Preparation and performance analysis of hierarchical hollow-structured TiO2 nanospherical photocatalysts
Hybrid solid TiO2-SiO2 nanospheres were synthesized through a hydrolysis-condensation reaction with his(acetylacetonate)-diisopropyltitanium and his-[γ-(triethoxysilyl)propyl]-tetrasulfide as starting materials.These nanospheres were then subjected to alkaline hydrothermal reaction and subsequent high-temperature calcination to prepare TiO2 nanoparticle photocatalysts with hierarchical hollow structure.The morphology,monodispersity,components,and crystalline phases of the photocatalysts were characterized and analyzed by using TEM,DLS,FT-IR,EDS,and XRD.The mechanism behind the formation of the hierarchical hollow structure under alkaline hydrothermal conditions was explored.The effect of the calcination temperature on the performance of the photocatalysts were examined.The activity of the photocatalysts was evaluated through photocatalytic degradation experiments of Rhodamine B,and compared with that of commercial P25.The results indicated that the nanospheres exhibited a distinct protruding surface and excellent monodispersity and titanate was the major component.The recrystallization of titanium salts and inward etching of the silica were identified as the key mechanisms in forming of the hierarchical hollow structure.After calcination at 500 ℃,the obtained photocatalyst maintained its hierarchical hollow structure and transformed into anatase-phase TiO2.These hierarchical hollow-structured photocatalysts demonstrated superior photocatalytic performance,with a degradation rate constant k of 113.49×10-3,min-1,three times that of solid structures,and 1.45 times higher than that of P25.The preparation method for the hierarchical hollow-structured TiO2 nonspherical photocatalysts is simple and effective,providing important reference and theoretical guidance for the photocatalytic degradation of organic dyes.
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