Healing of oxygen vacancies on reduced surfaces of gold-doped ceria
Healing of oxygen vacancies on reduced surfaces of gold-doped ceria
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DOI：
10.1063/1.3110702
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发表时间：
2009-04-14
影响因子：
4.4
通讯作者：
Nolan, Michael
中科院分区：
文献类型：
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作者：
Nolan, Michael
CeO_2作为氧化还原催化剂，可以催化分子氧化还原。人们一直关注于了解和加强空位形成过程，以提高CeO2的氧化能力。然而，重要的是也要解决表面空缺的愈合问题。为了研究CeO2中氧空位的修复，我们用密度泛函理论(DFT+U)研究了氧原子和分子氧以及NO2与金掺杂(110)和(100)表面氧空位的相互作用。对于原子和分子氧，在还原表面的吸附是有利的，并导致氧原子位于氧晶格位置，修复氧空位。在未掺杂的表面上，O-2以过氧基(O(2)2-)形式吸附。然而，在掺杂的(110)表面上存在超氧(O-2-)物种。当NO2(放热)吸附在双空位表面时，分子中的一个氧位于空位，N-O距离拉长，形成与未掺杂表面类似的[NO2](-)阴离子。CeO2表面的空位愈合是有利的，即使空位形成被增强，这证明了目前对提高CeO2氧化能力的关注是合理的。我们简单地考察了一个催化循环：CO与吸附在未掺杂和掺杂表面上的O-2的反应，发现掺杂的(110)表面促进了CO的氧化。
As an oxidation-reduction catalyst, ceria can catalyze molecular oxidation and reduction. There has been a focus on understanding and enhancing the vacancy formation process to improve the oxidative power of ceria. However, it is important to also address healing of the surface vacancy. To investigate healing of oxygen vacancies in ceria, we study the interaction of atomic and molecular oxygen and NO2 with oxygen vacancies on gold-doped (110) and (100) surfaces using density functional theory, corrected for on-site Coulomb interactions (DFT+U). For atomic and molecular oxygen, adsorption at the reduced surface is favorable and results in an oxygen atom sitting in an oxygen lattice site, healing the oxygen vacancy. On undoped surfaces, O-2 adsorbs as a peroxo (O(2)2-) species. However, on the doped (110) surface a superoxo (O-2-) species is present. When NO2 adsorbs (exothermically) at a divacancy surface, one oxygen of the molecule sits in the vacancy site and the N-O distances are elongated and an [NO2](-) anion forms, similar to the undoped surface. Vacancy healing of ceria surfaces is favorable, even if vacancy formation is enhanced, justifying the current focus on improving the oxidative power of ceria. We briefly examine a catalytic cycle: the reaction of CO with adsorbed O-2 on the undoped and doped surfaces, and find that the doped (110) surface facilitates CO oxidation.