LaCoO3-based sensors with high sensitivity to carbon monoxide

Abstract

LaCoO₃ nanoparticles with particle sizes of ∼82 nm were prepared by co-precipitation, and mesoporous LaCoO₃ thick films with a thickness of ∼7 μm were fabricated by screen printing the nanoparticles on Al₂O₃ substrates. The CO sensing properties of the LaCoO₃ thick films were characterized in the temperature range of 100 to 550 °C. Under 5000 ppm CO at 500 °C, the thick film sensor achieved a high sensing response of ∼279.86, with response and recovery periods of 181 and 311 s, respectively. Under 25 ppm CO at 500 °C, a reasonable response of 1.04 was also achieved. Moreover, the sensor demonstrated reliable dynamic response-and-recovery at a temperature as low as 100 °C, therefore, LaCoO₃ is very promising for CO sensing at low temperatures. The high response to CO could be ascribed to the high content of O₂²⁻/O⁻ species in LaCoO₃.