Based On The Preparation Of Cerium Oxide Nanocomposites And Its Application In Electrochemical Biosensors

Biosensors have to be a newly-interdisciplinary and frontier including biology,chemistry, physics, computer and electronics. Because to its good selectivity, highsensitivity, simplicity, fast response, low cost and potential ability for continuouson-line,on time detection and on-site analysis in complex system. Biosensors havebeen much accounted of and widely applied in various fields including clinicalbehavioral medicine, environment monitoring, food control and industrial processandso on. In recent years, nanotechnology triggered the revolution of human cognitionand industrial development. Nanotechnology in biosensors areas of development andapplication become the focus of scientists all over the world. The application of nanomaterials in the preparation can improve the performance of biosensors, especiallyproduce far-reaching and positive impact for ultra-thin mesoporous film andnon-enzyme biosensors, and has a broad development prospects.The main work of this work focuses on the preparation of cerium oxidenanocomposite materials and ultra-thin mesoporous membrane, also develop theelectrochemical biosensor analysis and detection of methanol, hydrazine hydrate,glucose, ascorbic acid, dopamine, uric acid. The main pionts of this thesis aresummarized as follow:（1）In chapter2，we have reportedAuNPs modified CeO₂was prepared by firstadsorb HAuCl4onto CeO₂surface and then reduce HAuCl₄with NaBH₄. TEM imagereveals spherical AuNPs with diameter of about5nm are decorated onto CeO₂surface.The as-synthesized AuNPs-CeO₂shows very high electrocatalytic activity towardshydrazine oxidation, indicating the AuNPs-CeO₂nanoparticles has good potentialapplication in fuel cells. Additionally, the AuNPs-CeO₂modified screen-printedelectrode has wide linear range toward hydrazine detection. The research work ofanchoring other metal nanoparticles, such as Pt and Pd onto CeO₂surface and use thesynthesized nanocomposite as novel catalyst are underway in our lab.（2）In chapter3，we have reported Palladium modified cerium oxide （CeO₂orceria） nanoparticles （Pd-CeO₂） were prepared by depositing palladium nanoparticleswith average diameters of3-5nm on the surface of CeO₂via chemical reduction ofthe precursor (Pd²⁺). The electrocatalytic activity of Pd-CeO₂towards the detection ofdifferent important compounds （i.e. glucose, ascorbic acid （AA）, dopamine （DA） and uric acid （UA）） has been investigated. Compared with the CeO₂or Pd modifiedelectrode, the Pd-CeO₂modified electrode has higher catalytic activity towards theoxidation of glucose, AA, DA, and UA. A nonenzymatic glucose sensor wasdeveloped for the sensitive and selective detection of glucose. Moreover, in themixture of AA, DA and UA, obvious electrochemical potential separations among thethree detected peaks were observed, making the simultaneously determination of AA,DA and UA possible. The attractive features of Pd-CeO₂provide potentialapplications in sensor and biosensor design.（3）In chapter4， we have reported a simple method to prepare Pt/Fe₃O₄-CeO₂catalyst. The catalyst was tested for the electro-oxidation of methanol in acid solutionand the results shows enhanced catalytic performance of Pt/Fe₃O₄-CeO₂，Thecatalytic current of Pt/Fe₃O₄-CeO₂towards methanol is about4times higher than thatof Pt-CeO₂。Also it’s good anti-poisoning ability and electrochemical stability showsgreat potential as cost effective electrocatalyst in direct methanol fuel cells..（4）In chapter5，we have reported Pd nanorod array modified sol-gel silica thinfilm was prepared by electro-deposition method. In solution containing silicaprecursor and surfactant, the film can be self-assembled onto the electrode surfaceunder a suitable potential. The synthesized silica film was composed of mesoporechannels that are oriented perpendicular to the electrode surface. If PdCl2solution wasadded into the above precursor, the mesopore channels can be used as template for thegrowth of Pd nanorod array. The structure of the film was characterized by scanningelectron microscopy （SEM）. The electrocatalytic activity of the thin film wasinvestigated for the detection of different important compounds, such as glucose,dopamine （DA） and uric acid （UA）. Experimental results demonstrated that themodified electrode can achieve non-enzymatic detection of glucose, as well as thesimultaneously detection of DA and UA in the mixture that contains ascorbic acid（AA）, UA and DA.