Controllable Synthesis And Catalytic Application Of Metalloporphyrin-encapsulated Metal-organic Framework Derivatives

Metal-organic frameworks?MOFs?are formed by self-assembly of metal ions/metal clusters and organic ligands,with well-defined pore structure,large surface area and structural flexibility.We can use the pore space of MOFs to specifically limit the guest and include different species,such as nanoparticles,metal complexes,organic dyes,porphyrins,etc.At the same time,MOFs are also excellent precursors for a variety of electrocatalytic and energy storage active materials.Since they already contain carbon and well dispersed metal atoms,MOFs can be converted to conductive carbon containing active metal species and doping elements by appropriate pyrolysis.In recent years,a large number of MOFs-derived carbon-coated metal nanoparticle materials have been reported to show great potential in electrocatalytic applications.Metal porphyrin is a general term for the formation of complexes between porphyrin and metal ions.It has strong thermal stability and high chemical stability.And it has broad application prospects in bionic catalysis,energy storage and probe detection.However,since the metalloporphyrin monomer is usually carried out in the solution phase when catalyzing some reactions,it is difficult to recycle after the reaction is completed,and the metalloporphyrin is also prone to oxidative deactivation during the reaction,and these disadvantages are gre atly limited the industrial application of metalloporphyrins.Therefore,the immobilization of metalloporphyrins on other materials has become a new research hotspot.Based on the above points,we carried out the research in the following two parts.?1?An encapsulated MOFs material Mn-TCPP@PCN-777 which was synthesized by encapsulating 5,10,15,20-tetrakis?4-carboxyphenyl?manganese porphyrin?Mn-TCPP?into PCN-777 was prepared by the"bottle-in-boat"synthesis strategy.And we applied it to the catalytic oxidation of thioanisole.The experimental results show that the catalyst has a good catalytic effect on thioanisole,the conversion rate is 97%,and the selectivity to phenyl sulfoxide is 96%.At the same time,we have extended the catalyst to the catalytic oxidation of other thioether compounds,and it has shown good catalytic effects.The catalyst also has good structural and chemical stability and is capable of maintaining good catalytic activity and selectivity for a long period of time.?2?Mn-TCPP and Co-TCPP were encapsulated into ZIF-67 by one-pot method to form Co-TCPP@ZIF-67 and Mn-TCPP@ZIF-67,then Co-TCPP@ZIF-67 and Mn-TCPP@ZIF-67 were pyrolyzed at different temperatures in an argon atmosphere to obtain a series of Co@NC-x and Mn/Co@NC-x materials?where x represents the pyrolysis temperature?.Finally,this series of nitrogen-doped carbon-coated metal nanoparticle materials was modified onto a glassy carbon electrode for electrocatalytic oxygen reduction reaction?ORR?.The experimental results show that Co@NC-800 exhibits excellent electrocatalytic oxygen reduction performance in alkaline medium.The initial potential E_onset,half-wave potential E_1/2 and ultimate diffusion current density J_L are 0.95 V?vs.RHE?,0.84 V?vs.RHE?and 5.7 mA cm^-2,respectively,its performance is very close to the commercial Pt/C electrocatalyst,and the chronopotentiometry test proves that Co@NC-800 has better Stability than Pt/C electrocatalyst.