CuWO₄ with CuO and Cu(OH)₂ Native Surface Layers for H₂S Detection under in-Field Conditions

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Monitoring

Background:

• Hydrogen sulfide (H2S) is a toxic gas requiring sensitive detection methods.
• Existing H2S sensors often struggle with selectivity, response time, and humidity interference.
• Copper tungstate (CuWO4) is explored as a potential material for H2S sensing.

Purpose of the Study:

• To synthesize and characterize CuWO4 materials for H2S detection.
• To evaluate sensor performance under varying relative humidity (%RH) and operating temperatures.
• To investigate the correlation between material properties and H2S sensing behavior.

Main Methods:

• Chemical synthesis of CuWO4 samples (CuW1, CuW2, CuW3).
• Material characterization using XRD, SEM, Raman spectroscopy, and XPS.
• Gas sensing measurements at 150 °C with electrical resistance and work function monitoring.

Main Results:

• CuW2 exhibited superior surface recovery and stability in the presence of moisture due to a Cu(OH)2 layer.
• Linear sensor response for CuW2 from 1 to 10 ppm H2S.
• High selectivity towards H2S over CO, CH4, NH3, SO2, and NO2.

Conclusions:

• CuW2 demonstrates significant potential for H2S detection in real-world conditions.
• The material's performance is linked to its surface chemistry and structural properties.
• The study provides a theoretical basis for the observed sensing mechanisms.