Nanoporous carbons from natural lignin: study of structural–textural properties and application to organic-based supercapacitors†
Lignin-derived nanoporous carbon with narrow and tuneable pore size distribution has been produced by activation with potassium hydroxide (KOH). The results manifest the competition between the oxidation reaction of carbon and the intriguing C–C bond re-organization provoked by the chemical activation. A trend between the average pore size and the in-plane crystal size of few-layer graphene is observed. The ability for non-Faradaic charge storage is negatively affected by the graphenization degree. The ion-sieving effect is detected for carbon materials with an average pore size below 0.9 nm, suggesting at least partial solvation of electrolyte ions inside pores. Capacitance values up to 87 F g−1 in an organic based electrolyte are obtained.