Optical Properties and Photocatalytic Performances of Pd Modified ZnO Samples

In this paper, Pd/ZnO samples with various palladium contents were prepared through a facile one-pot hydrothermal method. The crystal structures, chemical compositions, and optical properties of the samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV−vis spectroscopy, and photoluminescence (PL) spectroscopy. The results demonstrate that partial Pd loads on the surface and that the rest is doped in the lattice of ZnO. In addition, the relationship among the photoluminescence, photocatalytic performance, and electronic structure of the samples is investigated in detail. It is found that the modification of palladium not only modulates the electronic structure of ZnO but also affects the amount of surface hydroxyl. The former determines the optical properties of Pd/ZnO, leading to the shift of absorption and PL peaks, while the latter influences the photocatalytic activity of the samples. The modification of palladium at an optimal value not only promotes the separation of photogenerated electron−hole pairs but also increases the amount of the surface hydroxyl resulting in the promotion of photodegradation efficiency.