Pore size control of ordered mesoporous carbon by amino acid addition in solvent-free soft-template preparation

Abstract

The solvent-free soft template method is expected to be a promising scale-up preparation method for ordered mesoporous carbons because of its simple procedure. In order to expand the application possibilities of ordered mesoporous carbons prepared by solvent-free soft template method, we have developed the controlling method for pore size and structure by tuning the packing parameter of self-assembled carbon precursor composites. The self-assembled composites are composed of hydrophobic cores of triblock copolymers and hydrophilic shells of resorcinol interacted with hydrophilic tails of triblock copolymers. In this study, L-glutamic acid and L-cysteine with different hydrophilicity/hydrophobicity were added to the precursors. The addition of hydrophobic L-cysteine increased the packing parameter (the g value), which transformed the ordered structure from 1D channel-like pore structure to wormhole-like 3D pore structure. The mesopore size was decreased because the L-cysteine in the hydrophobic core is carbonized and incorporated into the pore wall. On the other hand, the addition of hydrophilic L-glutamic acid reduced the packing parameter (the g value) and the core-shell structure was no longer maintained. As a result, aggregates of uniform nanoparticles were formed. The size of mesopores formed between nanoparticles is larger than the above ordered carbons. The addition of amino acids appropriately increased the nitrogen content of carbon materials. When used as electrodes, mesoporous N-containing carbon with a larger pore size and 1D structure exhibited high double-layer capacitor performance. In summary, this study proposed a new method for controlling the pore size of ordered mesoporous carbons in solvent-free soft-template method.