Creating Highly Stable Single Atom Catalysts on Porous Supports through Magnetron Sputtering

通过磁控溅射在多孔载体上制备高度稳定的单原子催化剂

• 批准号: 2444678
• 金额: --
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2444678
• 关键词: Creating; Highly; Stable; Single; Atom

Project background (identification of the problem and its importance and relevance to sustainability) The need to replace fossil fuels with sustainable alternatives is understood to be one of the most pressing challenges for scientists today. There are multiple reasons for this: Fossil fuels are constantly being depleted, their linear lifecycle produces carbon dioxide and causes global warming, which produces a plethora of adverse environmental effects such as crop losses, ice cap melting and rising sea levels. One such alternative is hydrogen fuel, which is a sustainable alternative due to its circular economy and only producing water when burned. Hydrogen production is a hot topic in catalysis, and metal catalysts are crucial for this reaction, however these are often very expensive and rare, for example Platinum. This is a common predicament in catalysis, and the 2 main options are: Divert to more sustainable metals, or increase the activity of rare metal. Single atom catalysts (SACs) are a relatively new technology which has been shown to provide hugely increased activity for catalysts, touted as the 'next generation' of catalysts. The greatly improved activity compared to the classical supported metal catalysts is driven by 1 main trait; increased atom utilization. In heterogeneous catalysis only the surface atoms will be active, anything below the surface is wasted. As metal particle size decreases the proportion of atoms at the surface increases, therefore so does the atom utilisation. This yields greatly increased specific activity, as well as reported increases in selectivity. SACs provide 100% atom utilisation, as every atom is available for reaction, allowing the most effective and sustainable use of catalyst metals The main issue with SACs currently is their stability. SACs can quite easily leach into solution or sinter to create large particles, both of which are big problems for sustainable catalysis. Stabilising SACs with respect to this is the focus of my project, and is discussed in Proposed solution and methodology. The most popular method for synthesis of SACs is through co-precipiation and other wet chemistry methods, which is are wasteful processes. An innovative and sustainable method for SAC production is Magnetron sputtering, a solvent free method which directly deposits metal atoms onto a support while producing no waste. Proposed solution and methodology To address the issue of catalyst leaching and sintering, the catalyst particles must be stabilised on the support. In my project I will achieve this by tuning metal-organic frameworks to impart this stability. It is established that the high energy sites provided by defects allow for catalysts to anchor themselves more strongly, meaning that sintering and leaching occurs at a much slower rate. By introducing defects into MOFs during their synthesis and through post synthetic modification using argon plasma, I will create materials with specifically controlled defects (in both their defect type and quantity). To understand these defective MOFs, the main techniques used will be PXRD and TGA. After these defective MOFs have been created, metal deposition of metal catalyst will occur through magnetron sputtering. The methods will be tuned to create nanoclusters <2nm and SACs. These will then be applied to hydrogen production, where the metal atoms will be analysed after each reaction, primarily through the use of x-ray spectroscopy techniques. The results should show that by introducing defects, we are producing more robust SAC systems which can be re-used more times, which would hopefully be a step toward the eventual goal introduction of SACs on industrial scales.

项目背景（确定问题及其对可持续性的重要性和相关性）用可持续替代品取代化石燃料的必要性被认为是当今科学家面临的最紧迫挑战之一。这有多种原因：化石燃料不断耗尽，其线性生命周期产生二氧化碳并导致全球变暖，这产生了大量的不利环境影响，如作物损失，冰盖融化和海平面上升。其中一种替代品是氢燃料，由于其循环经济并且在燃烧时只产生水，因此是一种可持续的替代品。制氢是催化领域的一个热门话题，金属催化剂对此反应至关重要，但这些催化剂通常非常昂贵且稀有，例如铂。这是催化中常见的困境，两个主要的选择是：转向更可持续的金属，或增加稀有金属的活性。单原子催化剂（SACs）是一种相对较新的技术，已被证明可以大大提高催化剂的活性，被吹捧为“下一代”催化剂。与经典的负载型金属催化剂相比，大大提高的活性是由1个主要特征驱动的;增加的原子利用率。在多相催化中，只有表面原子是活性的，表面以下的任何原子都被浪费了。随着金属颗粒尺寸的减小，表面原子的比例增加，因此原子利用率也增加。这产生了大大增加的比活性，以及报道的选择性增加。SAC提供100%的原子利用率，因为每个原子都可用于反应，允许最有效和可持续地使用催化剂金属。SAC可以很容易地渗入溶液或烧结以产生大颗粒，这两者都是可持续催化的大问题。在这方面稳定SAC是我的项目的重点，并在建议的解决方案和方法中进行了讨论。目前最常用的合成SAC的方法是共沉淀法和其它湿化学法，这些方法都是浪费资源的方法。SAC生产的一种创新和可持续的方法是磁控溅射，这是一种无溶剂方法，直接将金属原子沉积到载体上，同时不会产生废物。 为了解决催化剂浸出和烧结的问题，催化剂颗粒必须稳定在载体上。在我的项目中，我将通过调整金属有机框架来实现这种稳定性。已经确定，由缺陷提供的高能量位点允许催化剂更强地锚自身，这意味着烧结和浸出以慢得多的速率发生。通过在合成过程中将缺陷引入到MOF中，并通过使用氩等离子体进行合成后改性，我将创建具有特定控制缺陷（缺陷类型和数量）的材料。为了了解这些有缺陷的MOF，使用的主要技术将是PXRD和TGA。在产生这些有缺陷的M0 F之后，将通过磁控溅射发生金属催化剂的金属沉积。这些方法将被调整以产生<2nm的纳米团簇和SAC。然后将这些应用于氢气生产，其中金属原子将在每次反应后进行分析，主要是通过使用X射线光谱技术。结果应该表明，通过引入缺陷，我们正在生产更强大的SAC系统，可以重复使用更多次，这有望成为最终目标在工业规模上引入SAC的一步。