Photocatalytic activity of spray deposited ZrO₂ nano-thin films on methylene blue decolouration

Nanostructured zirconium oxide (ZrO₂) thin films were deposited at various substrate temperatures (275–475 °C) through spray pyrolysis technique. The X-ray diffraction pattern of the products was indexed to the tetragonal phase of ZrO₂ and the crystallite size of the films increased by increasing substrate temperature. The Raman spectrum confirmed the crystalline structure of the sample. The spherical shape morphology of the materials was obtained by scanning electron microscopy and verified using transmission electron microscopy. The energy dispersive X-ray analysis indicated that the elemental ratio (Zr:O = 33.76:66.24) was similar to ZrO₂. The selected area electron diffraction pattern reveals the well-crystallized tetragonal form. From the UV–Vis spectra, the observed band gap values were increased with increase of substrate temperatures. The photoluminescence spectra showed emission peaks corresponding to blue emission. Mainly, the photocatalytic activity of the ZrO₂ catalyst was tested using methylene blue (MB) dye as a model contaminant for environmental remediation. The percentage degradation increases rapidly with the increase in time for MB-ZrO₂ solution.