Ligand-Regulated Amorphous Transition Layer in Cu@Ag Core-Shell Composites for Boosting Electromagnetic Interference...

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Electromagnetic interference (EMI) shielding effectiveness of core-shell composites depends heavily on silver shell morphology and core-shell interface.
• Controlling these features in-situ is difficult due to an unclear silver shell formation mechanism.

Purpose of the Study:

• To present a ligand-regulated synthesis for precise control over silver shell growth on copper nanoparticles.
• To investigate the impact of ammonia as a ligand on silver deposition kinetics and shell morphology.
• To enhance the electromagnetic interference shielding performance of Cu@Ag core-shell composites.

Main Methods:

• Utilized a liquid-phase reduction method with ammonia as a ligand to regulate silver shell growth.
• Formed stable [Ag(NH3)2]+ complexes to modify silver ion deposition kinetics.
• Analyzed the resulting silver shell morphology, core-shell interface, and electrical resistivity.

Main Results:

• Ammonia-mediated growth resulted in uniform, particle-like silver shells and an Ag-Cu transition layer.
• Electrical resistivity was reduced by several orders of magnitude (from 6.42 Ω·cm to 6.37 × 10⁻⁴ Ω·cm).
• Optimized composites achieved an EMI shielding effectiveness of 85.4 dB, with a peak radiation suppression of 26.8 dB, further enhanced to 101.7 dB via stratification.

Conclusions:

• Ligand regulation, specifically using ammonia, is an effective strategy for tailoring silver shell growth and enhancing EMI shielding.
• The controlled synthesis offers a pathway to superior electromagnetic interference shielding materials.
• The developed Cu@Ag core-shell composites show significant potential for advanced shielding applications.