Characterization of silver nanoparticles deposited on montmorillonite

Silver nanoparticles were prepared by reduction of silver ions intercalated into montmorillonite (MMT) with borohydride and formaldehyde. They were deposited on the external surface of the MMT particles. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and specific surface area (SSA) measurements revealed that borohydride produced very small particles with narrow size distribution (3–13 nm) evenly dispersed on the MMT surface. Silver ions reduced by formaldehyde formed both small particles and large aggregates. The Ag nanoparticles were composed of cubic and hexagonal and/or amorphous silver crystals. The Raman scattering (SERS) was significantly increased by montmorillonite covered with Ag nanoparticles, especially when prepared with borohydride.