A facile method for preparing nitrogen-doped graphene and its application in supercapacitors

Nitrogen-doped graphene (N-doped graphene) produced from dried distillers grains with solubles (DDGS) is an extremely attractive material for energy storage due to the high specific capacitance and low cost. The as-prepared samples are derived from DDGS, an inexpensive byproduct from fermentation processed optimized for first generation bio-fuel production. The scanning electron microscopy, transmission electron microscopy results demonstrate the 700 °C treated sample (N-700) displays crumpled nanosheets and few-layer graphene nanostructure. XRD and Raman spectroscopy indicate N-700 presents the distinctive graphene diffraction peaks. The XPS of N-700 shows the N 1s can be split into pyrrolic-N and pyridinic-N. The cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy were measured based on N-700. A high specific capacitance of 324 F g^-1, and a relatively low inner resistance of 0.1 ω were obtained.