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

Abstract

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.