Influence of pH on the structural, spectral, optical, morphological and photocatalytic properties of ZrO2 nanoparticles synthesized by sol-gel technique

In the present work, ZrO(2)nanoparticles are synthesized with different pH (3 to 8) by the sol-gel technique. From X-ray diffraction analysis, the synthesized particles show a tetragonal crystal structure, and the average crystallite size is found to vary from 7.35 to 4.7 nm as the pH increases from 3 to 8. From the FTIR analysis, the peak observed at 621 cm(-1)is ascribed to Zr-O vibrations in the nano-tetragonal ZrO2. The bandgap values are found to increase from 2.0 to 2.9 eV with an increase in pH. From the PL analysis, the observed peaks show a large band and considerable red shift in the band maximum compared to the bandgap of bulk ZrO2. This strongly expresses that the fluorescence involves extrinsic states. From the morphological analysis, the synthesized nanoparticles are found to be spherical in shape and EDS results confirm the presence of Zr and O. The photocatalytic analysis carried out using Alizarin yellow dye, shows that the degradation efficiency is 84.04% for ZrO2(S3-pH 6). This is attributed to the excess -OH group present on the surface of ZrO2.