A highly selective and sensitive H 2 S sensor at low temperatures based on Cr-doped α-Fe 2 O 3 nanoparticles.

Cr-doped α-Fe 2 O 3 nanoparticles were synthesized by a low-cost and environmentally friendly hydrothermal route. Their gas sensing properties were investigated and the sensor showed high sensitivity and selectivity to H 2 S gas. Different Cr doping levels from 0 to 8.0 wt% were studied, and the sensor of 4.0 wt% Cr-doped α-Fe 2 O 3 showed the largest response, with a response of 213 to 50 ppm H 2 S at 100 °C. The incorporation of Cr ions within α-Fe 2 O 3 nanocrystals increases the specific surface area, and promotes the oxidation of H 2 S and oxygen adsorption in the air. Thus, the doping of Cr into α-Fe 2 O 3 nanostructures would be a promising method for designing and fabricating high performance H 2 S gas sensors.