Edge sites enriched vanadium doped MoS2/RGO composites as highly selective room temperature ammonia gas sensors with ppb level detection

Abstract

The unparalleled physical and chemical properties of 2D transition metal dichalcogenides (TMDCs) render them the potential to be next-generation high-performance gas sensors. Herein, we report the fabrication of vanadium-doped MoS₂/RGO (MG) nanocomposite gas sensors with substantial ammonia sensing traits at room temperature via an in situ hydrothermal method. The characterization results reveal that the incorporation of vanadium dopants into the host lattice triggered more active edge sites and augmented charge carrier transport across the heterojunctions. The as-formulated hierarchical structured gas sensors (V5) with an optimal vanadium doping concentration of 5 at% exhibited a high selective response of 21.8% towards 50 ppm of ammonia gas at room temperature and a pronounced lowest detection limit of 600 ppb. The V5 gas sensor reflected a 21-fold enhancement in the gas sensing response towards 50 ppm ammonia relative to the pristine MoS₂/RGO (MG). The changes attributed to the depletion layer of the p–n heterojunction formed by V@MoS₂/RGO upon interaction with ammonia gas molecules and the influence of humidity on the sensing parameters were briefly discussed. The prepared V5 gas sensor proves to be a potential candidate for real-time sub ppb level detection of ammonia at room temperature.