A three-dimensional Pt@Ti₃C₂Tₓ-based smart platform for discrimination of hydrated ammonia in multi-scenario environmental monitoring.

Portable smart gas sensors are vital for hazardous gas monitoring, with ammonia (NH) sensors playing a key role in contamination tracking across agriculture, industry, and storage systems. However, precise detection of hydrated NH (NH·HO), the dominant form in humid environments, remains a significant yet often overlooked challenge due to fluctuating coexistence of multiple ammonia species, compounded by nonselective reactions and poor humidity tolerance in current sensors. Herein, a sensing platform by integrating highly active Pt catalysts into a 3D hollow spherical TiCT framework is presented. Mimicking the hierarchical structure of honeycombs, the 3D Pt@TiCT composite leverages its nest-like architecture, catalytic enhancement, and heterojunction formation to achieve excellent sensitivity, rapid response/recovery kinetics (24 s/2 s), superior selectivity (over 11.2-fold) and long-term stability (>60 days). DFT calculations validate the preferential chemisorption of NH·HO over gaseous NH and HO, enabled by Pt's higher adsorption energy and greater charge transfer quantities. The sensor is further integrated into a flexible, smart alarm platform using printed circuit technology. This platform successful determine NH·HO in smart agriculture monitoring, pipeline leakage warning and food freshness identification. Importantly, empowered by artificial algorithms, the system achieves nearly 80 % classification accuracy in differentiating NH·HO from interferents across various complex scenarios.