Four-electron reduction of O2 over multiple CuI centers:: Quantum theory
Four-electron reduction of O2 over multiple CuI centers:: Quantum theory
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DOI：
10.1016/j.jelechem.2007.01.012
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发表时间：
2007-09-01
影响因子：
4.5
通讯作者：
Anderson, Alfred B.
中科院分区：
文献类型：
--
作者：
Vayner, Ellen;Schweiger, Hannes;Anderson, Alfred B.
从理论上测试了一系列铜配合物对氧电还原的影响，从裸Cu和Cu+中心开始，带和不带n配体，以1、2和3个h2n -Cu-咪唑切割中心结束。利用B3LYP杂化密度泛函理论计算了4个单电子还原步骤中生成的反应中间体的吸附能，并利用线性自由能关系预测了每一步的可逆势。寻找未被O（ads）、OH（ads）和H2O毒害的切割位点，因此初步筛选是基于O（ads）还原为OH（ads）和OH（ads）还原为H2O的预测可逆电位以及O-2和H2O的吸附键强度。h2n - cu -咪唑和h2n - cu -咪唑中Cu-I中心的性能最好。前者用于模拟铜漆酶的四电子还原，其中一些铜漆酶的过电位很小。通过对由3个h2n - cu -咪唑组成的3-Cu-I松散缔合催化位点模型的计算，得出以下结论：(1)与模型结合的OH的还原电位高于Pt的计算值，这与观察到的Pt的过电位高于类相一致；（ii） H2O与切割中心的结合较弱，不会对其造成毒害；（iii）计算了非电子转移步骤的模型相关热损失，并显示了它们如何对整体四电子还原的过电位做出贡献。最后，证明了CH3S-Cu-（咪唑）2具有电子给体-受体性质，使其能够作为电子转移到催化位点的中间体。这项研究表明，松散协调的Cu-I中心在低过电位下为四电子氧还原提供了机会。(c) 2007 Elsevier B.V.版权所有
A series of copper complexes were tested theoretically for oxygen electro reduction, beginning with bare Cu and Cu+ centers, with and without N-bearing ligands, and ending with one, two, and three H2N-Cu-Imidazole Cut centers. Adsorption energies for reaction intermediates formed during the four one-electron reduction steps to water were calculated, using B3LYP hybrid density functional theory, and then used in a linear free energy relationship to predict the reversible potential for each step. Cut sites not poisoned by O(ads), OH(ads), and H2O were sought, and so initial screening was based on the predicted reversible potentials for O(ads) reduction to OH(ads) and OH(ads) reduction to H2O and the adsorption bond strengths Of O-2 and H2O. The Cu-I centers in H2N-Cu-Imidazole and H2N-Cu-Imidazole had the best properties in this screening. The former was used to model four-electron reduction by copper laccases, some of which have very little overpotential. On the basis of calculations on a model for 3-Cu-I catalytic sites composed of three H2N-Cu-Imidazole in loose association, the following conclusions were reached: (i) the reduction potential for OH bonded to the model is higher than calculated for Pt, which is consistent with the higher observed overpotentials for Pt compared to lacasses; (ii) H2O bonds weakly to the Cut centers and does not poison them; (iii) model-dependent heat losses were calculated for non-electron transfer steps and it is shown how they contribute to the overpotential for the overall four-electron reduction. Finally, it is shown that CH3S-Cu-(Imidazole)2 possesses the electron donor-acceptor properties that allow it to be an intermediate in electron transfer to the catalytic site. This study shows that loosely coordinated Cu-I centers present opportunities for four-electron oxygen reduction at low overpotential. (c) 2007 Elsevier B.V. All rights reserved.