TiO2纳米管阵列电极电催化降解甲基橙的研究

采用阳极氧化法制备了TiO2纳米管阵列电极.采用场发射扫描电子显微镜（FESEM）和X-射线衍射仪（XRD）表征了电极的表面形貌和晶体结构,应用电化学阻抗谱（EIS）技术研究了不同阳极极化电位下电板的导电性能,应用荧光光谱法研究了电极产生羟基自由基（·OH）的活性,考察了3种支持电解质（Na2SO4、NaNO3和NaCl）对甲基橙（MO）电催化降解效率的影响,通过加入捕获剂探讨了MO分子的降解机理.结果表明,TiO2纳米管阵列电极电极的导电性随阳极极化电位的升高而增强;在电场作用下,TiO2纳米管阵列电极表面生成大量·OH;Na2SO4和NaNO3不参与MO分子的氧化反应,MO的降解符合一级反应动力学模型,而NaCl参与了TiO2纳米管阵列电极电催化降解MO的过程,呈现出复杂的动力学行为;在捕获剂存在的情况下,MO分子仍能发生降解,显示MO分子可在TiO2纳米管阵列电极表面直接氧化.

Electrocatalytic Degradation of Methyl Orange on TiO2 Nanotube Array Electrode

TiO2 Nanotube array electrodes were prepared using anodic oxidation method. 1he morphology and the crystal structure of TiO2 nanotube array electrode were characterized by filed emission scanning elec- tron microscope （FESEM） and X-ray diffraction （XRD）,respectively. Using electrochemical impedance spec- troscopy （E/S） technique,the difference of conductivity of TiOz nanotube array electrode was investigated un- der various anodic polarization potentials. The electrode activity for producing hydroxyl radicals （ · OH） was studied by fluorescence spectrum technique using terephthalic acid as · OH capture agent. The effects of three kinds of supporting electrolytes were investigated on electrocatalytic degradation efficiency of MO. The degra- dation reaction mechanism of MO was discussed in the presence of · OH capture agent. The results indicated that the conductivity of TiO2 nanotube array electrode increased with anodic polarization potentials. A great quantity of · OH generated on the surface of TiO2 nanotube electrode in the presence of electric field. The two kinds of supporting electrolytes, Na2 SO4 and NaNO3, had not been involved in the oxidizing reaction of MO and the electrocatalytic degradation of MO accorded with the first ocder reaction kinetics by the action of TiOz nanotube array electrode. However, the supporting electrolyte of NaC1 took effect to electrocatalytic degradation of TiO2 nanotube array electrode for MO,leading to the complex reaction kinetics. In the presence of ·OH cap- ture agent,the degradation of MO still took place,suggesting that MO could be directly oxidized on the surface of TiO2 nanotube array electrode.