Pyrolytic synthesis of boron-doped graphene and its application as electrode material for supercapacitors

• Boron-doped graphene was prepared by pyrolysis of graphene oxide with boric acid at 900 °C under an argon atmosphere.
• The boron doping content reached the highest value of 4.7% after 3 h of pyrolysis at 900 °C.
• The BG-900-3h electrode exhibited the highest specific capacitance of 172.5 F g−1 at 0.5 A g−1 and maintained 96.5% of initial capacity after a continuous of 5000 times cycling.

Chemical doping with foreign atoms is an effective approach to intrinsically modify the properties of the carbon materials. Herein, boron-doped graphene (BG) was prepared through pyrolysis of graphene oxide (GO) with boric acid (H3BO3) in an argon atmosphere at 900 °C. Both boron-doping and reduction of GO to graphene were simultaneously achieved under the thermal treatment processing. Namely, at high temperature condition, H3BO3 was converted into boron oxide (B2O3) accompanied by diffusing B2O3 vapor into the graphene nanosheets, then boron atoms can replace the carbon atoms inside the graphene layers and thereby substitutionally doped into the graphene lattice. The boron content in BG increased with prolonging the reaction time and reached the highest value of 4.7% after 3 h of pyrolysis, which in turn affected their electrochemical properties. The as-prepared electrode of BG-900-3h exhibits the highest capacitive behavior (172.5 F g−1, 0.5 A g−1) and superior cycling stability (maintaining 96.5% of initial capacity after 5000 times of cycling). Remarkably, the boron-doping increased the capacitance of BG-900-3h by about 80% compared to pristine graphene. These results imply that the doping of boron into graphene lattice induces remarkable performance enhancement, and thus make the doped materials superior to those of pristine graphene as electrode materials for supercapacitors.