CO sensing mechanism of LaCoO3

• LaCoO3 thick films have very good CO gas sensing properties at low temperatures.
• The sensor response to 1% CO is 7.83 at a temperature as low as 200 °C.
• The CO sensing mechanism is clarified by the DRIFT investigations.
• The reaction of CO with adsorbed O2 on the LaCoO3 surfaces plays a key role.

Porous LaCoO3 films with a thickness of ~ 5 μm were printed on Al2O3 ceramic substrates by means of screen printing, and the CO gas sensing properties of the LaCoO3 thick films were characterized in the CO concentration range of 0.01%–1% and the temperature range of 200 to 600 °C. Sensors based on LaCoO3 films displayed high response, excellent recovery and good stability to CO gas; the sensor response to 1% CO was 49.23 at 600 °C, and 7.83 at a temperature as low as 200 °C. According to the DRIFT spectroscopy investigation, the CO sensing is a thermally activated surface oxidation process.