Watermelon Peel‐Derived Heteroatom‐Doped Hierarchical Porous Carbon as a High‐Performance Electrode Material for Supercapacitors

Abstract This work presents for the first time the systematic characterization and excellent supercapacitor performance of heteroatom‐doped porous carbon materials (HPC) synthesized by direct pyrolysis of watermelon peel and urea via molten salt template route in air with non‐toxic activating agent. The molten salt not only protects the derived carbon from burning during high‐temperature pyrolysis, but can also be etched to generate abundant hierarchical pores in the final products. The obtained HPC exhibits a high specific surface area of 1660 m 2 g −1 and shows high specific capacitances of up to 278 F g −1 in 1 M H 2 SO 4 electrolyte. The symmetrical device also demonstrates a remarkable specific capacitance of up to 226 F g −1 and ultrahigh initial capacitance retention of 98 % after 10,000 cycles of charge/discharge at the current density of 10 A g −1 . The porous carbon produced via this green chemical activation route demonstrates great potential as electrode materials in supercapacitor.