Low concentration Cu-doped CeO₂ nanoparticles for faster degradation of Rhodamine-B dye under UV-light irradiation

Cerium dioxide (CeO₂) also known as ceria, is an extensively studied popular wide band gap semiconductor that is optically transparent in the visible region and exhibits strong luminescence behavior in the visible and near UV region. In this study, we report the influence of low concentration copper doping on the structural, optical and morphological properties in ceria nanoparticles. The nanoparticles were synthesized using a well-known sol-gel method at room temperature under ambient condition. Characterization techniques like XRD, FESEM and UV-Vis analysis reveal minor structural changes due to the substitution of Ce-ions with comparatively smaller Cu-ions. Such atomic replacement leads to the creation of vacancies and dislocations in the crystal. XRD results further support the fact indicating higher dislocation density after Cu doping. These defects create trapping states near the conduction bands, enabling electronic transitions via unoccupied Cu-3d orbitals and causing a red-shift in the bandgap. Cu-doped CeO₂ degrades more than 50% of Rhodamine-B under UV-light within optimal duration, which demonstrates its enhanced and fast photocatalytic performance. The observations exemplify low level Cu-doped CeO₂ NPs integrated with optimized morphology are potentially effective candidates for sustainable wastewater treatment.