Application Of MOFs Synthesized By Ionothermal Method In Electrochemical Sensing

The sensors,as modern detection device,are widely applied in social production and life,and can capture the information in surroundings,and then convert the form of information captured according to the predetermined rule.At present,electrical signal is the most common form of conversion.Therefore,electrochemical sensors detected electrical signals have been widely studied.They are simple to operate,easy to carry,low in cost,and have good sensitivity.Due to these advantages,electrochemical sensors are widely applied in significant areas such as public health and food safety,environmental monitoring and early disease diagnosis.Metal-organic frameworks(MOFs)are widely used in catalysis,sensing,gas adsorption and separation fields,which can attributed to its adjustable pore size,unsaturated metal sites,larger specific surface area(up to several thousand m2·g-1)and ordered lattice structure.At present,the research generally focuses on the application of MOFs-derived materials,which originated from the poor conductivity of MOFs materials.Ionic liquids(IL)have been widely used in MOFs synthesis and electrochemistry due to their low vapor pressure,excellent solubility,high ionic conductivity and remarkable designability.In this paper,the ionic liquid is loaded into the cavity of MOFs by ionothermal synthesis,which improves the electrochemical response performance of MOFs.As mentioned above,ionic liquid supported Ni-MOF and Co-MOF modified electrodes were prepared in this paper,which can realize the sensitive detection of dopamine and glucose,respectively.The main research content and experimental results of this article are as follows:(1)Electrochemical sensing of dopamine using an ionic liquid supported Ni-based metal-organic frameworkA nickel-based metal-organic framework(Ni-MOF)supported with ionic liquids was synthesized by ionothermal reaction,which was used for the electrochemical dopamine detection.The microscopic surface morphology of the Ni-MOF were characterized by scanning electron microscope(SEM).Meanwhile,the structure and composition of Ni-MOF were explored by X-ray diffraction(XRD),thermogravimetric analysis(TGA)and attenuated total reflection Fourier transform infrared spectroscopy(ATR-FTIR).Electrochemical responses of the Ni-MOF modified electrode toward dopamine were performed by using differential pulse voltammetry(DPV).The electrochemical sensing performance of the Ni-MOF modified electrode toward dopamine was improved by the introduction of ionic liquid.Ni-MOF modified electrode had a wide linear range(0.2-100 μmol·L-1)and a low detection limit(60 nmol·L-1).Further studies indicated that the modified electrode exhibited significant electrocatalytic performance and great selectivity to dopamine in complex mixtures,and the Ni-MOF modified electrode also had excellent stability and reproducibility.Moreover,the analysis of real samples confirmed that the modified electrode had a certain reliability.(2)Ionic liquid supported cobalt-based metal-organic framework as a non-enzymatic electrochemical glucose sensorCobalt-based metal-organic framework(Co-MOF)and MOF-derived cobalt hydroxide(Co(OH)2)were successfully prepared by ionothermal reaction and one-pot conversion methods,respectively.Due to the introduction of ionic liquid,the Co-MOF/GCE modified electrode enhances the conductivity of the electrode-solution interface,which improves the electrocatalytic performance of glucose.The morphologies and structural compositions were characterized by SEM,XRD,TGA and ATR-FTIR.Compared with the Co(OH)2,the Co-MOF displayed higher electrochemical sensing performance toward glucose via cyclic voltammetry(CV)and amperometry(i-t)investigations.The detection range of the Co-MOF modified electrode for glucose is 5-900 μmol·L-1,and the detection limit is 1.6 μmol·L-1(S/N=3).The electrochemical glucose sensor also exhibited excellent stability,reproducibility and better selectivity.Furthermore,the modified electrode can achieve detection of glucose in urine sample.The ionic liquids supported MOFs probably are capable of overcoming the disadvantage of the traditional MOFs,and can provide a direction for the bioactive molecules determination.