Effect of oxygen vacancy on structural, optical, and photocatalytic properties of ceria films grown by magnetron sputtering deposition

• Published in: Surface & coatings technology Vol. 358; pp. 36 - 42
• Main Authors: Wang, Yanlong, Zhang, Shaoqian, Li, Yimin, Lv, Qipeng, Deng, Songwen, Li, Gang, Jin, Yuqi
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.01.2019; Elsevier BV
• Subjects: Cerium oxide; Cerium oxides; Crystal structure; Crystallinity; Density functional theory; Deposition; Diffraction patterns; Electric currents; Magnetic properties; Magnetron sputtering; Methylene blue; Optical properties; Oxygen; Oxygen vacancy; Photocatalysis; Photodegradation; Photoelectrons; Raman; Raman spectroscopy; Vacancies; X ray photoelectron spectroscopy; X-ray diffraction; XPS; XPS; Raman; Magnetron sputtering; Cerium oxide; Oxygen vacancy
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2018.11.017

Cerium oxide is of crucial importance for intrinsic redox reaction, which is attributed to the active sites neighboring oxygen vacancies. However, the role of oxygen vacancy (Ov) on the various properties of ceria films remains to be elucidated. Herein, ceria films were deposited by magnetron sputtering and the effect of electric current intensity on the creation of Ov was systematically investigated. X-ray photoelectron spectroscopy (XPS) results show that the Ce4+ concentration decreases with the increase of current intensity, which demonstrates that Ov can be created and tuned during film deposition by controlling electric current intensity. The film fabricated by 6 A current intensity has 42% Ce4+, approaching that of rhombohedral-Ce7O12, which is a stabilized bulk phase ceria. X-ray diffraction patterns reveal that 6 A film shows mixed crystalline phases with the majority of peaks very close to rhombohedral-Ce7O12, while 1 A, 2 A, and 4 A ceria films show simple crystalline phase. Raman analysis presents that dioxygen species are heavily absorbed on the surface of 6 A film with more active sites on different crystalline surfaces, which is confirmed by photocatalytic degradation of Methylene Blue. The calculated bandgap by DFT (density functional theory) + U is consistent with that obtained from Tauc plots curves. This work demonstrates that Ov plays an important role on the properties of the ceria film. •Role of oxygen vacancy on the structural, optical, and photocatalytic properties of ceria films is systematically studied.•Oxygen vacancies were controllably introduced and confirmed by XPS.•Ce3+ and active sites were created by Oxygen vacancies.•6 A film close to rhombohedral-Ce7O12 shows surface photo-catalysis.