Coal tar-pitch derived porous carbons with zinc oxide nanoparticles as a dual-functional template and activating agent for high-performance supercapacitors

The development of advanced carbon materials is indispensable for high-performance supercapacitors. Herein, we report the direct pyrolysis of waste coal-tar pitch (CTP) with ZnO nanoparticles (Zn NPs) to produce hierarchical porous carbon materials (HPCs). The CTP served as a carbon source, and the embedded ZnO NPs as a simultaneous templating and activating agent for HPCs. At an optimum temperature of 800 °C, the produced HPCs (HPC-800) realized an optimal specific surface area (1267 m² g^-1) and pore volume of 1.71 cm³ g^-1, enabling the devised capacitor to exhibit a specific capacitance of 172 F g^-1 at a current density of 0.1 A g^-1 in 6 M KOH electrolyte and a capacitance retention of 81% (0.1–30 A g^-1). The as-symmetrical device could deliver an energy density of 8.3 Wh∙kg^-1 at a high-power density of 50.0 W∙kg^-1 and retained energy density of 4.9 Wh∙kg^-1 at a power density of 11.9 kW∙kg^-1.