Synthesis, characterization and photocatalytic studies of visible light responsive K 3 MTe 3 O 12 (M = Cr, Fe and Ga)

Quaternary metal oxides, particularly those of pyrochlore-type, form a rapidly emerging class of new functional materials for photocatalytic applications in environmental purification and water splitting because of their intriguing structural and photocatalytic properties. In this work, pyrochlore structured compositions with the general formula K 3 MTe 3 O 12 (M = Cr, Fe, Ga) were synthesized by a solid-state method and their photocatalytic properties are reported. The synthesized materials were subjected to X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM–EDS), transmission electron microscopy-selected area electron diffraction (TEM-SAED), N 2 adsorption–desorption, Fourier transform infrared (FT-IR), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) techniques. All the compositions were crystallized in a cubic system with the Fd3m space group. All the compositions were evaluated for the photocatalytic degradation of methylene blue (MB), a toxic aromatic cationic dye, under visible light irradiation. Among the materials tested, K 3 CrTe 3 O 12 offers the highest photocatalytic activity with a 96% degradation over 180 min of irradiation. Scavenger experiments were performed to find out the role of reactive oxygen species during the photocatalytic degradation of MB. The · OH radicals were found to play a major role in the MB degradation. Furthermore, the recyclability and the chemical stability of K 3 CrTe 3 O 12 were also presented.