Sol–gel synthesis of Ce-doped α-Al2O3: Study of crystal and optoelectronic properties

Abstract

Abstract Pure Al2O3 and Ce-doped Al2O 3 nanoparticles (NPs) were fabricated in different Ce dopants’ percentages of 2, 4, and 6% by CeCl3.7H2O and AlCl3.6H2O precursors in the presence of ethylene glycol (EG) as a capping agent, and polyvinylpyrrolidone (PVP) as stabilizer using sol–gel method. The crystal, morphological, optical, and electronic properties of the samples were investigated using powder X-ray diffraction (XRD), field emission scanning electron microscope transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), diffused reflection spectroscopy (DRS) and photoluminescence (PL) analyses The XRD analysis showed that the samples’ structures were as α -alumina that stayed single-phase and unchanged increasing Ce dopants. In addition, FESEM analysis indicated that increasing dopants (2%) led to an increase in uniformity of NPs. Furthermore, the results of FTIR optical analysis showed that an increase in AlO4 adsorption peak in the frequency of 819 cm−1 compared to AlO6 adsorption peak at 624 cm−1 was due to the dominance of vibrating bonds of tetrahedral sites rather than octahedral sites in alumina. Moreover, adsorption in these areas showed Ce ions penetration inside the alumina lattice and increased Al4＋ and Al6＋ ions in tetrahedral and octahedral faces. The DRS analysis also showed the redshift configuration in a sample by increasing Ce impurities’ percentage and reducing bandgap energy from 4.06 eV of the (pure sample) to 3.29 eV of (6% Ce-doped alumina) as a new result. The result of PL test revealed that increasing Ce dopant reduced electron–hole recombination leading to an increase in photocatalytic activity in alumina sample. Finally, the photocatalytic activity test showed that increasing Ce dopant increased the degradation of methylene blue (MB) by Ce-doped Al2O3 catalyst.