TiO2 nanobelts - Effect of calcination temperature on optical, photoelectrochemical and photocatalytic properties

The immobilized TiO2 nanobelts (NBs) were prepared by anodization and calcined at different temperatures in air. The influence of calcination temperature on the crystallinity, crystal phase and crystallite size were investigated using X-ray diffraction (XRD). The XRD analysis showed that the as-prepared specimen without calcination was completely amorphous and the crystallinity was improved as enhancing the calcination temperature. The crystalline structure of the samples calcined at 350,450 and 550 degrees C was pure anatase phase. A phase transition to rutile phase occurred at 650 degrees C. The crystallite size of TiO2 NBs increased as increasing calcination temperature except for 650 C. Experimental results revealed that the optical, photoelectrochemical and photocatalytic properties of TiO2 NBs were significantly affected by the calcination temperature. The charge transfer and separation efficiency increased gradually with increasing the calcination temperature from 350 to 550 degrees C and then decreased at 650 and 750 degrees C. The photocatalytic activity was assessed by detecting the formation of hydroxyl radicals and photocatalytic degradation of dye rhodamine B. Accordingly, the sample calcined at 550 degrees C showed the highest photocatalytic performance, which is a combined result of appropriate crystallinity, crystal phase, crystallite size and impurity doping. Furthermore, the prepared samples were applied to remove antibiotic amikacin from aqueous solution under simulated sunlight irradiation. Approximately 70% of amikacin was decomposed after irradiation of 150 min for the TiO2 NBs calcined at 550 degrees C, and the photocatalytic degradation of amikacin fits pseudo first-order kinetics. This work indicates that the calcination temperature is an important parameter by which the activity of TiO2 nano catalysts can be tailored. (C) 2013 Elsevier Ltd. All rights reserved.