New Carbon Control And Application Of Mesoporous Materials

Mesoporous carbon is a class of advanced materials and is considered as "the next generation of mesoporous materials". Mesoporous carbon possesses several fascinating properties including high surface areas, large pore volumes, high mechanism and chemical stability, and good electric conductivity, showing promising potential applications for adsorption, separation, delivery of biomolecules, catalysis, electrochemistry, and so on. In comparison with the traditional mesoporous silica that is widely studied, there are still many issues of mesoporous carbon that need further investigation. For example, the structure and morphology are not abundance enough, the methods of synthesis are lack of innovation, the mechanisms are not understood very well, and the applications are not widely exploited. Therefore, investigating the synthesis, structures and applications of mesoporous carbon is of great significance for enriching the contents of mesoporous carbon and its real world application.This thesis presents a systematic study regarding the following well-connected aspects of mesoporous carbon, including synthetic method for large-scale production, exploring of new synthetic methods, controlling of unique morphology, manipulating of framework functionality, and their applications in adsorption, supercapacitors and lithium ion batteries.In chapter2, a novel post-cure method has been developed for synthesizing high-quality ordered mesoporous carbons in kilogram-scale utilizing only commercial chemicals. By using triblock copolymer Pluronic F127as a template, phenolic resol as a carbon precursor and polyurethane (PU) foam as a sacrificial scaffold, ordered mesoporous carbons have been successfully synthesized through an organic-organic self-assembly on PU foam induced by solvent evaporation. Post-cure evidently promotes the mesoporosities of carbons, especially for mesoporous size and surface area. The effects of the concentration and the loading amount of resol on the mesostructure of the carbons are systematically investigated. The results indicate high-quality ordered mesoporous carbons can be synthesized in a wide tunable range of the concentration and the loading amount of resol, which is propitious to convenient manipulation. The kilogram-scale ordered mesoporous carbons with highly ordered2-D hexagonal mesostructure, large surface area (～690m2/g), large pore volume (～0.45cm3/g) and uniform pore size (～4.5nm) show high specific capacitances when used as electrodes of supercapacitors. In chapter3, a novel synthetic method has been developed for the synthesis of ordered mesoporous carbons by a hydrogen bond interaction induced cooperative assembly in an additive-free system containing low-molecule-weight phenol/formaldehyde resol and triblock copolymer template F127. By varying the thickness of vessel moulds or the polymerization temperature, the pore size of ordered mesoporous carbon can be turned from2.3to4.5nm, the surface area from560to807m2/g and the pore volume from0.21to0.45cm3/g. The assembly process during the polymerization has been investigated by SAXS measurement. Moreover, a possible formation mechanism of mesoporous carbon in this additive-free organic-organic system is also demonstrated. This noval approach is simple, low-cost, timesaving, and more suitable to facilitate the mass-production of ordered mesoporous carbons.In chapter4, micro-mesoporous carbon materials with a unique morphology of hollow polyhedra have been fabricated through selective removal of the skeletal scaffolds of PU foam. Hollow micro-mesoporous carbon polyhedra with an irregular shape molded from the cellular cavities of PU foam have been synthesized by using phenolic resin as a carbon precursor, triblock copolymer F127as a template, PU foam as a skeletal scaffold and triethyl phosphate as a reaction agent. By a reaction with triethyl phosphate, PU foam skeletal scaffolds in monolithic mesostructured resin/PU composites can be degraded, simultaneously leading to the disassembly of monolithic structure into separated hollow polyhedral particles which turn into hollow carbon polyhedra after carbonization. This method can also be used for the synthesis of hollow micro-mesoporous carbon-silica polyhedra, using TEOS as a silica source. Moreover, after etching the silica away, hollow micro-mesoporous carbon polyhedrons possessing an ordered hexagonal mesostructure (space group p6mm), large particle sizes of65～500/μm, a uniform pore size of～3.2nm, a high surface area of～1400m2/g and a large pore volume of～1.15cm3/g as well as a high mesoporosity of～81%can be obtained, which exhibit excellent adsorption performance toward methylene blue compared with the active carbon having a similar surface area.In chapter5, large-pore phosphorus-doped mesoporous carbons have been successfully synthesized by an organic-organic co-assembly approach, wherein tricresyl phosphate is used as a phosphorus precursor, phenolic resol is used as a carbon precursor and triblock copolymer F127is used as a template. By using tricresyl phosphate as a phosphorus precursor, the carbon framework can be modified and the mesopore size can be well turned. Tricresyl phosphate can be accommodated into the hydrophobic parts of the copolymer micelles as a result of the hydrophobic character and can be considered as a pore swelling agent. The resultant phosphorus-doped mesoporous carbons with homogeneous distributions of phosphorus have wormlike mesostructures. Increasing the tricresyl phosphate, the mesopore size can be enlarged from3.6to14.2nm and the content of phosphorous increases from1.06to5.95wt%. The resultant phosphorous-doped mesoporous carbons show much higher electrochemical performance than the pure mesoporous carbon when they were used as anodes for lithium-ion batteries.In chapter6, the whole thesis is summarized.