| Summary: | 碩士 === 中原大學 === 化學工程研究所 === 105 === Strontium titanates, a cubic perovskite structure (ABO3) which have BO6 octahedron arrangement can led to the separation of photogenerated charge. In this study, strontium titanates with various morphologies, i.e., nanofibers and cubic-like particles, were prepared as photocatalysts using the electrospinning (ES) and solid-state (SS) methods. X-ray diffraction (XRD) analysis showed that ES and SS samples were assigned to perovskite SrTiO3 (ICSD 23076) phase. Scanning electron microscope (SEM) analyses revealed that ES SrTiO3 had an uniform fibrous structure with length and diameter of several microns and 100-200 nm, respectively.
To improve the photocatalytic activity, nanoparticulate Ag was employed as a co-catalyst to load onto the SrTiO3 surface. UV-vis spectra showed that the visible light absorption of Ag/SrTiO3 increased with increasing the silver content. With further Ag content the visible light absorption did not improved. Therefore 2AgES exhibit the highest photocatalytic activity under UV light irradiation among these Ag/SrTiO3 samples. To further enhanced the photocatalytic activity of SrTiO3 under visible light irradiation, p-BiOI was coupled with n-SrTiO3.
A p-n heterostructure fromed by n-SrTiO3 and p-BiOI was prepared to improve the charge separation and hence the photocatalytic degradation activity. Microwave-assisted solvothermal method was used to shorten the reaction time to prepare BiOI/SrTiO3 composite. UV-vis spectra showed that the absorbance of BiOI/SrTiO3 composite was red-shifted toward longer wavelength with increased BiOI contents. Under visible light irradiation (>400nm), 0.8BS15 sample obtained from solid-state mehtod showed the highest photocatalytic activity toward the degradation of methyl orange (MO) dye among these samples and compared to photocatalyst prepared using electrospinning method. High photocatalytic activity can be attributed to its high crystallization, extended visible light absorbance, and facile electron transport resulting from p-n junction at the BiOI/SrTiO3 interface.
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