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

MoO42-/WO42- 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 center dot, h(vB)(+), and O2(-center dot) anions by using appropriate scavengers. The substantial decrease of chemical oxygen demand (COD) during photocatalytic degradation has been established.