Fabrication of TiO2 nanofiber assembly from nanosheets (TiO2-NFs-NSs) by electrospinning-hydrothermal method for improved photoreactivity

Abstract

Hierarchically structured nanomaterials have attracted much attention owing to their unique properties. In this study, TiO2 nanofibers assembled from nanosheets (TiO2-NFs-NSs) were fabricated through electrospinning technique, which was followed by hydrothermal treatment in NaOH solution. The effect of hydrothermal reaction time (0–3 h) on the structure and properties of TiO2 nanofibers (TiO2-NFs) was systematically studied, and TiO2-NFs was evaluated in terms of the photocatalytic activity toward photocatalytic oxidation of acetone and the photoelectric conversion efficiency of dye-sensitized solar cells. It was found that (1) hydrothermal treatment of TiO2-NFs in NaOH solution followed by acid washing and calcination results in the formation of TiO2-NFs-NSs; (2) upon extending the hydrothermal reaction time from 0 h to 3 h, the BET surface area of TiO2-NFs-NSs (T3.0 sample) increases 3.8 times (from 28 to 106 m2 g−1), while the pore volume increases 6.0 times (from 0.09 to 0.54 cm3 g−1); (3) when compared with those of pristine TiO2-NFs (T0 sample), the photoreactivity of the optimized TiO2-NFs-NSs toward acetone oxidation increases 3.1 times and the photoelectric conversion efficiency increases 2.3 times. The enhanced photoreactivity of TiO2-NFs-NSs is attributed to the enlarged BET surface area and increased pore volume, which facilitate the adsorption of substrate and penetration of gas, and the unique hollow structure of TiO2-NFs-NSs, which facilitates light harvesting through multiple optical reflections between the TiO2 nanosheets.