Construction And Application Of MOF And Its Derivative Composite Film Phenolic Electrochemical Sensors

As a persistent organic pollutant in the environment,naphthol is a serious threat to marine ecology and human health.So it is an urgent requirement to simultaneously detectα-naphthol(1-NAP)and β-naphthol(2-NAP)isomers,which will make contributions to both the public safety and the environment management in China.Electrochemical sensing has been widely used in the detection of phenolic compounds due to its advantages of high sensitivity,fast and simple,real-time detection.However,by designing and synthesizing nanocomposite materials to prepare modified electrode,the enrichment ability of naphthol on the surface of modified electrode can be enhanced and its electrocatalytic performance on substrate can be improved.Therefore,it is still a great challenge to establish a highly sensitive,highly selective and highly stable electrochemical analysis method for naphthol.Based on this,this paper synthesized three kinds of nanocomposite based on MOF structure,and nanocomposite film modified electrode,then studied the electrochemical behavior of naphthol compound,established the corresponding electrochemical analysis method,and carried out the determination of naphthol in real samples.The main contents are as follows:1)The 2D MOF compound was used as the precursor,and the cobalt carbon porous nano complex was obtained after calcining at high temperature,denoted as Co/NC.The Co/NC/GCE modified electrode was prepared by the modification of Co/NC nanocomposite on the surface of glassy carbon electrode through drop coating method.The electrochemical behavior of 2-NAP modified electrode was characterized by cyclic voltammetry(CV)and electrochemical impendance spectroscopy(EIS).The results show that the N-doped porous carbon structure doped with Co nanoparticles has good conductivity and large electroactive area,which improves the catalytic performance of2-NAP.It is a typical diffusion control process on Co/NC/GCE surfaces.Differential pulse voltammetry(DPV)was used to quantitatively analyze 2-NAP under optimal experimental conditions.The sensor showed good selectivity and reproducibility,and presented a good linear relationship with the oxidation peak current within the concentration range of 0.08 μmol/L~5.5 μmol/L,and the detection limit was 1.13 nmol/L(S/N=3).Satisfactory results were obtained by the determination of 2-NAP in real samples.2)The cobalt-aluminum hydrotalcite nanocrystals were stripped in formamide to form ultrathin nanocrystals on which ZIF-67 was grown in situ.The cobalt-aluminum hydrotalcite nanocrystals@ZIF-67 complex(Co-Al ELDH@ZIF-67)was prepared.The X-ray powder diffraction(XRD)and scanning electron microscopy(SEM)results showed that most of the ELDH in the complex had been transformed into ZIF-67.The electrochemical behavior of 1-NAP and 2-NAP is studied by the corresponding Co-Al ELDH@ZIF-67 modified glassy carbon electrode.Aggregation of ELDH was inhibited due to the ZIF-67 composite membrane in situ growth in ultra-thin ELDH surface,and The synergistic effect of them can improve the electrode surface area,increased the electrochemical active sites,realized the high sensitivity and selectivity detection of naphthol isomers at the same time,the linear detection range was 0.3 μmol/L~150μmol/L,the detection limit of 1-NAP and 2-NAP were 62 nmol/L and 94 nmol/L.The modified electrode is simple to prepare,the detection method has good stability and high sensitivity,and has been successfully applied to the simultaneous detection of two isomers in real water samples.3)The 2-methylimidazole solution was added into the reaction tube containing the agar-gel matrix of graphene oxide.The GO@ZIF-8 nanocomposite was prepared by natural diffusion and penetration.The sample was divided into three layers according to the diffusion depth.The SEM and XRD results show that ZIF-8 crystals grow uniformly on the GO surface,with large specific surface area and high electrochemical properties.The GO@ZIF-8/GCE was prepared with the drop coating method and the electrochemical behavior of 1-NAP and 2-NAP on different electrodes was studied.The results showed that the electrochemical catalytic performance of the intermediate RGO@ZIF-8 modified electrode was the best.DPV was used for quantitative analysis of naphthol isomers,and the electrochemical sensor constructed showed a wide linear range(8 nmol/L~100 nmol/L)for naphthol isomers,in which the detection limit of 1-NAP was2.7 nmol/L and the detection limit of 2-NAP was 2.6 nmol/L.This method has shown good stability,high sensitivity and anti-interference performance,and achieved good results for the simultaneous detection of isomers in real water samples.