Redox-Inert Cations Enhancing Water Oxidation Activity: The Crucial Role of Flexibility
Redox-Inert Cations Enhancing Water Oxidation Activity: The Crucial Role of Flexibility
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DOI：
10.1021/acscatal.6b01218
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发表时间：
2016-10-01
期刊：
影响因子：
12.9
通讯作者：
Luber, Sandra
中科院分区：
文献类型：
--
作者：
Hodel, Florian H.;Luber, Sandra
全球气候变化的破坏性影响，部分是由化石燃料的人为二氧化碳排放造成的，迫使我们寻找以环保方式生产的清洁燃料。利用太阳能将水分解成氧气和氢气是一种可能的解决方案，其成功实施不仅取决于高效水氧化催化剂（WOCs）的发展。通过光系统II的水裂解反应，特别是以氧化还原惰性金属为中心的立方结构的析氧配合物，大自然为我们构建这样的woc提供了线索。任何比简单的试错法更复杂的方法都将依赖于对仿生催化剂机理细节的了解。最近，在这个方向上迈出了一步，计算研究了基于a {Co(II)(4)O-4}古巴烷的WOC的不同可能的催化途径。本研究的重点是{Co(II)(3)LnO(4)} (Ln = Er, Tm) cubane家族，是对先前研究的补充，并阐明了氧化还原惰性Ln（3+）阳离子在水氧化机制中的重要性。利用密度泛函理论和显式溶剂化壳层，以及溶剂连续介质模型，比较了WOCs的催化状态的相对自由能，以及水侵蚀和氧释放的反应障碍。此外，对催化剂的电子和分子结构进行了深入的研究，发现了在催化循环过程中立方体笼的灵活性。
The devastating effects of global climate change, which is in part caused by anthropogenic CO2 emissions from fossil fuels, force us to find clean fuels produced by environmentally friendly methods. Splitting water into oxygen and hydrogen using solar light is one possible solution, the successful implementation of which depends not least on the development of efficient water oxidation catalysts (WOCs). With the water splitting reaction of photosystem II, specifically the oxygen evolving complex, which features a cubane structure with a redox-inert metal center, nature provides us with clues for the construction of such WOCs. Any approach more sophisticated than a simple trial-and-error method will rely on knowledge of mechanistic details of biomimetic catalysts. Recently, a step in that direction has been made with computational investigations of the different possible catalytic pathways of a {Co(II)(4)O-4} cubane-based WOC. The present study, which focuses on the {Co(II)(3)LnO(4)} (Ln = Er, Tm) cubane family, is complementary to the previous one and sheds light on the importance of redox inert Ln(3+) cations for the mechanism of water oxidation. Using density functional theory and an explicit solvation shell, as well as a solvent continuum model, the WOCs are compared in terms of relative free energies of their catalytic states, and the reaction barriers of water attack and oxygen release. Furthermore, in-depth investigations into the electronic and molecular structures of the catalysts are carried out, resulting in the discovery of a flexibility of the cubane cage during the catalytic cycle.