Spontaneous Silver Reduction and Nanostructure Formation at Water–Hydrophobic Interfaces

Here, we report the spontaneous formation of monodisperse silver nanostructures at WHIs in the absence of added reducing agents, surfactants, or light. Across a variety of silver salts and hydrophobic media, a free-standing interfacial film reproducibly develops and can be transferred onto diverse substrates.

Electron microscopy reveals extended domains composed of monodisperse silver nanoparticles arranged in ordered assemblies over micrometer length scales despite the absence of conventional directing agents. Transmission electron microscopy further uncovers a continuous silver-rich amorphous phase containing ultrasmall nanoparticles (∼2 to 3 nm) distributed throughout the interfacial film. Time-resolved observations reveal a progressive structural evolution from this amorphous phase through defect-rich and non-<i>fcc</i> intermediates toward crystalline <i>fcc</i> silver, suggesting a non-classical pathway for nanoparticle formation.