Reductive Self-assembling of Pd and Rh Nanoparticles on Silicon Nanowire Templates

Palladium and rhodium nanoparticles have been reductively fabricated on the hydrogen-passivated surfaces of silicon nanowires (SiNWs), which exhibited moderate reactivity toward the reduction of Pd(II) and Rh(III) to metal in aqueous solution. We observed, with high-resolution transmission electron microscopy (HRTEM), the formation of nanoparticles of different shapes, such as round, elliptic, polyhedral, and so forth, on the SiNW surfaces, depending on the size of these metal nanoparticles. Two interesting phenomena, "nanoparticle departure" and "nanoparticle submersion" attributable to nanoparticle interface oxide interaction as well as some interesting structures self-assembled by the nanoparticles and the SiNWs, were observed under HRTEM. The electronic properties and local structure of these metal nanoparticles and the SiNWs templates have been investigated by X-ray absorption fine structures. The Pd and Rh nanoparticles with a small diameter (<5 nm) showed a noticeable size effect.