BiFeO3/ITO Fabrication Using Hydrothermal Synthesis and Its Piezophotocatalytic and Photoelectrochemical Applications

Abstract

The pure BiFeO3 was successfully fabricated on the ITO/glass substrate for the first time using spin coating for grow a seed layer first and subsequently employing hydrothermal method using the condition of 1 g NaOH at 180 ?C for 4 5 hrs The SAED shows polycrystalline-like patterns of seed layers in which the (010) and (-110) planes of BFO were observed The film formed on the polycrystalline BFO seed layer is the single crystalline BFO The corresponding SAED pattern shows the (-110) (010) and (-120) planes of BFO The EDS analysis indicated approximately Bi:Fe = 1:1 However if the film grew directly on the ITO/glass substrate without seed layers polycrystalline nanowire-like Fe2O3 impurity was formed The asymmetrical current density-voltage curve showed piezotronic properties of BFO agglomerates JD under negative bias was negatively enhanced when the applied stress was increased This enhancement was attributed to the lowering of the Schottky barrier height which was lowered from approximately 32 mV (at 2 12 GPa) to approximately 22 mV (at 1 25 GPa) The variation as a function of applied pressure was found to follow an approximate first-order relationship The piezophotocatalysis indicated that introducing fixed pressure using a transparent glass and ultrasonic vibration on the BFO agglomerates in a 2-ppm MB solution resulted in substantially enhanced photocatalysis compared with that of the BFO sample only without any other external stresses This was attributed to alternating vibration which reduced the charge screening and dissipation thus improving BFO agglomerates active sites and enhancing MB mass transfer The photodegradation kinetic behavior showed the first-order linear relationship for each sample The BFO sample under pressure from ultrasonic vibration and a piece of glass exhibited a k value of approximately 0 003 min-1 which is approximately 3 times higher than that of BFO without any stress

Date of Award	2016 Aug 26
Original language	English
Supervisor	Kao-Shuo Chang (Supervisor)