Progress in sonochemical fabrication of nanostructured photocatalysts

In recent years, nanostructured photocatalysts have become the research focus due to their immense potential application in environmental purification and energy conversion. The photocatalytic performance of photocatalysts is closely related to their synthesis methods. High-intensity ultrasound irradiation could provide a unique tool for fabrication of photocatalysts with novel nanostructures. Ultrasound induces acoustic cavitation which generates unique physicochemical conditions, e.g., hot spot (5000 °C), high pressure of 100 MPa, fast rate of heat conduction (≫1 × 1010 °C·s−1). These unique physicochemical conditions allow for the synthesis of various nanostructured photocatalysts. This review summarized the recent development in fabrication of photocatalysts with special nanostructures and their applications. The typical sonochemical reactors and parameters in sonochemical synthesis are introduced and discussed. Sonochemically prepared structures including nano-/microspheres, one-dimensional (1D) nanorods, two-dimensional (2D) nanosheets (nanoflakes, nanosquares), noble metal nanoparticle (NP)-deposited and element-doped photocatalysts are described and summarized. It is believed that sonication is a green methodology, and it holds great potential in the near future for nanostructured photocatalyst fabrication.