Band Structure Engineering and Optical Properties of Pristine and Doped Monoclinic Zirconia (m-ZrO2): Density Functional Theory Theoretical Prospective

Unraveling the effect of Cu doping on the structural and morphological properties and photocatalytic activity of ZrO2

Pristine ZrO2 and doped with different concentrations of Copper (0-7 %) were synthesized using a sol-gel combustion route. Several advanced techniques like XRD, EDX, TEM, XPS, P.L., and UV-vis spectrophotometer have characterized the compositions. The XRD proved that all peaks matched with a tetragonal phase of ZrO2 without any impurities of other phases. An average crystallite size rises from 20 to 55 nm by increasing the concentrations of Copper. The elemental analysis was examined by EDX and confirmed the presence of Cooper, Zirconium, and Oxygen. The red shift was observed due to a decrease in the bandgap (5.5-4.01 eV) with increasing the Cu concentrations. From the analysis of photocatalysis of pure ZrO2 and different concentrations of Cu-doped ZrO2 for M.B., RHB, and mix of them. The increase in doping of Cu led to enhancing the performance of the removing MB from 35 to 80 %, however, the RHB degradation was from 42 to 81 % while the mix of M.B. and RHB reached 85 % with 7 % Cu-doping ZrO2.

Reduced Graphene Oxide–Metal Oxide Nanocomposites (ZrO2 and Y2O3): Fabrication and Characterization for the Photocatalytic Degradation of Picric Acid

Herein, reduced graphene-oxide-supported ZrO2 and Y2O3 (rGO-ZrO2 and rGO-Y2O3) nanocomposites were synthesized by hydrothermal method and used as the catalysts for photodegradation of picric acid. The structural and morphological properties of the synthesized samples were characterized by using an X-ray diffractometer (XRD), scanning electron microscope (SEM) with energy dispersive absorption X-ray spectroscopy (EDAX), UV-Vis spectrophotometer, Raman spectrophotometer and Fourier transformation infrared spectrophotometer (FT-IR) techniques. In this work, the wide band gap of the ZrO2 and Y2O3 was successfully reduced by addition of the reduced graphene oxide (rGO) to absorb visible light for photocatalytic application. The performance of as synthesized rGO-ZrO2 and rGO-Y2O3 nanocomposites in the photocatalytic degradation of picric acid were evaluated under UV light irradiation. The photodegradation study using picric acid was analyzed with different energy light sources UV (254, 365 and 395 nm), visible light and sunlight at different pH conditions (pH = 3, 7 and 10). The photocatalytic activity of rGO-ZrO2 and rGO-Y2O3 nanocomposites showed excellent photocatalytic activity under optimum identical conditions with mild variations in pH 3. Compared to rGO-Y2O3, the rGO-ZrO2 nanocomposite showed a better action, with a degradation percentage rate of 100, 99.3, 99.9, 100 and 100% for light conditions of UV-252, 365, 395, visible and sunlight, respectively. The excellent degradation efficiency is attributed to factors such as oxygen-deficient metal oxide phase, high surface area and creation of a greater number of hydroxyl groups.