Structural and Gas-Sensitive Characteristics of In₂O₃: Effect of Hydrothermal/Solvothermal Synthesis Conditions

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Indium oxide (In2O3) is a promising semiconductor material for gas sensors.
• Controlling the synthesis of In2O3 nanoparticles is crucial for optimizing their performance.
• Solvent choice and additives significantly influence nanoparticle properties.

Purpose of the Study:

• To investigate the effect of different solvents (water, alcohol, ethylene glycol) and additives (urea, glycine) on the synthesis of In2O3 nanoparticles.
• To characterize the synthesized In2O3 nanopowders.
• To evaluate the hydrogen gas-sensing properties of the In2O3-based sensors.

Main Methods:

• Hydrothermal/solvothermal synthesis of In2O3 precursors at 200 °C.
• Annealing of precursors to obtain In2O3 nanoparticles.
• Characterization using X-ray diffraction (XRD), electron microscopy (SEM, TEM), nitrogen adsorption, and X-ray photoelectron spectroscopy (XPS).
• Gas sensing measurements for hydrogen detection in air.

Main Results:

• The solvent type determined the phase composition and structure of In2O3.
• Organic additives (urea, glycine) reduced particle size and increased specific surface area.
• Addition of glycine to an alcohol solvent induced a phase transformation in In2O3.
• The sensor based on In2O3 synthesized with glycine in alcohol exhibited superior hydrogen sensing properties.

Conclusions:

• Solvent and additive selection are critical parameters for tailoring In2O3 nanoparticle properties for gas sensing applications.
• Glycine as an additive in an alcohol solvent is particularly effective for enhancing hydrogen sensitivity.
• The developed In2O3 nanoparticles show significant potential for hydrogen gas detection.