Facile preparation of Mn3O4/rGO hybrid nanocomposite by sol-gel in situ reduction method with enhanced energy storage performance for supercapacitor applications

Pure Mn3O4 and Mn3O4/rGO hybrid nanocomposites were synthesized by sol-gel based in situ reduction method. The structural properties of pure and nanocomposite materials were studied by XRD. The crystallite size of the Mn3O4 nanoparticle was reduced in the nanocomposite as observed by XRD analysis. SEM and TEM images depict the spherical morphology of pristine Mn3O4 nanoparticles and decoration of Mn3O4 nanoparticle on rGO sheets. Raman spectra confirm the formation of Mn3O4/rGO nanohybrid composites as the A(g) mode of Mn3O4, D, and G bands of rGO were observed in the spectra. FTIR spectra confirm the presence of various functional groups of GO and the in situ reduction of GO into rGO. The electrochemical properties of the Mn3O4 and Mn3O4/rGO composites were investigated by cyclic voltammetry analysis using 1 M KOH as an electrolyte. The cyclic voltammetry results show the pseudocapacitance behavior of Mn3O4, whereas the hybrid nanocomposite exhibits the combined behaviors of pseudocapacitance and EDLC. The chronopotentiometry analysis demonstrated that the specific capacitance of Mn3O4/rGO nanocomposite (427 F g(-1)) was relatively higher than that of Mn3O4 (136 F g(-1)) at 1 A/g. The impact of KOH electrolyte over the specific capacitance of a electrode material was comparatively analyzed with different electrolytes. The enhancement in the specific capacitance of the nanohybrid composite was attributed due to the strong electrode-electrolyte interaction of hybrid electrode material and synergetic effect of Mn3O4 and rGO.