Preparation Of Metal Organic Frameworks Modified Electrode And Its Electrochemical Sensing Performance

The metal organic frameworks have unique electronic structures to improve its selectivity and electrochemical response in electrochemical detection,but the insulation of MOFs hinders the development and progress of this field.Thus,how to improve the conductivity of MOFs with redox activity for use in electrochemical sensors is attracting the attention of researchers.In this thesis,the conductivity and redox activity of MOFs by improving different strategies as a chemically modified electrode material and then the electrocatalytic activity of the modified electrode was investigated.The results are as follows:（1）A facile electrochemical plating strategy has been employed to prepare the electroactive metal-organic framework film（NENU-3）onto a copper electrode.The as-made NENU-3 films have been characterized using powder XRD,SEM,FT-IR and TGA.These analyses indicate that NENU-3 films have high phase purity and high stability.Further,different electrochemical techniques are utilized for measuring the electrochemical behaviors of the NENU-3 film electrodes.Accordingly,the kinetic parameters for NENU-3 film electrode towards electrocatalytic reduction of bromate are obtained,including the electron transfer coefficient（α）,the catalytic rate constant（k_s）,and the diffusion coefficient（D）.The film electrodes present excellent electrocatalytic ability for the bromate reduction,and can be used successfully for amperometric detection of bromate.Under the optimized conditions,the proposed sensor exhibits a wide linear range（0.05⁷2.74 mM）and a lower detection limit（12μM）measured by chronoamperometry.Moreover,the films possess high electrochemical stability and strong anti-interference capability in bromate detection process.It has been demonstrated that the electrochemical plating method reported here offers a reliable and effcient way to fabricate MOF films on conductive substrates for bromate detection.（2）A novel ZIF-Ni composite film has been successfully prepared by a facile method involving the in-situ deposition of ZIF-8 on a nickel porous film.Cyclic voltammetric and amperometric studies show the enhanced electrocatalytic properties for the ZIF-Ni composite film electrodes toward hydrazine oxidation relative to the synergistic effect of ZIF-8 and porous Ni films.Additionally,a high sensitivity of 805.5μA mM^-1 for hydrazine detection with a low detection limit of 0.021μM（S/N=3）and a wide linear range from 2.5μM to 28 m M are revealed for this new type of the composite film as the detecting electrode.Moreover,the composite films exhibit excellent selectivity and remarkable stability for the oxidation of hydrazine.This can take new opportunities for fast and selective detection of hydrazine and provide a promising platform for sensor designs for hydrazine detection.（3）The nature of the host and guest of the metal organic frameworks could be controlled and modified by embedding the guest species in the cavity.The MOFs are used for supporting the electrocatalytic guest molecules due to their high surface area,porosity and chemical stability to expand the materials in the application of electochemistiy analysis.Bismuth ion-loaded MIL-101（Cr）has been coated on the pre-treated carbon cloth as the working electrode,and Pb²⁺and Cd²⁺have detected by anodic stripping voltammetry.The Bi/MIL-101（Cr）has been characterized using powder XRD,SEM,EDS,FT-IR,XPS and ICP.These analyses indicate that bismuth ion has been loaded in the cavity of MIL-101（Cr）,and Bi/MIL-101（Cr）has been successfully coated on the carbon cloth electrode.The electrochemical techniques have been used to determine the looping of bismuth ion loaded in MOF,the enrichment time and potential,and the optimum pH.The Bi/MIL-101（Cr）/CC towards Pb²⁺and Cd²⁺detections has a broad linear range（0.1⁹0μg/L）,the high sensitivity,the low detection limits,and all with strong anti-interference ability.