Effects of surface structure and defect behavior on the magnetic, electrical, and photocatalytic properties of Gd-doped CeO2 nanoparticles synthesized by a simple chemical process

Abstract

Magnetic, electrical, and photocatalytic characteristics of a series of nanoparticles (NPs) of Gd-doped CeO2 (GdxCe1-xO2 (100x% GDC); x = 0.03, 0.05, 0.10, and 0.20) were analyzed in correlation with their surface structure and defect behavior. The GDC NPs were synthesized by a simple chemical process through a polymer-based precursor. X-ray diffraction (XRD) studies confirmed the effective substitution of Gd3+ in the face centered cubic (fcc) lattice of the host matrix of CeO2. The optical band gap (Eg) and oxygen vacancies (VO) increased with Gd-doping as validated by UV–visible reflectance and Raman spectroscopy. Further analysis with X-ray photoelectron spectroscopy (XPS) substantiated the formation of non-stoichiometric CeO2 structure through Ce4+ → Ce3+ reduction to maintain charge neutrality after Gd-doping. Samples of 20% GDC processed at 400 °C, showed the highest saturation magnetization (MS) of 17.58 memu/g at room temperature. A maximum conductivity of 2.11 × 10−3 S/cm was recorded at 650 °C in air in the 20% GDC samples processed at 1100 °C. Using 20% GDC NPs processed at 400 °C, a typical value of apparent degradation rate constant (k) of 2.13 × 10−2 min−1 was obtained for methyl orange (MO) dye under UV–visible irradiation for 10 min.