Synthesis of phase pure high entropy perovskites with unique electrocatalytic and oxygen transport properties

具有独特电催化和氧传输性能的相纯高熵钙钛矿的合成

• 批准号: 538516601
• 负责人: Professor Dr. Armin Feldhoff
• 金额: --
• 依托单位: Institut für Physikalische Chemie und Elektrochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/538516601?language=en
• 关键词: Synthesis; phase; pure; entropy; perovskites

This project focuses on the synthesis of phase-pure, chromium-free, high-entropy perovskites that are expected to exhibit exceptional properties, such as enhanced temperature and chemical stability and improved catalytic and oxygen transport performances. Therefore, the hypothesis that compounds with high configurational entropy are phase pure at high temperatures and that rapid cooling leads to phase purity at room temperature is being tested. For this reason, nebulized spray pyrolysis is chosen as the synthesis method that enables rapid cooling so that the metastable phase stabilized at high temperatures by entropic effects is also retained at room temperature. In addition to cooling, overall synthesis using nebulized spray pyrolysis is also more time efficient than other synthesis methods. After the chromium-free high-entropy perovskite powders have been synthesized, they are next analysed structurally using X-ray diffraction and scanning electron microscopy. The process parameters and elemental compositions can thus be optimized via iteration loops until phase purity of the product is achieved, for which additionally crystal structure, morphology and particle size are determined. Chromium should be omitted from the composition due to potential environmental and safety issues. If the synthesis of the perovskite powders with an equimolar composition of cations is successful, the nickel proportion of the composition should be varied. This could result in an exsolution of nickel, which would have positive effects on the catalytic properties of the powder. In order to classify the resulting particles structurally, transmission electron microscopy and electron energy-loss spectroscopy are used in addition to the methods already mentioned, which provides more precise information on particle size and structure. The powders are then processed into membranes by pressing and sintering. Iteration loops in which the parameters are adjusted, in combination with structural analysis, should enable the phase purity to be maintained despite the high temperatures required for sintering. The electrical conductivity and oxygen permeation of the membranes are investigated. In addition, the electrocatalytic properties of the powders and the membranes are analyzed. Electrocatalytic oxygen-transporting membranes are thus obtained, which can be used in various heterogeneous catalytic processes.

该项目的重点是合成纯相、无铬、高熵的钙钛矿，这些钙钛矿有望表现出优异的性能，如增强的温度和化学稳定性以及改善的催化和氧传输性能。因此，具有高构型熵的化合物在高温下是相纯的并且快速冷却导致在室温下相纯的假设正在被测试。为此，选择雾化喷雾热解作为能够快速冷却的合成方法，使得在高温下通过熵效应稳定的亚稳相也保留在室温下。除了冷却之外，使用雾化喷雾热解的整体合成也比其他合成方法更省时。在合成无铬高熵钙钛矿粉末后，接下来使用X射线衍射和扫描电子显微镜对其进行结构分析。因此，可以通过迭代循环优化工艺参数和元素组成，直到实现产物的相纯度，为此另外确定晶体结构、形态和粒度。由于潜在的环境和安全问题，铬应该从组合物中省略。如果具有等摩尔组成的阳离子的钙钛矿粉末的合成是成功的，则组合物的镍比例应该变化。这可能导致镍的出溶，这将对粉末的催化性能产生积极影响。为了在结构上对所得颗粒进行分类，除了已经提到的方法之外，还使用透射电子显微镜和电子能量损失光谱法，这提供了关于颗粒尺寸和结构的更精确的信息。然后通过压制和烧结将粉末加工成膜。调整参数的迭代循环与结构分析相结合，应该能够保持相纯度，尽管烧结需要高温。研究了膜的电导率和透氧性能。此外，还对粉体和膜的电催化性能进行了分析。由此获得电催化氧传输膜，其可用于各种多相催化过程。