The synthesis of hollow carbon nanospheres from potato starch and the application in supercapacitor

The synthesis of high-valued carbon nanomaterials from biomass has always been a hot topic. The work reports the preparation of hollow carbon nanospheres (HCNs) from potato starch with one-step carbonization, in which self-made MgO powder is utilized as the template. In this study, an attempt was made to change carbonization temperature to control HCNs in diameter, wall thickness and pore distribution. Results show that the sample obtained at 800 degrees C (HCN-800) has a thinner wall thickness (about 12.1 nm), smaller and more uniform diameter (average diameter of 46.2 nm), as well as possesses a high specific surface area (619.53 m2 g- 1) and the largest pore volume (2.8994 cm3 g- 1). An application in supercapacitor has been verified for the HCNs in the work. In the three-electrode system, the HCN-800 exhibits excellent electrochemical performance, such as superior specific capacitance (324.8 F g- 1 at 0.5 A g- 1), high rate performance (215.7 F g- 1 at 50 A g- 1) and outstanding cycling stability (92.83 % capacitance retention after 10,000 cycles). Moreover, an assembled symmetric supercapacitor shows an energy density of 11.1 Wh kg- 1 at a power density of 427 W kg- 1, far exceeding that of previously reported carbon electrode materials. In short, the work provides a novel way to synthesize high-valueadded HCNs from cheap biomass precursors, which have potential applications in the field of supercapacitors and other energy storage devices.