纳米氧化钛/β-环糊精膜光电化学传感器的研究

【作者】 彭芳；

【导师】 司士辉；

【作者基本信息】 中南大学 ， 分析化学， 2008， 硕士

【摘要】 光电化学型半导体传感器是一种利用半导体的光电特性来检测与光生电流或光生电压相关的待测物质浓度及生化过程参数的分析新技术。随着新型半导体功能材料及相关加工技术的不断涌现,光电化学型半导体传感器已在微型化、集成化、多点及多参数测量方面显现出优势,将纳米半导体材料应用于光电化学传感器领域的研究,有望在复杂体系中实现在线高灵敏、快速测定,在生物、医药、环境监测、食品等领域显示出更加广阔的应用前景。本研究将纳米材料技术与光电化学传感器结合在一起,主要做了以下三方面的工作:1、采用溶胶-凝胶法在金电极上逐层自组装了纳米TiO₂/β-CD膜,利用石英晶体微天平现场技术（QCM）、电子能谱图扫描、电镜扫描、红外光谱等手段考察了纳米氧化钛与环糊精自组装过程,证明了β-CD羟基与TiO₂表面羟基存在分子间缔合;对纳米TiO₂与β-CD组装机理进行了推断,根据β-CD上伯羟基活性较高和TiO₂表面吸附羟基的作用原理,提出了β-CD与TiO₂组装膜的结构形式。2、以甲基橙为目标物,采用电化学体系在纳米TiO₂/β-CD膜电极上进行光电催化降解反应研究,比较了复合薄膜在电催化、光催化、光电催化体系中光电催化降解效率;在光电催化体系中考察了电压、pH值、β-CD的掺入对光电催化降解效率的影响。实验结果表明:随着外加电压的增加,甲基橙的降解率在100min内从53.4%提高到91.8%,但是偏电压也不是越高越好,当外加电压达到一定值时,光生载流子已达到充分分离,形成饱和的光电流。因此,在光电流接近饱和状态时,继续增加电压对光电催化反应速率提高幅度不大;溶液的pH值对光电催化反应有较大的影响,酸性条件有助于光电催化降解有机物;由于β-CD的包合作用,改善了TiO₂的表面特性,增加了包合物的客体与TiO₂的相互作用,提高了TiO₂对包合物中的有机物催化降解效率。3、制备了基于逐层自组装纳米TiO₂/β-CD膜光电化学传感器,并将其用于水体化学需氧量（COD）的测定。实验证明纳米TiO₂/β-CD膜电极比单纯的TiO₂膜电极具有更好的光电催化作用,能提高水体有机物的降解率,使该传感器具有更高的灵敏度及更宽的线性范围。COD值在4.6～138.0mg·L^-1浓度范围内与传感器的光电流感应信号成良好的线性关系。将该方法用于实际水样的测定,测定结果与重铬酸钾标准分析法有较好的一致性,且具有操作简单、响应快速、无二次污染等优点,具有广阔的应用前景。更多还原

【Abstract】 Photoelectrochemical semiconductor sensor is a new kind of analytical technology for the detection of the concentration of analytes and the parameters of biochemical processes related to photocurrent or photopotential.Photoelectrochemical semiconductor bioseneors have advantages in the aspects of micromation、intergration、multipoint and multiparameter measurement along with the appearance of new semiconductor functional materials and related technologys.It is hopeful to achive high sensitivity and rapid detection online in the complicated systems and to find wide applications in the fields of biology、medicine、environment monitoring、foodstuff and so on.We combined nano-material technique with photoelectrochemical semiconductor sensor and the main research contents and conclusions are as follows:（1）A nanometer TiO₂/β-CD films photoelectrochemical sensor was prepared by a sol-gel layer-by-layer self-assembly method.In-situ quartz crystal microbalance（QCM）、scanning electron microscope（SEM）、electronic energy spectrogram,FT-IR spectra were employed to prove the molecule combination between-OH ofβ-CD and-OH of TiO₂;the combination mechanism of nano-TiO₂ andβ-CD was deduced and the structural style of nano-TiO₂ andβ-CD assembly film was superior according to the high activity of C₁-OH ofβ-CD and principle of adsorption on the surface of TiO₂.（2）The methyl orange（MO）was used as detected material to study the photoelectrical catalytic degradation reaction on the nano-TiO₂ andβ-CD film electrode in the electrochemical system.The efficiency of photoelectrical catalytic degradation of composite film was compared with those of the systems of electrical catalytic degradation,photic catalytic degradation and photoelectrical catalytic degradation reaction; the influence of voltage、pH and addition ofβ-CD was studied in the system of photoelectrical catalytic degradation.The results showed that the degradation rate of MO was improved from 53.4%to 91.8%in 100 min.When the voltage achieved a certain value,photo-induced carriers separated adequately and formed saturated photo electricity.So increasing voltage can not improve the degradation rate obviously when photo electricity was saturated;the pH value of solution had great influence on photoelectrical catalytic degradation reaction,acidity is helpful to photoelectrical catalytic degradation of organics;the surface characteristic of TiO₂ was ameliorated、the mutual action between object of inclusion compound and TiO₂ was enhanced and the degradation rate of organics in the inclusion compound was improved because of the inclusion action ofβ-CD.（3）A nanometer TiO₂/β-CD films photoelectrochemical sensor was prepared by a layer-by-layer self-assembly method and applied to the detection of chemical oxygen demand（COD）of water.The results showed that nanometer TiO₂/β-CD film electrode had better photoelectrical catalytic degradation affection than TiO₂ electrode which can improved the sensitive and expanded the linear range of sensor.The photo electricity of sensor responded linearly to the COD in the range of 4.6～138.0 mg·L^-1.Its application in practical water analysis has achieved results in good agreement with those from the conventional dichromate method;meanwhile,the process required easy operation、less analysis time and no hyper toxic reagents,suggesting that it would have a good prospect of application.更多还原