Ag facilitated shape control of transition-metal nanoparticles

Controlling the morphology of transition-metal nanoparticles (TMNPs) can be an effective way to produce nanomaterials with favourable properties (activity and selectivity, etc.). Here we reported the shape control syntheses of TMNPs including Ru, Rh, Pd, Os, Ir, Pt, alloy PtRu, PtOs, and PtRuOs by co-reducing their metal precursors and Ag(I) ions in an organic medium. In this approach, Ag(I) ions were reduced first for their higher reduction potential, leading to the formation of spherical Ag nanoparticles. Then the subsequently reduced atoms of other transition-metals grew on the pre-existing Ag nanoparticles, resulting in the TMNPs with spherical or quasi-spherical shapes. In the absence of Ag precursors, the TMNPs obtained under same experimental conditions were dominated by irregular shapes, for example, rods, multi-pods, worm-like, or star-like, etc. The dependence of the property on the shape of the particles was also demonstrated using the catalytic oxidation of methanol as an example.