Enhanced performance in the photocatalytic degradation of 2,4,5-Trichlorophenoxyacetic acid over Eu-doped Bi₂WO₆ under visible light irradiation

Abstract

In order to make long-lived photoexcited charges for efficient catalytic photodegradation, rare earth elements are often incorporated into semiconductors. We studied the doping effect on photodegradation efficiency of Bi₂WO₆ samples with europium ions which were successfully synthesized by a simple one-step. The prepared catalyst was characterized by multiple techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic activities of pristine Bi₂WO₆ and xEu-Bi₂WO₆ (x=1, 2, 3, and 4) were investigated in the presence of H₂O₂ for 2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) as a target contaminant under visible light irradiation. The incorporation of Eu³⁺ into Bi₂WO₆ where Eu³⁺ ion played the role of an electron acceptor was favorable for transferring photoinduced electrons from Bi₂WO₆ to Eu³⁺, thereby increasing separation efficiency of photoinduced electron-hole, leading to enhanced photocatalytic activity of xEu-Bi₂WO₆. Under optimized condition, the photodegradation efficiency of 2,4,5-T by 2Eu-Bi₂WO₆ samples was 1.7-fold higher than that of pristine Bi₂WO₆ sample. We demonstrate that Eu³⁺ ion is a promising candidate for the development of a visible-light active semiconductor catalyst for environmental remediation.