Preparation And Sensing Properties Of Boron And Nitrogen Doped Carbon Loaded Metal Composites

Metal nanoparticles（MNPs）are widely used in catalytic reactions due to their unique properties.But in practical applications,nanoparticles often aggregate and migrate due to high surface energy,resulting in reduced catalytic efficiency.As a biocompatible metal nanoparticle carrier,carbon nanomaterials are characterized by abundant pore structure,excellent stability and easy surface modification.The purpose of using heteroatom-doped carbon material as the carrier of metal nanoparticles is to increase the metal anchoring site and improve the catalytic properties,stability and bio-compatibility of the composite materials by utilizing the synergistic effect between nanoparticles and carbon materials.Based on this,this experiment prepared a series of heteratomic-doped carbon material loaded metal nanoparticle composite materials through simple synthesis methods such as layer self-assembly and high-temperature calcination.Combined with a variety of characterization methods and electrochemical testing methods,the physical and chemical characterization and testing of the prepared composite materials were conducted.The effect of the microstructure of composite materials on the properties of catalyst under different preparation methods was investigated.At the same time,a series of sensing platforms were constructed using composite materials as probe elements to detect biological small molecules.Specific work contents are as follows:1.Based on the structure of iron nanoparticles wrapped in boron and nitrogen co-doped carbon nanotubes,a series of Fe/BNC composites were designed and prepared.The experimental results showed that Fe/BNC synthesized at 900℃,pyrolysis time of 6h and dosage of 0.015 g of Fe（acac）₃ had better catalytic performance and stability.A novel electrochemical sensor was constructed using Fe/BNC as sensing element for the detection of dopamine（DA）and uric acid（UA）in biological samples.Under optimized conditions,when the concentration of DA was in the range of 1-630μM,and the concentration of UA was in the range of 0.5-2065μM,the oxidation peak current of both showed a good linear relationship with the concentration,and the detection limits（LOD）were 0.80μM and 0.28μM,respectively.The sensor showed good selective response to DA and UA in the presence of other biological small molecules and inorganic metal ions.Finally,the prepared Fe/BNC sensor had been successfully applied to the detection of DA and UA in human serum samples with satisfactory results.2.Based on the experiments in the previous chapter,we found that Fe/BNC had oxidase-like activity under acidic conditions,which could catalyze O₂ to produce reactive oxygen species（ROS）to oxidize color developing substrate TMB.According to ROS radical scavenging experiments,superoxide radical（O₂·^-）was the main product produced during the reaction to promote the oxidation of TMB.Based on the fact that glutathione（GSH）can inhibit the oxidation of TMB,we designed a colorimetric biosensor based on TMB-Fe/BNC color development system for the detection of GSH.When the concentration of GSH was in the range of 1-80μM,the absorbance difference of the color developing system had a good linear relationship with the concentration of GSH,and the detection limit was 0.50μM.The experimental method had been successfully applied to the selective detection of target objects in actual samples of human serum.3.Combined with the excellent electrocatalytic performance of Pt NPs and stable carbon structure derived from ZIF-8,a nitrogen-doped carbon-supported platinum nanoparticle catalyst（Pt/N-C）was prepared.Then,an efficient and sensitive caffeine（CAF）electrochemical biosensor was constructed on this basis.The electrochemical activity of Pt/N-C composite nanomaterials and the sensing performance of the sensor were studied by electrochemical technique.When the CAF concentration was in the range of 0.5-532.5μM,the oxidation peak current showed a good linear relationship with the CAF concentration,and the LOD was 0.16μM.Pt/N-C had excellent ability to selectively detect CAF in complex systems,and the constructed electrochemical sensor had been successfully used to quantitatively detect caffeine content in commercially available coffee and green tea drinks.