Hierarchical rattle-like N-doped anatase TiO2 superstructure: one-pot synthesis, morphological evolution and superior visible light photocatalytic activity

Morphology control and impurity doping have been considered as two potent strategies for improving the photocatalytic activity of TiO2 photocatalysts. Here, a one-pot solvothermal method was developed for the preparation of N doped rattle-like TiO2 with spherical mesoporous cores and hierarchical shells composed of ultrathin nanosheets to simultaneously realize those two strategies. This method involves the formation of nascent nanoparticles in a sonication treatment before the solvothermal reaction, and the morphology evolution from condensed spheres to core@shell structures, and eventually to a core@void@shell architecture, switched by the crystalline nature of the products during the solvothermal reaction. The as-prepared sample features a high surface area (258.5 m2 g−1), abundant porous texture and a unique rattle-like structure, which allows for multiple reflections of incoming light and thus optimizes light absorption ability. The concomitant N doping helps to extend the light absorption edge to the visible light region, optimizing the utilization of solar energy. As expected, when used as a photocatalyst for degradation of Rhodamine B and formic acid under visible light irradiation, the as-prepared N doped rattle-like TiO2 exhibited superior vis-photocatalytic activity thanks to its unique structure and specific N doping.