The Study On The Design Of Nickel-based MOFs Source Materials And Their Performances In Electrocatalysis

As a new class of porous crystalline materials,metal organic frameworks(MOFs)have attracted widespread attention in recent years.MOFs are usually assembled by metal ions or clusters and organic ligands through coordination bonds.Due to its unique structure,it is endowed with high porosity,large specific surface area,uniform but adjustable pores,fully exposed active sites,adjustable morphology and rich and variable components,which can be used in catalysis,gas separation and storage,Supercapacitors and drug delivery fields show great potential.However,due to its poor chemical stability and low electronic conductivity,people to MOFs with other functional materials such as inorganic compounds,carbon materials,polymer,etc.),the formation of new composite materials,composite materials obtained not only inherited the advantages of MOFs and other materials,and due to the interaction between them and breeds new functions.In this paper,based on the original work of the research group,the function of electrocatalytic methanol oxidation as the guide,under the precondition of keeping the original structure of MOF material unchanged,the design and synthesis of Ni-MOF crystalline material and its composite material,to explore the application of nickel MOF source material in electrocatalytic methanol oxidation(MOR).The main research contents are as follows:Part ?:First introduced the characteristics of MOFs materials,classification and application of MOF derivatives,the second list MOFs materials carried out in the field of methanol oxidation related work,mainly illuminates the nickel-based MOF again material advantages and disadvantages of the research in the field of MOR,lay a foundation for the further design of synthesis and summing up experience,finally clarify this paper selected topic basis and research direction.In the second part,Four cases of Ni-MOF materials were synthesized under solvothermal conditions using triangulated ligands H₃TATB and H₃BTB,with metal ion Ni²⁺as the metal center,and different small organic molecules as the radiating ligands.Then,the crystal structure and the related basic characterization are discussed emphatically.The MOR properties of pure materials were investigated.{[Ni₃(?₃-O)(?₂-OH)_0.5(TATB)(Ina)_2.5(H₂O)]}_n1{[Ni₃(?₃-O)(TATB)(NIC)₂(H₂O)₃]}_n2{(Ni₄(?₃-OH)₄(BTB)_4/3(dpe)₂)}_n3{[Ni₃(?₃-OH)(BTB)(Tpt)₂(Me₂NH₂)]}_n4Part?:In order to improve methanol oxidation performance,we choose MOF-74 with good chemical stability and high efficiency electrocatalytic performance as the MOF unit,and choose Ni(OH)2 with special morphology and relatively stable under alkaline conditions as the MOF unit Heterogeneous composite components.A Ni(OH)₂ template-oriented semi-sacrificial transformation strategy was designed to prepare a series of hierarchical MOF-74/Ni(OH)₂composites(represented as Ni-Ni),and its MOR performance was explored.In order to further verify the universality of the above strategy,a series of MOF-74/Ni_1-xCu_x(OH)₂(Ni-Ni Cu)composite materials were prepared and their MOR properties were investigated.The research results show that the above-mentioned unique Ni-Ni-based heterogeneous composite material can effectively enhance the MOR activity,and the area activity of the Ni-Ni-2 heterogeneous composite material is 24.6 m A cm^-2;the synergy between the two types of monomer materials The effect and unique hierarchical structure not only have a large electrochemical surface area and abundant active sites,but also can adjust the coordination environment of Ni ions,thereby improving MOR performance.The synergistic effect produced by the combination of MOFs and nickel hydroxide may also provide a convenient and sustainable mass transfer diffusion channel.The normalized nickel K-edge XANES spectrum shows that the K-edge XANES spectrum of Ni-Ni-2 appears.There is a slight blue shift,which may be related to the interaction of Ni and Ni-2 phase.This phenomenon further proves that there is a certain binding effect between the embedded Ni and Ni-2.The above composite strategy provides a new idea for the composite design of functional materials,especially electrocatalytic materials.This strategy can be extended to other types of levels.Energy conversion and storage related applications of structured catalysts.Part?:In order to improve the MOR performance of MOF crystalline materials,we have worked from two perspectives:1.First,take the M₃(?₃-O)unit Ni-based crystalline material 4as the research object to improve its conductivity,And conductive materials(superconducting Ketjen black(KB)and acetylene black(AB))mechanically combined to construct composite materials,it is found that the composite ratio is different,the MOR performance of the material is also quite different,in which Ni-MOF-4:KB(AB)When the composite ratio of)is 4:3,the corresponding optimal MOR area activity is 28.5 m A cm^-2(KB)and 26.1 m A cm^-2(AB)in order;in order to enhance the stability and synergy of Ni-MOF-4,The Ni-MOF-4/Ni OOH heterogeneous composite material was synthesized by in situ hydrothermal reaction of the synthesized Ni OOH precursor as a metal source with organic ligands,and its MOR area activity was increased by 8 m A cm^-2 compared with Ni-MOF-4,But the Ni-MOF-4/Ni OOH&conductive material after mechanically compounding it with the conductive material KB/AB greatly improves the MOR performance.When the composite ratio of Ni-MOF-4/Ni OOH:KB is 4:5,the MOR area activity is 49.9 m A cm^-2 When the Ni-MOF-4/Ni OOH:AB composite ratio is 4:6,the MOR area activity is 31.7 m A cm^-2.From the perspective of integrating conductive materials,a two-pronged approach is an effective strategy to improve the MOR performance of MOF materials;2.Taking the classic Ni-BTC as the research object,from the synthesis of Nickel elemental alloy vulcanization and introduction of carbon quantum dots to in-situ synthesis,a nickel-based heterogeneous composite The material Ni-BTC/Ni S@C has a MOR area activity of 30.4 m A cm^-2,which also shows that a reasonable construction of a multiphase heterostructure is also an effective way to improve the electrochemical performance of the material.Part?:Summarize and look forward to the work of the paper.