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相关概念视频

Catalysis02:50

Catalysis

22.9K
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
22.9K
Factors Influencing the Rate of Chemical Reactions01:22

Factors Influencing the Rate of Chemical Reactions

8.0K
A variety of factors influence the rate of chemical reactions. For a chemical reaction to happen, atoms must collide with enough energy to overcome the repulsion between their electrons. This energy is called activation energy. Factors influencing the rate of reaction either lower the activation energy or increase the likelihood of a successful collision.
Concentration and Pressure:
The more particles present within a given space, the more likely those particles are to bump into one another....
8.0K
Factors Affecting Activity Coefficient01:17

Factors Affecting Activity Coefficient

1.6K
The extended Debye-Hückel equation indicates that the activity coefficient of an ion in an aqueous solution at 25°C depends on three partially interdependent properties: the ionic strength of the solution, the charge of the ion, and the ion size. 
The activity coefficient value for an ion is close to one when the solution has almost zero ionic strength, i.e., when the solution shows close to ideal behavior. As the ionic strength of the solution increases from 0 to 0.1 mol/L, a...
1.6K
Heterogeneous Catalysis01:22

Heterogeneous Catalysis

141
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...
141
Processes at Electrodes01:30

Processes at Electrodes

98
The electrode interacts with ions in the electrolyte solution at its interface. The rate of oxidation and reduction depends on the speed at which electrons can transfer through this interface. As ions attach to or leave the electrode surface, the electrode acquires a charge, and an electrical potential forms across the interface, making the process more difficult to reach equilibrium. The charge on the electrode affects the local ion concentrations in the solution, though thermal motion...
98
Acid Attack on Concrete01:21

Acid Attack on Concrete

1.1K
When acids come into contact with concrete, they initiate a chemical reaction that dissolves the hydrated cement paste. This process leads to softening and structural weakening of the concrete. This issue is commonly observed in environments such as chimneys, sewers, and industrial settings. The severity of the damage increases as the pH of the water interacting with the concrete drops below 6.5. In particular, a pH under 4.5 can cause significant concrete damage.
The rate at which hydrogen...
1.1K

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Simple Methods for the Preparation of Non-noble Metal Bulk-electrodes for Electrocatalytic Applications
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Simple Methods for the Preparation of Non-noble Metal Bulk-electrodes for Electrocatalytic Applications

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为什么在酸性条件下化碳电催化剂的性能会下降?

Kenji Hayashida1, Junji Nakamura2, Kotaro Takeyasu3,4

  • 1Graduate School of Science and Technology, University of Tsukuba, Sapporo, Hokkaido, 0010021, Japan.

Angewandte Chemie (International ed. in English)
|May 2, 2025
PubMed
概括
此摘要是机器生成的。

化碳催化剂在酸性燃料电池电解质中降解. 它们的活动丧失与酸的酸有关.

关键词:
碳催化剂是一种碳催化剂.氧降解反应是氧降解反应.重新激活机制的机制表面科学是一门科学.

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科学领域:

  • 电化学 电化学 电化学
  • 材料科学 材料科学 材料科学
  • 催化剂是一种催化剂.

背景情况:

  • 添加碳 (NDC) 显示出作为低成本催化剂的氧减少反应 (ORR) 的承诺.
  • 在酸性电解质中,NDC的催化活性下降,阻碍了燃料电池应用.
  • 酸 (pyri-N) 被确定为NDC催化剂中的主要活性位点.

研究的目的:

  • 阐明NDC催化剂在酸性介质中的降解机制.
  • 调查酸酸平衡在催化剂失活中的作用.
  • 为提高NDC催化剂性能制定准则.

主要方法:

  • 对NDC催化剂的电化学分析.
  • 研究涉及酸和氧的反应途径.
  • 催化活性与的基本性之间的相关性.

主要成果:

  • 电化学化pyri-N到pyri-NH,加上氧吸附,是关键的降解过程.
  • 这种反应发生在酸性电解质中较低的电位,这是由于pyri-N质子化.
  • 酸中的催化剂活性下降与pyri-N的基本性直接相关.

结论:

  • 酸的酸性质决定了NDC催化剂在酸性电解质中的稳定性.
  • 控制pyri-N的基本性 (pKa) 对于改善ORR和其他电极反应至关重要.
  • 这项研究为设计强大的NDC电催化剂提供了基本的理解.