Room-temperature high-performance ammonia gas sensor based on layer-by-layer self-assembled molybdenum disulfide/zinc oxide nanocomposite film

A high-sensitivity ammonia gas sensor based on molybdenum disulfide/zinc oxide (MoS2/ZnO) nanocomposite film was reported in this paper. The multilayered film of MoS2/ZnO was fabricated on a PCB substrate with interdigital electrodes (IDE) via layer-by-layer self-assembly technique. The surface morphology, nanostructure and elemental composition of the MoS2/ZnO nanocomposite were described by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that ZnO and MoS2 had good contact in terms of electric and structure. Ammonia-sensing properties of the sensor were investigated by exposing it to various concentrations of ammonia at room temperature. The experimental results revealed that the MoS2/ZnO nanocomposite film sensor exhibited ultra-high sensitivity, good repeatability, excellent stability, outstanding selectivity and fast response/recovery characteristics. Moreover, the sensing device exhibited significantly enhancement in ammonia gas sensing compared to the drop-casted pure ZnO and layer-by-layer self-assembled MoS2/polymer sensors. These results render the MoS2/ZnO nanocomposite a promising candidate for high-performance ammonia sensing at room temperature. The underlying sensing mechanisms of the MoS2/ZnO sensing device towards ammonia gas were ascribed to the excellent electrochemical properties and special nanostructure of the nanocomposite.