Physicochemical properties and supercapacitor behavior of electrochemically synthesized few layered graphene nanosheets

The study emphasizes on the scalable production and comparison of few layered graphene nanosheets (FLGNSs). The FLGNSs have been electrochemically synthesized by anionic intercalation from three different acids of 1 M of H₂SO₄ (S1), 1-M HClO₄ (C1), and 1-M HNO₃ (N1). The size distribution and stability of the as-prepared FLGNSs colloidal have been analyzed thoroughly. A yield of around 50 % was found irrespective of experimental condition. A mixed phase of graphene and its oxide form has been confirmed X-ray diffraction patterns. C1- and N1-conditioned FLGNSs had higher oxygenation as compared to S1, as confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The disorderness in the FLGNSs has been analyzed by Raman spectra. The aromaticity, surface hydroxylation, and oxygenation of the as-synthesized FLGNSs due to electrochemical reactions have been confirmed by Fourier transform infrared spectroscopy. The UV-visible spectra of FLGNSs colloidal show the electronic transition of π-π* as well as n-π*. From morphological studies, the layered and crumpled edges of the exfoliated FLGNSs have been revealed. Again, from the probe conductivity analysis, the measured conductivity of the dispersed sulfate-, perchlorate-, and nitrate-intercalated FLGNSs has been found with a decreasing trend from 1.652, 0.315, to 0.300 mS/cm for S1, C1, and N1 conditions, respectively, due to increasing of oxygen endowment in the graphene sheets. Detailed supercapacitor investigations demonstrated that the S1-conditioned FLGNSs show enhanced supercapacitor performance than C1 and N1. It possesses a maximum energy density of 20 Wh kg⁻¹ and a maximum power density of 2.5 kW kg⁻¹.