Synthesis of Ag–Au bimetallic film at liquid–liquid interface and its application in vapor sensing

We demonstrate a novel process for preparing densely packed film of silver nanoparticles at the liquid–liquid interface followed by a transmetallation reaction with gold ion to yield a film of bimetallic nanoparticles. Films of assembled silver as well as Ag–Au bimetallic were characterized by UV–vis-spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. I–V measurement shows linear behavior for both the films with ca. five orders of magnitude drop in resistance for the Ag–Au bimetallic film. Temperature dependent I–V measurement revealed a semiconductor to metal transition after transmetallation reaction. The films where checked for their potential application in chemical vapor sensing to ammonia vapors.