Effects of rare earth, transition and post transition metal ions on structural and optical properties and photocatalytic activities of zirconia (ZrO2) nanoparticles synthesized via the facile precipitation process

This work aims to study the structural, optical and photocatalytic properties of pure and different metal ions, such as rare earth samarium, transition scandium and post transition stannic ions doped zirconia (ZrO2) nano-particles, synthesized via the facile precipitation process. The effects of the different metal ions on the physic-chemical properties of zirconia were analysized by using different techniques. The structural properties of the synthesized samples were studied by the XRD and FTIR analyses, which confirm that both the pure and different metal ions doped zirconia nanoparticles reveal a tetragonal structure with an average crystallite size in the range of 9.46-4.05 nm and are in good agreement with the TEM results. The smooth spherical surface morphologies and presence of elements of the samples have been confirmed by the SEM and EDX analyses. The Optical properties of the different metal ions doped ZrO2 nanoparticles were evaluated using UV-vis absorption and PL emission spectroscopies. Blue shifts were observed and the band gap energies of the samples found to be in the range of 5.51-5.65 eV, which are higher than that of bulk ZrO2. The enhanced broad green emissions at 578 nm in the PL spectra correspond to the D-5(0)-F-7(1) transition, which contributes to the crystallinity and presence of defects concentration in the samples. The performances of the pure and different metal ions doped zirconia nanoparticles in the photocatalytic degradation of methyl orange (MeO) dye under UV light were evaluated, and the degradation percentage (%) found to be in the range of 58.48-98.24%; the results have been comparatively discussed. The detailed mechanism for the degradation of the MeO dye by using metal ions doped ZrO2 catalyst is discussed. The Chemical oxygen demand (COD) test has been done to confirm the total quantity of oxygen required for the oxidation of the organic MeO dye solution into mineralization.