Porous Carbon Prepared from Coal Tar Pitch was Doped with N/S to Prepare Supercapacitors

Coal tar pitch (CTP), a hazardous coal-chemical byproduct, requires high-value recycling for sustainable energy applications, yet precise structural and electrochemical regulation of pitch-derived carbon materials remains challenging. Herein, a facile postcarbonization N/S codoping strategy via thiourea-assisted hydrothermal treatment is developed to optimize porous carbon for supercapacitors. Traditional one-step inorganic doping severely damages carbon frameworks and restricts pore development, while hydrothermal-first preparation also delivers inferior porous structures. To overcome these drawbacks, we adopt a sequential strategy: preconstructing hierarchical porous carbon skeleton followed by thiourea-mediated N/S doping. This method well preserves carbon integrity and porous features, overcoming the inherent deficiencies of conventional doping routes. Combined SEM, XRD, and Raman results verify that this strategy enhances graphitization by eliminating amorphous carbon while maintaining intact porous architecture. The optimized PC-NS-2 sample possesses an ultrahigh micropore proportion of 97% and a large specific surface area of 1426.73 m²/g. It achieves a specific capacitance of 307 F g^-1 at 0.5 A/g and maintains 93.98% capacitance retention after 10,000 cycles at 5 A/g, showing superior electrochemical kinetics and cycling stability. The assembled symmetric supercapacitor delivers an energy density of 27.8 Wh/kg at 0.5 A/g. Such excellent performance benefits from well-preserved hierarchical pores, optimized graphitization and improved conductivity brought by N/S codoping. This work provides an efficient structure-stable doping strategy for CTP high-value utilization and offers a feasible reference for advanced carbon electrode design.