X-Ray Scattering Studies of Gold Nanoparticle Synthesis at the Liquid-Liquid Interface

The temporal evolution of the structure of gold nanoparticles was investigated during their synthesis at an electrified liquid-liquid interface. Although nanoparticles are often grown at internal liquid-liquid interfaces, we studied a novel synthetic route that allowed the growth to be triggered in time by voltage and confined in space to the interface. The electrodeposition of gold was achieved by the reduction of AuCl−1 with tri-p-tolylamine at the interface between water and 1,2-dichloroethane in a custom made electrochemical cell. Grazing incidence small angle X-ray scattering (GISAXS) at the Advanced Photon Source was used to follow the temporal evolution of the gold nanoparticle synthesis. GISAXS results are produced by an initial fast reduction of Au ions to form gold nanoparticles of about 20 nm in radius, which slowly increase in size to about 24 nm. Subsequent fast coalescence forms larger nanoparticles.