Graphene quantum dots (GQDs) are small graphene sheets (<100 nm) with a higher solubility relative to traditional graphene. This allows for simple chemical functionalization using traditional organic synthetic techniques. Thus far, novel functionalized GQDs have been used in materials such as organic photovoltaics and light emitting sources. However, GQDs have not seen much use in energy storage applications.

Dwight S. Seferos, University of Toronto, Canada, and colleagues have developed GQD/polymer films with properties well suited for energy storage and catalysis. Here, the outer edge of the GQDs was functionalized with 3,4-ethylenedioxythiophene (EDOT). The GQD/EDOT monomer units were subsequently electropolymerized on an Au coated Si wafer to form conjugated polymer films. The team investigated galvanostatic charge/discharge curves to calculate the capacitance, the materials ability to store electric charge, of both PEDOT (polyethylenedioxythiophene) and GQD/PEDOT films.

The capacitance of GQD/PEDOT films was found to be 152.8 F/cm³ at 1.84 A/cm³ while the capacitance of the GQD/PEDOT films had a capacitance of 120.1 F/cm³ at similar current intensities. An increase of capacitance of ca. 30 % upon incorporation of GQDs into the conducting polymer shows the promise of GQD/polymer films as materials for energy storage applications.

• Electrochemical Polymerization of Functionalized Graphene Quantum Dots,
  Mark B. Miltenburg, Tyler B. Schon, Emily L. Kynaston, Joseph G. Manion, Dwight S. Seferos,
  Chem. Mater. 2017.
  DOI: 10.1021/acs.chemmater.7b01700