Facile synthesis of nitrogen and sulfur co-doped hollow carbon nanobowls for supercapacitor applications

Bowl shaped carbon nanomaterials are attractive for supercapacitor applications due to their structural advantages and excellent electrochemical performance, as demonstrated by their specific capacitance and cycling stability in this study. This article presents the shape-controllable synthesis of N/S co-doped hollow single-layer and double-layer carbon nanobowls (HSCNs (Hollow Single-layer Carbon Nanobowls) and HDCNs (Hollow Double-layer Carbon Nanobowls), respectively) for supercapacitors via a facile, sustainable, and cost-effective one-pot hydrothermal carbonization method. The micromorphology, physical properties, and chemical composition of the HSCN and HDCN samples are analyzed. According to micromorphological analyses, both HSCN-8 and HDCN-8 samples have uniform sizes, with diameters and wall thicknesses of ∼400 nm and ∼50 nm, respectively. The formation mechanism of the double-layer structure of HDCNs is discussed. Furthermore, the performances of the supercapacitors employing activated HSCN-8 and HDCN-8 (PHSCN-8 and PHDCN-8) as electrode materials are compared, demonstrating that PHDCN-8 provides a higher specific capacitance (156.0 F g −1 ) at a current density of 1 A g −1 than that of PHSCN-8. These results indicate that PHDCN-8 has a superior electrochemical performance owing to its double-layer bowl-shaped structure and relatively higher N content. These novel electrode materials have great potential for supercapacitor application.