Humidity-Tolerant ppb-level NOx Sensors Based on Ag2Te/CeO2 Nanocomposites for Smart Greenhouse Farming

Monitoring trace levels of nitrogen oxides (NOx) in high-humidity agricultural greenhouse environments is essential for both crop growth and workers' health. However, achieving reliable NOx detection under extreme humidity remains challenging. Herein, this work presents an ultralow-detection-limit and highly humidity-tolerant NOx sensor based on Ag2Te/CeO2 nanocomposites. To the best of our knowledge, this is the first demonstration of Ag2Te/CeO2 heterostructures for gas sensing. Among the as-prepared samples, the optimal Ag2Te/CeO2 sample, with a molar ratio of 1:2, exhibited superior response and an ultralow detection limit of 5 ppb NO2 at 65 °C. The sensor response retained over 92% of its regular response even at 99% relative humidity. Density functional theory (DFT) calculations suggest that minimal H2O adsorption on Ag2Te and strong NO2 adsorption on CeO2, along with the formation of an n-n heterojunction, synergistically enhanced performance. Moreover, the sensor was further integrated into an Internet of Plants (IoP) environmental monitoring system. This work provides a new strategy for designing humidity-tolerant NOx sensors and offers a core device for smart agriculture.