The impact of the Au/Ag ratio on the photocatalytic activity of bimetallic alloy AuAg nanoparticle-decorated ZnO nanorods under UV irradiation

Zinc oxide (ZnO) is a semiconducting material that is widely used in photocatalytic applications. Unfortunately, due to the rapid electron-hole pair recombination, the photocatalytic efficiency of ZnO is very low. Creating new nanocomposites of ZnO with bimetallic nanoparticles (NPs) is a promising research effort. In this study, the AuAg NPs were deposited onto ZnO nanorods (NRs) grown on a glass substrate using one-pot hydrothermal with five different molar ratios of the HAuCl₄ and AgNO₃ precursors (1:0, 3:1, 1:1, 1:3, and 0:1). The result shows that the photocatalytic dye degradation performance of ZnO/Au₁Ag₃ is comparable to that of ZnO/Au (49–50%, k = 0.00709 min⁻¹), which is twice as efficient as the performance of the pristine ZnO (25%, k = 0.00254 min⁻¹). The high number of deposited Au₁Ag₃ NPs roughened the surface of the nanocomposites, and their role in inhibiting the exciton recombination rates may have a significant effect on enhancing the photocatalytic activity of pristine ZnO.