Controlled fabrication of Cu–Sn core–shell nanoparticles via displacement reaction

Highly stable Cu–Sn core–shell nanoparticles with an average size of 30   nm are synthesized by displacement reaction, which is triggered by the complexation of thiourea with copper nanoparticles. A thin Sn metal shell of 2–3   nm thickness has been fabricated onto the surface of Cu nanoparticles, resulting in the Cu–Sn core–shell structure. SEM, HR-TEM, EDS, DLS, UV–vis, IR, XPS and TGA measurements have been employed to characterize the special core–shell structure, and to confirm the stability of nanoparticles toward oxidation. It has been found that the thin Sn shell prevents the Cu core from oxidation. The effect of thiourea on the Sn reduction is also discussed. Conductive ink prepared using the nanoparticles shows high stability over a long period of storage, and are hopeful to be applied for inkjet printing technology.