Structure and properties of molybdenum disulfide : based inclusion materials

The use of exfoliated MoS2 layers as surfaces for adsorption have been examined. The properties of exfoliated and restacked MoS2-malachite green (MG) inclusion compounds have been examined to provide insight into the MG-MoS2 interactions that characterize these materials. The results of X-ray diffraction experiments indicate that MG included into the restacked structure adopts a flat orientation approximately parallel to the MoS2 sheets. Second-harmonic generation (SHG) experiments conducted on the exfoliated and restacked materials provide information regarding the average orientation of the MG. Together with adsorption isotherm data, SHG results provide a model for the exfoliation, adsorption, and subsequent restacking of these MG-based inclusion materials and demonstrate the utility of nonlinear optical techniques as probes of these interesting layered structures. The synthesis, structure and order of exfoliated and restacked MoS2 ́ђأ stearic acid inclusion materials are also reported. Highly ordered layered inclusion materials of MoS2 and stearic acid are formed through exfoliation at the air/water interface followed by subsequent Langmuir-Blodgett deposition. The results of X-ray diffraction and molecular resolution AFM imaging experiments indicate that from this unique exfoliation process, the compound adopts a Y-type architecture with the stearic acid chains on a slight tilt with evidence of crystalline ordering within the amphiphile layers. The sum frequency generation vibrational spectroscopy data of the monolayer films show distinct and characteristic features in its CH stretching region. Spectral analysis of the modes of alkyl chains of the adsorbate indicates a slight tilt of the terminal methyl groups. These methods were used to gain insight into the driving forces for adsorbtion and stabilization of inclusion structures. Finally, the synthesis and structure of exfoliated and restacked MoS2 ́ђأ gold nanoparticle inclusion materials are reported. The results of TEM experiments indicate that gold nanospheres have been included in between MoS2 layers to form a layered nano-inclusion composite. This new structure is characterized by an increase in conductivity of the material compared to exfoliated and restacked MoS2 by more than one order of magnitude. These results represent a new method for the fabrication of three-dimensional architectures of nanoparticles and promise new material properties derived from their structure.