Enhanced photocatalytic activities of CeO2@ZnO core-shell nanostar particles through delayed electron hole recombination process
2022
Mīn̲āṭci, G. | Sivasamy, A.
Crystalline CeO₂@ZnO core-shell nanostars were fabricated through hydrothermal and precipitation methods further characterized by XRD, UV-DRS, FT-IR, FE-SEM, EDAX, HR-TEM, SAED, AFM, XPS, BET and EPR analyses. The core-shell nanostar particles consist of ceria as core and zinc oxide as which were confirmed by FE-SEM and HR-TEM analysis. XRD analysis confirmed that the core-shell nanostar particles were highly crystalline in nature and nanosized. AFM analysis showed that the core-shell nanostar particles were highly porous with high surface roughness of 91.64 nm. The photocatalytic activity of CeO₂@ZnO nanostars were evaluated by photocatalytic degradation of a model pollutant such as Orange-G (OG) under UV and visible light irradiations. The in-situ generation of OH. radicals was confirmed by EPR analysis. The maximum 90% of photocatalytic degradation of dye was observed by CeO₂@ZnO CNS compared to pristine ZnO (>60% degradation) in neutral pH under UV and visible light irradiations. The pseudo-order rate constants were varied from 158 to 12 and 12 to 2 kₒbₛ × 10⁻³ (min⁻¹) under UV and visible irradiations respectively for the different initial dye concentration from 5 to 25 ppm using CeO₂@ZnO CNS. The higher photo activities of the core-shell nanostars are due to 4f shell of Ce⁴⁺ which traps the excited electron and further controls the rate of electron-hole pair recombination process under UV and visible light irradiations. The core-shell nanostars retain its photo activities for more than three cycles of reusability with better stability.
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