Facile synthesis of Ag2ZrO3 nanocrystals with highly enhanced visible-light photocatalytic activity

This paper describes the synthesis of Ag2ZrO3 nanocrystals using coprecipitation and microwave-assisted hydrothermal methods. These nanocrystals were characterized by means of X-ray diffraction, micro-Raman spectroscopy, Fourier transform infrared absorption spectroscopy, field emission scanning electron microscopy, and UV–Visible spectroscopy, and their photocatalytic performance for methylene blue degradation under visible-light irradiation has been tested. The X-ray diffraction, micro-Raman spectroscopy, Fourier transform infrared absorption spectroscopy analyses indicate that the Ag2ZrO3 nanocrystals have good crystallinity and no secondary phases. The UV–Visible spectroscopy results showed a variation in the optical band gap values (2.71–2.97 eV) with increasing temperature, which indicates the possible presence of defects in the crystal lattice at a medium range. Field emission scanning electron microscopy images revealed that the nanocrystals have uneven spherical shapes and average particle size around 50–70 nm. The good photocatalytic efficiency can be attributed to defects in the silver zirconate structure capable of forming the active adsorption sites. Finally, we discuss a photocatalytic mechanism to understand the photocatalytic process in cationic dye (methylene blue) degradation in aqueous solution.