Synthesis and structural, morphological and optical characterization of CeO₂ nanoparticles

Full text: Ceria (CeO₂) has earned intensive interest in the past decade because it plays a vital role in emerging technologies for environmental and energy-related applications, such as fast-response gas sensors, ultraviolet ray detector, environmental-friendly pigments, as an oxidation catalyst, and as a counter electrode for electrochromic devices [1-3]. In the work presented here, CeO₂ nanoparticles were synthesized by a microwave-assisted hydrothermal method with different NaOH concentrations (1, 5 and 10M). The microwave-assisted hydrothermal method combines the advantages of both hydrothermal and microwave-irradiation techniques such as very short reaction time, production of small particles with a narrow size distribution and high purity which might be attributed to fast and homogeneous nucleation of the mixture [4]. The samples were characterized by X-Ray diffraction, BET surface area, UV-visible spectroscopy and transmission electron microscopy (TEM). The photocatalytic efficiency was tested towards degradation of methylene blue dye. X-Ray diffraction measurements detected the presence of pure cubic CeO₂ for all synthesized samples. Samples presented BET specific surface area as high as 200 m²/g. TEM images revealed that the sample synthesized with 1M NaOH is constituted of spherical particles with size between ~10-20 nm, while sample synthesized with 10M NaOH is constituted of nanorods with an average diameter of 10 nm and 100 nm in length. The sample synthesized with 10M NaOH was the more active in the degradation of methylene blue dye. References: [1] C. Sun et al, J. Phys. Chem B. 110, 13445 (2006). [2] Y. Li et al, Phys. E. 41, 1550 (2009). [3] H. Wang et al, Phys. Chem. Chem. Phys. 4, 3794 (2002). [4] F. Gao et al, J. Nanosci. Nanotechnol. 6, 3812 (2006). (author)