N- and O- Doped Porous Carbon Nanosheets Prepared from Templating Methodology for Supercapacitors

Heteroatom-doped biomass-derived porous carbon materials show promising applications as electrode components in energy storage technologies. In this investigation, we present a template-assisted pyrolysis procedure to fabricate nitrogen–oxygen dual-doped carbon materials. Firstly, the precursor and template initially polymerized to form a white jelly-like gel, which was freeze-dried to create a nanosheet-assembled structure. Subsequent high-temperature pyrolysis induced the formation of a porous structure with nanosheet morphology. The CMC-ZnK sample derived from the dual template of potassium citrate and zinc acetate pyrolyzed at 800 °C exhibits optimal electrochemical performance, delivering a specific capacitance of 271.4 F g−1at 1 A g−1in a three-electrode configuration, along with outstanding rate capability (90% retention, 244 F g−1at 10 A g−1). The constructed supercapacitor demonstrated an energy density of 6.5 Wh kg−1under a power density of 500 W kg−1. Furthermore, this study systematically investigated the performance variation mechanisms at different temperatures, revealing the relationship between structural composition and temperature in biomass materials.