Preparation And Property Studies Of Meso-/Macroporous Materials Based On The Soft Template Method

Benefiting from the advantages of large specific surface area and pore volume,rich mesostructures,diverse morphologies（nanosphere,nanosheet,nanotube）,tunable pore size,mesoporous materials have a wide range of application prospects in the fields of adsorption and separation,catalysis,energy storage and biomedicine,and have gradually become one of the main research directions of researchers.In recent years,there have been many reports on the synthesis of mesoporous materials,which are generally divided into two synthesis methods:the hard template and the soft template methods.The hard template method is a method that the precursors are filled into the pores of the hard template by impregnation or chemical vapor deposition,and then the hard template is removed to obtain mesoporous materials.The soft template method is a method that use amphiphilic surfactants as templates to co-assemble with skeletal precursors to form mesostructured nanocomposites,and mesoporous materials are obtained after removing the templates.In recent years,more and more mesoporous materials have been prepared by using soft template method due to its advantages of easy operation,fewer processes,and directional synthesis of various morphologies and structures.By using soft template method,a series of mesoporous materials with diverse morphologies and abundant matrix types have been prepared,such as mesoporous silica,metal oxides,carbon,and noble metals.However,most reported mesoporous materials are large in size or have small pore diameters,which restrict the efficiency of mass transport and the size of the guest species that can be loaded in the mesochannels.Therefore,the development of new synthesis strategies for the preparation of mesoporous materials with larger pore diameters is essential.In this thesis,we employed a dual-soft-template strategy to prepare meso-/macroporous carbon and Pd nanoparticles,and systematically investigated the effect of synthesis conditions on the pore structure,pore size,and morphology of materials.We believe that the studies in this thesis can provide new methods for synthesizing meso-/macroporous materials with different structures and,more importantly,provide new insights into the interfacial assembly and synthesis.Main contents of this thesis are as follows:1.We employed a dual-soft-template strategy to prepare meso-/macroporous polydopamine nanospheres with open channels.In this method,a mixture of two block copolymers F108 and P123 were used as a structure-directing agent to manipulate the structure of the synthesized polydopamine particles.The mesostructure can be realized from columnar to bicontinuous and finally to lamellar structure by varying the mass ratio of P123 and F108.The open pore structure and high specific surface area(338 m²g^-1)enable it to be used as a carrier of iron ions.After carbonization,Fe、N doped meso-/macroporous carbon spheres（Fe@NMMCS）are obtained.The polydopamine has good thermal stability,with no change in morphology and structure after carbonization.Fe@NMMCS exhibits excellent electrocatalytic activity,superior stability and methanol tolerance in the Oxygen Reductive Reaction（ORR）.2.We demonstrate a novel emulsion-induced interface anisotropic assembly strategy to fabricate asymmetric bowl-like particles with meso-/macroporous channels.In this method,a mixture of two block copolymers F108 and L64 were used as a structure-directing agent to control dopamine polymerization and directed growth.By varing the mass ratio of L64 and F108,asymmetric bowl-shaped polydopamine particles with different pore structures and pore sizes can be obtained.These meso-/macroporous bowl-like polydopamine particles can be easily carbonized into nitrogen-doped carbon nanoparticles with unchanged morphology and pore structure.Due to the open pore structure,high specific surface area,and abundant active sites,the meso-/macroporous bowl-shaped nitrogen-doped carbon particles exhibit good ORR electrocatalytic activity,high stability and methanol tolerance.3.Based on the work of the previous chapter,we utilized F108 and L64 dual-surfactants as structure-directing agents,with dopamine as the precursor,to achieve polymerization and crosslinking growth on the surfaces of functional nano-sized particles with diverse surface properties and dimensions（0D Si O₂,1D Fe₂O₃,2D GO,3D Ui O-66,3D Ni-Co PBA）,resulting in various meso-/macroporous polydopamine（MMPDA）coated nanocomposites.The synthesized Ni-Co PBA@MMPDA underwent carbonization and selenization treatments,and was transformed into Ni-Co-Se@MMC with the essentially constant morphology.The selenized core consists of stacked nanoparticles,creating aperatures that facilitate electrolyte impregnation and expose more active sites.Ni-Co-Se@MMC exhibits favorable charge storage capacity as an electrode material in supercapacitors,and demonstrates good cyclic stability,attributed to the protection of the internal Ni-Co-Se by the meso-/macroporous carbon shell,effectively reducing interior expansion and damage after consecutive reactions.4.We selected two types of ionic surfactants（CTAC and SDS）as templates to prepare monodisperse,asymmetrically spherical meso-/macroporous Pd nanoparticles.In this method,CTAC forms micelle composites with the precursor Pd Cl₄^2-through electrostatic interactions,while SDS competes with Pd Cl₄^2-to slow down the growth rate of Pd nanoparticles,leading to the final assembly of the desired product.Tuning the mass ratio of CTAC to SDS,controllability in porosity and morphologies can be achieved.Due to its open structure,it exhibits higher mass transfer rates and electrochemically active specific surface area(54.9 m² g^-1),showcasing enhanced oxygen reduction reaction（ORR）electrocatalytic activity and excellent stability compared to the commercial Pt/C catalyst.