Template-based growth of titanium dioxide nanorods by a particulate sol-electrophoretic deposition process

TiO₂ nanorods have been successfully grown into a track-etched polycarbonate (PC) membrane by a particulate sol-electrophoretic deposition from an aqueous medium. The prepared sols had a narrow particle size distribution around 17 nm and excellent stability against aging, with zeta potentials in the range of 47-50 mV at pH 2. It was found that TiO₂ nanorods were grown from dilute aqueous sol with a low, 0.1-M concentration. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed that a full conversion of titanium isopropoxide was obtained by hydrolysis, resulting in the formation of TiO₂ particles. X-ray diffraction (XRD) results revealed that TiO₂ nanorods dried at 100 °C were a mixture of anatase and brookite phases, whereas they were a mixture of anatase and rutile structures at 500 °C. Moreover, the rutile content of the TiO₂ nanorods was higher than that of TiO₂ powders. Transmission electron microscope (TEM) images confirmed that TiO₂ nanorods had a smooth morphology and longitudinal uniformity in diameter. Field emission scanning electron microscope (FE-SEM) images showed that TiO₂ nanorods grown by sol-electrophoresis from the dilute aqueous sol had a dense structure with a uniform diameter of 200 nm, containing small particles with an average size of 15 nm. Simultaneous differential thermal (SDT) analysis verified that individual TiO₂ nanorods, grown into a PC template, were obtained after annealing at 500 °C. Based on kinetic studies, it was found that uniform TiO₂ nanorods with high-quality morphology were obtained under optimum conditions at an applied potential of 0.3 V/cm and a deposition time of 60 min.