Characterising metal nanoparticle catalytic activity by the work function

通过功函数表征金属纳米颗粒催化活性

• 批准号: 391170465
• 负责人: Professor Dr. Michael Reichling
• 金额: --
• 依托单位: Centre Interdisciplinaire de Nanoscience de Marseille
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/391170465?language=en
• 关键词: Characterising; metal; nanoparticle; catalytic; activity

We will demonstrate that the combination of non-contact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM) can be used to quantify the adsorption/desorption characteristics of fundamental gases in heterogeneous catalysis at the single nanoparticle (NP) level as a function of NP size, shape, composition and temperature, and how properties are affected by the oxide support. Furthermore, we will explicitly demonstrate that KPFM is capable of quantifying phenomena of contamination and dissolution at single NPs that is most important for many catalytic processes.While NC-AFM will be used to reveal the surface structure and morphology determined by the size, shape, distribution and sintering of NPs, the task of KPFM will be to monitor the local electronic structure determined by changes in the NP's work function (WF) providing a quantitative measure for adsorbed molecular species or dissolved atomic species in NPs. The techniques will be established as calibrated standard tools in heterogeneous model catalysis involving metal NPs. Local measurements by NC-AFM and KPFM will be supported by an analysis with X-ray photoelectron spectroscopy (XPS) and Ultraviolet photoelectron spectroscopy (UPS) to obtain the chemical fingerprints and average WF of the molecule-NP- surface system. Experiments will be backed by density functional theory (DFT) analysing and predicting the adsorption of reactants on NPs and related WF changes. The ultimate and challenging goal is to observe and to quantify simple reactions at single NPs, namely the oxidation of CO and the hydrogenation of hydrocarbons.For the project, we will first focus on pure NPs of platinum group materials (PGMs), in particular on palladium (Pd) and gold (Au), commonly used for industrial catalytic converters. Furthermore, we consider bi-metallic NPs with the focus on Pd and Au. During the course of the project, we optionally consider other metals like Fe, Co or Cu. The support will be ultra-thin and thick films of cerium oxide (ceria).The adsorption and desorption of CO, oxygen, hydrogen and simple hydrocarbon gases (e.g. ethylene) will be investigated in detail; species that are known to adsorb at metal nanoparticles like PdNPs. Contamination experiments will focus in particular on carbon contamination and dissolution, phenomena most relevant for many catalytic reactions like the hydrogenation of hydrocarbons, Fischer-Tropsch process and in the synthesis of carbon structures like graphene or nanotubes.

我们将证明非接触式原子力显微镜（NC-AFM）和开尔文探针力显微镜（KPFM）的结合可以用来量化在单纳米颗粒（NP）水平上多相催化中基本气体的吸附/解吸特性，作为NP大小、形状、组成和温度的函数，以及氧化物载体如何影响性质。此外，我们将明确证明，KPFM能够量化污染和溶解现象在单个NPs，这是最重要的许多催化过程。NC-AFM将用于揭示由NP的大小、形状、分布和烧结决定的表面结构和形态，而KPFM的任务将是监测由NP的功函数（WF）变化决定的局部电子结构，为NP中吸附的分子物种或溶解的原子物种提供定量测量。这些技术将被建立为涉及金属NPs的多相模型催化的校准标准工具。通过x射线光电子能谱（XPS）和紫外光电子能谱（UPS）分析，支持NC-AFM和KPFM的局部测量，以获得分子- np -表面体系的化学指纹图谱和平均WF。实验将通过密度泛函理论（DFT）来分析和预测NPs上反应物的吸附和相关的WF变化。最终和具有挑战性的目标是观察和量化单一NPs下的简单反应，即CO的氧化和碳氢化合物的加氢。对于该项目，我们将首先关注铂族材料（PGMs）的纯NPs，特别是钯（Pd）和金（Au），它们通常用于工业催化转化器。此外，我们考虑了双金属NPs，重点是钯和金。在项目过程中，我们可选择考虑其他金属，如Fe， Co或Cu。支撑将是超薄和超厚的氧化铈（ceria）薄膜。将详细研究CO、氧、氢和简单碳氢化合物气体（如乙烯）的吸附和解吸；这些物质会吸附金属纳米粒子，比如PdNPs。污染实验将特别关注碳污染和溶解，这是许多催化反应最相关的现象，如碳氢化合物的氢化，费托过程和碳结构的合成，如石墨烯或纳米管。