Spatially Resolved In Situ X-ray Absorption Spectroscopy Studies of ZnS Nanoparticle Synthesis at the Water-Toluene...

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Two-phase synthesis offers precise control over nanoparticle properties.
• Understanding chemical transformations in heterogeneous systems is challenging.
• Zinc sulfide nanoparticles (ZnS NPs) have diverse applications.

Purpose of the Study:

• To introduce a two-phase synthesis route for ZnS NPs at the water-toluene interface.
• To elucidate the diffusion, coordination, and reaction intermediates of Zn²⁺ species.
• To monitor the nucleation and growth mechanisms of ZnS NPs.

Main Methods:

• Spatially resolved in situ high-energy resolution fluorescence-detected X-ray absorption spectroscopy (HERFD-XAS).
• Density functional theory (DFT) calculations.
• Total X-ray scattering analysis.

Main Results:

• Identified the formation of [Zn(H₂O)₆]²⁺ and octahedral [Zn(OA)₆]²⁺ complexes, driving Zn²⁺ diffusion.
• Observed an intermediate tetrahedral [Zn(SR)₄]²⁺ complex at 60 °C.
• Tracked the transformation to noncrystalline ZnS nuclei at 80 °C and crystalline ZnS NPs at 100 °C.

Conclusions:

• In situ X-ray spectroscopy effectively elucidates Zn²⁺ ion coordination and diffusion in two-phase systems.
• Combined X-ray scattering reveals the emergence of atomic and electronic structures during ZnS NP synthesis.
• This work provides a detailed mechanistic understanding of two-phase nanoparticle formation.