Photocatalytic reduction of graphene oxides hybridized by ZnO nanoparticles in ethanol

Graphene oxide platelets synthesized by using a chemical exfoliation method were dispersed in a suspension of ZnO nanoparticles to fabricate ZnO/graphene oxide composite. Formation of graphene oxide platelets (with average thickness of ∼0.8 nm) hybridized by ZnO nanoparticles (with average diameter of ∼20 nm) was investigated. The 2D band in Raman spectrum confirmed formation of single-layer graphene oxides. The gradual photocatalytic reduction of the graphene oxide sheets in the ZnO/graphene oxide suspension of ethanol was studied by using X-ray photoelectron spectroscopy for different ultra violet (UV)–visible irradiation times. After 2 h irradiation, the relative concentration of the C–OH, CO and OC–OH bonds showed nearly 80% reduction relative to the corresponding concentrations before irradiation. The chemical reduction was accompanied by variations in the optical absorption of the ZnO/graphene (oxide) suspension, as its color changed from light brown to black. The current–voltage measurement showed that electrical sheets resistance of the ZnO/graphene oxide sheets decreased by increasing the irradiation time. Therefore, the ZnO nanoparticles in the ZnO/graphene oxide composite could be applied in gradual chemical reduction and consequently tuning the electrical conductivity of the graphene oxide platelets by variation of UV irradiation time in a photocatalytic process.