Heterojunction formation in In2O3–NiO nanocomposites: Towards high specific capacitance

Abstract

This study focuses on (In2O3)x(NiO)100-x nanocomposites intended to be used in supercapacitors as electrode materials. Nanocomposites with different ratios of NiO and In2O3 have been synthesized and characterized using XRD, FTIR, TEM and UV–visible spectroscopy. The bandgap energy (Eg) data reveals that the minimum value of Eg in (In2O3)x(NiO)100-x nanocomposites is associated with the formation of p-n heterojunction, for (In2O3)50(NiO)50 nanocomposite, based on its highest electrical resistance, obtained through I–V measurement. The electrochemical measurements depict the pseudocapacitive behaviour of (In2O3)x(NiO)100-x nanocomposites. The CV analysis shows the highest specific capacitance for (In2O3)30(NiO)70 nanocomposite, i.e., 340, 472, 782, 1002, 1381 and 2628 Fg-1 at different scan rates 100, 50, 20, 10, 5 and 1 mVs−1 respectively. Specific discharge capacitance of the same sample is measured as 831, 707, 658 and 449 Fg-1 at 1, 2, 3 and 4 Ag-1 current densities respectively. The strong interaction between closely packed In2O3 and NiO interfaces show the superior specific capacitance in (In2O3)30(NiO)70 nanocomposites compared to neat NiO and In2O3 nanostructure, thus making (In2O3)x(NiO)100-x (x = 30) nanocomposite a suitable candidate for electrode material in electrochemical application.