Non-aqueous synthesis of AuCu@ZnO alloy-semiconductor heteroparticles for photocatalytical degradation of organic dyes

Heteroparticles with anisotropic structure have emerged as a focus of research. They contain two distinct sides with different composition, structures, ionization potential and surface chemistry. The asymmetric structure allows a tuning of chemical, optical, electrical, magnetic, mechanical and thermodynamic properties within a single particle by controlling composition, size, shape and organization at the nanoscale. Here we report the preparation of AuCu@ZnO heteroparticles using non-aqueous solution chemistry by in situ alloying of the metal domains of AuCu@ZnO nanoparticles. The size, shape and optical properties of the AuCu@ZnO hybrid nanoparticles were characterized by transmission electron microscopy and UV–visible spectroscopy. The nanocrystals have a multipod-like morphology with ZnO domains connected to an AuCu alloy core. The AuCu@ZnO nanoparticles showed a pronounced red-shift of the plasmon band compared to Au@ZnO heteroparticles. The crystal structure and phase purity were confirmed by X-ray powder diffraction. Surface-functionalization with imidazole-type ligands rendered the AuCu@ZnO nanoparticles water soluble. The AuCu@ZnO alloy heteroparticles showed an enhanced activity compared to Au@ZnO for the photocatalytic degradation of organic pollutants, as demonstrated with the model compound rhodamine B.