Preparation Of Several Metal Organic Frameworks Composites And Their Application In Electrochemical Sensors

Metal-organic frameworks(MOFs)are a class of highly ordered porous crystalline material consisting of metal ions(or metal clusters)and organic ligands by coordination bond linkage.Diverse structures,high porosity and large surface area make MOFs have many important potential applications for preparing chemical modified electrode.However,to use MOFs directly as electrode modified materials is still very difficult due to their poor electric conductivity.The thesis proposed an efficient strategy for improving the sensitivity and selectivity of the resulted modified electrode in which MOFs were combined with some nanoscale carbon materials or metal nanoparticles with high conductivity and excellent electrocatalytic activities.And as a result,some noval electrochemical sensors based on nickel and copper MOFs composites were successfully prepared and applied in assays of some medicine and environmental small molecules.The main contents of this thesis include the following four aspects:1.A novel selective electrochemical toward acetaminophen(ACOP)and dopamine(DA)was prepared by using copper porphyrin metal organic frameworks(CuP-MOF)and Au@Ag core-shell nanoparticles decorated multi walled carbon nanotubes(MWCNT)as modified materials.Due to a synergistic effect of high surface area of CuP-MOF(400.54 m2·g-1)and excellent conductivity and electrocatalytic performance of MWCNT-Au@Ag nanocomposites,this obtained sensor CuP-MOF/MWCNT-Au@Ag/GCE showed a remarkable performance for the electrocatalytic detection ACOP and DA.Low detection limits of 0.23 and 0.082 ?M for ACOP and DA,wide linear ranges and excellent interference tolerance were delivered by DPV.The developed procedure was successfully used simultaneously and rapidly to determine ACOP and DA contents in acepaminophen tablet,human urine and serum samples.2.A novel electrochemical sensors based on gold nanoparticles(Au),metal-organic framework with amino groups(NH2-Cu3(btc)2)and reduced graphene oxide(RGO)composites were successfully prepared for determination of acetaminophen(ACOP)and p-aminophenol(4-AP).The developed method with a high sensitivity,good selectivity and wide linearity can be used to deterimine rapidly the target molecules in acetaminophen tablet and Yellow water.The results showed that the sensitive current reponse resulted from high adsorption capacity of the MOFs and good conductivity of RGO,while the specific recognition resulted from hydrogen bond interaction between the amino group of the MOF framework and the target molecules.3.A novel and rapid electrochemical sensor for the simultaneous determination of dopamine(DA),uric acid(UA)and L-tryptophan(L-Trp)was fabricated based on modification of bare glassy carbon electrode with Ni-ZIF-8/N S-CNTs/CS composite.The electrochemical results illustrated that these three analytes displayed the well-resolved and intense electrochemical signals on the designed electrode,owing to the synergic effect of Ni-ZIF-8 with highly porous framework structure and N S-CNTs with excellent conductivity and their outstanding electrocatalytic acitivty.The obtained sensor demonstrated wide linear ranges of 8-500 ?M,1-600 ?M and 5-850 ?Mand low detection limits of 0.93,0.41 and 0.69 ?M,respectively,for DA,UA and L-Trp could be employed to determine the analytes in the real samples.4,With nickel ion-terephthalic acid frameworks as basic raw material,by composition with palladium nanoparticles-supported reduced graphene oxide,a novel nickel-bas ed metal-organic framework/palladium-reduced graphene oxide(NiTPA-MOF/Pd-RGO)nanocomposite electrochemical sensing platform was constructed.The sensor showed sensitive and independent current responses toward hydroquinone(HQ)and catechol(CC)and could be exploited for individual or simultaneous determination of the targets.The corresponding dynamic ranges and detection limits were 0.8?260 ?M,0.096?M for HQ and 2?280 ?M,0.66 ?M for CC.The proposed method has been successfully used to measure the analytes in commercially available whitening cream,Yellow river water,and tap water with satisfied recovery results.