Preparation Of Nanocomposites And Their Applications On Hydrogen Peroxide Sensors

Nanotechnology is a hot and wide multidisciplinary field, in which theresearches have an amount of opportunities and challenges. Various nanomaterialsand nano-devices have been designed and invented since1990s. These achievementswill indubitably promote the development of society and economy. Aside from thewell demonstrated size effect, surface effect and quantum effect in variousnanomaterials, the synergistic effect as well as the interface effect in thenanocomposite has emerged and attracted more attentions recently. Especially, thesynergistic effect can drastically improve the performance of various biological andchemical sensors based on the nanocomposite. Hydrogen peroxide is not only animportant chemical product, but also a by-product of most enzymatic reactions, andtherefore the hydrogen peroxide sensor plays an important role in the medicaldiagnosis and the security for the food and industry. The conventional biosensor todetect the hydrogen peroxide is based on the special bio-enzyme, such as the horseradish peroxidase, cytochrome C, microperoxisome and myoglobin. However, theinstability of bio-enzyme can degrade the performance of biosensors andconsequently the non-enzymatic sensor has been proposed due to the active catalysisof the nanomaterial. In this thesis, we will focus on the synthesis of nano-compositesand design the hydrogen peroxide non-enzymatic sensor. The contents of the thesisare arranged as follows.In chapter one, we first summaried the status of the development ofnanotechnology and nanomaterial. Then, we showed several outstanding properties ofnanocomposites as well as their application for the non-enzymatic hydrogen peroxidesensor. Finally, we outlined the aim and the work of this thesis.In chapter two, the non-enzymatic hydrogen peroxide sensor was constructed bythe composite of ZnO nanostructure and metallic nanoparticles （NPs）. The uniformZnO nanorods were first prepared by the electrochemical method onto the gold filmprefabricated on the silicon oxide substrate, and then the two kinds of NPs （platinumor gold） were deposited on the ZnO nanorods respectively. The density and size ofNPs can be well controlled by varying the deposition condition. The nanocomposite demonstrated much high catalytic activity as compared to those of the pure ZnOnanorod and Au film. The non-enzymatic hydrogen peroxide sensor was fabricatedbased on the nanocomposite and it exhibited a series of good performances includinghigh detection sensitivity, rapid response time, and outstanding anti-interferent ability.The mechanism was also discussed.In chapter three, the non-enzymatic hydrogen peroxide sensor based on thenano-composite of graphene oxide（GO） and Fe₃O₄NPs was presented. It has beenknown that the Fe₃O₄NPs possess an intrinsic enzyme mimetic activity similar to thenatural peroxidases and GO is well biocompatible and has good electron transportproperties. The GO/Fe₃O₄nano-composite was synthetized by the co-precipitationmethod. It was found that the Fe₃O₄NPs on the GO were well-crystallized, uniform insize and distribution. The non-enzymatic hydrogen peroxide sensor based on thenano-composite exhibited a high detection sensitivity （688μAmM-1cm-2）, wide linearresponse range （0.1to6mM）, low detection limit （2.07μM，S/N=3）, rapid responsetime （<5s）, outstanding anti-interferent ability, and excellent repeatability andstability. Moreover, the cause for the enhancement of the catalysis and sensing of thenano-composite was also discussed.In chapter four, we summaried the results of our work and tried to present theperspective for the non-enzymatic hydrogen peroxide sensor.