Xanthate Capping of Silver, Copper, and Gold Colloids

Abstract

We cap silver, copper, and gold nanocolloids with long-chain alkylxanthates. In comparison to thiol capping, the particles are less hydrophobic and are stable in aqueous solutions for over a month, though being less stable than the corresponding oleate-capped particles. They can be transferred into relatively polar organic media (such as dichloromethane) but not into nonpolar solvents (such as dodecane). Unlike noncapped, thiol-capped, and oleate-capped colloids, they are temperature sensitive, as a result of the thermal decomposition of the xanthate molecule itself, and can be applied as thermally decomposable colloids. They demonstrate exceptional resistivity toward cyanide-induced corrosion by oxygen, when compared to noncapped or even to oleate-capped colloids. Xanthate capping enables the production of stable copper nanocolloids in aqueous solution under ambient conditions.