Nano-titanium Dioxide / ¦Â-cyclodextrin Film Optical Chemical Sensors

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.