Synthesis, Characterization And Photocatalytic Behaviors Of Three Dimensionally Ordered Macroporous TiO₂/Ta₂O₅ And TiO₂/ZrO₂ Nanoscale Photocatalysts

Nanoscale inorganic porous materials have being attracted more and more attentions dueto their unique properties such as high porosities,large specific surface area and strongsurface adsorption ability,which permitted them the superior candidacy of catalysts andcatalyst supports.Therefore,design and preparation of the novel inorganic networks withcontrolled morphology and functions is significant in the field of catalysis.In this paper,three-dimensionally ordered macroporous(3 DOM)M/Ti(M=Zr or Ta)mixed oxides wereprepared by cohydrolysis of a mixture of Zr(n-OC4H9)4/TTIP or TaCl5/TTIP(TTIP = titaniumisoproroxide)combined with a polystyrene(PS)latex sphere templating technique.Thestructures and physicochemical properties of the composites were characterized by powderX-ray diffraction (XRD),Inductively coupled plasma atomic emission spectrophotometry(ICP-AES),Raman scattering studies,UV diffuse reflectance spectroscopy (UV/DRS),X-ray photoelectron spectroscopy(XPS),field emission scanning electron microscopy(SEM), transmission electron microscopy (TEM)and surface analyzer.The resulting products exhibited homogeneous wall compositions,namely,ZrO2 orTa2O5 was uniformly dispersed into the TiO2 framework with the loading levels of 5, 10,and20 mol% for Zr and 2.5, 5.0,and 7.5 mol% for Ta,respectively.The estimated macroporediameter,wall thickness,and particle size of the products ranged from 280 to 290 nm,40 to70 nm,and 10 to 12 nm,respectively,and they showed only anatase phase although theirstarting solitary metal oxides exhibited suitable crystalline structures under the samepreparation conditions.Raman scattering spectroscopy showed that the crystal structure oftitania had a slight interference due to the incorporation of ZrO2 or Ta2O5, and UV-vis diffusereflectance spectroscopy (DRS) showed the narrower band gap of the products comparedwith that of pure anatase TiO2.The products exhibited mesoporous walls,and the surfaceareas of which were higher than the corresponding pure 3 DOM metal oxide framework.Thephotocatalytic efficiencies of the products were assessed by monitoring the photodegradationof two organic molecules,i4-nitrophenol and rhodamine B (RB).Both the photocatalyticreactions confirmed that the presence of the second metal oxide in the titania frameworkresulted in enhanced photocatalytic activity relative to the pure titania framework, and thereasons were discussed.