Processing and characterisation of Mo6S2I8 nanowires

Area of Science:

• Materials Science
• Nanotechnology
• Inorganic Chemistry

Background:

• One-dimensional nanostructures based on the Mo-S-I system are of interest as alternatives to carbon nanotubes.
• Previous Mo-S-I stoichiometries (Mo(6)S(3)I(6), Mo(6)S(4.5)I(4.5)) exhibit solubility in common solvents and debundling properties.

Purpose of the Study:

• To investigate the solubility, debundling behavior, and composition of Mo(6)S(2)I(8) nanowires (NWs).
• To explore the electronic properties and structural characteristics of Mo(6)S(2)I(8) NWs.
• To refine models of nanowire debundling based on concentration-dependent behavior.

Main Methods:

• Solubility tests in various solvents, including dimethylformamide and water.
• UV-vis-NIR spectroscopy to analyze electronic transitions.
• Atomic force microscopy (AFM) to determine bundle diameter distributions.
• Energy-dispersive X-ray spectroscopy (EDX) for elemental composition analysis.

Main Results:

• Mo(6)S(2)I(8) NWs demonstrate significant solubility in dimethylformamide (retaining up to 66 wt% at 5 g/L) but are insoluble in water.
• Surface energy was determined to be 67 mJ/m², higher than other Mo-S-I NWs.
• UV-vis-NIR spectra revealed characteristic peaks at 1.8 and 2.8 eV, plus new peaks at 3.5 and 4.4 eV, indicating a different structure.
• AFM analysis showed decreasing bundle diameter with decreasing concentration, with extrapolation suggesting a finite bundle size at infinite dilution.
• EDX confirmed the stoichiometry as Mo(6)S(2.3)I(8.6), supporting the nominal Mo(6)S(2)I(8) composition.

Conclusions:

• Mo(6)S(2)I(8) nanowires possess distinct solubility and electronic properties compared to previously studied Mo-S-I systems.
• The observed spectral features suggest a more strongly bonded structure in Mo(6)S(2)I(8) NWs.
• An extended debundling model is proposed to account for the finite bundle size observed at infinite dilution.