Nanocrystalline ZnO Doped on Lanthanide Oxide Dy₂O₃: A Novel and UV Light Active Photocatalyst for Environmental Remediation

Abstract

Doping of ZnO on Dy2O3 was studied for its enhanced photocatalytic activity under UV light irradiation. Various doping concentrations were prepared employing precursor nitrates, and 20 mol % ZnO-doped Dy2O3 was found to be highly active under UV irradiation for the degradation of a model pollutant, Orange G dye. The photocatalyst was highly crystalline with a particle size of 40–50 nm and possessed a highly porous and rough surface (26.12 nm) as evidenced by X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and atomic force microscopy analysis. The band alignment and surface area were determined by X-ray photoelectron spectroscopy and Brunauer–Emmett–Teller analyses. The band gap energy of the prepared photocatalyst was found to be 3.15 eV from UV–diffuse reflectance spectroscopy measurements, and the metal oxide stretching frequencies were analyzed by Fourier transform infrared analysis. Free radical formation by the photocatalyst during the in situ process was confirmed by electron paramagnetic resonance studies. The photocatalytic degradation of Orange G dye was monitored with a UV–visible spectrophotometer, COD, and positive mode electrospray ionization mass spectrometry analyses.