Enhanced surface and electrochemical properties of nitrogen-doped reduced graphene oxide by violet laser treatment for high charge storage and lower self-discharge supercapacitors

Abstract This work demonstrated that the performance improvement of nitrogen-doped reduced graphene oxide (N-rGO) electrodes over reduced graphene oxide (rGO) electrodes for supercapacitors could be further enhanced by violet laser treatment (VLT). A specific capacitance of 30 and 145 F g−1 was obtained for rGO and N-rGO electrodes, respectively. When using N-rGO with proper VLT, a high specific capacitance of 214 F g−1 could be achieved. In addition, the percentage of capacitive retention of the N-rGO with VLT remaining 94% after 10,000 cycles with a slower self-discharge rate at 0.55 V h−1, comparing to 0.91 V h−1 for N-rGO. Systematic investigations of N-rGO with VLT were carried out by using different film characterization techniques. The surfaces of N-rGO with VLT exhibit an increase in the number of exfoliated graphene oxide sheets with more roughness when increasing the fluence of laser. It was also found that there are the decrease in oxygen/nitrogen-containing functional groups contents and the increases in graphitic carbon phase with C C sp2-hybridization with the influence of laser. These may explain the improvements of the reported charge storage ability, electrode stability, and self-discharge rate.