Facile synthesis and photocatalytic properties of light emitting layered compounds of Zn[sbnd]La[sbnd]Tb hydroxide and oxoanions

Abstract

Layered hydroxide containing Zn2+, La3+ and Tb3+ ions intercalated with acetate anions (CH3COO–) have been synthesized by a simple hydrolysis method and characterized. Further ion exchange of this with tungstate, molybdate and vanadate ions in acetic acid medium resulted in layered compounds intercalated with these anions. The phases were characterized by high resolution PXRD, ICP, SEM, FTIR, Raman, UV–visible, PL spectroscopy and TGA techniques. Intercalation of vanadate and tungstate ions in the interlayer of the host hydroxide salt was evident and according to XRD, the samples did not show the presence of any other crystalline impurities. On intercalating molybdate anion, the sample showed two different types of ordering in the PXRD pattern. In the UV–visible absorption spectra of these oxoanion intercalated samples, prominent red shift was observed due to the HOMO-LUMO LMCT transitions. While tungstate and molybdate intercalated samples were green emitters (arising primarily from the Tb3+-ions of the host lattice), strong blue emission, (quenching of green emission of Tb3+) was observed for the vanadate intercalated sample. Superior catalytic performance in terms of photo degradation of aqueous rhodamine-6G dye solutions has been exhibited by the intercalated samples over the acetate intercalated one.