Ultrahigh surface area polypyrrole-based carbons with superior performance for hydrogen storage

Abstract

Ultrahigh surface area carbons (3000–3500 m² g⁻¹) have been obtained via chemical activation of polypyrrole with KOH. The carbon materials exhibit large pore volumes (up to ∼2.6 cm³ g⁻¹) and possess two pore systems: one of pores in the micropore range (∼1.2 nm) and the other in the small mesopore range (2.2–3.4 nm). Some carbons also possess a significant proportion of 0.6 nm pores. Tuning of the carbon textural properties was achieved through the control of the activation parameters (temperature and amount of KOH). The carbons achieve an excellent hydrogen storage capacity of up to 7.03 wt% at −196 °C and 20 bar, which is the highest ever reported for one-step activated carbons and amongst the best for any porous material. The gravimetric hydrogen uptake of the carbons translates to a very attractive volumetric density of up to 37 g H₂ L⁻¹ at 20 bar. These carbons exhibit excellent gravimetric and volumetric capacity due to the fact that their high porosity is not at the detriment of packing density.