Doping ordered mesoporous carbon with electron-donating nitrogen and sulfur heteroatoms is a promising strategy to enhance its electrochemical performance. Here we demonstrate the successful fabrication of nitrogen and sulfur co-doped ordered mesoporous carbon (NSOMC) materials with high specific surface areas (978–1021 m² g⁻¹), large pore volumes (1.10–1.20 cm³ g⁻¹), highly-ordered pore structures and controlled dopant contents (10.0–4.8 at.% for nitrogen and 1.7–2.6 at.% for sulfur) using the oligomer of pyrrole as the precursor and sulphuric acid as the catalyst and sulfur source. NSOMC materials exhibit enhanced electrochemical double-layer capacitance (EDLC) performances due to their improved surface activity and conductivity compared with pure carbon CMK-3. The fabrication of nitrogen and sulfur co-doped ordered mesoporous carbon with enhanced electrochemical capacitance performance provides a viable route to promote its applications in electronic devices.

The utilization of electrode materials with high-performance and low-cost is crucial for the development of electrochemical energy storage devices. Waste engine oil is a toxic and hazardous waste; it is estimated that about 45 million tons of waste engine oil are generated per year worldwide. Herein, waste engine oil was first recycled as a raw material to fabricate hierarchical porous carbon nanosheets. The obtained material exhibited high specific surface area (up to 2276 m² g⁻¹), hierarchical porous structure, and excellent capacitance performance. Its specific capacitance reached 352 F g⁻¹, and more than 87.7% of initial capacitance was retained when the current density was increased from 0.5 to 20 A g⁻¹. In addition, no apparent capacitance drop was observed after 5000 charge and discharge cycles. The superior capacitance performance than that of the commercial activated carbon and most of the waste-derived porous carbons, cheap and readily available raw materials, and environmental benefit due to proper recycling of the hazardous waste make the reported hierarchical porous carbon nanosheet a promising energy storage material.