Fe2O3-Functionalized MoS2 Nanostructure Sensor for High-Sensitivity and Low-Level SO2 Detection.

Real-time sulfur dioxide (SO2) monitoring is essential to mitigate its severe health and environmental impacts while ensuring compliance with industrial safety and emission regulations. Two-dimensional MoS2 stands out as a promising material for developing low-temperature-operated gas sensors due to its exceptionally high surface-to-volume ratio and ease of surface functionalization. However, monitoring the SO2 level faces challenges, including limited selectivity, sensitivity, and detection range, with high operating temperatures (200-600 °C) or external light source requirements. To address these issues, we present a highly sensitive SO2 sensor based on Fe2O3 nanoparticle-functionalized vertically aligned MoS2 nanostructure material, which is fabricated using a scalable sputtering process. The Fe2O3-MoS2 sensor exhibits a broad detection range from 100 ppb to 100 ppm, with a theoretical detection limit of around 22.8 ppb. When exposed to 5 ppm of SO2, the sensor achieves a response of around 32.2%, with response and recovery times of approximately 104 and 141 s, respectively. The fabricated sensor demonstrated impressive sensitivity (4.9%/ppm) for SO2 concentration in the range of 0.1 to 5 ppm, coupled with excellent reproducibility and stability at 150 °C. This enhanced performance is attributed to the catalytic effect of Fe2O3 and modulation of the heterojunction barrier at the interface. This study introduces a highly scalable, reliable, and stable Fe2O3-MoS2 sensor, which paves the way for developing energy-efficient and miniaturized SO2 sensors.