Comparative characterisations of structural and optical properties of zinc oxide modified by carbon nanotubes and graphene

In the present work, we report on the fabrications of ZnO/carbon nanotubes (CNTs) and ZnO/graphene composites based on a simple solution synthesis route. The effects of CNTs and graphene on the structure and optical properties of ZnO were investigated by X-ray diffraction (XRD), Raman scattering, optical absorption and photoluminescence measurements. The XRD patterns indicated that both CNTs and graphene could enhance the diffraction intensity of ZnO and the diffraction peaks shifted toward lower 2θ angles. The optical band gap of ZnO/CNTs and ZnO/graphene composites was narrower compared with that of undoped ZnO. Raman scattering spectra showed that the scattering intensities of both the oxygen atom and Zn sublattice-related phonon modes were reduced with the CNTs or graphene doping. The photoluminescence intensities of ZnO samples modified by both CNTs and graphene layers were significantly decreased compared with that of undoped ZnO owing to the interfacial charge-transfer between ZnO and CNTs (graphene).