Acetone sensing properties and mechanism of nano-LaFeO3 thick-films

LaFeO3 nanocrystalline powders prepared by sol-gel method with annealing at 800 °C for 4 h can sensitively detect low concentration of acetone. When exposed to 0.5 ppm acetone, the response of LaFeO3 thick film at 260 °C is 2.068 with response time of 62 s and recovery time of 107 s, respectively. The possible acetone sensing mechanisms for LaFeO3 sensor are investigated with first principles calculations. Calculated results demonstrate that acetone could release electrons to the surface of LaFeO3 (010) pre-adsorbed with oxygen species O− and O2−. The acetone molecule reacts with oxygen species in the following ways: (1) adsorbs on oxygen species O− or (2) replaces of the weakly pre-adsorbed oxygen species O2− on Fe site, accompanying the formation of oxygen molecule. These above two processes may play important roles in acetone sensing for LaFeO3. We also find that the acetone molecule can be directly adsorbed on Fe site, transferring some electrons to the LaFeO3 (010) surface. The latter processes may also provide additional contribution to acetone sensing.