Design,Synthesis And Applications Of Polymer-based Porous Catalysts

In recent years,the porous structure has been proved as a key factor in improving the catalytic performances.Therefore,advanced porous materials are critical in the development of catalytic science and technology.Compared to the traditional inorganic porous materials,porous polymers not only have the advantages of high specific surface areas and large pore volumes but also possess the intrinsic merits of polymers.The diversity of synthetic routes for polymers facilitates the design and construction of numerous porous polymers which are capable of incorporating multiple chemical functionalities into the porous framework or at the pore surface.Moreover,porous polymers are easy in fine tuning the morphology and pore geometry.As a result,porous polymers exhibit great potentials in the field of catalysis.Apart from the inherent active centers,porous polymers could also serve as supports to improve the catalytic activity and stability of guest catalysts.In addition,porous polymers have recently emerged as important precursors for porous carbons with advantageous characteristics from both structural and compositional viewpoints.This doctoral thesis mainly focuses on the facile fabrication of high-performance polymer-based catalysts through designing the compositions and the structures.This work would advance the future researches in developing polymer materials for specific catalytic applications.The details are as follows:1.A facile and efficient y-ray radiation method has been developed to incorporate surface-clean metal nanoparticles(MNPs)into metal-organic frameworks(MOFs)without the assists of stabilizing agents and reductants.The Pd2+ absorbed on MOFs were reduced by e-aq and H·species derived from water radiolysis.As a result,highly dispersed Pd nanoparticles(NPs)with narrow size distribution were generated and evenly embedded in UiO-66-NH2.More importantly,the radiation-reduced Pd NPs exhibit significantly enhanced catalytic activity and stability in olefin hydrogenation and reduction of 4-nitrophenol.Furthermore,the proposed radiation methodology could be successfully extended to prepare other metal NPs such as Au and Pt loaded on different MOFs.Considering that y-ray radiation is widely used in industry,this study provides a potentially scalable approach to incorporate metallic nanomaterials into MOFs with improved catalytic performance.2.Graphdiyne(GDY),which is an emerging ?-conjugated polymer comprising with sp and sp2 hybridized carbon,exhibits remarkable potential for visible-light-driven photocatalytic water splitting.Graphdiyne oxide(GDYO)nanosheets were fabricated by oxidation and exfoliation of GDY,which displayed an ultrathin sheet-like structure with the average size of?120 nm and a thickness of?1.7 nm.The band gaps of GDY and GDYO nanosheets are?1.46 and?1.64 eV,respectively.Compared to GDY,GDYO nanosheets exhibited a-30-fold enhanced photocatalytic oxygen evolution.These results confirmed that oxidation and exfoliation treatments successfully enh anced the light absorption and reduced the recombination of charge carriers,which collectively contributed to the improved photocatalytic performance.Moreover,GDYO nanosheets exhibited excellent singlet oxygen(1O2)generation and photothermal performance.This work provides a valuable guidance to improve photocatalytic activity of conjugated polymers at a molecular level.3.We developed a facile method for the fabrication of nitrogen and sulfur dual-doped hollow carbon spheres(NSHCS)with a high surface area(up to 713.6 m2 g'1),hierarchical pore structures,and highly dispersed N,S atoms.This fabrication method used polystyrene(PS)microspheres as the template and porogen,and conducting polymer(polypyrrole and poly(3,4-ethoxylene dioxy thiophene))as the carbon source and N,S-doping sources,respectively.The removal of template and carbonization of conducting polymer were realized simultaneously via one-step calcination.The content of doped N,S of NSHCS could be easily tailored through controlling the ratio of feeding precursors.The NSHCS has been demonstrated as an outstanding metal-free carbon catalyst for selective hydrogenation of nitroarenes.The prominent performance of NSHCS would attribute to the synergistic effect between uniforamly dispersed N and S to favor the exposure of active sites and unique hollow mesoporous structure to facilitate mass transfer.The density functional theory(DFT)calculations revealed that the graphitic N and-C-S-C-favored the preferential adsorption of nitro group,which might be responsible for this unique selectivity.The present investigation provides a new prospect for efficient preparation of doped hollow carbons as metal-free organic catalysts with remarkable performance.