A green chemistry of graphene: photochemical reduction towards monolayer graphene sheets and the role of water adlayers.

Clean sheets: Stable aqueous dispersions of graphene sheets (GSs) are obtained by exposing graphene oxide to irradiation with light at room temperature, without using any chemical additives. The photochemical reduction method is sustainable and scalable, repairs a majority of defects in the graphene layers, and can be used to fine-tune surface functional groups. Interestingly, the aqueous GS dispersions are stable without any added surfactant. The existence of a water layer that is strongly bound to GS is evidenced.