Enhanced capacitance properties of nitrogen doped reduced graphene oxide obtained by simultaneous reduction and nitrogen doping

Abstract

One of the strategies employed to improve the capacitance of reduced graphene oxide is nitrogen doping. Herein, we report the effectiveness of hydrazine hydrate as a nitrogen dopant cum reducing agent. Graphene oxide synthesized by modified Hummer's method is reduced hydrothermally in the presence and in the absence of hydrazine hydrate and are labeled as NRGO-H and RGO-H, respectively. Hydrothermal reduction of graphene oxide in the presence of a small amount of (6 mu L) hydrazine hydrate results in doping of 1.66 atomic weight % of nitrogen as inferred from X-ray photoelectron spectroscopic studies. The effect of nitrogen doping on the morphology and textural properties of reduced graphene oxide is systematically studied using Raman spectroscopy, transmission electron microscope and nitrogen sorption studies. The protruding dopant prevents restacking of graphene layers, resulting in comparatively less number of graphene layers in NRGO-H than in RGO-H. Nitrogen doping also increases number of mesopores and thereby surface area. Owing to Faradaic reaction of the dopant, NRGO-H delivers higher specific capacitance (332 F g(-1)) than RGO-H (149 F g(-1)) in aqueous electrolyte (0.25M H2SO4).