| Two-dimensional nanosheets possess a thickness of molecule or atom. Compared with bulk materials, they exhibit some novel properties, which lead great application potential. Being different from the conductive graphene, molybdenum compound nanosheets are kinds of excellent functional semiconductor materials. In this paper, two kinds of molybdenum compound nanosheets: Mo S2 nanosheets and Mo O3-x nanosheets have been studied. Exfoliated from bulk Mo S2 which is indirect band gap materials, Mo S2 nanosheets are turned into direct band gap. This phenomenon makes them appear some specific reactions to light, electric, magnet and et al. Besides, Mo O3-x nanosheets possess tunable LSPR, which couldn’t appear in common semiconductor. That also makes them exhibit great application potential in electricity and optics fields.Prepare Mo S2 nanosheets, Mo O3-x nanosheets and their polymer matrix composites. And two novel features were explored: one of them is that by utilizing the property that the PL signal from Mo S2 nansosheets varies as strain changing, we can obtain the strain of the Mo S2/polymer by testing PL changing in a non-contact way. The other is to prepare bulk tunable LSPR composites based on the Mo O3-x nanosheets.Utilize high-speed shearing process to optimize general liquid sonicating exfoliation. Mo S2 nansosheets suspensions were prepared by NMP as dispersion solvent. The suspensions were characterized by UV-Vis absorption spectra and photoluminescence(PL). The results show the absorbance and PL of the Mo S2 nansosheets suspensions prepared by high-speed shearing are both enhanced, which indicates high-speed shearing is an efficient optimized method. The Mo S2 nansosheets were characterized by PL, Raman and morphology. The results shows: the PL signal of Mo S2 nansosheets is enhanced evidently and the main peak is located at 652 nm which corresponds to the band gap of 1.9e V. And the characteristic peaks of Raman spectrum get closer. The lateral sizes of most Mo S2 nansosheets range from hundreds of nanometers to several micrometers and the thicknesses are several nanometers.Use mixing method and layer-by-layer(LBL) method to prepare Mo S2 nanosheets/epoxy and Mo S2 nanosheets /TPU composites respectively. And the composites were characterized by PL, tensile property and morphology. The PL signals of both two kinds of composites above are enhanced, indicating some polymer could not influence the band gap property of Mo S2 nansosheets. Due to the obvious brittleness of epoxy and the disordered dispersing of Mo S2 nansosheets, the PL of Mo S2 nanosheets/epoxy doesn’t vary as strain changing. However, because of the excellent toughness of Mo S2 nansosheets and their dispersion strengthening on epoxy, the toughness of Mo S2 nanosheets/epoxy is improved. LBL method could make Mo S2 nanosheets tiled in TPU. And when more times of spin-coating are used in preparing Mo S2 nanosheets thin film, the PL of Mo S2 nanosheets /TPU varies as strain changing.Prepare Mo O3-x nanosheets suspensions by high-speed shearing method, bulk Mo S2 is raw material, and ethanol/H2 O that exhibit relatively high chemical reactivity is solvent. High-speed shearing leads the exfoliation of Mo S2 nanosheets firstly, and then causes H2 O to be OH* radicals which oxidize Mo S2 nanosheets to be Mo O3 nanosheets. After that, Mo O3 nanosheets are reduced to Mo O3-x nanosheets by ethanol and H atoms intercalation. LSPR spectra demonstrate the Mo O3-x nanosheets suspensions exhibit obvious LSPR in near infrared(NIR) and visible regions. UV light irradiation could promote more H atoms to intercalate into Mo O3-x nanosheets and tune the LSPR spectra of Mo O3-x nanosheets suspensions. The Mo O3-x nanosheets in suspensions and some other matter were characterized by morphology, XPS and Raman. The lateral sizes of most Mo O3-x nanosheets are about 100 nm 150nm and the thicknesses are about 5 8nm. And most parts of Mo O3-x nanosheets are amorphous except few parts. XPS indicates there three valence states of +6, +5, +4 exist in the Mo from Mo O3-x nanosheets and S exist in SO4-2. Raman spectra further confirm the generation of Mo O3-x nanosheets.By mixing method, prepare Mo O3-x nansoehets/epoxy and Mo O3-x nanosheets/TPU composites. Mo O3-x nansoehets/epoxy composites maintain the tunable LSPR and UV light irradiation and heating at certain temperature could tune the LSPR spectra of Mo O3-x nansoehets/epoxy. The residual amidogens() in the composites, which possess reducibility and could supply the intercalated H atoms, are the key matter to cause the tunable LSPR of the composites. Due to Mo O3-x nansoehets/TPU composites don’t contain this kind of functional group, they don’t exhibit LSPR. |
