Hydrothermally synthesized N and S co-doped mesoporous carbon microspheres from poplar powder for supercapacitors with enhanced performance

The N and S co-doped mesoporous carbon microspheres are prepared using poplar powder as a carbon source and L-cysteine as nitrogen and sulfur co-precursors via a hydrothermal process, carbonization in a tube furnace, and the removal of silica template. The as-prepared mesoporous carbon microspheres exhibit globular carbon with a variety of sizes and relatively high specific surface areas of 88.46 m2g−1. X-ray photoelectron spectroscopy (XPS) analyses reveal that the surfaces of mesoporous carbon microspheres are rich in various functional groups that contain nitrogen and sulfur. The capacitance performances of the N and S co-doped mesoporous carbon microspheres were tested using an electrochemical workstation. At a current density of 1 Ag−1, the specific capacitance of the mesoporous carbon microspheres reaches 173.66 Fg−1, which is 42.9% higher than that of the reference group. This is because co-doping with N and S reduces internal resistance of the material. Meanwhile, the diffusion impedance of the materials is reduced because of the formed pores with an increased specific area. Overall, these findings open new opportunities in the field of energy storage for the synthesis of well-developed, poplar wood carbonaceous material that has relatively high surface area and is rich in nitrogen and sulfur.Graphical abstract