Diethylenediamine-assisted template-free synthesis of a hierarchical TiO2 sphere-in-sphere with enhanced photocatalytic performance
With the assistance of diethylenediamine (DETA), a template-free solvothermal approach is employed to one-step synthesize a hierarchical TiO2 sphere-in-sphere, which has a unique structure: an interior nanosized sphere is contained in the cavity of another hollow microsphere, and numerous nanosheets of width ca. 20–26 nm vertically distribute on the surface. It is proved that DETA added in solution plays an important inducing role in the formation of both the hollow sphere-in-sphere structure and surface sheet-assembled network. Therefore, a DETA-assisted formation mechanism of the hierarchical TiO2 sphere-in-sphere has been described in detail. The unique hierarchical sphere-in-sphere structure endows the TiO2 product with increasing light-harvesting efficiency and specific surface area, resulting in its enhanced photocatalytic activity for the degradation of various organic pollutants under the illumination of UV light.