Ultraviolet activation of heterostructures based on gold-decorated rhenium disulfide nanoflowers enables sensitivity-enhanced detection of low-concentration ammonia at room temperature

Transition metal dichalcogenides (TMDs) hold potential for gas sensors owing to their inherently large surface areas and remarkable carrier properties, but their application is generally hindered by their poor response and incomplete recovery at room temperature. Herein, ultraviolet (UV) activation of heterostructures based on gold (Au)-decorated rhenium disulfide (ReS₂) nanoflowers is demonstrated for low-concentration ammonia (NH₃) detection at room temperature. The heterostructures based on Au nanoparticle-decorated ReS₂ nanoflowers were easily constructed via a simple hydrothermal and in-situ reduction process. The gas sensors based on the resulting heterostructures showed enhanced sensing performance for NH₃ detection with the assistance of UV activation. Compared with bare ReS₂, the UV-activated Au/ReS₂ heterostructure with 5 mol% Au exhibited a fourfold improvement to 50 ppm NH₃ with an extremely low detection limit of 12 ppb at 25 °C. Through the synergistic effect of Au nanoparticles and UV activation, the as-fabricated heterostructure gas sensor achieved complete recovery in 103 s, showing outstanding selectivity, repeatability, and long-term stability. The sensing enhancement arises from the synergistic interaction between the electronic and chemical sensing properties of Au/ReS₂ heterostructures and the activation effect of UV irradiation. The heterostructure and its activation strategy can provide guidance for the systematic fabrication of high-performance TMD-based gas sensors.