▎ 摘　　要

The aqueous extract of Hibiscus sabdariffa L., which is inherently non-toxic, environmentally friendly and cost effective, was used as a green reducing agent to chemically reduce graphene oxide (GO). The GO and reduced graphene oxide by the aqueous extract of Hibiscus sabdariffa L. (HRGO), prepared under different conditions, were characterized. The characterization was conducted to better understand the evolution of HRGO from GO. The flexible graphene film electrodes were fabricated using the synthesized HRGO as a primary material that exhibited a good specific capacitance of 133.07 F g(-1), which attributed to the surface modification of the HRGO using the extract of Hibiscus sabdariffa L. Furthermore, over four orders of magnitude in electric conductivity (while the sheet resistance decreased from 0.63 M Omega/sq. to 36.50 Omega/sq.) were achieved with an excellent specific capacitance of 204.38 F g(-1) when the HRGO was treated in a household microwave oven. (C) 2014 Elsevier Ltd. All rights reserved.