Nitrogen-doped and crumpled graphene sheets with improved supercapacitance

Nitrogen-doped thermally expanded graphene oxide (NtGO) was prepared by a facile thermal expansion and hydrothermal doping process. The thermal expansion process plays a vital role in improving the electrochemical performance of N-doped graphene by preventing its aggregation and improving its conductivity. The specific capacitance of NtGO is 270 F g(-1) at a discharge current density of 1 A g(-1) and the capacitance retention is 97% after 2000 cycles at this density. The strategy developed here provides an efficient and facile way to prepare nitrogen-doped graphene.