Preparation Of Copper-containing Nanostructured Electrode Materials And Their Non-enzymatic Glucose Sensing Performances

Blood glucose concentration is an important indicator of human physiological status.Blood glucose detection plays a key role in the monitoring and treatment of diabetes and some metabolic disorders.In view of the shortcomings of traditional enzyme electrochemical glucose sensors,the non-enzymatic electrochemical glucose sensing has become the research hotspot and frontier in the field of biosensors.On the basis of ensuring appropriate detection limit and sensitivity,the non-enzymatic electrochemical glucose sensor with a wide linear response range and high selectivity（anti-interference ability）would have much more practical value for blood glucose detection.Copper-containing materials with high catalytic activity and good stability show promising application in non-enzymatic glucose sensors,but linear response range and anti-interference ability still need to be further improved.Glucose sensing performances of copper-containing electrode materials are optimized through the synthesis of hierarchical nanomaterials and the combination with high catalytic activity materials.The main contents and results of this thesis are as follows:（1）Conductive CC was used as substrate;Copper nitrate trihydrate,sodium hydroxide and sodium dodecyl sulfate were raw materials;Hydrothermal method was performed at 120℃ for 6 h to grow hierarchically porous Cu O particles on the surface of carbon cloth.Spindle-like Cu O particles were formed by oriented aggregation of single crystals.With the use of surfactant,Cu O grains were in a relatively stable dispersion state.The prepared spindle Cu O particle/CC electrode material could be directly used for glucose detection.The linear range,sensitivity and detection limit were 0.05～3.70 m M,794μA m M^-1 cm^-2 and 10.1μM（S/N=3）,respectively.At the potential of 0.55 V,with existence of interferents,the current response after final addition of glucose still retained 92.0%of current response upon first addition,indicating anti-interference ability of spindle Cu O particle/CC electrode material.（2）Cu O particles/Ni（OH）₂ nanosheets/CC composite electrode materials were prepared with solvothermal method in methanol solution containing Ni（NO₃）₂·6H₂O and Cu（NO₃）₂·3H₂O at 180℃ for 6 h.Hexagonal Ni（OH）₂ nanosheets with smooth surface and interconnect structure were uniformly grown on the surface of CC substrate.Monoclinic Cu O particles were randomly decorated on the surface of Ni（OH）₂ nanosheets.The composite structure not only offered abundant active sites for glucose oxidation,but also provided porous channels for electrolyte ion diffusion and ensuring the sufficient contact between active materials and electrolyte.Cu O/Ni（OH）₂/CC showed better glucose sensing performance than that of Ni（OH）₂/CC and Cu O/CC.The sensitivity,linear response ranges and detection limit of Cu O/Ni（OH）₂/CC were 602μA m M^-1 cm^-2,0.05～8.0 m M and 25.6 mΜ（S/N=3）,respectively.At the potential of 0.55 V,with the existence of interfering species,the current response after final addition of glucose still retained 91.7%of current response upon first addition,indicating anti-interference ability of Cu O/Ni（OH）₂/CC.（3）Bimetallic Cu/Co-ZIF nanosheet array electrode material was prepared by solution method at room temperature with the use of copper nitrate trihydrate,cobalt nitrate hexahydrate and 2-methylimidazole.Cu/Co-ZIF remained original topology structure of ZIF-L.With the addition of Cu²⁺ions,local structure disorder was observed,leading to the decrease of nanoflake thickness of Cu/Co-ZIF.When Cu²⁺concentration increased to 30 m M,nanosheet arrays were collapsed.Compared with Co-ZIF,Cu/Co-ZIF-20 electrode material had large electrochemical active surface area and bimetallic active sites.Its sensitivity,linear response range and detection limit were 1030μA m M^-1 cm^-2,0.05～6.0 m M and 41.2μM（S/N=3）,respectively.Under the potential of 0.55 V,with the existence of interfering species,the current response after final addition of glucose was highly closed to the current response upon first addition,indicating good selectivity of Cu/Co-ZIF-20 electrode material.Higher working potential of 0.65 V caused the adhesion of bubbles on the surface of working electrode,the falling off of active materials and enhanced current response from interferents,which led to low current response towards glucose and poor anti-interference ability.（4）Cu_0.3Co_2.7O₄ nanosheets were obtained by pyrolysis of Cu/Co-ZIF-20 at 300℃ and 400℃.Compared with surface morphology of sample pyrolyzed at 300℃,the Cu_0.3Co_2.7O₄ nanosheets of sample pyrolyzed at 400℃ showed relatively loose distribution.In comparision with the sensitivity of Cu/Co-ZIF-20(1030μA m M^-1cm^-2),the samples pyrolyzed at 300℃ and 400℃ had lower sensitivity with 669μA m M^-1 cm^-2 and 538μA m M^-1 cm^-2,respectively.For Cu/Co-ZIF-20,thick nanosheets with interconnected structure densely grew on the surface of substrate.After pyrolysis,thin Cu_0.3Co_2.7O₄ nanosheets showed loose growth.Although Cu_0.3Co_2.7O₄showed high conductivity,low loading of active materials led to the reduction of active sites and thus the decrease of sensitivity.In order to improve loading of Cu_0.3Co_2.7O₄,the"growth-pyrolysis cycle process"was adopted.Namely,Cu/Co-ZIF was grown again on the surface of Cu_0.3Co_2.7O₄ nanosheets and then pyrolyzed under the same heat-tretament regime.Scanning electron microscopy images confirmed that secondary Cu_0.3Co_2.7O₄nanosheets were on the suface of first-growth Cu_0.3Co_2.7O₄.Fourier transform infrared spectra indicated the existence of Cu/Co-ZIF.The sample prepared by secondary growth for 30 min had better glucose sensing performance.Its sensitivity,linear response range and detection limit were 931μA m M^-1 cm^-2,0.05～7.0 m M and20.2μM（S/N=3）,respectively.Compared with the single growth material,the performance of secondary growth sample was improved.At the potential of 0.55 V,with existence of interfering species,the current response after final addition of glucose still retained 95.8%of current response upon first addition,indicating good selectivity.