Electrophoretic deposition of TIO2 nano-particles : the peroxo-titanium route to fabricating photocatalytic films
Toh, Alicia Guek Geok
Date of Issue2009
School of Mechanical and Aerospace Engineering
TiO2 materials are inorganic semi-conductors that experience electron- hole separation when irradiated with UV light (lumbda,<380nm) possessing energy greater than its band gap. This photon- induced charge separation is widely considered to react with ambient oxygen and water to produce reactive oxygen species (ROS) such as -OH, O2-, ·0, 102 and H2O2. ROS produced on photo-activated TiO2 films undergo reactions with organic compounds to produce hannless by-products. Concomitant to these photo-sensitized reactions is the UV-induced super-hydrohilicity of TiO2 surfaces. As such, the photocatalytic and hydrophilic properties of TiO2 films have been utilized in commercial products such as self-cleaning coatings, solar conversion cells and water/air purification reactors. There are several established techniques to produce TiO2 thin films including sol-gel dip coating, atmospheric chemical vapour deposition (APCVD) and electrophoretic deposition. In terms of cost and energy efficiency, low temperature aqueous electrophoretic deposition provides an attractive alternative to the other techniques. Conventional electrophoretic deposition (EPD) processes utilize acidic and/or organic suspensions. These acidic and organic EPD suspensions pose environmental problems such as the evolution of volatile organic compounds (VOCs) during EPD and the need for acidic waste disposal after EPD. In the present work, the electrophoretic deposition of TiO2 films was achieved within a neutral, aqueous and low temperature environment.
DRNTU::Engineering::Materials::Microelectronics and semiconductor materials::Thin films