Ultrathin 2D nitrogen-doped carbon nanosheets for high performance supercapacitors: insight into the effects of graphene oxides.

Ultrathin 2D nitrogen-doped carbon nanosheets with a thickness of about 5 nm have been facilely synthesized from potato starch by using graphene oxides (GO) as the structure-directing agent. The pore structures and surface properties can be feasibly and rationally tailored by addition of a certain amount of GO in the precursor. The addition of GO to the potato starch can increase the surface areas and the pyridinic-N and pyrrolic-N ratios of the as-prepared 2D carbon nanosheets. The as-obtained ultrathin nitrogen-doped carbon nanosheets with the optimized amount of GO in potato starch (3 wt%) possess a unique 2D structure, a high N content, and high ratios of pyridinic-N and pyrrolic-N, exhibiting a high capacitance of 301 F g-1 at 0.5 A g-1, superior rate capability of 81% at 50 A g-1, and good cycling stability in 6 M KOH electrolyte. Experimental and theoretical results show that high pyridinic-N and pyrrolic-N ratios in the NCNSs are beneficial for improving the electrochemical performance. This work may provide helpful guidance for understanding the effect of the addition of GO to biomass precursors on the electrochemical performance of the 2D nitrogen-doped carbon electrodes for supercapacitors.