Soft-templating Synthesis Of Ordered Nitrogen-doped Mesoporous Carbons And Its Electrochemical Performance

Ordered mesoporous carbon?OMC?materials have attracted considerable attention in relation to their applications in energy storage/conversion systems such as supercapacitors,fuel cells and Li-ion batteries,most likely owing to their unique features including regular and diverse pore arrays,large specific surface areas,tunable pore sizes as well as good electrical conductivity.In recent years,the researchers have found that heteroatoms doped in porous carbon materials,such as boron,nitrogen,sulfur and phosphorus,can enhance the surface polarity and electron-donor affinity of carbon materials,leading to desired performance in many aspects of their applications.For example,when porous carbons are used as the electrode materials of supercapacitors,nitrogen doping can improve electrode wettability and electrical conductivity while providing additional pseudocapacitance,contributing to a high energy density and power density.So far,the nitrogen doping of OMCs is mostly based on the conventional hard-template route,the non-aqueous solvent evaporation induced self-assembly?EISA?route or the post-synthesis modification.These step-by-step methods exist many common shortcomings,such as involved multiple time-consuming processing steps,limited batch size and high cost,not suitable for large-scale producing and industrial application.In this paper,aiming at the shortcomings of the above synthesis methods,we developed new routes to synthesize NOMCs in large-scale employing organic-organic self-assembly method whether in aqueous media or in a solevent-free condition.The specific works are as follows:1.We have described a simple aqueous cooperative assembly route to produce highly ordered nitrogen-doped mesoporous carbons by using basic amino acids as either polymerization catalysts or nitrogen dopants.This method allows the large-scale production of nitrogen-doped OMCs with tunable composition,structure and morphology while maintaining highly ordered mesostructures.As demonstrated,two phenol derivatives,resorcinol and 3-aminophenol,can be used as carbon sources to synthesize OMCs with adjustable nitrogen contents from ¹wt% to ⁶ wt%;two commercial block copolymers with different hydrophilic/hydrophobic feature,F127 and P123,can be used as micelle templates to synthesize OMCs with cubic Im₃m or hexagonal p6 m symmetry;two typical basic amino acids,L-lysine and L-arginine,can be used as catalysts to synthesize OMCs with different product sizes.The specific surface area of the produced OMCs is typically ⁶00 m2g-1,and the BJH pore size can be adjusted from 2.4 to 5.4 nm.An additional chemical activation can boost the surface area up to 1866 m2 g-1 without destroying ordered mesostructures or causing nitrogen functionality loss.When used as the supercapacitor electrode material,this material shows a high specific capacitance and a good rate capability.With an areal mass loading of ³ mg cm-2,the activated OMC yields a high specific capacitance of 186 F g-1at a current density of 0.25 A g-1and a good capacitance retention of 75% at a high discharge current density of 20 A g-1 in ionic liquid electrolyte.Increasing the mass loading to ¹2 mg cm-2 only gives rise to a 10%capacitance decay at 20 A g-1.2.We have improved a simple and one-pot solvent-free cooperative assembly approach for the synthesis of highly ordered mesoporous carbons with good thermal stability by employing 3-aminophenol and terephthalaldehyde as a precursor pair.The main features of this method include three aspects.?a?we directly adopted 3-aminophenol as a precursor instead of conventional resorcinol to produce NOMCS without destroying the ordered mesostructures in a solvent-free method.?b?with a deep understanding of polymerization mechanism of phenol and formaldehyde in solvent-free system,we have changed the way of polymerization process by adjusting the molar proportion of 3-aminophenol and tere-phthalaldehyde,as a result we obtained ordered mesoporous carbon product with high thermal stability.?c?two commercial block copolymers with different hydrophilic/hydrophobic feature,Pluronic F127 and F108,can be used as micelle templates to synthesize OMCs with hexagonal p6 m or cubic Im₃ m symmetry.This solvent-free method a simple and efficient route to produce highly ordered nitrogen-doped mesoporous carbons which brings in much good in chemical economy,environmental benignity,and scaling-up.