Synthesis of colloidal Au-Cu ₂S heterodimers via chemically triggered phase segregation of aucu nanoparticles

Uniform colloidal AuCu alloy nanoparticles were shown to react with dissolved sulfur and bubbling oxygen to form uniform colloidal hybrid Au-Cu ₂S nanoparticles. Representative transmission electron microscopy (TEM) images of the Au-Cu ₂S product show that the AuCu nanoparticles are uniform and spherical with an average diameter of 10 ∓ 1 nm, while the product nanoparticles appear biphasic. The XRD data implies that the dark-contrast component is predominantly Au, perhaps with a small amount of alloyed Cu. The Cu signal does not disappear in the Au region, which could originate from an overlapping Ni signal or indicate that a small amount of Cu remains alloyed with the Au. The relative sizes of the Au and Cu ₂S components in the Au-Cu ₂S heterodimers are also consistent with a phase segregation pathway.