Synthesis And Photocatalytic Degradation Study Of TiO₂@h-CeO₂ Composite Yolk-shell Microsphere

In this paper, a composite yolk-shell microsphere with TiO₂ as core and CeO₂ as shell（TiO₂@h-CeO₂） was synthesized successfully. The intermittent SiO₂ layers protective method was carried out to protect the microstructure and crystalline phase of TiO₂@h-CeO₂ during calcination. The morphology, chemical composition and optical property of TiO₂@h-CeO₂ were verified by systematic characterization techniques, including SEM, HRTEM, XRD, Raman spectroscopy, FT-IR and UV–vis DRS. Influence of SiO₂ protective method on crystallization temperature was also studied. The catalytic activity of TiO₂@h-CeO₂ was evaluated by photodegradation of methylene blue. TiO₂@h-CeO₂ showed enhanced photocatalytic efficiency compared with anatase sphere, hollow-CeO₂（h-CeO₂）, and mixture of anatase sphere & h-CeO₂. We suspected that the hydrophilia of CeO₂ shell would absorb more water, compared with anatase sphere; and the cooperation of CeO₂ & TiO₂ would improve the generation of photo-produced holes. Therefore, it is beneficial to combine absorbed water and holes to form hydroxyl radical. Further hypothesis of photocatalytic activity improvement have been advanced.