Intrinsic defect-rich porous carbon nanosheets synthesized from potassium citrate toward advanced supercapacitors and microwave absorption

Rationally introducing intrinsic defects in porous carbon framework is highly desired for extending the utilizing scope of carbon materials, but it remains a challenge. Herein, a simple yet effective strategy has been proposed to fabricate intrinsic defects-rich porous carbon nanosheets in a sealed tube (S–PCN) by using potassium citrate as the only raw material. The interior pressure in the sealed tube induces the formation of intrinsic defects, and the density of defects can be regulated by the volume of sealed tube. The obtained S-PCNs give rationally organized pore structures with uniformly distributed intrinsic defects. Benefitting from the redistributed surface charges, enhanced wettability, and electrochemical surface area, the supercapacitors with optimal S–PCN as the electrodes perform much higher specific capacitances and excellent rate capability, and deliver a high energy density of 5.54 Wh kg−1 at ultrahigh power density of 50 kW kg−1. In addition, the high density intrinsic defects can also bring strong polarization loss and balance the impedance matching. As a result, even with an ultralow filler loading of 5 wt%, the optimal S–PCN as electromagnetic waves absorbers exhibits a maximum reflection loss as strong as −58.2 dB, meaning that nearly all the incident microwaves can be effectively consumed.