Pyrochlore-type La2Sn2O7 for highly selective NH3 gas sensor operating at room temperature: Sensing performance, mechanism study and application to detection of meat spoilage

Ammonia (NH 3 ), with its characteristic pungent odor, serves as a key indicator of meat spoilage, necessitating reliable detection methods for the precise assessment of meat freshness. However, the practical application of existing NH 3 sensors is limited by bottlenecks such as insufficient selectivity, relatively low sensitivity, and high operating temperatures. This study successfully fabricated high-performance NH 3 gas sensors using La 2 Sn 2 O 7 nanoparticles prepared via a facile one-step hydrothermal synthesis method. Gas-sensing performance tests revealed that the sensor exhibits a significant response value of 4.52 towards 100 ppm NH 3 at room temperature, a low detection limit down to 1 ppm. Furthermore, the sensor demonstrated superior selectivity for NH 3 compared to common interfering gases, outstanding long-term stability, and high repeatability. The research combined microstructural characterization and electrical property analysis to deeply elucidate its gas-sensing mechanism. Finally, an NH 3 detection alarm prototype device integrated with the La 2 Sn 2 O 7 sensor was designed and validated. This device effectively identified the spoilage status of chicken, beef, and lamb. Experimental results confirmed that the sensor can reliably determine the initial stage of meat spoilage by capturing trace amounts of NH 3 released at the onset of decay. This study provides a promising room-temperature operable sensor solution for practical meat quality monitoring.