Photoinduced Formation of Peroxide Ions on La2O3 and Nd2O3 under O2: Effects of Excitation Wavelength and Crystal Structure. Issue 10 (2nd July 2015)

• Record Type: Journal Article
• Authors: Jing, Xiao‐Lian; She, Wen‐Yu; Li, Jian‐Mei; Chen, Qing‐Chuan; Weng, Wei‐Zheng; An, Dong‐Li; Wan, Hui‐Lin
• Is Part Of: Chemistry, an Asian journal. Volume 10:Issue 10(2015:Oct.)
• Page Start: 2162
• Page End: 2168
• Publication Date: 2015-07-02
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1002/asia.201500312
• Languages: English
• ISSNs: 1861-4728

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Photoinduced formation of peroxide ions on La<sub>2</sub>O<sub>3</sub> and Nd<sub>2</sub>O<sub>3</sub> under O<sub>2</sub> was studied by in‐situ microprobe Raman spectroscopy with attention focused on the effect of excitation wavelength and crystal structure on the O<sub>2</sub><sup>2−</sup> formation. It was found that photoexcitations at 633, 532, 514, and 325 nm can induce O<sub>2</sub><sup>2−</sup> formation over La<sub>2</sub>O<sub>3</sub> at 450 °C. By contrast, photoexcitation at 785 nm does not cause formation of O<sub>2</sub><sup>2−</sup> up to 500 °C. Photoexcitation at 325 nm can induce O<sub>2</sub><sup>2−</sup> formation on cubic Nd<sub>2</sub>O<sub>3</sub> at 25 °C, but cannot induce O<sub>2</sub><sup>2−</sup> formation on hexagonal Nd<sub>2</sub>O<sub>3</sub> up to 200 °C. The significant difference in the behavior of O<sub>2</sub><sup>2−</sup> formation over the Nd<sub>2</sub>O<sub>3</sub> samples of the two structures can be related to the difference in the capacity to adsorb O<sub>2</sub>. Since the number of oxygen vacancies in cubic Nd<sub>2</sub>O<sub>3</sub> is larger than that in the hexagonal one, the former has a higher capacity than the latter to adsorb O<sub>2</sub>. As a result, cubic Nd<sub>2</sub>O<sub>3</sub> is more favorable to the reaction of O<sub>2</sub> with O<sup>2−</sup> to generate O<sub>2</sub><sup>2−</sup>. The structural similarity between cubic Nd<sub>2</sub>O<sub>3</sub> and Nd<sub>2</sub>O<sub>2</sub>(O<sub>2</sub>) may be another factor in favor of peroxide formation.</p> </abstract>