CO2-induced architectural transition of hierarchically porous carbon in reverse microemulsion system

Abstract

A novel approach is provided to control the morphology and the structure of hierarchically porous carbon (HPC) materials with well-ordered mesoporous structure. A water-in-oil reverse microemulsion (F127/MMA) was employed as the reactive system and resorcinol and p-phthalaldehyde as the reactant with one-pot method by using compressed CO2. Specially, the morphology of the as-made HPC can be transformed from nanosphere to 3D network by simply increasing the pressure of CO2. Meanwhile, the porous structure of the obtained sample can be turned from mesopores/micropores to macropores/mesopores/micropores. The obtained HPC exhibits excellent performance in the CO2 adsorption, drug delivery, and supercapacitor electrode. Furthermore, the mechanism of the transformation of HPC was discussed via investigating the solution. The results imply that CO2 plays a decisive role to change the state of solution from the reserve microemulsion to Winsor type I microemulsion, leading to morphological and porous structural transformation of the as-prepared HPC. Different from conventional acid/base or inorganic additives as catalyst, CO2 can not only be employed as an acid catalyst in the crosslinking of the precursors, but also be a controller of the structure transformation of HPC. This strategy can provide a novel route to develop architectural design of HPC in green processes.