Porous LaFeO3/SnO2 nanocomposite film for CO2 detection with high sensitivity

Perovskite LaFeO3 nanocrystalline powder, synthesized by sol-gel method, was composited with SnO2 nanopowders to fabricate porous LaFeO3/SnO2 thick film sensors. The as-prepared sensors exhibit high gas sensitivity, fast response and low working temperature for CO2 detection. The optimal sensing performance of LaFeO3/SnO2 thick film sensors is obtained with the molar ratio of La/Sn = 1:1. The observed response is nearly 2 times higher than that of bare LaFeO3 at 4000 ppm CO2 and the response time is less than 20 s at 250 °C. CO2 sensing mechanism of the as-prepared nanocomposites porous film is addressed. The results demonstrate that the as-formed P-N junctions can greatly enhance the carrier transfer efficiency which is attributed to the improved sensing performance. Moreover, the hydroxyl species absorbed on the surface of the nanocomposites are also involved in the sensing process.