| Summary: | 碩士 === 國立交通大學 === 材料科學與工程學系所 === 104 === With the inherently high degree of complexity, semiconductor nanoheterostructures have exhibited superior synergistic properties that are difficult to acquire from their individual constituents. Particularly, great progress has been made in creating Z-scheme semiconductor-metal-semiconductor nanoheterostructures, in which the vectorial charge transfer scenario may increase the oxidizing and reducing powers for photoconversion applications. In this work, a ZnO nanorod-based Z-scheme nanoheterostrutcure system was proposed and realized for studying the photoelectrochemical properties in water splitting. The samples were prepared by selectively depositing a thin layer of SnO2 on the Au surface of Au nanoparticle-decorated ZnO nanorods using the photodeposition method. For Z-scheme ZnO-Au-SnO2 nanorods, the decorated Au may mediate interfacial charge transfer by promoting the electron transfer from the conduction band of SnO2 to the valence band of ZnO. This vectorial carrier transfer resulted in the situation that the photoexcited electrons accumulated at ZnO while the photogenerated holes remained at SnO2, rendering ZnO-Au-SnO2 sufficiently high redox powers. Time-resolved photoluminescence spectra and photovoltage analysis suggested that charge carrier separation was significantly improved in the ZnO-Au-SnO2 nanorods as a result of the Z-scheme charge transfer scenario. With the pronounced charge separation and sufficiently high redox powers, Z-scheme ZnO-Au-SnO2 nanorods performed much better in photoelectrochemical water splitting than pristine ZnO, two-component ZnO-Au and type-Ⅱ ZnO-SnO2 nanorods did. The demonstrations from this work may facilitate the use of Z-scheme nanoheterostructures in various photoconversion processes, in which the pronounced charge separation and high redox powers of Z-scheme charge transfer can be well employed.
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