Exploration of the Piezo-photocatalytic Effect of Nano-structured ZnSnO3 Using Hydrothermal Synthesis

Abstract

Studies have reported various excellent properties of the novel lead-free ZnSnO3 material applied to gas sensors and photocatalyst However the piezoelectric performance of ZnSnO3 did not obtain an equivalent attention In addition its semiconductor characteristics allow to exhibit the piezotronic effect which means stress modulation of piezo-potentials built in the Schottky contact to enable different electrical performances of a device If the system also exhibits the photonic features under light irradiation the piezo-phototronic effect is developed These characteristics were not observed in most of materials No studies reported the piezo-photocatalytic effect which is a coupling between the piezophototronic and photocatalytic effects In this work 1D nanostructured ZnSnO3 nanowires were fabricated using a two-step hydrothermal reaction to explore the novel piezo-related properties for the first time The X-ray diffraction pattern and TEM analyses showed that the ZnSnO3 phase of single crystalline nanowires The piezotronic and piezophototronic effects were demonstrated using a probe station which enabled to quantitatively apply stresses during the I-V measurement We found the Schottky barriers were modulated as a function of applied stresses at the local contacts between the probe and the sample These features implied the novel application to piezo-photocatalysis In the piezo-photocatalytic experiment we found the piezo-phototronic effect did significantly enhance the photocatalytic efficiency of ZnSnO3 nanowires without any other external bias An energy band diagram was simply used to explain the increased efficiency which was attributed to the improved mobility of photogenerated carriers resulting from the enhanced piezo-potentials under stresses There still exists numerous challenges for this project to further enhance the piezo-related properties of ZnSnO3 including 1) fabrication of much well-aligned ZnSnO3 nanowires 2) fabrication of different aspect ratios (morphology) of ZnSnO3 3) seeking less basic conditions (pH <12 5) for growing ZnSnO3 nanowires 4) growing ZnSnO3 on a flexible substrate Various promising applications such as sensors and photoelectrochemical cells can then be expected

Date of Award	2014 Aug 5
Original language	English
Supervisor	Kao-Shuo Chang (Supervisor)