A chemical vapor deposition technique using electron cyclotron resonance technology was used to grow graphene sheets perpendicular to a silicon substrate. The sheets were then doped with nitrogen microwave plasma, up to a record atomic mass value of 17%. The morphology of the sheets was observed by scanning and transmission electron microscopy. Their structure was monitored using Raman and X-ray photoelectron spectrometry. Finally, electrochemical measurements were conducted in two- or three-electrode configurations using the Inac's Hybriden platform, of which one of the characterization benches is dedicated to electrochemical storage.

Doping modified the morphological (surface and porosity defects, etc.) and structural properties (electrical conductivity), significantly improving the electrical storage performances of doped graphene in comparison to non-doped material.  

Encouraged by these results, the researchers developed a button cell-type supercapacitor, using an ionic liquid electrolyte with doped graphene nanosheets. This supercapacitor was able to power an LED for 7 minutes, after only charging for less than 20 seconds.