Optical and recyclable photocatalytic properties of silica supported ZnO/Au heterostructures under sun light

ZnO/Plasmonic noble metal heterostructures promise the visible light functioning photocatalysis. Here we report, silica supported ZnO/Au heterostructures for recyclable visible light photo-degradations under sun light. Firstly, silica supported ZnO nanostructures was obtained by thermal decomposition of surface adsorbed zinc acetate molecules. Further, the Au nanoparticles were formed on SiO₂/ZnO in successive ionic layer adsorption and reaction process. Electron microscopic images obtained for the nanocomposite indicated the ZnO layers of ~ 30 nm and Au nanoparticles of ~ 5 nm on silica surface. Absorption spectrum of the nanocomposite indicated the bandgap value of ZnO grown on silica as 3.44 eV. Remarkably, absorption of visible region photons have got enhanced ~ 7 times for the Au nanoparticles incorporation in the silica/ZnO composite. The photocatalytic degradation of methylene blue conducted for the silica/ZnO/Au nanocomposite under sunlight have showed the 4–5 times enhanced photocatalytic effect over silica/ZnO nanocomposite. The manifestations of electron transfer from the Fermi level of Au to the ZnO facilitates the visible light functioning of the catalyst. In addition, the silica/ZnO/Au catalyst have showed the adequate efficiency in the recycled reactions.