Surface-dependent localized surface plasmon resonances in CuS nanodisks

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Localized surface plasmon resonances (LSPRs) are optical properties of metallic nanoparticles.
• Tuning LSPR properties is crucial for developing advanced plasmonic devices.
• Copper sulfide (CuS) nanostructures offer unique plasmonic behavior.

Purpose of the Study:

• To demonstrate revertible shifts of surface-dependent LSPRs in CuS nanodisks.
• To investigate the role of surface ligands and oxygen exposure in modulating LSPR properties.
• To explore the potential of tunable CuS nanodisks in advanced plasmonics.

Main Methods:

• Synthesis of CuS nanodisks via thermolysis of copper ethylxanthate (Cu(ex)2) using oleylamine (OYA) as solvent and ligand.
• Controlled unloading and reloading of OYA ligands on the CuS nanodisk surface.
• Exposure to varying doses and times of oxygen to study surface passivation effects.
• Analysis of LSPR wavelength shifts in response to surface modifications.

Main Results:

• Reversible blue-shifts and subsequent reversion of LSPR wavelengths were observed in CuS nanodisks.
• Ligand unloading led to blue-shifting due to increased oxygen exposure.
• Surface repassivation through ligand reloading reverted the LSPR wavelengths.
• The observed shifts were primarily governed by the concentration of free holes in CuS, modulated by surface ligand coverage and oxygen exposure.

Conclusions:

• Surface ligand engineering provides a viable route for tuning LSPR properties in CuS nanodisks.
• The tunability is linked to the modulation of free carrier concentration by surface chemistry and oxidation.
• CuS nanodisks with tunable LSPRs hold promise for applications in advanced plasmonics and sensing.