在Pt和LaFeO3之间的表轴和强支相互作用中,膜稳定了Pt分散
Xinyu Mao, Alexandre C Foucher, Tiziano Montini1
1Department of Chemical and Pharmaceutical Sciences, University of Trieste, via L. Giorgieri 1, Trieste 34127, Italy.
Journal of the American Chemical Society
|May 20, 2020
概括
在催化剂中稳定小 (Pt) 晶体至关重要. 这项研究表明,在使用氧化物 (MgAl2O4) 上的铁酸 (LaFeO3) 薄膜进行苛刻处理后,Pt纳米颗粒在1-2纳米处保持稳定.
科学领域:
- 材料科学
- 催化剂
- 纳米技术
背景情况:
- 在恶劣的条件下稳定小 (Pt) 晶体在支金属催化剂中是一个重要的工业挑战.
- 保持纳米粒子大小对于高温应用中的催化剂活性和寿命至关重要.
研究的目的:
- 研究由MgAl2O4支持的兰铁 (LaFeO3) 薄膜上的1-2纳米Pt晶体的稳定性.
- 通过多个高温氧化和还原周期评估这些Pt纳米颗粒的稳定性.
主要方法:
- 在MgAl2O4基板上沉积0.5nmLaFeO3膜的原子层 (ALD).
- 高温氧化还原循环 (1073K的氧化和还原).
- 使用扫描传输电子显微镜 (STEM) 和X射线吸收光谱 (XAS) 的表征.
主要成果:
- 在1073K的多个氧化还原循环后,Pt粒子成功保持在1-2nm范围内.
- 在氧化过程中,STEM分析表明Pt结晶体与LaFeO3支相比的方向.
- XAS证实了Pt环境的变化,表明强烈的金属支相互作用.
- 在五次高温氧化还原循环后,催化剂的CO氧化率保持不变.
结论:
- 在LaFeO3薄膜上Pt集群的长轴生长有助于增强稳定性.
- Pt和LaFeO3之间强大的金属支相互作用是维持纳米粒子完整性的关键.
- 开发的催化剂系统在恶劣条件下表现出了显著的稳定性和持续性.
相关概念视频
Weak Acid Solutions
31.4K
Few compounds act as strong acids. A far greater number of compounds behave as weak acids and only partially react with water, leaving a large majority of dissolved molecules in their original form and generating a relatively small amount of hydronium ions. Weak acids are commonly encountered in nature, being the substances partly responsible for the tangy taste of citrus fruits, the stinging sensation of insect bites, and the unpleasant smells associated with body odor. A familiar example of a...
31.4K
Common Ion Effect
34.2K
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Châtelier’s principle. Consider the dissolution of silver iodide:
34.2K
Crystal Field Theory - Octahedral Complexes
28.5K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
28.5K
Ionic Strength: Effects on Chemical Equilibria
3.0K
The addition of an inert ionic compound increases the solubility of a sparingly soluble salt. For example, adding potassium nitrate to a saturated solution of calcium sulfate significantly enhances the solubility of calcium sulfate. Le Châtelier's principle cannot predict this shift in the equilibrium. Instead, this could be explained in terms of changes in the effective concentration of the ions in solution in the presence of added inert salt.
In this solution, the primary...
In this solution, the primary...
3.0K
Colloidal precipitates
5.7K
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
5.7K
The Colloidal State
189
The formation of a colloidal system is exemplified by an aqueous solution containing Cl− ions is introduced to another containing Ag+ ions, resulting in the precipitation of solid AgCl as extremely tiny crystals. Instead of settling out as a filterable precipitate, these crystals remain suspended in the liquid, showcasing a colloidal system.A colloidal system involves colloidal particles within the approximate range of 1 to 1000 nm in at least one dimension, dispersed in a medium called...
189


