Novel nanostructured catalysts for the high-temperature electro-oxidation of small organic molecules

我们的目标是深入了解：1)铂金属(铂，钯，…)的结构-反应性关联。纳米颗粒，使用形状和小面取向明确和可变的纳米颗粒，以及ii)形状限定的双金属纳米颗粒在小有机分子(甲酸、甲醇、乙醇…)氧化中的表面组成。除了了解具有明确形貌和结构的纳米粒子的分子尺度反应机理，以及表面结构和组成的影响外，我们还特别感兴趣的是反应条件(浓度、温度)所造成的影响，涵盖了广泛的反应条件，直到燃料电池相关的反应和运输条件。基于对机理的理解，我们的目标是系统地改进这些纳米粒子催化剂在有机小分子氧化中的催化行为。此外，我们将阐明预成型纳米颗粒在形状松弛和烧结方面的稳定性，这将是应用的关键。这些目标应优先定向，直径在5-10 nm范围内的不同形状的纳米颗粒，其尺寸和形状将以可控的方式变化。纳米粒子的合成及其进一步的系统完善是该项目的重要组成部分。由于小面特定的表面结构，纳米颗粒形状的变化对应于表面结构的变化。机理解释将在很大程度上基于电化学和现场光谱测量的组合(差示电化学质谱(DEM)和ATR-FTIR)，这些测量是在燃料电池相关的反应条件下进行的。它们提供了关于吸附和挥发的反应中间体和反应副产物的性质和作用的详细信息。此外，我们将利用现有的实验和理论数据以及对各自反应的机理建议，以及合作理论小组的结果。

We aim at an in-depth understanding of i) the structure-reactivity correlation in platinum metal (Pt, Pd, ...) nanoparticles, using nanoparticles with well defined and variable shape and facet orientation, and of ii) the surface composition of shape-defined bimetallic nanoparticles in the oxidation of small organic molecules (formic acid, methanol, ethanol …). In addition to understanding the molecular scale reaction mechanism on nanoparticles of well defined morphology and structure, and the effect of surface structure and composition, we are particularly interested in effects caused by the reaction conditions (concentration, temperatures), covering a wide range of reaction conditions, up to fuel cell relevant reaction and transport conditions. Based on the resulting mechanistic understanding, we aim at a systematic improvement of the catalytic behavior of these nanoparticle catalysts in the oxidation of small organic molecules. Furthermore, we will elucidate the stability of the pre-shaped nanoparticles with respect to shape relaxation and sintering, which will be crucial for applications.These objectives shall be reached using preferentially oriented nanoparticles with diameters in the 5-10 nm range and different shapes, whose size and shape will be varied in a controlled way. Synthesis of the nanoparticles and its further systematic improvement is an important part of the project. Variations in the nanoparticle shape correspond to changes in the surface structure, due to the facet specific surface structure. The mechanistic interpretation will largely be based on combined electrochemical and in-situ spectroscopic measurements (Differential Electrochemical Mass Spectrometry (DEMS) and ATR-FTIR), which are performed under up to fuel cell relevant reaction conditions. They provide detailed information on the nature and role of adsorbed and volatile reaction intermediates and reaction side products. Furthermore, we will make use of existing experimental and theoretical data and mechanistic proposals for the respective reactions, and of results in collaborating theory groups.