Fabrication of composition spread of TiO2-Y2O3 nanorod-array composites using combinatorial reactive magnetron sputtering for photocatalytic applications

Abstract

To enhance the separation of the photo-generated electron-hole pairs to obtain high photocatalytic activity of materials an innovative concept was proposed in this research where oxygen vacancies in a high-k material are utilized as charge carrier traps to inhibit the recombination In addition nanorod structures were aimed to improve charge carrier transport Based on these ideas a comprehensive investigation of Y2O3-TiO2 nanorod-array composite composition spread was employed by using combinatorial reactive magnetron sputtering The novel idea incorporating the high-k material Y2O3 into TiO2 is to compromise the disadvantages of each material and to acquire a synergistic photocatalytic performance through a close coupling The excellent Y2O3-TiO2 nanocomposite composition spread was achieved by obtaining optimal conditions of each constituent first and then a moving shutter was suitably controlled to make thickness gradients of Y2O3 and TiO2 across a substrate To study the various features as a function of compositions the Y2O3-TiO2 nanocomposite composition spread was cut into six pieces from #1 (Y2O3-rich) to #6 (TiO2-rich) along the composition variation direction The characterization tools such as XRD SEM TEM UV-Vis PL and XPS were employed to determine the various characteristics including the phases morphologies microstructures optical properties compositions and chemical bondings Photodegradation activities were determined by decomposing 5 ppm of MB for 180 min using 30 W UV irradiation It was found that the sample #6 (TiO2-rich) exhibited the superior performance in which 60% of MB was decomposed in 180 min even outmatched that of TiO2 nanorods indicating the coupling effect between Y2O3 and TiO2 indeed enhanced the TiO2 photocatalytic properties Cycling test was also used to examine the stability of the sample #6 in which consistent photocatalysis was observed throughout the three-cycle test demonstrating it a promising photocatalyst for the application of environment sustainability The PL results manifested optimal oxygen vacancies were required to achieve synergistic photocatalysis which was effectively achieved by incorporating a suitable amount of Y2O3 The sample but effective composition spread strategy demonstrated its value in accelerating exploration of optimal compositions from a wide range of composition variations

Date of Award	2015 Aug 10
Original language	English
Supervisor	Kao-Shuo Chang (Supervisor)