Hierarchically Structured Squama-like Cerium-Doped Titania: Synthesis, Photoactivity, and Catalytic CO Oxidation

A series of hierarchical nanostructured/porous titania materials doped with different contents of cerium (Ce/TiO2) were synthesized by utilizing the oil-in-water (O/W) emulsion technique. N-2 sorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis confirm that the synthesized Ce/TiO2 samples possess a hierarchical squama-like nanoarchitecture of high surface area with wormhole-like mesopores of nanoparticle assembly in each squama. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) analysis show that all of the hierarchical Ce/TiO2 samples exhibit a pure anatase crystalline phase and the doped cerium exists mainly in the form of metal oxides with a mixture of Ce3+/4+ oxidation states. The UV-vis diffuse reflectance spectra show that the absorption edge of the synthesized hierarchical pure titania red-shifted to 441 nm, while the cerium-doped samples exhibit obviously enhanced absorbance in the visible light region compared with pure titania. The catalytic applications of these hierarchical Ce/TiO2 squamae in the photodegradation of Rhodamine B and in catalytic CO oxidation were investigated, and the results indicate that the synthesized cerium-doped titania materials can be used as not only an effective photocatalyst for organic waste degradation but also an excellent support of gold nanoparticles to remove CO by catalytic oxidation, demonstrating their promising potential in environmental remediation.