Dual-Mode Sensitization Enabled by Oxidatively Engineered Hierarchical VS ₂ Heterostructures for High-Performance, Room-Temperature NH ₃ Sensing Applications

Heterostructuring via oxidative transformation of transition metal dichalcogenides unveils new horizons for improving key sensor performance parameters, including sensitivity, selectivity, and stability, by leveraging the synergistic interplay of charge carrier dynamics and surface interactions at the interfaces. Herein, the NH₃ sensing characteristics of VS₂ are significantly enhanced by forming VO_<i>x</i>/VS₂ heterostructures through a facile oxidative modification, wherein VO_<i>x</i> induces strong interfacial coupling with the hierarchical, flower-like VS₂. Detailed material characterization and electrical analysis reveal significant structural reconfiguration and electronic modulation within the VO_<i>x</i>/VS₂ architecture, both of which are pivotal to the superior NH₃ sensing performance. The optimized VO_<i>x</i>/VS₂ sensor showcases ultralow NH₃ detection down to 280 ppb across a wide dynamic range of 0.4-200 ppm at room temperature. The designed sensor exhibits remarkable stability, long-term reliability (>10 weeks), exceptional selectivity, and consistent response and recovery properties. Further investigation into the sensing mechanism discloses that chemical sensitization by VO_<i>x</i> promotes selective NH₃ adsorption, while electronic sensitization at the VO_<i>x</i>/VS₂ heterointerface modulates charge transfer dynamics. By employing the VO_<i>x</i>/VS₂ sensor, this study proposes three innovative sensor prototypes: (i) an autonomous self-triggered sensing switch, (ii) a piezoelectric nanogenerator-driven self-powered gas detector, and (iii) flexible wearable sensors, demonstrating the potential of the developed devices for diverse application scenarios.