Escape from the destruction of the galvanic replacement reaction for solid → hollow → solid conversion process in one...

Area of Science:

• Nanomaterials Science
• Chemical Synthesis
• Materials Chemistry

Background:

• Galvanic replacement reactions typically create hollow nanostructures.
• Excessive etching in these reactions often leads to structural collapse.
• Controlled synthesis of solid nanostructures from hollow precursors is challenging.

Purpose of the Study:

• To demonstrate the growth of solid nanostructures from hollow architectures during galvanic replacement reactions.
• To achieve morphology-preserving composition transformation of silver and copper nanostructures.
• To investigate the role of surfactants in controlling the reaction kinetics.

Main Methods:

• Utilizing the difference in redox potentials for galvanic replacement reactions.
• Employing cetyltrimethylammonium bromide (CTAB) surfactant to control reduction rates.
• Sequential dissolution of silver and backfilling with gold to form solid structures.
• Demonstrating conversion of various silver nanoshapes and copper foil to gold.

Main Results:

• Successfully synthesized solid nanostructures (plates, decahedra, rods, prisms, spheres, foils) from hollow precursors without morphology destruction.
• Achieved composition transformation of solid silver nanostructures (<10 nm to 5 μm, ~4 mm² area) to solid gold.
• Demonstrated conversion of solid nano-silver to solid nano-palladium and 10 μm thick copper foil to gold foil.
• Identified CTAB as a key parameter that retards metal reduction by forming complex species with metal salt precursors.

Conclusions:

• A novel method for synthesizing solid nanostructures from hollow precursors via galvanic replacement is established.
• The process allows for precise control over composition and morphology, overcoming typical structural collapse.
• This technique offers a versatile route for creating various solid noble metal nanostructures and foils.