Tunable-constructed Multi-shell Hollow Micro-/nanomaterials With Hierarchically Porous Structure And Their Structure-activity Relationships

Since the 21 st century,material industry as one of the pillar industries of modern industry,has made great progress and promote the rapid development of modern society.Hollow core-shell materials,especially in the micro/nano materials with multi-shell hollow structure,have been widely aroused people's concern and been of great development prospect in the field of electrochemistry,biomedicine and environmental protection duo to its large specific surface area,rich in active site,low density,short mass transfer path,and the advantages of wide cavity structure.Meanwhile,hierarchical porous materials,namely on the surface of nanometer materials with complex channel structure(for micropore-mesoporous,mesoporous-macropore and so on)also gradually come to the attention of people.This is mainly due to the complex channel structure,which endows material not only more active site and larger specific surface area but also increasing the mass transfer efficiency and reducing the mass transfer resistance.Based on this,the micro/nano materials with not only multi-shell structure but hierarchical porous structure have good development prospect.The multi-shell hollow micro/nano materials with hierarchical porous structure are synthesized successfully by the sacrifice-template method.Using X-ray diffraction(XRD),field emission scanning electron microscope(FESEM)and transmission electron microscopy(TEM),chemical composition,morphology and application of sample is analyzed.In the meantime,the research about the formation mechanism of sample is expected to provide theoretical foundation and experiment evidence for the synthesis of multi-shell hollow micro/nano materials with hierarchical porous structure.Performance study analyzes the application of micro/nano materials with special composite structure in the electrochemical and environmental protection.The result provides a reliable experimental basis to further optimize the multi-shell hollow and hierarchical porous structure and improve its performance.The works of this paper are as follows:(1)We controllably construct the multi-shell hollow silica microspheres with hierarchical porous structure,and study its formation mechanism and electrochemical performance.We successfully synthesize the multi-shell hollow silica microspheres(MHSM)with hierarchical porous structure via a simple sacrificial template method and the numbers of shell can be controlled by the precursor(Na2SiO3)loading.Through the characterization of the sample,we study the morphology and chemical composition of sample.Through exploring the formation mechanism of the sample,we realized that the adsorption depth of precursor on the template play a key role in the formation of samples.We further research the electrochemical performance of triple-shell hollow silica microspheres(THSM)as anode materials in the lithium ion battery.The results show the charge-discharge special capacity increase with the increasing of the shell numbers.Especially for THSM,it not only has high charge-discharge specific capacity and good cycle stability.(2)We controllably construct the multi-shell hollow silica microspheres with hierarchical porous structure,and study its formation mechanism and the phosphate removal performance.We successfully synthesize the multi-shell hollow lanthanum oxide microspheres(MHLM)with hierarchical porous structure via a simple sacrificial template method and the numbers of shell can be controlled by the precursor((CH3COO)3La2)loading.Through the characterization of the sample,we study the morphology and chemical composition of sample.Through exploring the formation mechanism of the sample,we put forward a stratified heating mechanism.We recognize that affect the morphology structure of the sample is not only the adsorption depth of precusor,but also decided by the stratified heating of template.Especially for the latter,more slowly core-shell heat separation process improves the mechanical,structural integrity and stability of shell.At the same time,the samples have more active sites,due to the complexity of self-assemple particles on the surface of shell.Based on this,the stratified heating mechanism provides theoretical basis for synthesis with similar structure material.(3)We further research the phosphate removal performance of triple-shell hollow lanthanum oxide microspheres(THLM)as a phosphate absorbent in the water treatment.Experimental results show the THLM has big monolayer adsorption capacity for phosphorus adsorption(109.02 mg P/g),and the phosphate adsorption performance of THLM increases step by step with an increase in the amount of adsorbent.Meanwhile,the adsorption between THLM and phosphorus is mainly for the chemistry and the internal diffusion effect between particles.The adsorption mechanism between THLM and phosphorus is mainly for ligand transformation mechanism.In addition,the THLM have good adaptation for acid and alkali and excellent cyclic adsorption performance.Based on the above research,the THLM as phosphorus adsorption material used in wastewater treatment has a good application prospect.(4)We controllably construct the multi-shell hollow hydroxyapatite or zirconium oxide microspheres with hierarchical porous structure.We successfully synthesize the multi-shell hollow hydroxyapatite microspheres(MH-HAP)or zirconium oxide microspheres(MHZM)with hierarchical porous structure via a simple sacrificial template method and the numbers of shell can be controlled by the dosage of template.Through the characterization of the sample,we study the morphology and chemical composition of sample and realize that the ionization effect of precursor on the template play a key role in the formation of samples.Especially for TH-HAP,the synthesis strategy has a guiding significance for the construction of complex phosphate.