Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (11): 2935-2940.doi: 10.3866/PKU.WHXB20101131

• ELECTROCHEMISTRY • Previous Articles     Next Articles

Kinetics and Electrochemical Impedance Properties of TiO2 Nanotube Array Photoelectrode

ZHANG Zhi-Yu, SANG Li-Xia, SUN Biao, ZHANG Xiao-Min, MA Chong-Fang   

  1. Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conversion, Beijing Municipality, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, P. R. China
  • Received:2010-06-01 Revised:2010-08-05 Published:2010-10-29
  • Contact: SANG Li-Xia E-mail:sanglixia@bjut.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (50806003) and Beijing Natural Science Foundation, China (3093018).

Abstract:

The 2μm and 650 nm TiO2 nanotube (TNT) arrays were fabricated by sonoelectrochemical anodic oxidation in ethylene glycol (TNT-E) and in aqueous solution (TNT-A) electrolytes at 20 V direct voltage. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize the crystal phase and surface morphology of the resulting oxide films. UV-Vis diffuse reflectance spectra (UV-Vis DRS), current-time (I-t) curves, Mott-Schottky plots and electrochemical impedance spectroscopy (EIS) were used to investigate their kinetics properties and their electrochemical impedance behavior. The 2 μm nanotubes of TNT-E can help to harvest more light and provide more surface active sites than the 650 nm nanotubes of TNT-A. We found that TNT-E had stronger light absorption than TNT-A after calcination in air at 500 ℃, but the photocurrent density differences between TNT-E and TNT-A was only about 0.05 mA·cm2 under UV illumination ((365±15) nm). Since the longer TNT-E tubes can increase the charge transport resistance and decrease the concentration of the reactants on the electrode surface, TNT-E needs to overcome a larger energy barrier and it has a low charge carrier density of 5.31×1020cm-3. TNT-A with relatively shorter tubes showed a better kinetics property and had a charge carrier density of 9.86×1020 cm-3.

 

Key words: TiO2 nanotube array, Charge transport resistance, Kinetics property, Charge carrier density

MSC2000: 

  • 649