Ag facilitated shape control of transition-metal nanoparticles

► We developed a Ag-facilitated approach to control the shape of transition-metal nanoparticles (TMNPs). ► Quasi-spherically shaped TMNPs were prepared by co-reducing the metal precursors and Ag(I) ions in an organic medium. ► The shape control of TMNPs was actually based on the formation of core-shell Ag-metal structures. ► The Ag facilitated alloy TMNPs showed superior catalytic activities towards methanol oxidation.