The Fabrication Of MoS₂-based Nanocomposites And Their Application

Molybdenum disulfide（MoS₂） is a layered material with strong in-plane bonding and weak out-of-plane interactions, enabling it easily exfoliated to few layers even to single layer. Specifically, MoS₂ has shown great potential in chemical and biological fields due to their tunable electronic characteristics, unique optical properties, high stability in aqueous environments, large surface area, easy functionalization and low toxicity. Noble metal nanomaterials, a class of materials whose properties are highly dependent on their size, shape, composition and morphology, have shown great potential applications in catalysis, electronics, sensors, and biomedicine.In this work, MoS₂-based nanocomposites have been synthesized by combining the advantages of nobel metal nanomaterials with high catalytic ability and MoS₂ with large surface area. On the basis of successful synthesis, MoS₂-based electrochemical and surface-enhanced Raman scattering sensors have been constructed. Therefore, my thesis is divided into the following three aspects:1. We presented a facile seeded growth method to prepare high-quality three-dimensional（3D） Au@Pt bimetallic nanodendrite-decorated molybdenum disulfide（MoS₂） nanosheets（Au@Pt/MoS₂）. The thickness of the Pt shell of the Au@Pt bimetallic nanodendrites on the surface of the MoS₂ nanosheets could be easily tuned via simply changing the synthesis parameters, such as the concentration of H2 Pt Cl6, reaction time and temperature, which greatly influence the catalytic ability of Au@Pt/MoS₂ nanohybrids. Both cyclic voltammetry（CV） and chronoamperometry（CA） demonstrated that the as-prepared Au@Pt/MoS₂ nanohybrids possessed much higher electrocatalytic activity and stability than Pt/MoS₂ or commercial Pt/C catalyst.2. We presented a reliable surface-enhanced Raman scattering（SERS）-active substrate has been prepared by synthesizing gold nanoparticles（Au NPs）-decorated MoS₂ nanocomposite. The Au NPs grew in situ on the surface of MoS₂ nanosheet to form effcient SERS hot spots by a spontaneous redox reaction with tetrachloroauric acid（HAu Cl4） without any reducing agent. The formation of hot spots greatly depended on the ratio of MoS₂ and HAu Cl4. When the concentration of HAu Cl4 was 2.4 m M, the asprepared Au NPs/MoS₂-3 nanocomposite exhibited a highquality SERS activity toward probe molecule due to the generated hot spots. The Au NPs@MoS₂-based substrate was reliable, sensitive, and reproducible, which showed great potential to be an excellent SERS substrate for biological and chemical detection.3. We present a new, surfactant-free synthesis method to synthesize gold nanostars（Au NSs）-decoatated MoS₂ nanocomposites. We used Au NPs/MoS₂ nanocomposite as nanoseeds to in-situ grow Au NSs/MoS₂ nanocomposites in the assist of AA, HCl and Ag NO3. Large numbers of Au NSs were supported on the surface of MoS₂ nanosheet, generating amounts of hot spots. Therefore, Au NSs/MoS₂ nanocomposites were used as SERS-active substrate for melamine detection. The Au NSs/MoS₂-based SERS sensor could detect as low as 10-7 M melamine with high stability and reproducivity.