Preparation Of Nano Oxide Semiconductor Electrode Materials And Its Electrochemical Biosensing Applications

Along with the growing demand of real time, fast and on-site detection of glucose andhydrogen peroxide, high sensitivity, low detection limit, good stability and anti-interference isproposed to biosensor fabrication. The new and high requirement of biosensing push people tosearch new electrode modified materials. Thence, researches put their eyes into the entirely newarea of nanotechnology, the fast development of nanotechnology provided a broad road todevelop electrochemical biosensor. For the metal oxide nanomaterials, because of its superiorelectric, optic and photoelectric properties, holds a promise application in the electrochemicalbiosensors. Three-dimensional porous electrode could provide suitable environment toelectrochemical reaction, so it is believed that the three-dimensional porous electrode whichbased on metal oxide nanomaterials will plays important role in electrochemical biosensors.Electrospinning is effective means to construct three-dimensional network structure, while hotpress could solve the adherence problem between the nanofiber and the FTO glass. Combinedwith these two methods, three-dimensional porous structure which fulfills glucose and hydrogenperoxide detection demand was fabricated.Photoelectrochemistry is expected to have the advantages of both fluorescence andelectrochemical sensors, good light harvest, fast electron transfer and good biocompatibility arethe demand of the photoelectrode. One-dimensional nanostructure arrays with goodbiocompatibility fabricated on FTO glass would satisfy the demand, while, hydrothermal is agood choice to prepare one-dimensional nanostructure array on conductive substrate. The mainresearch results are as follows:â‘´WO₃,TiO₂,CuO and NiO/Co₃O₄single/composite nanofiber were prepared byelectrospinning, also ZnO/Co₃O₄heterojunction nanofiber with tubular structure is prepared,which has a200nm diameter and50nm tube thickness. The CuO/TiO₂hierarchicalnanocomposites was prepared by electrospinning for the first time, which is compose ofsingle-crystal CuO nanoplate and polycrystal TiO₂nanotube, then the pN heterojunction wasformed, it holds promise applications in photocatalysis, photoelectric application, gas sensing and biosensing;⑵Combine with the electrospinning and hot press process, three-dimensional porouselectrode based on CuO/TiO₂hierarchical nanocomposites was formed, which was used tononenzymatic biosensing of glucose. Profit from the advantage of CuO/TiO₂hierarchicalstructure and network structure of electrode, fast electron transfer and substrate diffusion ispromised, as a result, the electrode shows a high sensitivity of1321μA mM^-1cm^-2, a lowdetection limit of390nM, a fast response time fewer than5s, good stability and reproducibility;⑶Further research is processed with the thickness controllable CuO three-dimensionalporous electrode, which is applied to hydrogen peroxide nonenzymatic biosensing. We havestudied the electrochemical behaviors to hydrogen peroxide of the electrode in the phosphatebuffer solution (PBS) and NaOH solution comprehensively, and the electrode presentdiffusion-control mechanism in phosphate buffer solution, while surface-control in NaOH, also,their exhibit different advantage in different solution. In the phosphate buffer solution, theelectrode exhibits a high sensitivity of407.1μA mM^-1cm^-2, a fast response time fewer than5sand wider linear response range and good selectivity compare to the result in NaOH. In NaOH, ahigh sensitivity of385.4μA mM^-1cm^-2, a fast response time fewer than5s is achieved, and alow detection limit of399nM. As a result, different test requirement would fulfill through theselection of the solution used. The electrocatalysis comparison of the three-dimensional porouselectrode made of nanofibers and particles was proposed, and the three-dimensional electrodemade by nanofibers shows higher sensitivity and wider linear range, we ascribed the betterperformance to the better electron transfer in one-dimensional structure and better substratediffusion in the network structure made by electrospinning;â‘·Fe₂O₃nanorod array was prepared by hydrothermal on FTO conductive glass, theelectrocatalysis properties towards hydrogen peroxide was tested and the photoelectric effect onthe hydrogen peroxide electrochemical detection was studied. The result shows that theelectrocatalysis of hydrogen peroxide is notable improve under illumination in NaOH solution,especially, reduction current change to oxidation current after illumination, but the enhancementeffect just find in oxidation current in PBS. Then, take photocurrent response and glucosecatalysis into consideration, the Fe₂O₃nanorod array electrode was applied to constructphotoelectrochemical biosensor, and the prepared electrode presents a stable and fast photocurrent response, then the glucose photoelectrochemical biosensing is achieved.