Nitrogen Self-Doped Porous Carbon Materials Derived from a New Biomass Source for Highly Stable Supercapacitors

Nitrogen self-doped porous carbon materials with large surface area and excellent cycle stability are successfully synthesized from the waste of Pteroceltis tatarinowii Maxim (PTM) bark for the first time. During the synthesis procedure, ethanol is introduced to ensure a homogeneous mixture and good contact of the precarbonized PTM bark with the activating agent (KOH or ZnCl2), resulting in a unique porous structure. The obtained KOH activated carbon (K-AC) possesses a hierarchical porous structure with a high specific surface area of 1721 m(2) g(-1) and small amount of nitrogen (0.3 wt%). Interestingly, ZnCl2-activated carbon (Zn-AC) shows a micropore structure with a narrow pore size distribution (0.5-2.0 nm) and a higher nitrogen content of 3.0 wt%. The electrochemical measurement results demonstrate that the as-prepared Zn-AC exhibits a high specific capacitance of 206 F g(-1) at a current density of 0.5 A g(-1), good rate performance and excellent cycle stability with capacitance retention of 99% over 10,000 cycles. In contrast, K-AC retains only approximately 89% of the initial capacitance value after 10,000 cycles. Thus, such waste PTM bark-derived carbon material, obtained by the ZnCl2 activated method, is a promising candidate material as an electrode for highly stable supercapacitors.