Ce_0.7La_0.15Ca_0.15O_2−δ nanoparticles synthesis via colloidal solution combustion method: Studying structural and physicochemical properties and Congo Red dye photodegradation

The present work described the enhanced photodegradation of the Congo Red (CR) dye under visible light irradiation. The co-doped ceria (Ce_0.7La_0.15Ca_0.15O_2−δ) was prepared by the colloidal solution combustion synthesis way using colloidal silica as a template. The characterization of the as-synthesized cerium oxide (CeO₂, known as ceria) nanoparticles was assessed by diffraction, scanning electron microscopy, Raman spectroscopy, differential thermal analysis, thermοgravimetric analysis, ultraviolet (UV)–visible spectroscopy, and photoluminescence measurements. It revealed the cubic spinel structure with space group Fd-3 m (JCPDS card No. 34-0394), average size between 23 and 92 nm, and bandgap energy from 2.69 to 2.73 eV. The photodegradation of the CR dye under solar irradiation allowed studying the photocatalytic activities of the prepared ceria. After 180 min of light irradiation with the ceria 2 catalyst, CR absorbance was almost nil. The highest degradation rate ∼13.7 × 10⁻⁴ min⁻¹ was recorded using co-doped ceria prepared with adding 1.0 ml of colloidal silica. This exciting activity can be attributed to the smallest particle size ∼23 nm, the smallest lattice parameter a = 5.4511 Å, and the catalyst’s highest bandgap ∼2.73 eV. Based on the investigation, ceria 2 nanoparticles have many possible uses in wastewater cleaning agent. Ceria 2 catalysts might be ideal for photocatalyst materials, UV filters, and photoelectric devices.