文献类型：期刊文献

英文题名：Probing the Surface Structure of α-Mn₂O₃ Nanocrystals during CO Oxidation by Operando Raman Spectroscopy

作者：Luo, Yan[1];Deng, Ya-Qing[1];Mao, Wei[1];Yang, Xue-Jing[1];Zhu, Kake[1];Xu, Jing[1];Han, Yi-Fan[1]

机构：[1]E China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China

年份：2012

卷号：116

期号：39

起止页码：20975

外文期刊名：JOURNAL OF PHYSICAL CHEMISTRY C

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000309375700042)】；

基金：The authors are grateful to the support from the Chinese Education Ministry 111 project (B08021), the National Science Foundation (21176071, 21106041, 21273070), Shanghai PuJiang Talent Program (2011/11PJ1402400), Science and Technology Commission of Shanghai Municipality (11JC1402700), Innovation Program of Shanghai Municipal Education Commission (11ZZ52, 12ZZ051), Shanghai Natural Science Foundation (11ZR1408400). Thanks Dr. Jiang Dong for the help to measure XPS in the center of analysis and test, East China University, Sci.&Tech., Shanghai, China.

语种：英文

摘要：The alpha-Mn2O3 nanocrystals with uniform morphology prepared by calcining a self-assembly Mn3O4 precursor show higher activity toward CO oxidation. Operand Raman spectroscopy is used to probe the near-surface structure of alpha-Mn2O3 nanocrystals during the adsorption and oxidation of CO for the first time. A surface phase-transformation from alpha-Mn2O3 to MnO-like species, as evidenced by the formation of a single band at 498 cm(-1), was observed only at or above 300 degrees C in the presence of CO. This modification is probably due to the loss of lattice oxygen at high temperatures that leads to the surface reconstruction. Very interestingly, a reversible phase-transformation was observed with decreasing the temperature to 25 degrees C. The shift of the symmetric stretching of Mn2O3 groups (632 -> 649 cm(-1)) due to the adsorption of CO was observed even at room temperature. In addition, the results of the temperature-programmed desorption of O-2 (TPD-O-2) and temperature-programmed surface reaction (TRSR) indicate that the oxidizing of CO may proceed through the Langmuir-Hinshelwood mechanism (<220 degrees C) to Mars-van-Krevelen mechanism (>350 degrees C) with the increasing of reaction temperature. In particular, the weakly adsorbed oxygen is deduced to be responsible for CO oxidation at low temperatures.