Synthesis of cerium-doped zinc oxide nanomaterials by precursor method with improved photodegradation activity for Methylene blue and Red CL-5B dye

The solar light-driven novel photocatalytic materials hold great potential for addressing water pollution and environmental remediation. The photosensitive cerium-doped zinc oxide materials were synthesized via the precursor method. The XRD of Ce_xZn_1−xO (where, x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, and 0.07 atom %) confirmed the hexagonal wurtzite ZnO structure. SEM/HR-TEM images revealed agglomerated particles with spherical to hexagonal-shaped crystallites, and sizes ranged from 30 to 55 nm. EDS and XPS ascertained the elemental composition, ionic states (Zn²⁺, O²⁻, and Ce⁴⁺), and chemical bonding in Ce_xZn_1−xO. The band gap energy (E_g) calculated from UV–Visible DRS, ranged from 3.21 to 3.17 eV. The PL emission spectra provided evidence of Ce⁴⁺ ions incorporated into ZnO lattice sites. The mid-gap energy levels caused a redshift in absorption edge and retarded (e⁻–h⁺) pair recombination. The photocatalytic degradation was carried out on aqueous Methylene blue (MB) and Red CL-5B dyes. The % degradation for MB in UV and sunlight at 120 min were 98 and 65%, while Red CL-5B dye exhibited 100 and 82% at 40 min. The photo-activity followed the Langmuir–Hinshelwood pseudo-first-order kinetics model. The highest rate constant, k = 0.03579 min⁻¹ was presented by Ce_0.05Zn_0.95O, which indicated an 8-times faster reaction compared to ZnO. The reactive species identified were (h⁺), (^⋅OH⁻), and (^⋅O²⁻). From the recyclability test, the catalyst exhibited good efficiency, stability, and reusability over 4 cycles. This work provides a simple and cost-effective method to fabricate photosensitive materials with high-degradation efficiency, excellent reusability, and its potential application in disintegrating organic pollutants.