A self-supporting UiO-66 photocatalyst with Pd nanoparticles for efficient degradation of tetracycline

In situ growth of UiO-66 on zirconium (Zr) substrate was performed to construct a self-supporting photocatalyst through a mild electrochemical method with 1,4-benzenedicarboxylic acid as organic ligand. The as-prepared three-dimensional UiO-66 nanoparticles have abundant pores and corners, providing an ideal interface with large surface area for subsequent decoration of Pd nanoparticles (NPs). The resultant Pd/UiO-66 can efficiently degrade tetracycline (TC) via hydroxyl radical (•OH) and superoxide radical (•O2–) governing pathway, exhibiting outstanding photocatalytic performance due to fast mass transport endowed by well-dispersed Pd NPs. Under the simulated sunlight irradiation, the electrons of UiO-66 are transferred to Pd NPs, promoting the effective separation of photogenerated electron-hole pairs. Transient fluorescence spectra show that the lifetime of electrons is decreased from 5.08 ns to 3.60 ns with the assistance of Pd NPs, indicating that photogenerated electrons can transfer rapidly. Electrons gathering on the Pd/UiO-66 can react with O2 to produce •O2–, and plenty of holes left in UiO-66 host generate •OH by oxidizing the adsorbed H2O, producing abundant active species for photocatalytic degradation of tetracycline.