Supercapacitor properties of V10O14(OH)2 and reduced graphene oxide hybrids: Experimental and theoretical insights

Abstract

In this work, V10O14(OH)2 nanostructure and its hybrid with reduced graphene oxide (rGO/V10O14(OH)2) have been synthesized by a simple hydrothermal process, and the supercapacitance property has been explored. The material's crystal structure, surface morphology, elemental compositions, and oxidation state of metal atoms are properly characterized. The structure and electronic properties of V10O14(OH)2 and rGO/V10O14(OH)2 are presented using Density Functional Theory (DFT) investigations. Using the cyclic voltammetry (CV) technique, the capacitance of the rGO/V10O14(OH)2 hybrid was found to be 558 Fg−1 at a scan rate of 1 mV/s, which is 2.9 times greater than the capacitance of the V10O14(OH)2 material. The hybrid material provides 94% operational stability over 5000 cycles. From the Trassatti plot, the capacitance contribution of rGO/V10O14(OH)2 and V10O14(OH)2 are estimated, and found that the maximum capacitance contribution is due to diffusion-controlled pseudocapacitance phenomena, i.e., 87.5% and 95.9%, respectively. Enhanced electronic states near Fermi level and improved quantum capacitance for the hybrid structure justify the superior charge storage performance of the integrated structure (rGO/ V10O14(OH)2) as observed in the experiment. Also, the mobility of the electrolyte ions increases in the hybrid structure due to lower diffusion energy barrier leading to better charge transfer kinetics.