Correlation of carbon monoxide sensing and catalytic activity of pure and cation doped lanthanum iron oxide nano-crystals

• Nano-crystalline LaFe0.8Co0.2O3 sensor is capable to sense 10 ppm CO at 100 °C.
• The sensor is completely selective to CO sensing at low operating temperature (≤125 °C).
• The selectivity characteristics is correlated to the superior catalytic activities of these perovskite toward CO oxidation.

For nano-crystalline cobalt (Co) and cobalt/lead (Pb) co-doped lanthanum ferrite (LaFeO3) ceramics, we have investigated the carbon monoxide (CO) sensing characteristics. The catalytic activities toward CO oxidation were investigated for LaFeO3 and LaFe0.8Co0.2O3 powders. At an operating temperature as low as 175 °C, Co doped LaFeO3 sensors exhibit excellent low concentration (<100 ppm) CO gas sensing characteristics. Also, La0.8Pb0.2Fe0.8Co0.2O3 (LPFC) ceramics selectively senses CO at 150 °C. For LaFe0.8Co0.2O3, 0.056 mmol of CO conversion per gram of catalyst was measured at 200 °C. On the other hand, for LaFeO3 ceramics, CO conversions per gram of catalyst were recorded to be 0.004 mmol. The superior low temperature CO sensing characteristics of nano-crystalline LaFe0.8Co0.2O3 ceramics correlates well with its excellent catalytic activity toward CO oxidation. For perovskite LaFe0.8Co0.2O3 sensors it was demonstrated that lower metal-oxygen binding energy, favorable d-orbital electron configuration of Co cation, and nature of surface composition are the three dominant factors control its superior catalytic activity and the CO sensing characteristics.