Understanding the diffusion-driven colloidal deposition of laser-generated ligand-free nanoparticles on dispersed catalyst supports

了解激光生成的无配体纳米粒子在分散催化剂载体上的扩散驱动胶体沉积

• 批准号: 428175685
• 负责人: Professor Dr.-Ing. Stephan Barcikowski, since 5/2020
• 金额: --
• 依托单位: Lehrstuhl für Technische Chemie I
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/428175685?language=en
• 关键词: Understanding; diffusion; driven; colloidal; deposition

The new and further developments of nano-based catalysts has a great economic potential. A flexible method for the preparation of heterogeneous catalysts is the colloidal deposition of nanoparticles on support materials. Particle deposition can be initiated by electrostatically attractive interactions of charged particles in liquids. However, diffusion driven processes are also important, which can be observed in particular in the case of defect-rich carrier materials. While particle adsorption in the electrostatically attractive regime suggests an inevitably spontaneous and nonspecific deposition mechanism, a selective and specific adsorption is expected especially on defect-rich adsorbents, in the case of the electrostatically repulsive region. Thus electrostatically-driven particle adsorption causes agglomeration due to the high charge density, while in the electrostatically repulsive (diffusion-controlled) area the particles can be deposited homogeneously. Due to an existing energy barrier in the electrostatic repulsive region, the adsorption of several nanoparticles at the same time is unfavorable. These Aspects have been less studied in the literature, in particular for ligand-free conditions. Such ligand-free colloids are undoubtedly ideal model materials for colloidal particle dynamic investigations. Therefore, the aim of this project is to gain an understanding of the diffusion-driven particle adsorption by systematic investigations and thus to enable targeted control in the production of heterogeneous catalysts. On the basis of a well-founded hypotheses, an effect mechanism will be developed, which will describe the role of various surface defects on particle adsorption. For this purpose, ligand-free nanoparticles will be used and supports with different oxygen vacancies, facets and functional groups will be selected. Various characterization methods are used to elucidate the nanoparticle-defect interaction: photoelectron spectroscopy (particle oxidation, electronic structure, particle-carrier interaction), Raman spectroscopy (vibrational band of carrier-nanoparticle interaction), electron microscopy (particle size, shape and distribution), X-ray diffraction (crystal structure), IR spectroscopy (functional groups), thermogravimetry (particle mass loading), BET method (catalyst surface), UV-VIS spectroscopy (band gap, deposition efficiency, colloidal stability), measurement of zeta potential (colloidal stability, surface charge) and electrocatalysis (catalytic activity and stability ORR). Finally, by means of systematic studies a wide-ranging model to elucidate the mechanism of diffusion-driven particle deposition will be established and transferred to different material systems.

纳米催化剂的新的和进一步的发展具有巨大的经济潜力。制备多相催化剂的一种灵活方法是将纳米颗粒胶态沉积在载体材料上。粒子沉积可以通过液体中带电粒子的静电吸引相互作用来引发。然而，扩散驱动的过程也很重要，特别是在富含缺陷的载体材料的情况下可以观察到。虽然在静电吸引制度的颗粒吸附表明一个不可避免的自发和非特异性的沉积机制，一个选择性和特异性吸附预计特别是在缺陷丰富的吸附剂，在静电排斥区域的情况下。因此，静电驱动的颗粒吸附由于高电荷密度而导致团聚，而在静电排斥（扩散控制）区域中，颗粒可以均匀地沉积。由于在静电排斥区域中存在能量势垒，同时吸附几个纳米颗粒是不利的。这些方面在文献中研究较少，特别是对于无配体条件。这种无配体的胶体无疑是胶体粒子动力学研究的理想模型材料。因此，本项目的目的是通过系统的研究来了解扩散驱动的颗粒吸附，从而在多相催化剂的生产中实现有针对性的控制。在充分假设的基础上，提出了各种表面缺陷对颗粒吸附的影响机理。为此，将使用无配体的纳米颗粒，并选择具有不同氧空位、晶面和官能团的载体。使用各种表征方法来阐明纳米颗粒-缺陷相互作用：光电子能谱（粒子氧化、电子结构、粒子-载流子相互作用）、拉曼光谱（载体-纳米颗粒相互作用的振动带），电子显微镜（粒度、形状和分布），X射线衍射（晶体结构），IR光谱（官能团），热重分析（颗粒质量负载），BET法（催化剂表面），UV-VIS光谱（带隙、沉积效率、胶体稳定性）、zeta电位测量（胶体稳定性、表面电荷）和电催化（催化活性和稳定性ORR）。最后，通过系统的研究，将建立一个广泛的模型来阐明扩散驱动的颗粒沉积机制，并将其转移到不同的材料系统。