Study On The Design Of Metal-Organic Frameworks Based Materials And Their Performances In Gas Sensing And Electrocatalysis

After more than 20 years of exploration of the synthesis,structures and fundamental properties,many researcheres of metal-organic frameworks?MOFs?materials have gradually turn their eyes towards the environment detection,energy conversion,and other potential practical energy applications.MOFs have shown great application in gas sorption and separation,luminescence properties,catalysis,proton conductivity,gas sensing and electrochemical energy storage.Meanwhile,the MOF composite,such as conductive additive&MOF,MOF derivatives,MOF nanosheets have opened a new way of research on MOFs materials,which has added new impetus to its research.In the research of MOF-based materials,the function-oriented composite design and synthetic route optimization are of great significance.Based on the design,synthesis,and function expansion of MOF-based materials,we devoted to study the design of MOFs,MOF composite,and MOF derivatives and investigate their performances of gas sensing and electrocatalysis.According to the different properties of MOF-based materials,main contents of this paper are shown as follows:Part one,literature review of advanced research.Firstly,we introduced the characteristics of metal-organic frameworks,synthesis and classification methods.Secondly,their applications of gas adsorption and separation,carbonization,gas sensing,and catalytic properties for the hydrogen evolution reaction?HER?and oxygen evolution reaction?OER?were also been discussed and the research progress of relevant research were summarized.Finally,the advantages of MOF as the source material for the preparation of metal oxide gas sensitive materials and its effect on performance was discussed.Part two,firstly,we detailedly discussed the synthesis,morphology,relevant characterization,and gas sensing performances of three types of MOF derivatives.More importantly,we have been discussed the effects on gas sensing performances resulting from various morphologies,different lattice plane,hierarchical structure of metal oxides.For example,CuO samples with morphologies such as octahedron,sponge-like and sphere have been prepareded by thermal decomposition of crystalline Cu?II?-organic frameworks?HKUST-1?.The relationship between morphologies and gas sensing performances of CuO particles has been explored.Moreover,polyhedral,spherical,fragmented In₂O₃ particles have been prepared via a thermal decomposition by calcining In-MOFs,constructing from4,5-Immidazoledicarboxylic acid ligand,at appropriate temperature and their gas sensing behavior was explored.Finally,a hierarchical Co₃O₄ nanostructure has been fabricated by calcining Co₅-based metal-organic framework?MOF?microcrystals.Such extraordinarily efficient properties might be resulted from hierarchically structures,larger surface area and unique pore structure.This strategy is further confirmed that MOFs,especially Co-clusters MOFs,could be used as precursor to synthesize 3D nanostructure metal oxide materials with high-performance,which possess high porosity and more active sites and shorter ionic diffusion lengths.Part three,two polymorphic Co-MOFs were crystallized into the pure 2D or 3D network by using an anionic or neutral surfactant.The HER performances of two polymorphic Co-MOF composites,which integrate with conductive additive,such as acetylene black?AB?and graphene were investigated.Experimental result demonstrates that AB&Co-MOF?1:4?exhibits superior HER properties.Both experimental and computational studies find that 2D Co-MOF which has coordinated water and more open access to the cobalt site has higher electrocatalytic activity than Co-MOF with the lattice water.What's more,three novel polymorphic Co/Ni-MOFs were synthesized by Naphthalene-1,4-dicarboxylic acid,1,4-Bis?imidazol?butane,and 4'4-Thiodipyridine under similar conditions.The HER performances were also investigated from the point of different metal sources and component.In addition,a novel porous metal-organic frameworks,namely{[Co₃?TTAB??dpy?₂]·2H₂O}_n?1?synthesized under solvothermal conditions.The hydrogen evolution reaction?HER?performances of the composites prepared by Co-MOF and acetylene black are studied.All above indicate that CTGU-9with adequate AB adding content possesses the optimal electrochemicalactivity and favors faster mass transport.This work exhibits the MOF-composited electrocatalyst,which combines active sites deriving from Co-MOF and conductivity of conductive materials,could be effectively expanded on other applications.{[Co₃?tatb??bipy?₂]·2H₂O}_n1{[Co?1,4-ndc??bib??H₂O?]}_n2{[Co?1,4-ndc??bib?]·H₂O}_n3{[Ni?1,4-ndc??bib??H₂O?]}_n4{[Co?1,4-ndc??dps??H₂O?]}_n5{[Ni?1,4-ndc??dps??H₂O?]}_n6Part four,starting from the simulated inorganic material Co?OH?₂ functional unit,we designed and synthesized four MOFs with different Co-OH cluster,moreover,the effect on OER performances of different number of Co?II?-cluster was confirmed.{[Co₄??₃-OH?₂?1,4-ndc?₂?adc??bip?₂]?2H₂O}_n7{[Co₅??₃-OH?₂?1,4-ndc?₄?bix?₂]}_n8{[Co₆??₃-OH?₄?1,4-ndc?₄?bip?₂?H₂O?₂]}_n9{[Co₈??₃-OH?₄?1,4-ndc?₆?btp??H₂O?₆]·H₂O}_n10...