High-sensitivity ethanol vapor detection using In₂O₃@ZnO core-shell nanomeshes fabricated via block copolymer...

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Metal-oxide semiconductor nanowires offer high surface area and tunable properties for gas sensors.
• Indium oxide (In2O3) nanowires are effective gas-sensing materials but can be further improved.
• Core-shell nanostructures can enhance the performance of semiconductor gas sensors.

Purpose of the Study:

• To fabricate and optimize In2O3@ZnO core-shell nanowires for enhanced ethanol gas sensing.
• To investigate the impact of ZnO coating and annealing on the sensing performance and stability.
• To explore the potential of these nanostructures for detecting volatile organic compounds (VOCs).

Main Methods:

• Single-step synthesis of In2O3 nanowires using block copolymer templates.
• Atomic layer deposition (ALD) to coat In2O3 nanowires with a thin ZnO layer.
• Annealing at 400 °C to optimize the core-shell heteronanostructure.
• Gas sensing measurements to evaluate response and sensitivity to ethanol vapors.
• Structural characterization using techniques to assess crystallinity and morphology.

Main Results:

• Optimized In2O3@ZnO core-shell nanowires (10 nm ZnO shell, annealed at 400 °C) showed a response ratio (R0/R) of ~245 at 100 ppm ethanol, a significant improvement over bare In2O3 nanowires (~120).
• The sensitivity of the core-shell structures was approximately 2.28 ppm⁻¹ in the 10-100 ppm range, compared to 1.01 ppm⁻¹ for bare In2O3.
• The In2O3@ZnO heterostructures demonstrated excellent long-term stability under varying humidity conditions.
• Structural analysis confirmed a porous, interconnected nanowire architecture with improved crystallinity after annealing.

Conclusions:

• The In2O3@ZnO core-shell heteronanostructures exhibit significantly enhanced ethanol-sensing performance due to their unique electronic structure and high surface-to-volume ratio.
• High-temperature annealing is crucial for improving the crystallinity and sensing capabilities of the nanostructures.
• These porous core-shell nanowires show great promise for sensitive and stable detection of low-concentration ethanol and other VOCs in advanced gas-sensing applications.