Mechanistic aspects of photo-induced formation of peroxide ions on the surface of cubic Ln(2)O(3) (Ln = Nd, Sm, Gd) under oxygen

作者：Jing, Xiao-Lian; Chen, Qing-Chuan; He, Chong; Zhu, Xue-Quan; Weng, Wei-Zheng^*; Xia, Wen-Sheng; Wan, Hui-Lin

来源：Physical Chemistry Chemical Physics, 2012, 14(19): 6898-6904.

DOI：10.1039/c2cp40086c

• NEODYMIUM(III) OXIDE PEROXIDE
• DENSITY-FUNCTIONAL THEORY
• SITU RAMAN-SPECTROSCOPY
• RARE-EARTH-OXIDES
• PARTIAL OXIDATION
• CATALYTIC PERFORMANCE
• ISOTOPIC EXCHANGE
• LATTICE OXYGEN
• METHANE
• SPECTRA

The photo-induced formation of peroxide ions on the surface of cubic Ln(2)O(3) (Ln = Nd, Sm, Gd) was studied by in situ microprobe Raman spectroscopy using a 325 nm laser as excitation source. It was found that the Raman bands of peroxide ions at 833-843 cm(-1) began to grow at the expense of the Ln(3+)-O-2 bands at 333-359 cm(-1) when the Ln(2)O(3) samples under O-2 were continuously irradiated with a focused 325 nm laser beam at temperatures between 25-150 degrees C. The intensity of the peroxide Raman band was found to increase with increasing O-2 partial pressure, whereas no peroxide band was detected on the Ln(2)O(3) under N-2 as well as on the samples first irradiated with laser under Ar or N-2 followed by exposure to O-2 in the dark. The experiments using O-18 as a tracer further confirmed that the peroxide ions are generated by a photo-induced reaction between O-2 and the lattice oxygen (O2-) species in Ln(2)O(3). Under the excitation of 325 nm UV light, the transformation of O-2 to peroxide ions on the surface of the above lanthanide sesquioxides can even take place at room temperature. Basicity of the lattice oxygen species on Ln(2)O(3) also has an impact on the peroxide formation. Higher temperature or laser irradiation power is required to initiate the reaction between O-2 and O2- species of weaker basicity.

• 出版日期2012
• 单位厦门大学