Molybdate/Tungstate Intercalated Oxo-Bridged Zn/Y LDH for Solar Light Induced Photodegradation of Organic Pollutants

Abstract

MoO₄^2–/WO₄^2– intercalated layered double hydroxide (LDH) was prepared by taking nitrate intercalated Zn/Y LDH (Zn/Y/N) by the ion exchange method. The structure, morphology, texture, optical absorption properties, and photocatalytic activities of all the as-prepared catalysts were studied in detail. Optical difference spectra (ODS) along with electron paramagnetic resonance (EPR) measurement revealed that the absorption in the visible region is attributed to the metal-to-metal charge-transfer (MMCT) excitation of oxo-bridged bimetallic linkage of Zn–O–Y in Zn/Y LDHs and can initiate the degradation of Rhodamine 6G (RhG) upon visible-light irradiation. The enhanced reactivity of tungstate and molybdate intercalated Zn/Y LDHs indicated that the interlayer space is the reaction field. The dye degradation process follows Langmuir–Hinshelwood first order kinetics. The possible photodegradation mechanism was studied by the examination of active species such as OH^•, h_VB⁺, and O₂^–• anions by using appropriate scavengers. The substantial decrease of chemical oxygen demand (COD) during photocatalytic degradation has been established