Structural changes during water-mediated amorphization of semiconducting two-dimensional thio-stannates.

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Two-dimensional thio-stannates possess open-framework structures and semiconducting properties, making them promising for catalysis and sensing.
• These materials, denoted R-SnS-1, feature porous polymeric [Sn3S7 2-] sheets with embedded molecular cations.
• Some R-SnS-1 compounds transform into amorphous phases when dispersed in water, but their stability and amorphous product nature are poorly understood.

Purpose of the Study:

• To investigate the fundamental chemical properties and water stability of thio-stannates.
• To elucidate the structural transformation from crystalline to amorphous phases in R-SnS-1 compounds upon water dispersion.
• To understand the nature of the amorphous products and their impact on material properties.

Main Methods:

• Time-resolved study of crystalline-to-amorphous phase transition using X-ray total scattering and pair distribution function analysis.
• Microscopy techniques including scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to observe particle morphology.
• Elemental analysis and X-ray photoelectron spectroscopy (XPS) to determine the loss of organic components.

Main Results:

• No change in local intralayer coordination was observed during amorphization.
• A rapid decrease in crystalline domain sizes and disordering of nanosheet stacking occurred upon suspension in water.
• Significant loss of organic components led to a decrease in interlayer distance, forming smaller particles alongside larger ones.

Conclusions:

• The amorphization of R-SnS-1 thio-stannates in water is primarily due to the loss of organic cations and subsequent stacking disorder.
• Despite structural changes, the light absorption properties of the amorphous thio-stannates remain intact.
• These findings are encouraging for the development of water-based catalytic and sensing applications using thio-stannate materials.