Scalable production of graphene with tunable and stable doping by electrochemical intercalation and exfoliationElectronic supplementary information (ESI) available. See DOI: 10.1039/c5cp06395g

Graphene's unique semimetallic band structure yields carriers with widely tunable energy levels that enable novel electronic devices and energy generators. To enhance the potential of this feature, a scalable synthesis method for graphene with adjustable Fermi levels is required. We here show that the electrochemical intercalation of FeCl 3 and subsequent electrochemical exfoliation produces graphene whose energy levels can be finely tuned by the intercalation parameters. X-ray photoelectron spectroscopy reveals that a gradual transition in the bonding character of the intercalant is the source of this behavior. The intercalated graphene exhibits a significantly increased work function that can be varied between 4.8 eV and 5.2 eV by the intercalation potential. Transparent conducting electrodes produced by these graphene flakes exhibit a threefold improvement in performance and the doping effect was found to be stable for more than a year. These findings open up a new route for the scalable production of graphene with adjustable properties for future applications. Electrochemical intercalation and exfoliation produces graphene with a finely tunable work function between 4.8 eV and 5.2 eV which enables a threefold increase in the performance of graphene electrodes.