A robust synthesis of reverse Au/ZnO core/shell nanostructures with high visible photocatalytic activity of methylene blue dye.

In this study, we report a robust electrochemical synthesis of reverse Au/ZnO core/shell nanostructures a galvanic replacement strategy, aimed at enhancing the photocatalytic degradation of methylene blue (MB) dye. ZnO nanoparticles were first electrochemically synthesized, followed by the formation of Au (core)/ZnO (shell) nanostructures. The shell formation is attributed to a galvanic interaction between ZnO and Au ions, resulting in the reduction of Au and subsequent ZnO encapsulation. The morphology, structure, optical properties, and photocatalytic activity of the resulting nanostructures were systematically characterized. The synthesized particles exhibited core/shell nanostructure with diameters of 30-50 nm, comprising Au cores (25-40 nm) and ZnO shells (5-10 nm). Under visible light irradiation, the Au/ZnO nanostructures achieved up to 98.9% MB degradation within 90 min. The enhanced photocatalytic performance is attributed to the localized surface plasmon resonance (SPR) of the Au core, which promotes efficient photo-induced electron transfer to the ZnO shell and extends light absorption into the visible range.