Synthesis and Study on Photogenerated Charge Behavior of Novel Pt/CeO2/ZnO Ternary Composites with Enhanced Photocatalytic Degradation Activity

A novel Pt/CeO2/ZnO ternary composite is synthesized via two simple procedures of hydrothermal and photoreduction. The crystal structure, morphology, and composition of as-prepared samples are characterized by XRD, SEM, HRTEM, XPS and UV-Vis DRS. Because both ZnO and CeO2 are good photocatalytic semiconductors, photocatalytic activities of the samples are evaluated by the degradation of phenol aqueous solution (25 mg/L). Under the strong interaction among the Pt, CeO2 and ZnO, the maximum photocatalytic activity is observed in the Pt/CeO2/ZnO ternary composites and 91% phenol can be degraded in 60 min under UV light irradiation. The probable photocatalytic mechanism is discussed by active species trapping experiments along with SPV, TPV, PL and PA measurements. The enhanced photocatalytic activity is attributed to the redox cycle of Ce4+ <-> Ce3+, the effective interface between ZnO and CeO2 as well as the electron transfer action of Pt nanoparticles. The photocatalytic activity almost unchanged after four cycles and proves excellent reusable photocatalysts. This work shows the synergistic effect of rare earth elements and noble metals in the photocatalytic process, which facilitates their practical application in toxic pollution abatement.