Facile synthesis of La2O2CO3 nanoparticle films and Its CO2 sensing properties and mechanisms

In this paper, we presented a simple method to fabricate size-controlled La2O2CO3 nanoparticle by annealing La(OH)3 nanocrystallines in air atmosphere. The microstructures of the samples were analyzed by high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and scanning electron microscope (SEM). TEM images indicate that the La(OH)3 precursors consists of uniform ellipsoids with width of 9-15 nm and length of 15-30 nm and La2O2CO3 are spheroidal particles with size of 12-25 nm. XRD patterns indicate that La(OH)3 nanocrystallines are hexagonal phase and transform to monoclinic La2O2CO3 after annealing. And then, La2O2CO3 nanoparticle is printed on an interdigital electrode as a sensing material for CO2 detection. La2O2CO3 sensor exhibits good cycle stability performance and fast response and recovery (53 s and 120 s) over the wide range of 300-5000 ppm CO2 in air condition. In addition, we also investigate the effect of oxygen concentration in the background atmosphere on CO2 response of La2O2CO3 sensor. The CO2 sensing mechanisms for La2O2CO3 sensor can be attributed to the interaction of CO2 with oxygen species on La2O2CO3 surface including chemisorption, surface reaction and desorption process, which also can be used to explain other metal oxide based CO2 gas sensor.