CHINESE JOURNAL OF CATALYSIS Volume 31, Issue 2, 2010 Online English edition of the Chinese language journal Cite this article as: Chin. J. Catal., 2010, 31: 163–170. Received date: 2 September 2009. *Corresponding author. Tel/Fax: +86-351-4041153; E-mail: lxk@sxicc.ac.cn Foundation item: Supported by the National High Technology Research and Development Program of China (863 Program, 2009AA063003), the Science and Technology Commission of Shanghai Municipality (08JC1411300, 0952NM01800), and the National Natural Science Foundation of China (20677039). Copyright © 2010, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier BV. All rights reserved. DOI: 10.1016/S1872-2067(09)60042-5 RESEARCH PAPER Kinetics and Mechanisms for Photoelectrochemical Degradation of Glucose on Highly Effective Self-Organized TiO 2 Nanotube Arrays LIU Bingchuan, LI Jinhua, ZHOU Baoxue*, ZHENG Qing, BAI Jing, ZHANG Jialing, LIU Yanbiao, CAI Weimin School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai 200240, China Abstract: The kinetics and mechanisms of photoelectrochemical catalytic degradation of glucose on self-organized TiO 2 nanotube arrays (TNAs) were investigated. A thin-layer cell was used to obtain an exhausted reaction condition with which an overall degradation process of glucose could be identified including surface reaction on TNAs and mass transfer from body solution to the diffuse layer. Current-time (I ph -t) and the corresponding differential coefficient profiles were used to analyze the micro-processes of photoelectrochemical catalytic degradation. The initially generated photocurrents on glucose degradation versus glucose concentrations fits well with Langmuir adsorption isotherm, I 0ph = 0.00008c 0 /(1+0.69274c 0 )+0.00034. This confirmed the adsorption of glucose on TNAs film catalyst was a single molecule layer adsorption, and the photoelectrochemical catalytic degradation reaction kinetics on TNAs surface belonged to a first-order reaction. After the initial quick reaction, three consecutive micro kinetic processes were revealed by the differential coefficient profiles (dI ph /dt-t) of the glucose degradation profiles (I ph -t). Key words: self-organized titania nanotube arrays; photoelectrochemical catalytic reaction; glucose; thin-layer cell, kinetic; mechanism Titanium oxide (TiO 2 ) has proven to be a promising catalyst for use in many aspects of environmental applications because of its high photocatalytic efficiency, nontoxicity, nonphoto- corrosiveness, favorable biological and chemical inertness, and inexpensive characteristics [1]. In spite of these advantages, TiO 2 has been reported to have three non-negligible limita- tions [2]: (1) The high rate of electron/hole pair recombination among TiO 2 particles greatly diminished the electron-trans- porting efficiency; (2) Poor activation was observed when traditional TiO 2 particles are illuminated by visible light; (3) Traditional TiO 2 catalysts are generally applied through dis- persion into the reaction solution, which can cause post-treatment problems. In order to overcome these deficiencies, new TiO 2 struc- tures such as nanorings, nanowires, nanorods, nanotubes, nanobelts, etc. were developed [3–5]. In 2001, Gong et al. [6] prepared highly ordered TiO 2 nanotube arrays (TNAs) about 500 nm in length by potentiostatic anodization of titanium in HF aqueous solution. The nanotubular microstructures were perpendicular to the electrically conductive Ti substrates, forming a Schottky-type contact naturally and providing a unidirectional electric channel for the transport of photo-generated electrons [7]. Hence, as an electrode in pho- toelectrochemical catalysis, TNAs have shown good charge transport properties and elevated photoelectrical and electro- chemical performance [8,9]. For example, TNAs-based photoanodes have been reported as an excellent photoelectro- catalyst for the degradation of various organic pollutants [10]. Titania materials have also been used to improve the pho- tosplitting of water [11] and for dye-sensitized solar cells [12,8]. In our recent work [13,14], a TNAs-based chemical oxygen demand (COD) sensor can achieve rapid and accurate COD determination of wastewater. Photoelectrochemical catalysis oxidation of organic com- pounds is multiphase reactions, involving gas-solid and liq- uid-solid inter-phase and interfacial reactions. Generally, the