Synthesis, structures and applications of single component core-shell structured TiO2: A review

Abstract TiO2 is the most important photocatalyst for numerous processes, but effective only under UV light irradiation due to its large band gap (3.0–3.2 eV). It is a long time goal to achieve visible light photocatalytic activity by tuning the band structure of TiO2. In recent years, the core-shell structured TiO2 has emerged as a novel material with enhanced visible light absorption and photocatalytic efficiency. It is generally recognized that core-shell structured materials are composite materials, namely, the core contains a component and the shell is comprised of another component. In contrast, the core-shell structured TiO2 is a single component core-shell structured material, in which the core and shell contain the same component but with different structures. As the first review for the single component core-shell structured TiO2, this article systemically evaluates the synthesis approaches of the novel core-shell TiO2 materials, discusses their unique structures, summarizes their applications, and provides a perspective for future research.