Electrochemical Sensing Application Based On Metal-Modified Covalent Organic Framework Composite

Covalent organic frameworks(COF)are a new type of porous polymer composed of organic molecules with periodic columnar ?-array structures,which provide a powerful platform for the construction of ordered ?-systems.COF can be synthesized by various methods,such as solvothermal synthesis,microwave-assisted synthesis,steam-assisted transformation,and sonochemical synthesis.COF have a series of excellent advantages,including low density,high crystallinity,high specific surface area,abundant functional groups,and tunable pore size.These benefits make COF a promising platform for catalysis,gas storage,sensing,and biomedicine.However,the poor conductivity of COF limits some applications on electrochemical sensors.To address this problem,COF are often combined with other materials with good electrical conductivity,including carbon materials,boron-doped diamond,polymers,metal nanoparticles,and metal oxides.Thereinto,metal nanoparticles are widely used in the field of electrochemical sensing due to their excellent catalytic and conductive properties.In this paper,we synthesized COF and post-modified the COF with metal nanoparticles,and the resulting composites exhibited excellent catalytic performance and electrical conductivity.Electrochemical sensors based on synthetic materials have excellent detection performance for specific analytes and can be used for practical sample detection.The actual work is as follows:Part one,A sensitive electrochemical platform based on bimetallic-modified covalent organic framework for levodopa detectionIn this work,a novel high electrocatalytic material was synthesized by incorporating bimetallic nanoparticles(AgCoNPs)in a two-dimensional porous TAPB-DMTP-COF.Subsequently,the resulting composite was applied to construct an electrochemical sensor for the ultrasensitive determination of levodopa.The analytical performance has been improved significantly due to the synergistic effect of both TAPB-DMTP-COF and AgCoNPs by increasing effective electroactive surface area and electron transfer efficiency.The linear detection range of the levodopa sensor was 0.010-100 ?mol/L.The limit of detection was found to be 0.002 ?mol/L.Moreover,the sensor exhibits an excellent stability and maintains its catalytic activity after 100 scanning rounds.Finally,the applicability of the electrochemical sensor was successfully applied for the determination of levodopa content in human urine and blood serum samples.Our study not only supplies a useful tool to accurately detect levodopa in actual samples and,meanwhile,but paves a feasible way to unlock high performance two-dimensiona COF based electrode materials.Part two,An effective electrochemical sensor based on FeNi@TAPB-DMTP-COF for detection of gallic acidThe potential applications of covalent organic frameworks can be further developed by encapsulating functional nanoparticles within covalent organic frameworks.However,the synthesis of monodisperse core@shell structured COF nanocomposites without agglomeration remains a major challenge.Here,we propose a general synthetic strategy,namely,to grow the COF shell on pre-synthesized functional nanoparticles,to prepare FeNi@TAPB-DMTP-COF.The synthetic material was expressed by X-ray diffraction,Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy,and high-resolution transmission electron microscopy.Among them,FeNi nanoparticles with remarkable conductivity can accelerate the charge transfer,while the TAPB-DMTP-COF shell with larger specific surface area can improve the stability of the prepared electrochemical sensor.With this design,the sensor based on FeNi@TAPB-DMTP-COF has good analytical performance for gallic acid(GA),with a wider linear detection range and a lower detection limit than other materials.Furthermore,the FeNi@TAPB-DMTP-COF-based sensor has been applied to the detection of GA in real water samples with satisfactory results,indicating a promising prospect in sensing applications.Part thrzee,Metalloporphyrin-based covalent organic framework for as reliable platform for electrochemical determination of butylated hydroxyanisoleCOF is promising crystalline porous organic materials due to their structural versatility and high stability.Herein,we report the designed synthesis of three isostructural metalloporphyrin 2D covalent organic frameworks(MPor-COF-366,M=Fe,Mn,Cu,),and it has been used for the trace detection of 3-tert-butyl-4-hydroxyanisole(BHA).These experimental results show that the MPor-COF-366 composite has higher electrocatalytic activity than pure Por-COF-366,which is due to the higher specific surface area of MPor-COF-366 and the combination of metalloporphyrin and C@N groups.In this work,FePor-COF-366/GCE show the best detection performance for BHA,with the lowest detection limit of 0.006?mol/L and the widest linear range of 0.04-1000?mol/L.