CO oxidation catalyzed by single-walled helical gold nanotube
CO oxidation catalyzed by single-walled helical gold nanotube
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DOI：
10.1021/nl072409t
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发表时间：
2008-01-01
期刊：
影响因子：
10.8
通讯作者：
Zeng, X. C.
中科院分区：
文献类型：
--
作者：
An, Wei;Pei, Yong;Zeng, X. C.
本文利用密度泛函理论研究了单壁螺旋状金纳米管Au（5，3）的催化性能。我们使用CO氧化作为基准探针，以获得洞察高催化活性的金纳米管。由Au（5，3）纳米管催化的CO氧化通过两步机理进行，CO + O-2-> CO2 + O和CO + O-> CO2。CO氧化是由CO + O-2-> OOCO-> CO2 + O反应引发的，活化势垒为0.29 eV。在反应路径上，形成过氧型O-O-CO中间体。此后，CO + O-> CO2反应沿着反应路径以非常低的势垒（0.03 eV）进行。注意，第二反应不能是CO氧化的起始点，因为自由O-2在金纳米管上的能量不利吸附。Au（5，3）纳米管的高催化活性可归因于吸附的中间物种的电子态与反应位点处的Au原子之间的电子共振，特别是Au原子的d态与C-O和O1-O2的反键2 π * 态之间的电子共振，伴随着部分电荷转移。螺旋状金纳米管中存在的配位不足的Au位点和应变也起着重要的作用。我们的研究表明，由螺旋状金纳米管催化的CO氧化可能在室温下发生。
We study the catalytic capability of unsupported single-walled helical gold nanotubes Au(5,3) by using density functional theory. We use the CO oxidation as a benchmark probe to gain insights into high catalytic activity of the gold nanotubes. The CO oxidation, catalyzed by the Au(5,3) nanotube, proceeds via a two-step mechanism, CO + O-2 -> CO2 + O and CO + O -> CO2. The CO oxidation is initiated by the CO + O-2 -> OOCO -> CO2 + O reaction with an activation barrier of 0.29 eV. On the reaction path, a peroxo-type O-O-CO intermediate forms. Thereafter, the CO + O -> CO2 reaction proceeds along the reaction pathway with a very low barrier (0.03 eV). Note that the second reaction cannot be the starting point for the CO oxidation due to the energetically disfavored adsorption of free O-2 on the gold nanotube. The high catalytic activity of the Au(5,3) nanotube can be attributed to the electronic resonance between electronic states of adsorbed intermediate species and Au atoms at the reaction site, particularly among the d states of Au atom and the antibonding 2 pi* states of C-O and O1-O2, concomitant with a partial charge transfer. The presence of undercoordinated Au sites and the strain inherent in the helical gold nanotube also play important roles, Our study suggests that the CO oxidation catalyzed by the helical gold nanotubes is likely to occur at the room temperature.