MOFs Composites And Its Derivatives: Preparation And Electrocatalysis Application

It is very important to develop a new type of highly active electrocatalyst to improve the sensitivity and selectivity of electrochemical sensors and efficiently catalyze the reaction of hydrogen and oxygen evolution.The development and application of new nanomaterials has opened up an effective way to obtain high-efficiency electrocatalyst.Metal-Organic Frameworks material is a new type of porous crystal,which has a three-dimensional pore structure,high porosity,specific surface area,strong controllability of skeleton structure,easy functionalization and unique photoelectric properties,it can also be modified by“post-synthesis”and other methods to achieve the purpose of design,tailoring and regulation of material structure and physical and chemical properties.MOFs composites and their derivatives as new nano electrocatalysts have shown good application prospects.In this paper,MOFs and porous carbon and conductive polymer composites were synthesized,and MOFs derivatives were quickly and easily prepared by laser engraving method.The properties of these materials as electrocatalysts in electrochemical detection and electrocatalytic hydrogen and oxygen evolution reaction are researched respectively.The main work can be seen as followed:(1)DUT-9/mesoporous carbon composites(DUT-9/MC)were prepared by in situ method for electrochemical detection of baicalein.DUT-9 is a two-dimensional lamellar mesoporous MOFs,which can accelerate material transfer.Mesoporous carbon(MC)as template is used to prepare Ca CO3.MC has large specific surface area,stable three-dimensional structure and large pore size.The combination of MC and DUT-9 can solve the accumulation of DUT-9 well and increase its electrical conductivity.Scanning microscopy(SEM)and transmission electron microscopy(TEM)show that the size of DUT-9 in the composite is much smaller than that of pure DUT-9,which resulted in the increase of specific surface area of the composite and expose more active sites to enhance the electrocatalytic activity of the composite.The electrochemical sensor constructed with DUT-9/MC has excellent performance for the detection of baicalein in neutral solution,which has a low overpotential,a wide linear range,high selectivity and reproducibility.(2)DUT-67/T-PPY composites were prepared by hydrothermal method for the electrochemical detection of nitrofurazone and ornidazole.Tubular conductive polypyrrole(T-PPY)synthesized by chemical template method has a cross-linked network structure.T-PPY as the carrier not only can enhance the stability of DUT-67 and the electrical conductivity in the composite,but also can restrict the accumulation of DUT-67 and make it uniformly distributed on the carrier to expose more active sites,which can improve the electrocatalytic performance of DUT-67/T-PPY.Compared with DUT-67/GCE,DUT-67/T-PPY-2/GCE shows enhanced electrocatalytic activity for the reduction of nitrofurazone and ornidazole,respectively.The electrochemical sensor has a wide linear range and good selectivity for the detection of nitrofurazone.Compared with the reported literature for detection ornidazole,DUT-67/T-PPY-2/GCE has the widest linear range with a low LOD and good selectivity.(3)Tubular poly(3,4-ethylenedioxythiophene)(T-PEDOT)coated nickel-based MOFs(Ni-MOFs)composites(Ni-MOF/T-PEDOT)were prepared by in-situ growth method for the electrochemical detection of gallic acid and tinidazole.The tubular crosslinked network structure of T-PEODT was synthesized by chemical template method for the first time.Ni-MOF is a three-dimensional mesoporous MOFs with small spheres.T-PEDOT as the substrate not only provides a suitable carrier for Ni-MOFs,but also improves the electrical conductivity of composite.The tubular crosslinked network structure of T-PEODT effectively prevents the accumulation of Ni-MOFs and limits the size of Ni-MOFs to expose more active sites.Ni-MOF/T-PEDOT/GCE shows high sensitivity and a wide linear range for the detection of gallic acid,and a wide linear range and good selectivity for the detection of tinidazole.(4)Preparation of porous nitrogen-doped graphene(PNG)loaded MOFs-derived FeNi nanoparticles(FeNi/PNGs)for electrocatalytic hydrogen and oxygen evolution reactions.Compared with the traditional pyrolysis method,the laser engraving method does not need high temperature and nitrogen protection,and it is fast and easy to operate.Another advantage of this method is that FeNi/PNG loaded on PI film can be directly used as the working electrode without the need of dispersing and dropping coating electrocatalyst preparation electrode to catalyze hydrogen evolution and oxygen evolution reactions.The overpotentials of hydrogen evolution and oxygen evolution reactions catalyzed by FeNi/PNG electrode are 132 and 353mV,respectively,and the Tafel slopes are 94 and 80 mV dec^-1,respectively.(5)Rapid and simple laser-assisted preparation of bimetallic Ru-ZIF-67-derived CoRu nanoalloy@nitrogen-doped graphene(CoRu@NG)as all-p H electrocatalyst for hydrogen evolution reaction.We rapidly prepared CoRu@NG-X electrocatalyst at room temperature and in air by laser engraving Ru-ZIF-67.Co doped with a small amount of Ru can further improve the catalytic performance of hydrogen adsorption.The results show that CoRu@NG-3(Ru,0.18 wt%)is an effective catalyst for HER in all-CoRu range.Compared with the reported literatures on electrocatalyst of ruthenium alloy,the content of ruthenium in CoRu@NG-3 is the lowest.CoRu@NG-3 shows overpotentials of 62,52 and 88 mV at the current density of10 mA cm^-2 in 1 M KOH,0.5 M H2SO4 and 1.0 M PBS solution for HER catalysis.CoRu@NG-3 shows good stability at all CoRu values.