Study On Synthesis And Electrochemical Properties Of Nickel-based MOF Composite Materials

Metal-organic frameworks?MOF?compounds have been widely used in gas storage and separation,drug delivery,molecular recognition,sensors,imaging and other fields,owing to large specific surface area,adjustable pore size and ordered structure.In recent years,the research of MOF as electrochemically active electrode materials has attracted more attention.However,the applications of MOF in electrochemical energy storage are limited by the poor electrical conductivity.In order to improve the conductivity,the layered Ni-MOF,conductive polyaniline?PANI?and carbon cloth?CC?substrate were prepared by in-situ growth method.The capacitive properties of Ni-MOF were improved by synergistic effects with PANI.In addition,the nanocomposites prepared by using Ni-MOF as precursor showed excellent electrochemical performance.The composites were characterized by X-ray diffraction?XRD?,thermogravimetry analyzer?TGA?,ultraviolet-visible spectroscopy?UV-vis?,fourier transform infrared spectroscopy?FITR?,and scanning electron microscope?SEM?.The electrochemical performances were examined by four-probe resistance analyzer,galvanostatic charge-discharge machine and electrochemical workstation.The results were obtained as follows:?1?The layered Ni-MOF was prepared by a one-pot hydrothermal method,then Ni-MOF/PANI composite materials were prepared by an in-situ polymerization method.The composites not only retained the layered structure of Ni-MOF,but also realized the three dimensional crosslinking between Ni-MOF and PANI.With the increase of Ni-MOF content,the specific surface area of Ni-MOF/PANI composites gradually increased.The galvanostatic charge-discharge results showed that at 30%weight content in Ni-MOF/PANI,the composites showed the specific capacitance of 285.7 F/g,which was higher than that of pure PANI?248.5F/g?.Cyclic stability test showed that the specific capacitance loss of Ni-MOF/PANI composite was just about 13.8%after 2000 charge/discharge cycles.?2?Firstly different Ni-MOF@CC films were prepared by surface coating and in-situ hydrothermal methods,with carbon cloth?CC?as flexible conductive substrate.Then by in-situ polymerization,PANI was introduced to the surface and the interspace of layered Ni-MOF.The electrochemical properties of the prepared composite electrodes were much better than that of both pure Ni-MOF and pure PANI.Compared with Ni-MOF/CC prepared by surface coating method,Ni-MOF/CC prepared by in-situ hydrothermal method can induce the slow growth of Ni-MOF crystals on CC.Therefore,Ni-MOF was strongly attached on carbon cloth fibers to form flexible substrate.After in-situ polymerization of aniline monomer,the resulting PANI/Ni-MOF@CC showed high stability.The galvanostatic charge-discharge results indicated that the specific capacitance of Ni-MOF/PANI@CC materials can reach 108.9 mF/cm².After1000 charge/discharge cycles,73.0%of the initial capacitance was retained.?3?NiO/Ni/C nanocomposites were synthesized by sintering Ni-MOF at high temperature.The composites exhibited high sensitive electrochemical responses to bioactive molecular glucose.In the range of 5.0×10^-7mol/L³×10^-3mol/L,NiO/Ni/C showed high sensitivity?1144.02?A/mM/cm²?and low detect limit of 5.0×10^-7mol/L to glucose.Also,due to the high stability and excellent selectivity,NiO/Ni/C nanocomposites have found potential applications in electrochemical detection.