Nitrogen-doped porous carbons with high performance for hydrogen storage

Abstract

Hydrothermally carbonized chitosan has been successfully used as a carbon source for the preparation of highly porous carbons via chemical activation. The porous carbons with different nitrogen contents (0.56–6.53 wt%) have high surface area (1362–3009 m2 g−1) and large pore volume (0.670–1.497 cm3 g−1). These properties can be varied from modifying the activation parameters (i.e., amount of activation agent and activation temperature). We observed hydrogen storage capacity of up to 2.71 wt% at 77 K and 1 bar, and 6.77 wt% at 20 bar, for PC-2-800 porous carbons. This result indicates that the hydrogen uptake of porous carbons mainly depends on the high micropore surface area related to optimum pore size. Furthermore, one found that high N-doping is beneficial for hydrogen storage at low pressure but it is detrimental at high pressure according to the analysis of hydrogen uptake isotherms.