Enhanced Photoelectrocatalytic Degradation of Methylene Blue on Smooth TiO2 Nanotube Array and Its Impedance Analysis
Enhanced Photoelectrocatalytic Degradation of Methylene Blue on Smooth TiO2 Nanotube Array and Its Impedance Analysis
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DOI：
10.1149/1.3089312
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发表时间：
2009-05
影响因子：
3.9
通讯作者：
Xiaomeng Wu;Yun-han Ling;Li Liu;Zhaohui Huang
中科院分区：
文献类型：
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作者：
Xiaomeng Wu;Yun-han Ling;Li Liu;Zhaohui Huang
在含F -乙二醇电解质中经两步阳极氧化和焙烧制备的光滑钛纳米管阵列在降解亚甲基蓝（MB）上具有光电催化（PEC）应用。结果表明，MB的降解动力学符合一级反应规律，光催化（PC）法降解速率常数为0.147 h -1， PEC法降解速率常数为0.853 h -1，在开路和零施加电位条件下分别提高了5.8倍。利用电化学阻抗谱分析了在PEC中相对于PC的降解增强现象，结果表明PEC过程的降解效率增强应归因于在光照和偏置电位的共同作用下，电容和电阻的系统变化导致半导体界面上的阻抗急剧下降。进一步的研究表明，tio2纳米管阵列的晶体结构及其空间电荷层的宽度（主要由纳米管壁的厚度和沿纳米管壁施加的电势决定）可能是由于其有效的电荷分离而提高降解效率的关键因素。
The smooth titania nanotube array fabricated via two-step anodization in F - -containing ethylene glycol electrolytes plus a post-calcination has been developed as a photoelectrocatalytic (PEC) application on degradation of methylene blue (MB). It was found that the MB degradation kinetics meets the law of first-order reaction, and the rate constants of MB degradation were 0.147 h -1 for photocatalytic (PC) process and 0.853 h -1 for PEC process, a 5.8-fold increase under the condition of open-circuit and zero applied potential, respectively. Electrochemical impedance spectroscopy was used to analyze the enhanced degradation phenomenon in PEC as compared to PC on such electrodes, and the results revealed that the enhanced degradation efficiency of PEC process should be ascribed to the systematic change of capacitance and resistance and thus leading to a dramatic decrease of impedance on the interface of semiconductor under combination of illumination and bias potential. Further investigation revealed that the crystal structure of TiO 2 nanotube array and the width of its space charge layer, which is mainly determined by the thickness of the nanotube wall as well as the potential applied across the wall of the nanotube, might be critical factors for the enhancing degradation efficiency due to its effective charge separation.