Hollow β-Bi2O3@CeO2 heterostructure microsphere with controllable crystal phase for efficient photocatalysis.

• Series of Bi 2 O 3 @CeO 2 hollow microspheres have been fabricated. • Kirkendall effect impels interior Bi 2 O 3 to diffuse outside microspheres. • Crystal phase of Bi 2 O 3 is transformed from α to β. • Bi 2 O 3 @CeO 2 -350 shows the superior visible-light photocatalytic performance. Herein, a two-step hydrothermal synthesis is used to successfully prepare a Bi 2 O 3 microsphere coated with CeO 2 nanosheets on the surface. The resultant core/shell Bi 2 O 3 @CeO 2 microsphere is calcined at different temperatures, yielding a series of Bi 2 O 3 @CeO 2 -t hollow microspheres. It is found that, with the increasing calcination temperature, the Kirkendall effect occurred can impel the interior Bi 2 O 3 to gradually diffuse outward the Bi 2 O 3 @CeO 2 microsphere, meanwhile the crystal structure of Bi 2 O 3 transforms from the metastable tetragonal phase (β) to the stable monoclinic phase (α) at 350 °C. Phase-controllable preparation of the Bi 2 O 3 @CeO 2 -350 composite with the highly active β-Bi 2 O 3 is pursued to obtain the high electron-transfer efficiency between β-Bi 2 O 3 and CeO 2 , thus exhibiting superior photocatalytic performance in the photocatalytic degradation of tetracycline (TC) under visible light irradiation. Therefore, Kirkendall effect can be exploited as a new methodology to effectively improve the photocatalytic performance of heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]