Facile aqueous-phase synthesis of Ag–Cu–Pt–Pd quadrometallic nanoparticles

Ag–Cu–Pt–Pd quadrometallic nanoparticles which small Pt and Pd nanoparticles were attached on the surface of AgCu Janus nanoparticles were firstly synthesized by sequential reduction of Pt and Pd precursor in the presence of Janus AgCu bimetallic nanoparticles as seeds in an aqueous solution. Even though there was a small amount of Cu₂O on the surface, the synthesized nanoparticles were mainly composed of four independent metallic part, not alloy parts. By theoretical calculation and growth mechanism study, we found that different reducing rate between Ag⁺ and Cu²⁺ and sequential reduction of Pt and Pd precursors would be key roles for the formation of the quadrometallic nanoparticles.