Synthesis Strategies And Catalytic Applications Of Hollow Micro/Nano Spheres Encapsulated Nanoparticles

Hollow micro/nano structures,as a new type of micro/nano materials,are named because of their hollow morphology.Thanks to its special hollow structure,this kind of material is endowed with some excellent properties,such as large specific surface area,low density and high carrying capacity,and the adjustability of its structural components.Since the 21st century,the research community has quickly realized that this unique hollow structure material has a broad development prospect,so that it has received more and more extensive attention.Hollow micro/nano materials of various materials have been reported and demonstrated in a variety of applications,including micro/nano reactors,catalysis,energy storage,biomedicine,sensors and environmental remediation.As the development of science and technology leads to the gradual shortage of various resources and materials and the gradual destruction of the ecological environment,the concept of green and sustainable development becomes particularly important.However,how to make better use of hollow micro/nano structure materials in the field of green chemical catalysis is still a difficult and challenging topic.This paper is divided into three chapters.The first chapter is the introduction,which mainly introduces the classification,synthesis methods and applications of hollow micro/nano structure materials,as well as the related background of heteropolyacid and organic-inorganic hybrid perovskite.In the second chapter,a"ship-in-bottle"method was used to encapsulate macromolecular size heteropolyacid in the inner cavity of hollow microporous polymer nanospheres,which was used to realize sustainable esterification catalytic nanoreactor.In particular,the diblock copolymer polylactide-b-polystyrene(PLA-b-PS)prepared by one pot method was used as the precursor,the hollow microporous polymer nanospheres were formed by hyper-crosslinking self-assembly based on Friedel-Crafts alkylation.Finally,hollow microporous polymer nanospheres encapsulated with phosphotungstic acid(HPW@H-MPNs)were obtained by“ship-in-bottle”method.The structure and properties of H-MPNs and HPW@H-MPNs were characterized by FT-IR?XRD?XPS?ICP?TEM and BET,etc.The results show that the perovskite molecules are successfully encapsulated and the final material has a good core-shell or yolk-shell structure.Through the esterification reaction of acetic acid and n-butanol as probe reaction,the results showed that HPW@H-MPNs had good catalytic activity,and the conversion rate of acetic acid could still be maintained above 85%after 15 catalytic cycles.It is strongly demonstrated that the synthetic catalyst has excellent sustainable recycling ability.In addition,this chapter also carried out the catalytic test of HPW@H-MPNs for the universality of esterification reaction,the results also show that it has a good universality of catalytic esterification reaction.In the third chapter,a nano-reactor for photocatalytic degradation of dyes was obtained by successfully encapsulating organic-inorganic hybrid perovskite with large molecular size into the cavity of the hollow microporous polymer nanospheres by means of"solvent nucleation".Similar to chapter two,the hollow microporous polymer nanospheres were formed by hyper-crosslinking self-assembly of PLA-b-PS based on Scholl reaction.Finally,hollow microporous polymer nanospheres encapsulated with MAPb Br₃(MAPb Br₃@H-MPNs)were obtained by“solvent-nucleation”method.The structure and properties of MAPb Br₃@H-MPNs were characterized by XRD?XPS?TEM and BET.The results show that the perovskite molecules are successfully encapsulated and the final material has a good core-shell or yolk-shell structure.The results of photocatalytic degradation of methyl orange(MO)show that the material has a good degradation effect,and still has a certain degradation ability after four catalytic cycles.This indicated that the synthesized catalyst could effectively protect the unstable MAPb Br₃ to a certain extent.