物理化学学报 >> 2010, Vol. 26 >> Issue (11): 2935-2940.doi: 10.3866/PKU.WHXB20101131

电化学 上一篇    下一篇

TiO2纳米管阵列光电极的电化学阻抗及动力学特性分析

张知宇, 桑丽霞, 孙彪, 张晓敏, 马重芳   

  1. 北京工业大学环境与能源工程学院, 传热强化与过程节能教育部重点实验室及传热与能源利用北京市重点实验室, 北京100124
  • 收稿日期:2010-06-01 修回日期:2010-08-05 发布日期:2010-10-29
  • 通讯作者: 桑丽霞 E-mail:sanglixia@bjut.edu.cn
  • 基金资助:

    国家自然科学基金(50806003)和北京市自然科学基金(3093018)资助项目

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).

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摘要：

采用声电化学阳极氧化法, 在无机溶剂(H3PO4+NaF水溶液)和有机溶剂(NH4F+水+乙二醇)体系电解液中加20 V 直流电压制得TiO2纳米管(TNT)阵列,其中无机溶剂样品(记为TNT-A)的管长为650 nm, 有机溶剂样品(记为TNT-E)的管长为2μm.基于X射线衍射(XRD)图谱、场发射扫描电子显微镜图(FESEM)、紫外-可见漫反射光谱(UV-Vis DRS)的表征和电流-时间(I-t)曲线、Mott-Schottky 图和电化学阻抗谱(EIS)的分析可知, 在空气中经500℃煅烧后, TNT-E 的吸光性能明显好于TNT-A 的吸光性能. 在紫外光((365±15) nm)辐照下, 测得TNT-E 的平均光电流密度与TNT-A 的仅差0.05 mA·cm-2, 这是由于管长的增长增大了电荷转移电阻, 并使得传质路径增长, 增大了反应所需克服的势垒, 降低了电极的反应速率, 两者的电荷载流子密度分别为5.31×1020 与9.86×1020 cm-3.

 

关键词: TiO2纳米管阵列, 电荷转移电阻, 动力学特性, 电荷载流子密度

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