Template-free formation of vertically oriented TiO2 nanorods with uniform distribution for organics-sensing application

High-density arrays of vertically oriented TiO2 nanorods with uniform distribution on Ti foil have been formed through template-free oxidation of Ti in hydrogen peroxide solutions. Subsequent thermal treatment was applied for growing mixed crystal structures to pursue higher performance. Morphology characterization using field emission scanning electron microscopy (FESEM) shows a nanorod diameter in the range of 20-50 nm with a length of 1.5 mu m. X-ray diffraction (XRD) measurement demonstrates the crystallization of the TiO2 nanorods prior to thermal treatment and the formation of anatase and rutile mixed phase after thermal treatment. The mixed crystal TiO2 nanorods show a much higher performance than pure anatase in photoelectrochemical experiments. Steady-state photocurrent resulted from photocatalytic oxidation of organic compounds by TiO2 nanorods is employed as response signal in determination of the organics to yield a linear range of 0-1.1 mM for glucose. For other organics, an excellent linear relationship between the net steady-state photocurrent and the concentration of electrons transferred in exhaustive oxidation for these organics is obtained, which empowers the mixed crystal TiO2 nanorods to serve as versatile material in organics-sensing application. (C) 2011 Elsevier B.V. All rights reserved.