Glucose-derived activated carbons for supercapacitors: comparison between single O doping and N/O co-doping

Single O-doped and N/O co-doped activated carbons (ACs) are prepared via hydrothermal synthesis (HTS) and a subsequent KOH activation with glucose as precursor and egg solution as nitrogen source. Controlling the activation temperature and mass ratio of activation agent KOH to HTS product (biochar), we tailor the surface area, porous structure as well as the amounts of heteroatoms of the prepared ACs. Using 6 M KOH solution as electrolyte, the electrochemical properties of all the prepared ACs are analyzed. For the same activation parameters, the single O-doped ACs exhibit very similar porous structure and possess a higher heteroatom amount than the N/O co-doped ACs. The N/O co-doped ACs exhibit superior capacitive behavior to the corresponding single O-doped ACs and achieve a specific capacitance of 417 F/g at a current density of 0.5 A/g and 334 F/g at 20 A/g. This work demonstrates a cheap and green route to produce high-performance ACs and helps to have a deeper understanding of the effects of the heteroatoms on the electrochemical properties of ACs.