Cobalt oxide surface chemistry:: The interaction of CoO(100), Co3O4(110) and Co3O4(111) with oxygen and water
Cobalt oxide surface chemistry:: The interaction of CoO(100), Co3O4(110) and Co3O4(111) with oxygen and water
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DOI：
10.1016/j.molcata.2007.08.023
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发表时间：
2008-02-18
影响因子：
--
通讯作者：
Langell, Marjorie A.
中科院分区：
文献类型：
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作者：
Petitto, Sarah C.;Marsh, Erin M.;Langell, Marjorie A.
钴氧化物包括两种容易接近的阳离子氧化态：Co2+和Co3+，它们在普通环境条件下具有热力学竞争，连接这两种状态的氧化还原机制是它们在部分氧化催化中成功的主要原因。在我们的研究中，用x射线光电子能谱（XPS）、高分辨率电子能量损失能谱（HREELS）和低能电子衍射（LEED）研究了CoO（10 0）、Co3O4（110）和Co3O4（111）单晶衬底对O-2和H2O的表面反应性以及它们在降低特高压条件下的稳定性。在氧化物表面，CoO和Co3O4的化学计量之间存在着很容易的相互转换，尽管成分变化，但在长程结构上保持良好的有序。然而，表面杂质可以将表面固定在CoO或Co3O4的极端成分上。与压力间隙在特高压下造成氧化物羟基化困难的报道相反，如果有足够的活化来解离水分子，则可以用H2O将一氧化碳和氧化尖晶石底物羟基化。(C) 2007 Elsevier B.V.版权所有
Cobalt oxides comprise two readily accessible cation oxidation states: Co2+ and Co3+ which are thermodynamically competitive under common ambient conditions, and redox mechanisms connecting the two states are largely responsible for their success in partial oxidation catalysis. In our studies, CoO(10 0), Co3O4(110), and Co3O4(111) single crystal substrates have been investigated with X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), and low energy electron diffraction (LEED) for their surface reactivity toward O-2 and H2O and for their stability under reducing UHV conditions. There is facile inter-conversion between CoO and Co3O4 stoichiometry at the oxide surface which, despite the compositional variability, remains well ordered in long-range structure. Surface impurities, however, can pin the surface at either CoO or Co3O4 compositional extremes. Contrary to reports of a pressure gap that creates difficulty in oxide hydroxylation under UHV it is possible to hydroxylate both cobalt monoxide and spinel oxide substrates with H2O, provided sufficient activation is available to dissociate the water molecule. (C) 2007 Elsevier B.V. All rights reserved.