Preparation of Functional Oxide Films Using Solution-based Synthesis and Study of Their Piezo- and Photo-related Performance

Abstract

This study focused on the preparation of four types of functional oxide films using solution-based synthesis and their piezo- and photo-related performance The highlights are summarized as follows (1) Cr-N codoped TiO2 nanorods Polymerized complex reactions and hydrothermal synthesis were developed the first time to synthesize single-crystalline TiO2 nanorods A growth model on the basis of complex species was proposed to study the positive impacts of the two solution processing In Cr and N doping TiO2 N2 doping was able to inhibit the production of Cr6+ ions and oxygen vacancies thus enhancing photocatalysis of TiO2 nanorods High photodegradation efficiency was achieved for methylene blue (MB) by a nanocomposite of 7% Cr and 0 0021% N doped and 3% Cr doped TiO2 nanorods (2) TiO2-reduced graphene oxide (rGO) nanorod libraries Combinatorial hydrothermal processing and spin coating were developed to fabricate TiO2–rGO nanorod libraries Spot 5 (7% TiO2–93% rGO) on the library exhibited the most promising photodegradation ability and reliability The sample also exhibited excellent PEC stability and photocurrent density without further treatment which was attributable to the strong coupling between the two gradient components (3) BaZnO2 Two-step solvothermal synthesis was adopted to synthesize BaZnO2 films on ITO and Si substrates using a moderate chemical condition (pH ? 8) The probable formation mechanism was the desirable coordination of O atoms in PEG with the ions of Ba2+ and Zn2+ The associated piezoelectricity was determined through the stress-induced piezopotential measurement (approximately 2 and 3 mV at ?1 9 and 2 9 GPa respectively) Our results indicate great promise for the use of BaZnO2 films in piezophotodegradation and PEC water splitting applications (4) BiFeO3 Pure BFO films were fabricated on BFO seed-layer-coated ITO substrates through a moderate hydrothermal condition A stress-induced piezopotential of ? 2 0 mV was determined under ?0 6 GPa The associated piezotronic effect was determined by the observation of the asymmetrical I–V curves under various pressures Our results indicate the promise of the BFO films in piezophotodegradation

Date of Award	2021
Original language	English
Supervisor	Kao-Shuo Chang (Supervisor)