Abstract
Core-shell heterostructures with a complex, flower-like morphology, comprising a ZnO core and a TiO2 shell decorated with reduced graphene oxide (rGO) sheets by hydrothermal wrapping, are reported to extend the absorption properties of the semiconductors toward the visible light range. The ternary photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, diffuse reflectance UV–Vis, and attenuated total reflectance-Fourier transform infrared spectroscopy. Its photocatalytic performance was evaluated under visible light irradiation using methylene blue dye as a model pollutant. The rGO-modified ZnO–TiO2 photocatalyst exhibited superior photoactivity compared to that of the parent ZnO–TiO2 core-shell structures, which was dependent on its graphene content. The enhanced photocatalytic response was attributed to the higher absorption in the visible light range, as well as the pronounced electron and hole separation in the ternary system.
Highlights
The intense industrialization of the last decades has resulted in the continuous introduction of industrial and agro-industrial wastewaters in aqueous matrices; heterogeneous photocatalysis has been proposed as an efficient alternative to conventional methods for their effective treatment
We report the development of complex ZnO–TiO2 core-shell, flower-like heterostructures and the extension of its photocatalytic response toward the visible light range via wrapping the inorganic surface with reduced graphene oxide (rGO) sheets
Complex ZnO–TiO2 core-shell, flower-like structures wrapped with rGO sheets were prepared by a simple and well-controlled synthetic approach
Summary
The intense industrialization of the last decades has resulted in the continuous introduction of industrial and agro-industrial wastewaters in aqueous matrices; heterogeneous photocatalysis has been proposed as an efficient alternative to conventional methods for their effective treatment. Previous reports on ternary TiO2, ZnO, and rGO photocatalysts focused on the nanocomposites of mixed inorganic particles prepared by conventional sol-gel, hydrothermal methods, or other modern synthetic approaches such as sonochemistry or microwave treatment [12,13,14,15,16,17,18,19,20]. Simsek et al immobilized rGO sheets on fluorine-doped tin oxide (FTO) substrates, followed by the hydrothermal growth of ZnO and TiO2 nanoparticles on graphene sheets They observed a band-gap narrowing for the ternary photocatalyst and superior photocatalytic performance against estrogen bisphenol-A and pharmaceuticals under UV and visible-light irradiation. We report the development of complex ZnO–TiO2 core-shell, flower-like heterostructures and the extension of its photocatalytic response toward the visible light range via wrapping the inorganic surface with rGO sheets. The photocatalytic performance of the obtained rGO–ZnO–TiO2 ternary photocatalysts was evaluated in the decoloration of aqueous solutions of methylene blue (MB) under visible light irradiation
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