Design and Fabrication of Bimetallic Colloidal “Janus” Particles

In this work, we demonstrate the results of a novel approach developed in our lab to prepare bimetallic Janus particles, which are composed of silica particles with differing metals on opposite hemispheres. SEM imaging, EDS mapping, and XPS analysis clearly indicate that beads are capped with two different metals, typically leaving an equatorial belt around the particle composed of uncoated silica. Oxidation of some metal components can be induced by oxygen plasma exposure, producing compositional and morphological changes. The facile conversion of metal to metal oxide heralds a wide variety of Janus particles with different electronic, optical, and magnetic properties.