Rapid and Stable Detection of Carbon Monoxide in Changing Humidity Atmospheres Using Clustered In₂O₃/CuO Nanospheres

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Carbon monoxide (CO) is a toxic gas requiring sensitive detection methods.
• Metal oxide semiconductors are widely used in gas sensors.
• Improving sensor performance, especially humidity resistance, is crucial for practical applications.

Purpose of the Study:

• To synthesize clustered indium oxide/copper oxide (In₂O₃/CuO) nanospheres for CO detection.
• To investigate the effect of CuO content on the sensing properties of In₂O₃ nanospheres.
• To evaluate the CO sensing performance under varying temperature and humidity conditions.

Main Methods:

• Synthesis of In₂O₃/CuO nanospheres with varying CuO concentrations.
• Characterization using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS).
• Gas sensing measurements for CO detection at different temperatures and relative humidity (RH) levels.

Main Results:

• The In₂O₃/CuO (InCu2, 2 mol % CuO) sensor demonstrated a threefold improvement in CO response compared to pure In₂O₃.
• The InCu2 sensor exhibited a quick response/recovery time, wide linearity, and a low detection limit at 200 °C and 25% RH.
• The sensor maintained stable performance with minimal resistance and response changes across a wide humidity range (25–95% RH).

Conclusions:

• Clustered In₂O₃/CuO nanospheres are promising materials for highly sensitive and fast CO detection.
• The enhanced performance is attributed to the synergistic effects between In₂O₃ and CuO.
• CuO's affinity for hydroxyl groups helps mitigate humidity interference, leading to superior anti-humidity properties.