Carbon Dioxide Gas Sensor Based on the LaCoO3/MXene Heterojunction

Carbon dioxide is one of the typical gases of a lithium battery thermal runaway. In this paper, lanthanum cobaltate (LaCoO3) nanospheres were successfully synthesized by hydrothermal synthesis route, sheet structure MXene nanomaterials were prepared by lithium fluoride (LiF) and hydrochloric acid (HCl) etching aluminum titanium-carbide (Ti3AlC2), and a CO2 sensor assembled by a LaCoO3/MXene nanocomposite was successfully constructed. The nanocomposite was observed and characterized by SEM, TEM, XRD, and XPS, and the gas sensitivity of the composite sensitive material and the single sensitive material to CO2 was systematically compared. The results show that the response of a LaCoO3/MXene nanocomposite sensor to 800 ppm of CO2 reaches 50.47% at the optimum operating temperature of 60 °C, which is 2.94 times higher than that of a pristine LaCoO3 sensor (17.16%). In addition, the LaCoO3/MXene sensors demonstrate low detection limits (50 ppm), short response/recovery times (14/32 s@ 800 ppm), and good long-term stability. The gas sensing properties of the composite may be due to the Schottky heterojunction formed between the LaCoO3 nanospheres and MXene. The results indicate that LaCoO3/MXene nanocomposites are potential CO2 sensing materials at low operating temperatures.