ZnO@Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene Hybrid Composite-Based Schottky-Barrier-Coated SAW Sensor for Effective Detection of Sub-ppb-Level NH<sub>3</sub> at Room Temperature under UV Illumination
Kedhareswara Sairam Pasupuleti, Alphi Maria Thomas, Devthade Vidyasagar, Vempuluru Navakoteswara Rao, Soon‐Gil Yoon, Young Heon Kim, Song‐Gang Kim, Moon‐Deock Kim
Abstract
Smart sensors capable of detecting NH 3 at sub-ppb levels are important for human health in our daily life. Here, we demonstrate a surface acoustic wave (SAW) sensor based on ZnO@MXene hybrid heterostructure for ultrahigh NH 3 gas detection under UV illumination at room temperature (RT). Under UV illumination, the ZnO@MXene SAW sensor not only significantly enhances the frequency response (Δ f ≈ 32.24 kHz/20 ppm) but also effectively improves the selectivity with a low detection limit (89.41 ppb), short response/recovery times (92/104 s), long-term stability, and robust sensitivity under various relative humidity conditions (dark) to NH 3 at RT. These unique NH 3 sensing properties might be attributed to the enriched functional groups, oxygen vacancies, and excellent charge transfer at the Schottky barrier via band bending, which is explained using an energy band theory sensing mechanism. Overall, the current study offers strategic insights for designing light-activated high-performance SAW-based RT NH 3 sensors in safety assurance and environmental monitoring.