Fabrication of multilayer porous structured TiO2–ZrTiO4–SiO2 heterostructure towards enhanced photo-degradation activities

Abstract

Multilayer porous structured TiO2–ZrTiO4–SiO2 photocatalyst with built-in TiO2/ZrTiO4 heterojunction and oxygen vacancies was synthesized by sol-gel method combined with template method using colloidal polystyrene spheres as templates. Results show that the multilayer porous structure can be fabricated by controlling the calcination system and the amount of template, and the fabrication of which can also contribute to the generation of oxygen vacancies by creating an anoxic environment. During the photodegradation process, high efficiency of visible light utilization can be achieved due to the slow photon effect of the multilayer porous structure, which can also increase the probability of the contact between Rhodamine B (RhB) with the active sites of the catalyst. Also, the synergistic effect of the generated TiO2/ZrTiO4 heterojunction and built-in oxygen vacancy defects jointly promoted the separation of photogenerated carriers. Thus excellent adsorption rate (75.6%, 60 min) and photodegradation rate (95%, 90 min) of the catalyst were obtained. Furthermore, the up-shifted conduction band and valence band maximum positions are beneficial for the mobility of photogenerated holes and inhibit their reaction with H2O to generate ·OH, while the photogenerated electrons can react with O2 to form ·O2−, resulting that the holes and ·O2− participated in the photodegradation of RhB over the as-prepared catalyst.