Formaldehyde gas sensor with 1 ppb detection limit based on In-doped LaFeO₃ porous structure

The real-time detection of formaldehyde is of great importance in the environmental pollution monitoring and healthcare. LaFeO₃ is one of the potential candidate sensing material for formaldehyde detection due to high sensitivity and good stability. However, the working temperature, the detection limits and the anti-jamming capability still need to be further improved. In this work, In-doped LaFeO₃ porous structure was synthesized by a facile sol-gel method to improve the material sensing capability. The gas sensing measurements indicates that the response value is 122 towards 100 ppm formaldehyde at optimal temperature of 125 °C, 2 times increment over that of pristine material. More importantly, the sensor demonstrates distinct response even when the concentration of formaldehyde steam reach as low as 1 ppb, which is as far as we know the lowest detection limit in the record. Further characterization and theoretical calculation reveals that the improved sensing performance closely relates to the increased surface area, abundant oxygen vacancies, and reduced surface adsorption energy. These results suggest that In-doped LaFeO₃ is a promising formaldehyde sensing material for the practical application.