Zulkarnain Zainal,* Chong Yong Lee, Anuar Kassim, Mohd Zobir Hussein, Nor Azah Yusof

Department of Chemistry, University Putra Malaysia, 43400 UPM Serdang, Malaysia.
Tel.: +603 89466810,
Fax: +603 89435380,
E-mail: zulkar@science.upm.edu.my.

Abstract:
TiO₂ thin films have been prepared using the sol-gel method. The chemically modified sol-gel precursor solution was obtained by the addition of polyethylene glycol and diethanolamine to the titanium alkoxide precursor. Hydrolysis and polycondensation reactions of the precursors in the presence of water were controlled. Electrochemical assisted photocatalytic degradation system has been investigated on a model pollutant, methyl orange dye. Properties of the films were determined as a function of calcination temperatures by surface morphology, X-ray diffraction and photoelectrochemical studies. The photoelectrochemical degradation rate is almost linearly increased with an increased in applied bias potential. The improved in percentage of degradation for about 30% for every increases of 0.5 V was observed for potential range between 0 V and 1.0 V. However, direct electrochemical oxidation of dye begins to occur at potential of 1.5 V and above due to dark current as indicated from current-potential curve behaviour. Introduction of more concentrated dye leads to a decrease in the photodegradation percentage but the rate of photoelectrochemical degradation was almost the same. Larger photocatalyst coated area gives higher degradation rate but showed less charge density.

Keywords: Photoelectrochemical degradation, calcination, methyl orange