Photocatalysis of nano-perovskites
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1171-S07-14
Photocatalysis of nano-perovskites Yen-Hua Chen, and Yu-De Chen Department of Earth Sciences, National Cheng-Kung University, Tainan, Taiwan
ABSTRACT In this study, we can successfully synthesize nano-perovskites, including nano-CaTiO3, nano-SrTiO3, and nano-BaTiO3, by a co-precipitation method. The band gap of the nanoperovskites are 3.65 eV, 3.44 eV, and 3.35 eV, for nano-CaTiO3, nano-SrTiO3, and nanoBaTiO3, respectively. The ability of photocatalysis for nano-BaTiO3 is a little bit better than other nano-perovskites. It is also observed the photocatalytic activity increases with the increasing amount of photocatalysts. Moreover, the ability of photocatalysis using a higher energy UV-light is not promoted with the low energy UV-light.
INTRODUCTION Very recently, the environmental pollution is more and more serious, such as waterpollution, air-pollution and so on. It is very important for researchers to find out the solution to the problem. The nano-perovskites have the catalysis and photocatalysis properties due to the strong redox and photocatalyzer [1-2]. For example, it can photocatalyze the toxic gas, organic materials, etc. [3-4]. In this study, nano-BaTiO3 (90 nm/ round shape), nano-CaTiO3 (80 nm/ rectangular morphology), and nano-SrTiO3 (50 nm/ square form) are synthesized by a co-precipitation method [5-9]. We want to investigate the photocatalysis on organic materials using nanoperovskites, which is compared with nano-rutiles (TiO2). In addition, the effects on the amount of nano-perovskites and the energy of UV-light for the photocatalytic property are also discussed.
EXPERIMENT In this study, we synthesize nano-perovskites by the co-precipitation method, which is shown in Fig. 1. First, the chemical powders of CaCO3, KOH, NaOH and TiO2 are added into deionized water. When the materials are dissolved completely, it is then heated with a constant stirring rate. After that, it is calcined, and then cooled down to room temperature. We use the UV-Vis spectrometer to examine the band gap of the nano-perovskites. Moreover, the 254 nm and 365 nm UV-light are used to perform the photocatalysis experiment, respectively. The organic material is Methylene blue solution (M.B.). The photocatalysts are nano-BaTiO3 (nanoBTO), nano-CaTiO3 (nano-CTO), and nano-SrTiO3 (nano-STO) with the amount of 0.03g and 0.1g. The experimental flowchart is shown in Fig. 2.
Fig. 1 The sketch of the co-precipitation method.
Fig. 2 The flowchart of the experiment.
DISCUSSION Fig. 3 shows XRD patterns of nano-CaTiO3, nano-BaTiO3, and nano-SrTiO3. NanoCaTiO3 has a orthorhombic structure; nano-SrTiO3 and nano-BaTiO3 are both cubic structure. From the XRD pattern, we can estimate the full width at half maximum (FWHM), which roughly represents the crystallinity of the specimens. The FWHM of nano-CaTiO3 is around 0.220, and that of nano-BaTiO3, and nano-SrTiO3 are about 0.210 and 0.200, respectively. It indicates the sample of nano-SrTiO3 probably has a better crystallinity. By the formula, D = K * λ / β * cosθ (nm), we can
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