A Strongly Acidic Aqueous Self-assembly Route To Mesoporous Carbons:Synthesis,Formation Mechanism,and Performance

Ordered mesoporous carbons?OMCs?with excellent physical and chemical properties show great potential applications in adsorption,catalysis,energy storage/conversion and so on.There are mainly three routes to synthesize OMCs,which are hard-template method,non-aqueous solvent evaporation-induced self-assembly?EISA?method and aqueous cooperative self-assembly method.Among them,the aqueous synthesis of OMCs generally involves the formation of mesostructured phenolic resins in dilute aqueous solutions via the hydrogen-bonding self-assembly of phenolic oligomers?or monomers?and amphiphilic block copolymers,and following high-temperature carbonization process.Compared with the other routes,the aqueous route is more intriguing because of its better reproducibility,highly regular mesostructures of the resultant products and unlimited batch size.Herein,we systematically investigated the synthesis of OMCs under strongly acidic conditions and discussed their formation mechanism.The detailed works are as follows:1 we developed a strongly acidic aqueous cooperative assembly route to synthesize OMCs through using the triblock copolymer P123 as a template and resorcinol/hexamine as a precursor pair.By replacing commonly used formaldehyde with hexamine as a cross-linking monomer,the self-assembly kinetics of resorcinol/formaldehyde resin and P123 can be well controlled,leading to the high-quality carbon materials with 2-D hexagonal mesostructure and fiberlike morphology.The sizes and structural properties of the fiberlike carbons can be tailored easily through varying reaction parameters,such as P123 concentration and reaction temperature.A coulombic interaction between resorcinolic species and P123 is proposed to be as the driving force that induces the organic-organic cooperative assembly.The produced OMCs typically possess the average mesopore size of ³.5 nm and specific surface area of ⁸00 m² g^-1.An additional KOH activation could double their specific surface area while the ordered mesostructure remains intact.The OMCs also possess excellent electrochemical capacitive performance owing to their hierarchically ordered porous structures.The specific capacitance of the activated OMCs reaches 298 F g^-1.More importantly,they also present good rate capability and cycling stability.With respect to the previously reported basic aqueous synthesis,this acidic synthesis should be adaptable to the scalable production of metal-doped mesoporous carbon materials with wide potential applications due to applied strongly acidic conditions.2 we developed a novel route for the synthesis of OMCs with 3-D body-centered cubic structure under strongly acidic conditions with the aid of inorganic salts.It was found that the structural regularity of cubic OMCs,which was templated by highly hydrophilic block copolymer F127,could be improved due to enhanced Coulombic interactions between the template and the phenolic resin in the presence of salts.Moreover,because the synthesis involved a typical Sol-gel process,the addition of the salts also gave rise to a significantly increased yield due to a “salting-out” effect.The synthesis were optimized after the influence of the conditions including salt concentrations,salt species,template concentration and reaction temperature on the structure of the carbon products was examined in detail.Based on the above investigation,the OMC single-crystals with rhombicdodecahedral morphology have been first synthesized under a strongly acidic aqueous media.The OMC single-crystals were formed through a typical layer-by-layer growth mechanism.