A novel method for fast and continuous preparation of superfine titanium dioxide nanoparticles in microfluidic system

Abstract Previously we had developed a microfluidic system that can be easily fabricated by bending a stainless-steel tube into large circular loops. In this study, a fast and continuous preparation method for superfine TiO2 nanoparticles (TiO2-NPs) was developed for the aforementioned microfluidic system. The proposed method can yield anatase TiO2 in 3.5 min, in contrast to the traditional hydrothermal reaction method, which requires hours or even days. Different reaction conditions, such as reaction temperature (120–200 °C), urea concentration (20–100 g/L), and tube length (5–20 m) were investigated. X-ray diffraction and Brunauer-Emmett-Teller analysis indicate that the as-prepared TiO2-NPs have crystalline sizes of 4.1–5.8 nm and specific surface areas of 250.7–330.7 m2/g. Transmission electron microscopy images show that these TiO2-NPs have an even diameter of approximately 5 nm. Moreover, because of their small crystalline sizes and large specific surface areas, most of these as-prepared TiO2-NPs exhibit considerably better absorption and photocatalytic performance with methylene blue than commercial P5 TiO2 does.