Thiourea-assisted nitrogen and sulfur dual-doped carbon nanofibers for enhanced supercapacitive energy storage

Herein, using thiourea is a simple and effective approach to produce the unique structure constructed by N and S dual-doped carbon nanofibers. The surface porosity is optimized by changing the thiourea amount in the polymer solution. The optimized N/S-CNF5, which the weight percentage of thiourea to polyacrylonitrile is 5, has a high specific surface area (144.2 m(2) g(-1)) and rich content of heteroatoms (N-4.66 at% and S-0.11 at.%), respectively. Because of these unique features, N/S-CNF5 demonstrates a large gravimetric-specific capacitance (312 F g(-1) at 10 mV s(-1) and 225 F g(-1) at 1 A g(-1)). The N/S-CNF5 electrode represents in the two-electrode system with a high specific capacitance of 160 F g(-1) at 1 A g(-1) and shows a remarkable rate of performance (87.5% retention) even at 5 A g(-1). Moreover, the symmetrical supercapacitor device (N/S-CNF5//N/S-CNF5) delivers specific energy of as high as 5.5 Wh kg(-1) with a specific power of 250 W kg(-1). Also, the device's cycling ability is 78.3% even after 30 000 cycles at 1 A g(-1). This strategy can be feasible to explore more dual heteroatom-doped carbon nanomaterials for a wide range of electrochemical applications.