Transition metal ion (Ni2+, Cu2+ and Zn2+) doped defect pyrochlore, KTaTeO6: Synthesis, characterization and photocatalytic studies

Abstract

One of the strategies to decrease the bandgap energy and increase the optical absorption ofthe catalysts is to dope with transition metal ions. In this paper, the results obtained for thedegradation of methylene blue (MB) pollutant in the presence of M²⁺ (M = Ni, Cu, and Zn) doped KTaTeO₆ (here after abbreviated as M-KTTO) upon visible light irradiation are presented.The parent KTaTeO₆ and the M²⁺ (M = Ni, Cu, and Zn) doped KTaTeO₆ were prepared by solidstate and ion-exchange methods, respectively. All the samples were characterized by XRD,SEM/EDX, FT-IR, UV-Vis DRS, XPS, and PL techniques. The metal ion doping in place of K⁺has influenced the electronic and optical properties considerably. The doping of M²⁺ into KTTOlattice has narrowed the bandgap energy, increased the visible light absorbance leading to higherphotocatalytic activity. The M-KTTO materials show higher photocatalytic activity compared toparent KTTO, in particularly Cu-KTTO. The scavenging experiments indicate that ^•OH radicalsare the main active species involved in the photodegradation of MB. The Cu-KTTO ischemically stable and can be used at least up to five cycles. The mechanistic pathway of MBdegradation was proposed over Cu-KTTO.