Photoinduced phase separation of gold in two-component nanoparticles

Photoinduced phase separation was developed to synthesize complex nanoparticles composed of more than one metal. Phase separation is due to the different reactivity of the metals towards light and oxygen as it was observed in a colloid comprised of pure silver nanoprisms and spherical gold particles. The small silver seeds were first prepared by rapidly injecting ice-cold, aqueous sodium borohydride into a stirring solution of silver nitrate and trisodium citrate to stabilize the nanoparticles. Photomediated process was developed for converting small silver nanoparticles into triangular nanoprisms as photomediated process provides the greatest control over resulting structure and particle uniformity. Nanoparticles with Ag and Au exhibited conversion to nanoprisms as it was observed after the collapse of the surface plasmon band at 400 nm for the nanoparticles and the concomitant growth of new bands at 330 nm, 450 nm, and 660 nm.