This article is the first demonstration of a molybdenum disulfide (MoS2)/tricobalt tetraoxide (Co3O4) nanocomposite film sensor toward NH3 detection. The MoS2/Co3O4 film sensor was fabricated on a substrate with interdigital electrodes via layer-by-layer self-assembly route. The surface morphology, nanostructure, and elemental composition of the MoS2/Co3O4 samples were examined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive spectrometry, and X-ray photoelectron spectroscopy. The characterization results confirmed its successful preparation and rationality. The NH3 sensing properties of the sensor for ultra-low-concentration detection were investigated at room temperature. The experimental results revealed that high sensitivity, good repeatability, stability, and selectivity and fast response/recovery characteristics were achieved by the sensor toward NH3. Moreover, the MoS2/Co3O4 nanocomposite film sensor exhibited significant enhancement in ammonia-sensing properties in comparison with the MoS2 and Co3O4 counterparts. The underlying sensing mechanisms of the MoS2/Co3O4 nanocomposite toward ammonia were ascribed to the layered nanostructure, synergistic effect, and heterojunction created at the interface of n-type MoS2 and p-type Co3O4. The synthesized MoS2/Co3O4 nanocomposite proved to be an excellent candidate for constructing high-performance ammonia sensor for various applications.
Keywords: ammonia sensor; heterojunction; layer-by-layer self-assembly; molybdenum disulfide; nanocomposite film; sensing mechanism.