Effect of meso- and micropore structures on the hydrogen storage properties of nanoporous carbon materials

We report on the pore structure and hydrogen storage properties of nanoporous carbon (NPC) prepared by KOH activation of rice husk ash. The specific surface area of the NPC increased from 220 to 2770 m2/g with an increase in KOH/rice husk ash weight ratio from 1:1 to 7:1. In addition, the micropore volume of the NPC increased from 0.08 to 0.73 cm3/g with an increase in KOH quantity. Furthermore, the mesopore volume also increased from 0.08 to 2.17 cm3/g. Results of pore size distribution studies indicated NPC pore size widening from the micropore to the mesopore scale with the addition of further KOH. The stored hydrogen content of the NPC therefore increased with the development of the pore structure. From these results, we propose that this change in pore size is responsible for the increase in stored hydrogen content in NPCs.