pyrolysis at 800 C in inert atmospehere + activating agent like H2O or CO2. Chemical activation, impregnation with activaqting agents like KOH or ZnCl2, pyrolysis at 600-800 C in inert atmosphere.
In addition, acid treatment can also improve the porosity and surface area, e.g., we treated pyrolyzed carbon with HNO3 which enhanced the meso- & macroporosity of the materials by creating new porosity and defect sites.