Probing the Structural Dynamics of In₂O₃ Using in Situ Raman Spectroscopy: Bridging Material Dynamics and Sensor...

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Metal oxide semiconductor (MOS) gas sensors require high operating temperatures, limiting their practical application.
• Understanding the dynamic evolution of active phases during sensing is crucial for optimizing MOS sensor performance but lacks real-time characterization.
• Room-temperature operation and enhanced sensitivity are key goals for next-generation gas sensors.

Purpose of the Study:

• To develop phase-engineered Indium oxide (In2O3) homojunctions for high-performance room-temperature gas sensing.
• To investigate the dynamic structural changes and active phases of In2O3 during gas sensing using in situ techniques.
• To establish a structure-activity relationship linking transient material dynamics to macroscopic sensor functionality.

Main Methods:

• Graphene-assisted hydrothermal synthesis to create cubic/rhombohedral In2O3 homojunctions.
• Fabrication of In2O3/graphene (In2O3/G) hybrid gas sensors.
• In situ Raman spectroscopy to monitor structural evolution during NO2 gas exposure.
• Performance evaluation of sensors at room temperature, measuring response and sensitivity.

Main Results:

• Optimized In2O3/G hybrid sensors demonstrated a 20-fold enhancement in NO2 response at room temperature compared to pure In2O3.
• A reversible phase transition between cubic and rhombohedral In2O3 was observed in real-time during gas exposure.
• The rhombohedral In2O3 phase was identified as the dominant active site for NO2 adsorption and desorption.
• High sensitivity and ultra-low power consumption were achieved for NO2 detection.

Conclusions:

• Phase engineering of In2O3 via homojunctions is an effective strategy for achieving high-performance room-temperature gas sensing.
• Real-time in situ characterization revealed the critical role of the rhombohedral phase and its reversible transition in NO2 sensing.
• The study provides a generalizable methodology to correlate nanoscale material dynamics with device performance, enabling rational sensor design.