Enhancing the carbon dioxide sensing performance of LaFeO3 by Co doping

Owing to the poor oxidizing and reducing properties of carbon dioxide (CO2), there are few materials suitable for developing CO2 semiconductor gas sensors, among which LaFeO3 (LFO) has been proven to have CO2 sensing properties. To enhance the CO2 sensing performance of LFO, a Co doping strategy is proposed in this work. Specifically, the LFO and LaCo0.1Fe0.9O3 (LCFO) nanoparticles were prepared via a simple sol-gel method, and the corresponding LFO and LCFO sensors were fabricated. The test results showed that the LCFO sensor exhibited wide detection range (25–10,000 ppm CO2), fast response/recovery time (6/42 s), and higher response (6.69% to 1% CO2) than that of LFO sensor at the optimal working temperature of 220 °C (51.9% relative humidity (RH)). In addition, the LCFO sensor showed good resistance to wide humidity range of 0–86.7% RH. Finally, the reasons for the enhanced CO2 sensing performance of LCFO were analyzed combining characterization and theoretical calculation, which could mainly be attributed to the enhancement of oxygen vacancy and large adsorption energy caused by Co doping. This work provides a useful strategy to develop high-performance semiconductor CO2 gas sensor.