Structural, optical and photocatalytic properties of graphene-ZnO nanocomposites for varied compositions

Graphene-ZnO nanocomposites (GZ) were prepared with different concentrations of ZnO by chemical method. Structural analysis by x-ray diffraction showed a hexagonal wurtzite phase of ZnO and Raman spectroscopy showed the formation of graphene. Shape of ZnO was found to be varied from sphere to rod with the increasing ZnO composition. Optical absorption at 369 nm (E-g=3.36 eV) was corresponding to the band edge emission of ZnO. Compared to pure ZnO, photoluminescence (PL) intensity of the nanocomposites had decreased drastically, due to quenching of photoemission, in the presence of graphene. The time resolved PL decay followed a triexponential behavior with a maximum lifetime of 27.97 ns. The BET surface area was in the range from 13 to 123 m(2)/g. Photocatalytic degradation study on methyl orange under UV light and Sun light showed a maximum degradation of 97.1% and 98.6% respectively. It was observed that the nanocomposites with optimum value of lifetime and surface area had shown the maximum degradation rate.