Pits confined in ultrathin cerium(IV) oxide for studying catalytic centers in carbon monoxide oxidation
Pits confined in ultrathin cerium(IV) oxide for studying catalytic centers in carbon monoxide oxidation
复制标题
超薄氧化铈（IV）中限制的凹坑用于研究一氧化碳氧化催化中心
DOI：
10.1038/ncomms3899
复制
发表时间：
2013-11-01
影响因子：
16.6
通讯作者：
Xie, Yi
中科院分区：
文献类型：
--
作者：
Sun, Yongfu;Liu, Qinghua;Xie, Yi
寻找理想的材料模型来研究催化活性中心的作用仍然是一个巨大的挑战。在这里，我们提出了坑局限在一个原子级薄片作为一个平台，以评估一氧化碳催化氧化在各个网站。具有约20%凹坑占有率的人造三原子层薄氧化铈（IV）片具有丰富的凹坑周围的铈位点，如通过X射线吸收光谱所揭示的，平均配位数为4.6。密度泛函计算揭示，四倍和五倍协调坑周围铈网站承担各自的作用，一氧化碳吸附和氧活化，这降低了活化势垒，避免催化中毒。此外，配位不饱和铈位的存在增加了载流子密度，并促进一氧化碳沿表面凹坑的二维导电通道沿着扩散。具有表面限制凹坑的原子级薄片表现出比本体材料更低的表观活化能（61.7对122.9 kJ mol（-1）），导致降低的转化温度和增强的一氧化碳催化能力。
Finding ideal material models for studying the role of catalytic active sites remains a great challenge. Here we propose pits confined in an atomically thin sheet as a platform to evaluate carbon monoxide catalytic oxidation at various sites. The artificial three-atomic-layer thin cerium(IV) oxide sheet with approximately 20% pits occupancy possesses abundant pit-surrounding cerium sites having average coordination numbers of 4.6 as revealed by X-ray absorption spectroscopy. Density-functional calculations disclose that the four- and five-fold coordinated pit-surrounding cerium sites assume their respective role in carbon monoxide adsorption and oxygen activation, which lowers the activation barrier and avoids catalytic poisoning. Moreover, the presence of coordination-unsaturated cerium sites increases the carrier density and facilitates carbon monoxide diffusion along the two-dimensional conducting channels of surface pits. The atomically thin sheet with surface-confined pits exhibits lower apparent activation energy than the bulk material (61.7 versus 122.9 kJ mol(-1)), leading to reduced conversion temperature and enhanced carbon monoxide catalytic ability.