Synthesis of In 2 O 3 nanostructures with different morphologies as potential supercapacitor electrode materials

In this study performed using a chemical vapor deposition (CVD) system, one-dimensional (1-D) single crystal indium oxide (In 2 O 3 ) nanotowers, nanobouqets, nanocones, and nanowires were investigated as a candidate for a supercapacitor electrode material. These nanostructures were grown via Vapor–Liquid–Solid (VLS) and Vapor–Solid (VS) mechanisms according to temperature differences (1000–600 °C). The morphologies, growth mechanisms and crystal structures of these 1-D single crystal In 2 O 3 nanostructures were defined by Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HR-TEM), X-Ray Diffraction (XRD) and Raman Spectroscopy analyses. The elemental analyses of the nanostructures were carried out by energy dispersive X-Ray Spectroscopy (EDS); they gave photoluminescence (PL) spectra with 3.39, 2.65, and 1.95 eV band gap values, corresponding to 365 nm, 467 nm, and 633 wavelengths, respectively. The electrochemical performances of these 1-D single crystal In 2 O 3 nanostructures in an aqueous electrolyte solution (1 M Na 2 SO 4 ) were determined by Cyclic Voltammetry (CV), Galvanostatic Charge Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS) analyses. According to GCD measurements at 0.04 mA cm −2 current density, areal capacitance values were 10.1 mF cm −2 and 6.7 mF cm −2 for nanotowers, 12.5 mF cm −2 for nanobouquets, 4.9 mF cm −2 for nanocones, and 16.6 mF cm −2 for nanowires. The highest areal capacitance value was observed in In 2 O 3 nanowires, which retained 66.8% of their initial areal capacitance after a 10000 charge-discharge cycle, indicating excellent cycle stability. © 2017 Elsevier B.V.