High performance of nanoporous carbon in cryogenic hydrogen storage and electrochemical capacitance

Nanoporous carbon materials were synthesized by a two-step casting process using zeolite 13X as template. The nanoporous structures were characterized by X-ray diffraction, high resolution transmission electron microcopy and nitrogen sorption at 77 K, and the results show that pore filling in the zeolite channels could play an important role in the replication of zeolite-like structural order. Better pore filling led to a more ordered structure as well as higher surface area and pore volume. Further potassium hydroxide (KOH) activation improved the microporous texture to the carbon framework and resulted in higher surface area and pore volume. A large hydrogen uptake capacity of 6.30 wt.% has been achieved at 77 K and 20 bar. Besides, a high gravimetric capacitance of up to 160 F g−1 and an energy density of 30 W h kg−1 have been obtained when tested as an electrode for supercapacitors. The high performance in cryogenic hydrogen storage and electrochemical capacitance were closely correlated with the pore structures of the carbon materials.