Monolayer MoS 2 is an emerging two-dimensional semiconductor with wide-ranging potential applications in the next generation electronic and optoelectronic devices. Understanding the influences of the supporting substrates on the physical properties of grown MoS 2 is an important step toward its applications. Here we synthesized two typical rhomboid shaped MoS 2 on MoO 2 and triangle shaped MoS 2 on SiO 2 /Si substrates and characterized them by multiple means of X-Ray Photoemission Spectroscopy, Atomic Force Microscopy , Electrostatic Force Microscopy, Raman and Photoluminescence techniques. We found that triangle shaped MoS 2 exhibits different core level spectra compared with rhomboid shaped MoS 2 , attributed to dissimilar charge transfer with the underlying SiO 2 substrate. Interestingly, the triangle shaped MoS 2 single crystals exhibit distinct electrostatic and photoluminescence properties at center and edges. The underlying mechanism is proposed that partial decoupling of MoS 2 at edges from SiO 2 substrate induces different doping level and strain effects, resulting in anomalous physical properties at edges. The results reported here demonstrate that doping and strain effects induced by substrates have a significant influence on physical properties of monolayer triangle shaped MoS 2 ，which can be generally applicable to other transition metal dichalcogenides materials.
Compared with the most studied monolayer MoS 2 , bilayer MoS 2 possesses many distinct fascinating physical properties and potential applications owing to interlayer interactions and structural symmetry. Here, bilayer MoS 2 domains with strict identical AB Bernal stacked order were controllably synthesized using chemical vapor deposition method. In addition, the electrostatic properties of bilayer MoS 2 were systematically investigated by multiple means of photoemission electron microscopy, electrostatic force microscopy, and kelvin probe force microscopy. We found that the work function of monolayer MoS 2 is homogeneous across single crystals and polycrystalline films except for grain boundaries. However, the work function of the Bernal stacked bilayer MoS 2 decreases by 50 ± 4 meV compared with that of monolayer MoS 2 due to the interlayer coupling and screening effects. The deeper understanding gained here on the electrostatic properties of the AB Bernal stacked bilayer MoS 2 should help in the creation of next-generation electronic and optoelectronic devices.
Monolayer MoS 2 is an emerging two-dimensional semiconductor with wide-ranging potential applications in novel electronic and optoelectronic devices. Here, we reported controlled vapor phase growth of hybrid spiral-like MoS 2 crystals investigated by multiple means of X-Ray photoemission spectroscopy, scanning electron microscopy, atomic force microscopy , kelvin probe force microscopy, Raman and Photoluminescence techniques. Morphological characterizations reveal an intriguing hybrid spiral-like MoS 2 feature whose lower planes are AB Bernal stacking and upper structure is spiral. We ascribe the hybrid spiral-like structure to a screw dislocation drive growth mechanism owing to lower supersaturation and layer-by-layer growth mode. In addition, the electrostatic properties of MoS 2 microflakes with hybrid spiral structures are obvious inhomogeneous and dependent on morphology manifested by kelvin probe force microscopy. Our work deepens the understanding of growth mechanisms of CVD-grown MoS 2 , which is also adoptable to other TMDC materials.
In this study, the effects of l -histidine (L-His) on the aggregation of bighead carp ( Aristichthys nobilis ) myosin induced by heating in low (0.1) or high (0.5) ionic strength solutions were studied. The solubility of natural myosin was significantly enhanced by L-His both in low and high ionic strength solutions. More small particles are suspended in the heated solution containing L-His, inducing a higher solubility than that solution without L-His. The surface hydrophobicity of myosin in a low ionic strength solution containing L-His is higher than that of myosin without L-His. The results of morphology show that L-His induced myosin to form finer aggregates and a honeycomb-like network in a low/high ionic strength solution during heat treatment. These results demonstrate that L-His might disrupt the electrostatic property of unfolded myosin heat-induced through electrostatic binding with the exposed negatively charged amino acid residues, which might disarrange hydrophobic surfaces, resulting in weakening hydrophobic interactions, which ultimately suppresses the fierce aggregation of carp myosin.
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