A highly selective and sensitive H₂S sensor at low temperatures based on Cr-doped α-Fe₂O₃ nanoparticles

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Iron oxide (α-Fe₂O₃) is a promising semiconductor material for gas sensing applications.
• Developing selective and sensitive H₂S gas sensors is crucial for environmental monitoring and industrial safety.

Purpose of the Study:

• To synthesize chromium (Cr)-doped α-Fe₂O₃ nanoparticles using a cost-effective and eco-friendly hydrothermal method.
• To investigate the gas sensing properties of Cr-doped α-Fe₂O₃ for hydrogen sulfide (H₂S) detection.
• To optimize the Cr doping concentration for enhanced H₂S sensing performance.

Main Methods:

• Hydrothermal synthesis of α-Fe₂O₃ nanoparticles.
• Systematic doping of α-Fe₂O₃ with varying concentrations of chromium (0–8.0 wt%).
• Characterization of gas sensing performance, including sensitivity, selectivity, and response/recovery times at different temperatures.

Main Results:

• The synthesized Cr-doped α-Fe₂O₃ nanoparticles exhibited high sensitivity and selectivity towards H₂S gas.
• The sensor with 4.0 wt% Cr doping demonstrated the highest response (213) to 50 ppm H₂S at 100 °C.
• Cr incorporation enhanced the specific surface area and promoted H₂S oxidation and oxygen adsorption.

Conclusions:

• Chromium doping is an effective strategy to improve the H₂S sensing performance of α-Fe₂O₃ nanostructures.
• The developed Cr-doped α-Fe₂O₃ material shows potential for fabricating high-performance H₂S gas sensors.
• The enhanced sensing mechanism involves increased surface area and improved catalytic activity for H₂S oxidation.