Hydrothermal Synthesis of Cu-Doped Au-ZnO Nanoparticles: Photocatalytic Activities

In this study, we report the successful hydrothermal synthesis of Cu-doped Au-ZnO hybrid nanoparticles with controlled doping levels (Au-Zn_1-xCu_xO, where 0 < x < 1.5%) through a one-pot method using diethylene glycol (DEG) as the solvent. Systematic characterization was performed using X-ray diffraction, UV–Vis diffuse reflectance spectroscopy, and transmission electron microscopy. The results confirmed the successful incorporation of Cu into the Au-ZnO lattice, enhancing optical and structural properties. These hybrid materials are characterized by small Au nanoparticles that are well-dispersed and anchored onto a Cu-doped ZnO nanoparticle substrate. The photocatalytic capabilities of the synthesized nanoparticles were assessed in the degradation of Methylene Blue (MB) under solar light irradiation. The addition of 1% gold to ZnO nanoparticles increased the degradation rate from 45% for pure ZnO to 62% for Au-ZnO, attributed to the enhanced separation and transfer of photoinduced electron-hole pairs. Furthermore, the introduction of Cu into ZnO exhibited a characteristic volcano-like pattern in degradation efficiency, with the highest rate of 92% achieved for Au-Zn_1-xCu_xO (x = 1%). These findings highlight the superior performance of Cu-doped Au-ZnO nanoparticles in degrading MB compared to undoped Au-ZnO and pure ZnO nanoparticles.