| Electrochemical sensors are used in the analysis and detection of food,environment,and clinic because of their simplicity,reproducibility,selectivity,and high sensitivity.With the continuous application of nanomaterials,nanomaterials have gradually been applied to electrochemical sensors and become a research hotspot.The content of transition metal oxides in the earth's crust is relatively abundant,the preparation of its nanomaterials is simple,its material properties are excellent,and it has high electrochemical catalytic activity.There are many types of noble metal and alloy nanomaterials with good conductivity.Among them,noble metals and alloy nanocrystals with polycrystal faces have a large specific surface area,and their properties can be controlled by controlling the size.However,the transition metal oxide nano-materials have relatively weak conductivity,and the noble metal and alloy nano-crystal properties are easily affected by the surfactant in the preparation method,which greatly limits its application in electrochemical sensors.The composite material is composed of multi-component materials,and its catalytic performance,electronic properties and optical properties are better than those of single-component nanomaterials.In this paper,three kinds of metal/transition metal oxide nanocomposites were designed and synthesized by seed method,hydrothermal method and in-situ precipitation method,in which noble metal and alloy nanocrystals or core-shell materials are used as carriers of transition metal oxides.The synthesized nanocomposites can not only enhance the conductivity of transition metal oxides,but also improve the performance of noble metals and alloys.Their electrochemical properties were studied and made it modified glassy carbon electrode to construction enzymeless sensors for the detection of glucose and dopamine.The specific research content is as follows:1.Non-enzymatic glucose sensor based on icosahedral AuPd@CuO core-shell nanoparticles and multi-walled carbon nanotubesAuPd@CuO core-shell nanoparticles were prepared by in situ precipitation method using an icosahedral AuPd bimetallic alloy synthesized by the seed method as a method to coat the CuO nanoparticles with smaller particles.In order to enhance the conductivity of the material and the specific surface area of the active component,multi-walled carbon nanotubes have also been introduced as substrates for AuPd@CuO core-shell nanoparticles.The prepared AuPd@CuO/MWCNT composite was modified on GCE for glucose content detection.Due to the good conductivity and high specific surface area of the icosahedral AuPd bimetallic alloys and multi-walled carbon nanotubes,the electrochemical signal was significantly amplified and the response time was less than 5 s.Enzyme-free detection of glucose was successfully performed.In the range of 0.03 to 9.31 mmol·L-1,the current value of the sensor showed a good linear relationship with the glucose concentration,and the detection limit of 0.10?mol·L-1 was obtained.The sensitivity was 744.98?A·m mo l-1·L-2·cm-2,and the stability and selectivity were good.2.Non-enzyme glucose sensor based on gold nanorods-CuO film nanocompositesThe Au NRs with an aspect ratio of 3 were synthesized by seeding method.Au NRs-CuO NPs were successfully prepared by CuO nanoparticle encapsulation onto Au NRs with Au NRs as the substrate.Composite material.The high specific surface area,good conductivity of Au NRs and the catalytic activity of copper oxide combine to reduce the response time,allowing rapid detection of glucose.In the range of 0.01 mmol·L-to 3.5 mmol·L-,the current value of the sensor showed a good linear relationship with the glucose concentration,and a detection limit of 2.57?mol·L-was obtained with a sensitivity of 1619.7?A·mmol-1·L-2·cm-2.The sensor manufacturing method is simple,has good stability and strong anti-interference ability.3.Based on multi-level structure of Au@NiO@CuO nanocomposites to build dopamine biosensorsAu@C NPs were synthesized by hydrothermal method.Au@NiO NPs were synthesized by calcination on Au@C NPs,and then Au@NiO@CuO NPs were synthesized by in-situ precipitation method using Au@NiO NPs.Due to the large surface area of Au@NiO NPs and the good conductivity of Au NPs,the immobilized loading of copper oxide on the electrode was increased,ie,the active sites on the surface were increased,so that the catalytic effect on dopamine was enhanced and dopamine was realized.Sensitive detection.In addition Nafion membrane gives the sensor a good stability and anti-jamming capability.The experimental results show that in the range of 5?mol·L-320?mol·L-,the sensor has a good linear relationship with dopamine concentration,and the detection limit is as low as 0.40?mol·L-. |
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