Effect of Cu Doping on Synthesis, Composition and Sensor Properties of In₂O₃ Nanostructures

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Indium oxide (In2O3) is a promising semiconductor material for gas sensing applications.
• Controlling the crystalline phase and morphology of In2O3 is crucial for optimizing its properties.
• Doping with transition metals like copper can significantly alter the electronic and sensing characteristics of In2O3.

Purpose of the Study:

• To synthesize copper-doped In2O3 nanocomposites using a hydrothermal method.
• To investigate the effect of solvent choice (water vs. alcohol) on the crystal structure and morphology of Cu-In2O3.
• To evaluate the influence of copper doping and crystal phase on the gas sensing performance towards H2 and CO.

Main Methods:

• Hydrothermal synthesis of Cu-doped In2O3 nanocomposites with varying copper content (1-3 wt.%).
• Solvent variation (water or alcohol) to control the resulting In2O3 crystal phase (cubic or rhombohedral).
• Characterization of structural, morphological, and compositional properties of the synthesized materials.
• Fabrication and testing of gas sensors based on the synthesized nanocomposites to assess H2 and CO detection.

Main Results:

• Synthesis yielded Cu-doped In2O3 nanocomposites with uniform Cu distribution.
• Water-based synthesis resulted in cubic In2O3, while alcohol-based synthesis produced rhombohedral In2O3, independent of copper content.
• All composites exhibited a porous structure influenced by the solvent.
• Copper doping increased film resistance and lowered operating temperature for both phases.
• Sensory response to H2 and CO increased in cubic Cu-In2O3 but decreased in rhombohedral Cu-In2O3.

Conclusions:

• The solvent plays a critical role in determining the crystal phase of hydrothermally synthesized In2O3.
• Copper doping enhances the gas sensing properties of In2O3, with the cubic phase showing improved sensitivity to H2 and CO.
• Cu-doped In2O3 presents a tunable platform for developing efficient gas sensors, with performance dependent on both doping and crystal structure.