Hydrothermal synthesis and photocatalytic properties of pyrochlore Sm2Zr2O7 nanoparticles

• Nanocrystalline Sm2Zr2O7 with the faceted morphology are successfully synthesized by a simple hydrothermal approach and an optimum hydrothermal process is proposed.
• The structural stability of Sm2Zr2O7 nanoparticles depend on the crystallite size.
• Pyrochlore Sm2Zr2O7 nanoparticles exhibit excellent photocatalytic activity.

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.