxide and other model free radicals of sufficient stability has also been proven recently by several experimental works [18,19]. For instance, Qiu et al [18] found that graphene exhibits significant antioxidant activity in the form of hydroxyl and superoxide radical scavenging, which may be associated with the pristine sp 2 carbon domains on basal surfaces.…”

Reduced Graphene Oxide-NiO/Ni Nanomembranes as Oxygen Evolution Reaction Electrocatalysts

“…They also provide an effective conducting network for electron transfer, massive pore structures for ion transport, and large surface areas for reaction. In addition, they scavenge reactive oxygen species [19][20][21][22][23][24][25][26] to enhance the catalyst stability. 8 When synthesized on the scaffolds of carbon nanostructures, it has been demonstrated that the electrocatalytic Ni oxide-based nanomaterials possess high performance for hydrogen and oxygen evolution.…”

Combustion Characteristics of HAN-based Green Propellant Assisted with Nanoporous Active Carbons

“…Such noticeable increase of burning rate is associated with good activity and high specific surface area from activated carbon CRH-KOH, which is almost 3000 m 2 /g. The surface and the edges of activated carbon have many defects, which can act as a matrix for the formation and stabilization of free radicals (OH radicals) [13], which are formed during the decomposition of nitric acid, is described in following reaction and were proposed by T.B. Brill, and Y.J.…”