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 NH 3 sensing characteristics of VS 2 are significantly enhanced by forming VO x /VS 2 heterostructures through a facile oxidative modification, wherein VO x induces strong interfacial coupling with the hierarchical, flower-like VS 2 . Detailed material characterization and electrical analysis reveal significant structural reconfiguration and electronic modulation within the VO x /VS 2 architecture, both of which are pivotal to the superior NH 3 sensing performance. The optimized VO x /VS 2 sensor showcases ultralow NH 3 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 x promotes selective NH 3 adsorption, while electronic sensitization at the VO x /VS 2 heterointerface modulates charge transfer dynamics. By employing the VO x /VS 2 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.