The Surface Modification Of Titanium Dioxide Nanotubes And Their Application In Electrochemical Sensor Research

In present work, we constructed a PEC sensor for silver ions sensing and a glucose EC biosensor by combining photoelectrochemical (PEC) or electrochemical (EC) analysis techniques with functionalized TiO2 nanotube arrays (TiNTs).In chapter 1, as one important branch of nanomaterials, a review of TiO2 nanotubes is given, including their characteristics, preparation methods, modification approaches and applications in sensor. The principle and classification of PEC sensor and its application are also decribed in this chapter. Finally, the development of electrochemical enzyme sensors, enzyme immobilization methods and the application in glucose detection are summarized.In order to achieve the sensitive detection of Ag+, the second chapter proposed a PEC sensor based on Pbs-TiNTs composite nanotube arrays. Firstly, anodic oxidation was carried out to prepare TiO2 nanotube arrays (TiNTs). And then 5 layers of PbS QDs were decorated on the tube walls of by continuous chemical bath deposition technique (CBD), the resultant Pbs-TiNTs showed a strong PEC signal. Ag+ ions can react with PbS by substitution reaction when they are introduced into the composite nanotubes. This process leads to the formation of Ag2S, and causes a significant decrease on the photocurrentby whichthe Ag+ sensing can be achieved. The linear range of the as-prepared sensor is 5.0×10-3?5.0×10-8 mol L"1, and the detection limit is about 1.5×10-8 mol L-1 with a signal-to-noise ratio of 3 (S/N=3). The PEC sensor exhibits a wide linear range, good specificity, rapid analysis speed and simple operation for Ag+sensing.Amperometric biosensors consisting of oxidase and peroxidase have attracted great attention because of their wide application. In chapter 3, we demonstrate a novel approach to construct an enzymatic biosensor based on TiO2 nanotube arrays (TiNTs) as a supporting electrode. AuNPs with good electrical conductivity and biological compatibility, Prussian Blue (PB)-an "artificial enzyme peroxidase" and enzyme glucose oxidase (GOx) are immobilized on the TiNTs. For this, AuNPs are attached to the tube surfaces and walls first by electrostatic adsorption, then PB nanocrystals are deposited onto the electrode photocatalytically by the intrinsic photocatalytical property of TiO2, and the GOx/AuNPs nanobiocomposites are subsequently immobilized into the nanotubes via the electrodeposition of polymer. The resulting (GOx/Au/pDAB)-PB/AuNP/TiNTs electrode exhibits a fast response, wide linear range, and good stability for glucose sensing. The sensitivity of the sensor is as high as 248 mA M"1 cm"2, and the detection limit is about 5 ?mol L-3 with a signal-to-noise ratio of 3 (S/N=3). These findings demonstrate a promising strategy to integrate enzymes and TiNTs, which could provide an analytical access to a large group of enzymes for bioelectrochemical applications including biosensors and biofuel cells.