Synthesis And Catalytic Appliction Of Metal Nanoparticles Based On The Confined Effect Of Microporous Organic Polymers

Due to quantum size effect,the tiny metal nanoparticles have more active sites and tend to exhibit higher catalytic performance.Therefore,controllable preparation of ultra-small metal nanoparticles has become a key strategy for improving heterogeneous catalytic activity.Porous materials with high specific surface area and pore volume have been widely studied,especially their unique pore structure not only prevents the metal nanoparticles from agglomerating,but also restricts the growth of metal nanoparticles and regulates the nanoparticles size.However,traditional porous materials have the disadvantages of complicated preparation and poor stability,which are not conducive to prepare the stable and highly efficient heterogeneous catalysts.In addition,chemical reduction methods can easily contaminate metal nanoparticles and block pores,seriously affecting their catalytic performance.Based on the results,this article selects highly stable hypercrosslinked polymers(HCPs)and covalent triazine frameworks(CTFs)materials as the support materials to control and load metal nanoparticles by thermal reduction method.What's more,no reducing agent is added to the system to study the effect of pore structure of microporous on the size and distribution of metal nanoparticles.The aim of this article is to load metal nanoparticles with smaller size and more uniform distribution in the MOPs materials to obtain high catalytic activity and high stability of the heterogeneous catalyst.This article mainly contains the following aspects:(1)Triphenylmethanethiol(TPMT)was utilized as the reaction monomer to prepare the hypercrosslinked microporous organic polymer HCP-TPMT by crosslinking the dimethoxymethane(FDA).Then,thermal reduction method was employed to load Au nanoparticles without adding any reducing agent and stabilizer.Under the confinement effect of HCP-TPMT micropores,the size of Au nanoparticles was successfully controlled within the range of 1.7-5.1 nm by simply changing the loading mass ratio of metal precursor to HCP-TPMT.Finally,the catalytic reduction of 4-nitrophenol(4-NP)was applied to investigate the effect of different sizes of Au nanoparticles on their catalytic performance.(2)Different reaction monomers were used to prepare CTFs with different pore size distributions and visible light absorption abilities by low temperature polycondensation.Then,Pd nanoparticles were loaded by the thermal reduction method to study the effect of pore size of CTFs on the size distribution of Pd nanoparticles.Finally,the photocatalytic performance of the obtained composites was tested by photocatalytic Suzuki-Miyaura coupling reaction,which was employed to investigate the effect of different size of Pd nanoparticles on catalytic performance and extend the application of CTFs materials in the field of photocatalysis.