Preparation of S/N co-doped graphene through a self-generated high gas pressure for high rate supercapacitor

At present, the application of doped graphene have been widely studied in supercapacitor, but the preparation of co-doped graphene electrode materials for high rate performance supercapacitor is still a challenge. In this work, we reported an effective method to prepare S/N co-doped graphene (SNG-H) through a self-generated high gas pressure by heating graphene with (NH4)(2)SO4 and melamine in a sealed vacuum copper tube under 600 degrees C. During heating treatment, the self-generated high gas pressure was formed by pyrolysis of the precursors in a sealed space. The X-ray photoelectron spectroscopy result showed that N and S atomic percentage of SNG-H were 6.22 at% and 2.82 at% which higher than that doped method using inert gas. This result indicated that the self-generated high gas pressure by pyrolysis of the precursors in a sealed space promoted the incorporation of heteroatoms into the lattice of graphene. Meanwhile, this method avoided the resources consumption of using inert gas (N-2 and Ar) and effectively reduced gas pollution emissions. As the supercapacitor electrode material, the specific capacitance of SNG-H electrode material reached 264.3 F g(-1) at 0.5 A g(-1) and showed excellent rate capability at 200 mV s(-1) in a three-electrode system. SNG-H also exhibited high capacitance performance, excellent rate capability (82% capacitance retention from 1 to 20 A g(-1)) and excellent cycling stability (95%) after 5000 cycles at 5 A g(-1) in a symmetric two-electrode system. SNG-H was prepared through a self-generated high gas pressure in a sealed vacuum copper tube under 600 degrees C. This method improved the content of doped heteroatoms in SNG-H and enhanced the supercapacitor rate performance of SNG-H as an electrode material.