Electrochemical Sensors Based On HKUST-1、Nickel-2-Methylimidazole Metal-Organic Frameworks-derived Materials

Metal-organic frameworks（MOFs）are a type of novel three dimensional（3D）porous materials with ultrahigh specific surface area,abundant metal sites,high porosity,etc.In this paper,we has synthesized HKUST-1,SGO@HKUST-1 and Ni₃C/Ni nanocomposite which based on nickel-2-methylimidazole MOFs as a precursor.Three kinds of novel electrochemical sensor were constructed by modifiction the materials on the surface of glassy carbon electrode（GCE）,and used for the detection of dihydroxybenzene isomers,hydrogen peroxide（H₂O₂）and glucose.The main contents are as follows:（1）The metal-organic framework（MOF）of HKUST-1 was covalently immobilized at chitosan（CS）-electrochemically reduced graphene oxide（ERGO）modified electrode,which was characterized by scanning electron microscope（SEM）,energy-dispersive X-ray spectra（EDS）,and electrochemistry.The MOF-based electrode was applied as an electrochemical sensing platform for the detection of dihydroxybenzene isomers（DBIs）of catechol（CT）,resorcinol（RS）and hydroquinone（HQ）.The results showed that the DBIs presented well-resolved and intense voltammetric signals at the modified electrode,due to the synergic effect contributing from HKUST-1 with unique porous framework structure and ERGO with high electronic conductivity.Quantitative analysis assays by differential pulse voltammetry showed that the sensor had wide linear ranges,and low detection limits of 0.44 μM for HQ,0.41 μM for CT and 0.33 μM for RS.The developed sensor was also applied for the determination of DBIs in the real water sample and the recoveries were in range of 98.0% to101.4%.（2）A novel metal-organic framework（MOF）-based electroactive nanocomposite containing graphene and HKUST-1 was synthesized through a facile solvothermal method using graphene oxide（GO）,benzene-1,3,5-tricarboxylic acid（BTC）,and copper nitrate（Cu（NO3）2）as the raw materials.The morphology and structure of materials were characterized by scanning electron microscope（SEM）,transmission electron microscopy（TEM）,X-ray diffraction（XRD）,Raman,fourier transform infrared（FT-IR）and Brunauer-Emmett-Teller（BET）,etc.The results showed that the GO could induce thetransformation of octahedral HKUST-1 to the three-dimensional hierarchical flower shape as a structure-directing agent,and meanwhile the GO itself was torn into the small fragments and embedded into the sheets of the HKUST-1 as the reduction form.Electrochemical assays showed that,due to the synergy of reduced GO and HKUST-1,the nanocomposite exhibited a higher electrocatalysis toward the reduction of hydrogen peroxide（H₂O₂）than the counterpart of HKUST-1.Under optimized conditions,the linear range was from 1 μM to 855 μM and a low detection limit of 0.49 μM.Also,the sensor was applied to determine the H₂O₂ in the human serum and living cells for real-time release.（3）In this paper,the one-dimensional chain Ni₃C/Ni nanocomposite was synthesized with a metal-organic frameworks as a precursor.The morphology and structure of materials were characterized by scanning electron microscope（SEM）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,etc.The results showed that 2-methylimidazole can effectively induce the formation of a one-dimensional chain structure.Then the hybrid material of Ni₃C/Ni and chitosan（CS）was cast on the glassy carbon electrode（GCE）to get a modified electrode（Ni₃C/Ni-CS/GCE）.Cyclic voltammetric method were used to investigate the catalytic properties of the assembled sensor.As the results,the Ni₃C/Ni-CS/GCE had a pair of well-defined redox peaks in Na OH solution and exhibited a high-performance electrocatalysis toward the oxidation of glucose.Under optimized conditions,the enzyme-less sensor exhibited excellent performance for glucose analysis selectively,offering a wider linear range（from 1.0 μM to 6.5 m M）,an low detection limit（0.68 μM）.Meanwhile,the sensing platform shows a perfect stability,reproducibility and selectivity.