Synthesis of Au−Cu₂S Core−Shell Nanocrystals and Their Photocatalytic and Electrocatalytic Activity

We synthesized stable Au−Cu 2 S core−shell-type hybrid nanocrystals, in which the spherical Au core encapsulates in the disk-type Cu 2 S nanocrystals (avg. size = 7 ± 1 nm), using the simple in situ solvothermal growth of Cu 2 S on Au nanoparticle seeds. Binding energy and band gap measurement provides evidence for the electron withdrawal of the Au core from the Cu 2 S shell. The Au encapsulation enhances the visible-light-driven photocatalytic degradation yield of methylene blue and rhodamine B dyes. In contrast, it reduces the photocatalytic and electrocatalytic activity toward the degradation of 1,4-dioxane. The efficient interfacial electron transfer from the excited Cu 2 S to the Au enhances the oxidative degradation of the dyes. However, the electron withdrawal of the Au core would suppress the catalytic ability of Cu 2 S to generate the H 2 O 2 intermediates, which decreases the degradation efficiency for 1,4-dioaxne.