活性氧化物对氧化物演变的性质
Michael Huynh1, Chenyang Shi2, Simon J L Billinge2,3
1Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States.
Journal of the American Chemical Society
|November 18, 2015
概括
通过潜在循环激活电子沉积的氧化 (MnOx) 薄膜显著提高了它们的氧化演化催化剂性能. 这种激活过程改变了材料,导致酸性溶液中的催化活性大大提高.
科学领域:
- 电化学
- 材料科学
- 催化剂
背景情况:
- 电子沉积的氧化 (MnOx) 薄膜作为稳定的氧化演化反应 (OER) 催化剂被探索.
- 通过恒定阳极电位沉积制成的初始MnOx薄膜表现出适度的活动,特别是在酸性介质中.
研究的目的:
- 研究潜在循环协议对电沉积MnOx膜的催化性能的影响.
- 在激活后观察到的性能增强背后的机制.
主要方法:
- 电化学沉积MnOx薄膜.
- 通过潜在的循环协议激活.
- 塔菲尔分析以量化催化活性.
- 电化学,光谱和结构性表征方法.
主要成果:
- 激活显著降低了Tafel斜率,表明了改善的OER动力学 (例如,在酸性溶液中从~650到~90mV/十年).
- 激活过程包括从birnessite-like MnOx (δ-MnO2) 转变为hausmannite-like中间体 (α-Mn3O4),然后形成高度活跃的无序birnessite-like 阶段.
- 与原始材料相比,激活的MnOx在pH2.5时电流密度增加了两级,接近贵金属氧化物的性能.
结论:
- 潜在循环是电沉积MnOx氧化演化催化剂的有效激活策略.
- 这种增强的活性源于可逆相变,导致一种无序的,高度活跃的MnOx结构.
- 活性MnOx为在酸性环境中氧气演变的贵金属催化剂提供了一个有希望的,具有成本效益的替代品.
相关概念视频
01:24Microbes and Other Elemental Cycles
41
Microbial activity plays a pivotal role in the biogeochemical cycling of iron and manganese, especially at the redox gradients characteristic of stratified aquatic environments. These cycles are driven by microbial transformations between oxidized and reduced forms of the metals, allowing organisms to exploit them for metabolic energy and structural purposes.Iron Cycling Across Redox GradientsIn neutral, oxygen-rich surface waters, iron is predominantly found in its oxidized, insoluble ferric...
41
01:27Redox Reactions
1.3K
Redox reactions are vital biochemical processes that underpin energy metabolism in cells. These reactions involve the transfer of electrons between molecules, occurring in tandem as oxidation and reduction. Oxidation refers to the loss of electrons, while reduction denotes their gain. This coupling ensures the seamless flow of electrons through metabolic pathways. For example, in bacterial metabolism, glucose undergoes oxidation to carbon dioxide, while oxygen is simultaneously reduced to...
1.3K
01:21Radical Oxidation of Allylic and Benzylic Alcohols
3.1K
Activated manganese(IV) oxide can selectively oxidize allylic and benzylic alcohols via a radical intermediate mechanism. Primary allylic alcohols are oxidized to aldehydes, while secondary allylic alcohols yield ketones. The redox reaction of potassium permanganate with an Mn(II) salt such as manganese sulfate (under either alkaline or acidic conditions), followed by thorough drying, yields the oxidizing agent: activated MnO2. While MnO2 is insoluble in the solvents used for the reaction, the...
3.1K
02:21Oxidation of Alkenes: Syn Dihydroxylation with Potassium Permanganate
17.9K
Alkenes can be dihydroxylated using potassium permanganate. The method encompasses the reaction of an alkene with a cold, dilute solution of potassium permanganate under basic conditions to form a cis-diol along with a brown precipitate of manganese dioxide.
17.9K
02:58Balancing Redox Equations
64.2K
Electrochemistry is the science involved in the interconversion of electrical and chemical reactions. Such reactions are called reduction-oxidation, or redox reactions. These important reactions are defined by changes in oxidation states for one or more reactant elements and include a subset of reactions involving the transfer of electrons between reactant species. Electrochemistry as a field has evolved to yield sufficient insights on the fundamental principles of redox chemistry and multiple...
64.2K
01:24Redox Reactions
59.3K
Oxidation-reduction or redox reactions involve the transfer of electrons from one molecule or atom to another. When an atom gains an electron, another atom must lose an electron, meaning oxidation and reduction must occur together. Since the redox occurs in pairs, the atom that gets oxidized is also called the reducing agent or reductant, and the atom that is reduced is also called the oxidizing agent or oxidant. A straightforward way to remember the definitions of oxidation and reduction is...
59.3K