XPS study of silver, nickel and bimetallic silver-nickel nanoparticles prepared by seed-mediated growth

► We have prepared Ag, Ni and AgNi NPs by derived seed-mediated growth method. ► The combined use of optical, structural and chemical characterization techniques allows to determine the presence of core-shell structures. ► The oxidation states of Ag and Ni at the outer layers of the NPs have been studied by XPS. ► Ag NPs are purely metallic with a fcc structure. ► Ni NPs are formed by Ni core@NiO + Ni(OH)2 shell structure. ► Ag core@NiO + Ni(OH)2 shell structure is determined for AgNi NPs, with oxidized silver atoms at the interface.