Molten salt activation for synthesis of porous carbon nanostructures and carbon sheets

We report here a molten salt (MS) process for the synthesis of nanoporous carbon structures and carbon sheets. Using glucose as the model carbon precursor, the process yields different porous carbon structures with specific surface area up to near 2000 m2/g in molten LiCl/KCl containing different dissolved oxysalts KNmOx, where Nm are nonmetal elements of H, B, C, N, P, S, and Cl. These oxysalts dissolved in LiCl/KCl exert a dominating influence on the pore formation as well as two-dimensional growth of the carbons in MS. Based on the energetics of the redox reaction between carbon and the above oxysalts, a general mechanistic explanation for the pore formation and the activation process in MS is presented. The process reported here not only provides an easy route to convert biomass molecules to carbon-based functional nanomaterials, but also opens up a new direction towards carbonization and two-dimensional growth in high temperature ionic solvent systems.