水分裂和由单核复合体形成氧-氧键的机制
Xinzheng Yang1, Michael B Hall
1Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA.
Journal of the American Chemical Society
|December 5, 2009
概括
密度函数理论 (DFT) 揭示了使用催化剂生产太阳能的新机制. 该研究详细介绍了一种新的生成途径,并确定了催化剂更有效的再生路径,这对于太阳能燃料应用至关重要.
科学领域:
- 计算化学的计算化学
- 光催化作用的光催化
- 无机化学 无机化学
背景情况:
- 太阳能气生产是可再生能源的一个关键领域.
- 基于的催化剂显示了水分裂的潜力.
- 了解反应机制对于催化剂优化至关重要.
研究的目的:
- 阐明报告的一种用于太阳能生产的光催化系统的详细机制.
- 为了研究连接体 Dearomatization 和水激活的作用.
- 确定最稳定的中间体和率决定步骤.
主要方法:
- 使用密度函数理论 (DFT) 的计算.
- 时间依赖的DFT被用来研究光解反应.
- 进行了热和光诱导反应通路的分析.
主要成果:
- DFT预测了一种涉及水协调,O-H键裂解和带芳香化的机制.
- 确定速率的步骤涉及 dearomatization 和 H ((2) 形成.
- 一个cis-dihydroxo复合物的光解分解通过三重状态产生H(2) O(2).
- 确定了催化剂的新,低能量的再生途径.
结论:
- 该研究提供了一个详细的DFT预测的太阳能生产机制.
- 提出了一种新的催化循环,涉及不同的再生路径.
- 这项工作为设计更高效的光催化剂提供了洞察力,用于太阳能燃料发电.
相关概念视频
Oxidative Cleavage of Alkenes: Ozonolysis
In ozonolysis, ozone is used to cleave a carbon–carbon double bond to form aldehydes and ketones, or carboxylic acids, depending on the work-up.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Radical Anti-Markovnikov Addition to Alkenes: Mechanism
The reaction of hydrogen bromide with alkenes in the presence of hydroperoxides or peroxides proceeds via anti-Markovnikov addition. The radical chain reaction comprises initiation, propagation, and termination steps.
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy radical...
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy radical...
Radical Formation: Homolysis
A bond is formed between two atoms by sharing two electrons. When this bond is broken by supplying sufficient energy, either two electrons can be taken up by one atom forming ions by the cleavage called heterolysis, or the two electrons are shared by two atoms, with one each creating radicals by the cleavage called homolysis.
Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
Radical Autoxidation
The oxidation of an organic compound in the presence of air or oxygen is called autoxidation. For example, cumene reacts with oxygen to form hydroperoxide. Autoxidation involves initiation, propagation, and termination steps. Many organic compounds are susceptible to autoxidation—especially ethers in the presence of oxygen, which form hydroperoxides. Even though this reaction is slow, old ether bottles contain small amounts of peroxide, which leads to laboratory explosions during ether...
Radical Formation: Overview
A bond can be broken either by heterolytic bond cleavage to form ions or homolytic bond cleavage to yield radicals. A fishhook arrow is used to represent the motion of a single electron in homolytic bond cleavage. There are two main sources from which radicals can be formed:
Radicals from spin-paired molecules:
Radicals can be obtained from spin-paired molecules either by homolysis or electron transfer. While two radicals are formed in the former, an electron is added in the latter, also known...
Radicals from spin-paired molecules:
Radicals can be obtained from spin-paired molecules either by homolysis or electron transfer. While two radicals are formed in the former, an electron is added in the latter, also known...


