Fabrication of cubical-shaped particles/flakes/rods and flower-like morphology of In₂O₃ nanostructures: Enhanced photocatalytic dye degradation and gas sensor applications

In this study, cubic indium oxide nanostructures (c-In₂O₃) were synthesized via facile hydrothermal method and their performances in photocatalytic and ethanol gas sensor applications were studied. The influence of hydrothermal processing times had great control over the c-In₂O₃ nanostructures. Structural analysis revealed that the cubic and rhombohedral phases were observed as the hydrothermal processing times increased. The morphological investigation (HRSEM) of c-In₂O₃ nanostructures exhibited different morphologies, including irregular shapes, flower-like, and multi-pod structures. The HRTEM study also confirmed that the c-In₂O₃ nanostructures had a lattice value of 0.32 nm, corresponding to the (222) plane and the SAED pattern showed that the c-In₂O₃ nanostructures were polycrystalline in nature. Band gap energy was calculated by UV–Vis DRS spectroscopy and varied from 3.38 to 3.45 eV. Photoluminescence (PL) spectra exhibited strong deep-level emissions in the visible region. The photocatalytic activity of c-In₂O₃ photocatalyst and methylene blue (MB) dye was tested under UV light. The alkaline medium showed higher efficiency (54%), compared to the acidic and neutral mediums. For gas sensing measurements, the ethanol gas based on c-In₂O₃ nanostructures exhibited good response and recovery times, along with better long-term stability. The better gas sensing capabilities of c-In₂O₃ nanostructures was potential candidates in the ethanol gas sensor industry.