Hard-template Preparation And Application Of Hierarchically Mesoporous Titania And Hierarchically Mesoporous Carbon

Studying on hierarchically mesoporous structure has being a research focus in materials field,because this structure not only can keep the characteristics of single modal mesoporous but also have a synergistic effect among different pore sizes.Compared with hierarchically mesoporous silica,it’s much more difficult to synthesize no-slilicon hierarchically mesoporous materials through traditional sol-gel method,and it’s hard to control the structure during the preparation process.Therefore,it’s still a big challenge to control morphology and hierarchically mesoporous structure simultaneously.This paper adopts hard-templating method and uses hierarchically mesoporous silica(HMS)microspheres as hard template to synthesize hierarchically mesoporous titania microspheres and hierarchically mesoporous carbon microspheres,and this research work has an important guiding significance in enriching the channel structure,preparation method and application area of hierarchically mesoporous materials.The first part of this work is adopting HMS microspheres as hard template,titanium tetraisopropanolate(TTIP)as Ti-precursor to prepare hierarchically mesoporous TiO2 microspheres,and the results show that:(1)The titania materials can duplicate the spherical shape and hierarchically meosporous structure of HMS microspheres through once-impregnation method when the amount of TTIP is ranging from 1.71 g to 2.00 g.However,there are lots of debrises and sticking bodies arrounding titania material,and the amount of these defects increases significantly when adopting more TTIP.(2)Compared with once-impregnation method,twice-impregnation method can eliminate defects effectively.The structure parameters of the sample prepared with the optimal conditions are:SBET=193.87 m2·g-1,Vtotal=0.68 cm3·g-1,DⅠ=2.9 nm,DⅡ=21.9 nm,DⅢ=115.3 nm.The second part of this work is adopting HMS microspheres as hard template,furfuryl alcohol(FA)as carbon-precursor to prepare hierarchically mesoporous carbon microspheres,and the results show that:(1)The carbon material has tubular hierarchically mesoporous structure when the amount of FA is ranging from 0.20 g to 0.26 g,and the structure parameters are that:SBE7-2294.85 m2·g-1,Vtotal=4.16 cm3·g-1,DⅠ=3.2 nm,DⅡ=5.2 nm,DⅢ=75.0 nm.(2)The carbon material has rod-like hierarchically mesoporous structure when the amount of FA is ranging from 0.32 g to 0.58 g,and the structure parameters are that:SBET=1565.61 m2·g-1,Vtotal=42.39 cm3·g-1,DⅠ=4.2 nm,DⅡ=85.6 nm.(3)Cyclic voltammetry test’s results show that:The mass specific capacitance of tubular hierarchically mesoporous carbon microspheres can reach as high as 180 F·g-1,which is better than the rod-like carbon microspheres.Meanwhile,tubular hierarchically mesoporous carbon is much more independent on scanning rates and has a lower charge transfer resistance,indicating that this structure is more conductive to the diffusion of electrolyte ions.The third part of this work is adopting single modal mesoporous silica(SMS)microspheres as hard template,FA as carbon-precursor to prepare single modal meosporous carbon microspheres and comparing with tubular hierarchically mesoporous carbon in supercapacitors area,the results show that:The mass specific capacitance and area specific capacitance of tubular hierarchically mesoporous carbon are larger than single modal carbon,indicating that the third mesopores(75.0 nm)in hierarchically mesoporous structure can improve the diffusion of electrolyte ions and increase the charge storage performance of traditional mesoporous carbon-based electrode materials.