Layer-by-Layer Self-assembly of Co3O4 Nanorod-Decorated MoS2 Nanosheet-Based Nanocomposite toward High-Performance Ammonia Detection

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.