Preparation And Oxygen Evolution Performance Of FeNi-Based Metal-Organic Framework Materials

Facing the increasing environmental problems caused by the excessive use of traditional fossil energy,which is very important to find clean and sustainable energy.Hydrogen is an ideal alternative to traditional fossil fuels.Hydrogen production by electrolysis of water provides a clean and effective method for large-scale hydrogen production.The anodic oxygen evolution half-reaction in the process of electrolyzing water involves a multi-step electron transfer process,and the kinetic process is slow,which is considered to be the main bottleneck hindering effective water decomposition.Therefore,our goal is to prepare a highly efficient and stable anode oxygen evolution catalyst.MOFs materials have a large specific surface area,a tunable pore size,a variety of metal ions and organic ligands,and a large number of catalytically active MO₆（M=metal）octahedral structures and exposed hydrophilic carboxyl groups.It exhibits excellent electrochemical OER performance,which has attracted wide attention in the field of electrocatalysis.However,due to the poor conductivity of MOFs and the small pore size,which is not conducive to the mass transfer process,there are some limitations in the field of electrocatalysis.At present,the application of MOFs in the field of electrolyzed water is mainly used as a sacrificial template to prepare oxides,phosphides,carbonitrides,or by doping conductive materials to enhance their water oxidation performance.A series of MOFs catalysts were prepared by solvothermal method and used directly as anodic oxygen evolution catalysts.The structure,morphology,composition and valence state were systematically analyzed by means of XRD,SEM,TEM,EDS and XPS.The specific research contents are as follows:1.FeNi-MIL-101 material was synthesized in one step by solvothermal method.These MOFs contain a large number of catalytically active MO₆octahedrons and exposed hydrophilic carboxyl groups,which are believed to be effective in enhancing OER activity.MIL-101 has a large pore size in the MIL series of materials,and its central ion is in a high valence state to make the structure more stable.The results show that Fe₂Ni-MIL-101 has good OER performance.The overpotential at a current density of 20 mA·cm^-2 in a 1 M KOH solution was 237 mV and the corresponding Tafel slope was 44.2 mV·dec^-1.2.The FeNi-MOF/NF electrode was successfully synthesized by one-step solvothermal method.This special three-dimensional electrode grows FeNi-MOF in situ on the surface of the foamed nickel,benefiting from the porous structure of the MOFs itself and the metal synergy between Fe and Ni.The catalyst exhibits excellent electrochemical properties.Since the in-situ preparation has a stronger bonding force,it exhibits good stability,and the overall resistance of the binderless catalyst electrode is reduced.The overpotential at 10 mA·cm^-2 is only190 mV and the corresponding Tafel slope is only 27.6 mV·dec^-1.Also.At a current density of 100 mA·cm^-2,only an overpotential of 223 mV is required.