Browsing by Author "Mishra, Ajay Kumar"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Doping of iron transition metal onto cerium oxide lattice for enhanced photocatalytic degradation of acid violet 7 azo dye under solar irradiation
    (Elsevier B.V., 2025) Mishra, Ajay Kumar; Malatjie, Kgolofelo; Ndlovu, Lloyd
    Dye-contaminated water possess a severe environmental problem due to its adverse effects on ecosystems, human health, and water resources. In this study, cerium oxide (CeO2) was successfully produced and doped with different ratios of iron (5,10 and 15 mol%) via a facile co-precipitation method for use in photocatalytic degradation of acid violet 7 (AV7) from an aqueous solution. The physicochemical properties of the nanophotocatalysts were studied using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Ultraviolet–Visible spectrophotometer (UV–Vis), Raman spectroscopy, photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD), and Brunauer-Emmett-Teller (BET). SEM-EDS confirmed the presence of Fe, O and Ce elements in the photocatalysts. The 5 mol% Fe-dopped CeO2 possess high photocatalytic activity with the removal efficiency of approximately 98 % of AV7 dye when compared to pristine CeO2 (38 %), 10 % Fe-doped CeO2 (85 %) and 15 % Fe-doped (86 %). The higher photodegradation of 5 mol% Fe-doped CeO2 was attributed to suppressed recombination of photogenerated charge carriers as displayed by PL, as well as the high surface area observed from BET analysis. In addition, the electrochemical characterization confirmed high migration of photogenerated electron-hole pairs for 5 mol% Fe-CeO2/FTO which substantiates the enhanced photocatalytic degradation of AV7.
  • Thumbnail Image
    Item
    Sunlight-driven charge separation for a heterojunction of nano-pyramidal CuWO4-MOF modified TiO2 nanoflakes for photocatalytic degradation of ciprofloxacin
    (Springer Science and Business Media Deutschland GmbH, 2024) Mishra, Ajay Kumar; Mabape, Kgaugelo S.; Mishra, Shivani Bhardwaj; Moloto, Makwena Justice
    The study presents a breakthrough of a balanced charge separation for heterojunction CuWO4-TiO2 cocatalyst to efficiently enhance visible light photocatalytic degradation of ciprofloxacin (CIP). A solvothermal-synthesized nanopyramid-like CuWO4 semiconductor was assembled before sol–gel treatment with TiO2 precursors to generate CuWO4-TiO2 nanocomposites. The optical, structural, and morphological properties of CuWO4-TiO2 were elucidated using UV–Vis DRS, XRD, FTIR, Raman spectroscopy, and TEM/SEM techniques. The UV–Vis DRS spectroscopy of as-synthesized CuWO4-TiO2 cocatalyst demonstrated enhanced visible light absorbance. The XRD patterns of CuWO4-TiO2 revealed a triclinic phase nanocrystal. The O-Ti–O functionality was confirmed by FTIR spectroscopy. The photoactive bands corresponding to anatase redshift were observed from Raman spectroscopy of CuWO4-TiO2 nanocomposite. The PL studies attributed this redshift to the elevated extra energy bands that aid electron/hole pair charge separation in a co-catalyst heterojunction CuWO4-TiO2 nanocomposite afforded by embedding CuWO4-MOF within TiO2 crystalline.