Enhanced UV-Visible photocatalytic activity of Cu-doped ZnO/TiO2 nanoparticles

Cu-ZnO/TiO2 nanoparticles were prepared by entrapping copper ions into crystalline matrix of ZnO/TiO2 through sol-gel synthesis method. The photocatalyst matrix loaded with different copper concentrations was calcined at 500 and 700 A degrees C. Thermal property, crystalline structure, surface morphology and absorption spectra of Cu-ZnO/TiO2 were characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscope and UV-Vis spectrophotometry. Besides, its specific surface area and band gap energy level were estimated through BET surface area method, Kubelka-Munk model and Planck's equation. The results revealed that Cu-ZnO/TiO2 had a more thermally stable lattice compared to TiO2/ZnO and hence the phase transformation from anatase to rutile is retarded under higher calcination temperature in Cu-ZnO/TiO2 lattice. The photoactivity of Cu-ZnO/TiO2 was then evaluated through degradation of methyl orange under visible light irradiation. Among different samples, the samples that were calcined at 500 A degrees C exhibited the highest photocactivity compared to those calcined at 700 A degrees C. Cu-ZnO/TiO2 with a Cu content of 3 wt% was observed to have the maximum activity, giving C/C-0 value of 0.03 after 150 min. This value was about 12 and 28.3 times higher than that of ZnO/TiO2 and TiO2, respectively.