Catalyst-free solvothermal synthesis of ultrapure elemental N- and B-doped graphene for energy storage application

Abstract

Even though atomically thin graphene has excellent electronic mobility, is flexible and promptly removes unwanted heat from device interfaces, the wonder material is not yet been able to be employed in energy sector due to unavailability of electrochemically active sites. Doping graphene not only is expected to generate electrochemically active sites, will enhance inter-layer distance as a consequence of doping (up to 6 Å). On-demand tunable high level of doping of graphene is thus desirable to enable it for energy sector applications. While Raman spectroscopy of doped graphene attained via solvothermal method, attests to chemical fingerprints of doped graphene systems, X-ray photoelectron spectroscopy establishes that doping of graphene (as high as ~19.8%) by nitrogen and boron has been attained. While pristine as well as B-doped graphene exhibited EDLC behaviour, N doped graphene exhibited excellent signatures of pseudo-capacitive energy storage behaviour with energy density of 170 Wh/kg and power density as high as 8.3 kW/kg. Solvothermal technique of doping graphene being single step, facile and economic; seems to have great potential for pseudo-capacitive energy storage applications where scalable production of doped graphene is needed.