| In recent years,biosensors have received great attention and achieved rapid development in the fields of life science,medical diagnosis,food safety,drug research and environmental protection.Both glucose and hydrogen peroxide are important small-molecule chemicals in human body which affect cell function and metabolism,so biosensors for detecting them are in high demand.Traditional enzymatic sensors have been widely developed due to their high sensitivity,but they have some inherent defects,such as complex preparation process and susceptible activity under environmental influences.Therefore,the development of non-enzymatic sensors with enzyme-like nano-catalysis materials replacing biological enzymes has become a research hotspot at home and abroad,but the existing non-enzymatic sensors still have problems such as low sensitivity and narrow linear detection range.In this thesis,two common metal oxide nanomaterials(NiO and Cu2O)were modified from the perspective of constructing hierarchical structures and optimizing energy band relationship.The TiO2@NiO core-shell nanostructures and Cu2O-BiOI composite materials were prepared.Electrochemical and photoelectrochemical non-enzymatic sensors were constructed based on these two materials respectively,and excellent non-enzymatic sensing performance was obtained.The specific work is as follows:(1)TiO2@NiO core-shell nanostructured composite electrodes with excellent glucose electrochemical sensing performance were designed and fabricated by wet chemical etching method.In this work,we innovatively used TiO2 with high electrochemical stability and high mechanical properties as a "protective cage" to encapsulate NiO with high electrochemical catalytic activity.This special nanostructure effectively combines their advantages,solves the problems of agglomeration and dissolution of NiO particles in the sensing process,and effectively improves the sensitivity and stability of the sensing electrode.The morphology,phase,and chemical composition of the composite electrode materials were analyzed by scanning electron microscopy(SEM),X-ray diffraction(XRD)and other characterization methods.Through comparative experiments,the deposition time of the electrode was optimized,and the TiO2@NiO composite electrode prepared with the optimal deposition parameters(3 min)was used for non-enzymatic glucose sensing.This electrode achieved a sensitivity of up to 918.4 ?AmM-1 cm-2,which provided a new thought for improving the electrochemical sensing performance of materials through structural design.(2)A novel isotype(p-p)heterojunction,on the basic of Cu2O coupled with BiOI,has been designed and synthesized via a facile two-step electro-deposition approach at room temperature.The morphology,phase compositions and chemical bonding state were verified by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction measurements(XRD)and X-ray photoelectron spectra(XPS).The optimized Cu2O-BiOI hybrid electrode exhibited boosted photoelectrochemical(PEC)H2O2 non-enzymatic sensing performance under visible light illumination,with a phenomenally broad linear range(1.99 ?M?17.54mM),a high sensitivity of 213.87 ?AmM-1 cm-2,as well as a low detection limit of 0.44 pM(S/N=3).Additionally,the sensor presented satisfying selectivity,repeatability,stability and its feasibility in real samples was corroborated.The photoelectrochemical sensing mechanism was clarified in the view of band structure and p-p heterojunction.Our work would enlighten the perspective research on the application of isotype heterojunction in PEC bio-sensing and provide a promising non-enzymatic biosensor platform for effective detection of H2O2 in food,biomedical and environment analysis. |
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