Synthesis, characterization and photocatalytic activity studies of tellurium containing defect pyrochlores, MSn_0.5Te_1.5O₆ (M = K, Ag, Cu_0.5 and Sn_0.5)

Abstract

Four new metal tin tellurites, MSn_0.5Te_1.5O₆ (M = K, Ag, Cu_0.5 and Sn_0.5), have been synthesized by standard solid-state and facile ion exchange reactions and characterized by powder X-ray diffraction, FTIR, SEM-EDS and UV-vis diffuse reflectance spectroscopic techniques. All the compositions crystallize in cubic lattice with <i>Fd<img src='/image/spc_char/3_bar.gif' border=0>m</i>space group, and are isomorphous with KTi_0.5Te_1.5O₆. The photocatalytic activity of the as prepared materials for methylene blue and methyl violet degradation has been investigated under visible light irradiation. The AgSn_0.5Te_1.5O₆ photocatalyst exhibits higher photocatalytic activity than MSn_0.5Te_1.5O₆ (M = K, Cu_0.5 and Sn_0.5) for photodegradation of methylene blue and methyl violet. The higher photocatalytic performance of AgSn_0.5Te_1.5O₆ is ascribed to its low band gap energy, which endows it with a very strong photooxidation ability to produce OH^● and O2^●- radicals as active species. The catalyst stability and mechanism of photocatalysis is also discussed.