Hydrothermal synthesis and photocatalytic properties of pyrochlore Sm₂Zr₂O₇ nanoparticles

Pyrochlore Sm₂Zr₂O₇ nanoparticles were synthesized by a facile hydrothermal method and their photocatalytic properties were investigated. The effects of hydrothermal temperature, reaction time and pH value on structures and morphologies of the resultant products were investigated. An optimum hydrothermal process was proposed based on these experiments. Pyrochlore Sm₂Zr₂O₇ nanoparticles with an average size smaller than 18 nm were successfully prepared. The results showed that the structural stability of Sm₂Zr₂O₇ nanoparticles was related to their crystal sizes. The nanoparticles with the sizes larger than 10 nm are found in the pyrochlore structure, while the smaller-size nanoparticles crystallize in the fluorite structure. The absorption spectrum of the Sm₂Zr₂O₇ nanoparticles with the average size of 15 nm evidenced the existence of an absorption edge in the visible-light range. The photodegradation of the Congo red organic dye revealed that Sm₂Zr₂O₇ nanoparticles exhibit excellent photocatalytic activity.