Influence of functional groups on the degradation of graphene oxide nanomaterials

The influence of functional groups on the degradation of graphene oxide nanomaterials under direct sunlight was investigated by systematically varying the surface chemistry. Using a solvothermal reduction process, graphene nanomaterials with varying oxidation levels, including graphene oxide, partially reduced graphene oxide and fully reduced graphene oxide, were prepared. The physical and chemical properties of the nanomaterials were extensively characterized before and after exposure to simulated sunlight. The degradation of the nanomaterials was determined to be directly related to the functional groups present on the basal plane of the graphene nanomaterials. Specifically, the hydroxyl and epoxy functional groups are the most susceptible to photodegradation. Upon sunlight exposure, the amount of oxygen-containing functional groups on all graphene nanomaterials decreases over time, with fully reduced graphene oxide showing the lowest degradation rate due to the presence of fewer reactive functional groups on the surface. Overall, these results suggest that the oxygen-containing functional groups on the basal plane are the major initiators of the photodegradation of graphene nanomaterials.