A highly sensitive ammonia sensor and multifunctional monitoring system based on MoO ₃@Ti ₃C ₂T _X (MXene) at room temperature for intelligent agriculture

To address the persistent challenges of low sensing performance, ambiguous sensing mechanisms, and difficult portable monitoring in existing MXene-based NH₃ sensors, this study developed a high-performance MoO₃@Ti₃C₂Tₓ room-temperature NH₃ sensor through ultrasonic composite modification. The MoO₃@Ti₃C₂Tₓ sensor demonstrates significant sensitivity to NH₃ at room temperature, with excellent long-term stability, fast response recovery time (14 s/24 s), and excellent selectivity, superior to most reported Ti₃C₂Tₓ-based and intrinsic MoO₃ sensors. The unique microstructure of the MoO₃@Ti₃C₂Tₓ, the dual active sites of Ti₃C₂Tₓ functional groups (-O/-F/-OH) and oxygen vacancies facilitate the oxidative adsorption and dissociation process of NH₃. The formation of interfacial Schottky junction and charge regulation significantly enhances the gas sensitivity of MoO₃@Ti₃C₂T_X towards NH₃. DFT simulations further reveal the enhanced NH₃ adsorption energy and the strong atomic orbital hybridization at the heterointerface. Furthermore, this study integrated the MoO₃@Ti₃C₂Tₓ sensor into a multifunctional IoT monitoring system, which enables real-time visualization of NH₃ detection through threshold-triggered alarms, demonstrating the utility in smart agriculture.