One-pot sol–gel synthesis of reduced graphene oxide uniformly decorated zinc oxide nanoparticles in starch environment for highly efficient photodegradation of Methylene Blue

Abstract

ZnO NPs + reduced graphene oxide (rGO) nanocomposites were synthesized using a sol–gel method with starch as the polymerisation agent. Long-chain starch compounds were used to terminate the growth of the ZnO NPs on rGO and stabilise them. The resulting products were annealed at 350 °C to remove the starch and produce a reduced graphene oxide (rGO) sheet in one-pot without any post-annealing processes. Microscopic studies showed that the NPs were dispersed on the rGO sheet. They had a spherical shape and a size of approximately 25 ± 10 nm. In addition, these studies revealed that the NPs were single crystals. The X-ray diffraction pattern of the NPs indicated a hexagonal (wurtzite) structure. The results of Fourier transform infrared spectrum analysis (FTIR) revealed that the GO sheet was transformed into rGO via the sol–gel method in the starch environment. The results of photoluminescence spectroscopy demonstrated that the incorporation of reduced graphene oxide (rGO) sheets with ZnO NPs suppressed the electron–hole recombination of the composite. Therefore, a significant enhancement in the photocatalytic degradation of methylene blue (MB) was observed with the ZnO NPs + rGO nanocomposite compared to the bare ZnO nanoparticles.