Controlled routes to aluminium-containing alloys from molecular precursors

许多重要的化学过程都是电解的，这意味着它们是由电流通过反应混合物来驱动的。通常，增加这些过程的速率的材料（电催化剂）用于提高过程的能量效率和容量，但这些材料通常含有所谓的“贵金属”，例如钯或铱。贵金属稀缺且昂贵，因此以工业所需的大规模进行这些过程可能具有挑战性。一种这样的过程是将水电解转化为氢和氧。由于氢气作为“绿色”燃料的可行性，氢气是一种重要的产品，因此随着我们寻求摆脱传统的碳基燃料，氢气的高效生产变得越来越重要。因此，有必要找到有效的新的电催化剂，它含有更便宜和更丰富的金属，以便可以更容易地进行所需的大规模制氢。一类潜在的材料是铝（地壳中最丰富的金属）与贱金属（如铁或锰）的合金（含有元素混合物的金属）。由于铝的熔点非常低，这些合金的合成具有挑战性，因此需要替代路线。一种选择是合成含有Al-M键的分子化合物，其在高温下分解以形成所需的合金。这种化合物（称为单源前体或SSP）使我们能够生产出其他方法无法获得的材料。这种方法带来的一个挑战是找到一种系统的方法来合成各种金属的Al-M键合化合物。这种化合物存在于一些选定的金属中，但它们的合成不容易推广（因此可以制造和测试的可能的电催化剂材料较少），并且Al-M键通常较弱，因此它们可能不适合于合金的热生成。最近发现的一类新的化合物，铝基，其特征是由有机支架支撑的阴离子（带负电荷）铝原子，提供了一个解决方案。这种类型的化合物适合与大量其他金属化合物反应，因此提供了一种制备各种含有强（共价）Al-M键的SSP的一般途径。因此，本项目的目的是使用这些铝基化合物（以及潜在的相关镓和铟类似物）来合成含有各种贱金属的SSP的广泛库。这些化合物将被研究，以提供深入了解他们的化学行为，然后探索他们转化为含铝合金的热分解。这些合金将被分析以确定它们的确切成分和表面结构，最后作为电催化剂进行测试，以比较它们与传统贵金属材料的性能。使用铝基和相关系统作为获得这类化合物的手段，以及它们随后转化为潜在活性合金，是该领域的一种新方法。该项目属于EPSRC制造未来研究领域的福尔斯。该项目将与牛津大学材料系的穆迪小组合作（用于合金材料的分析和表征）和来自柏林工业大学化学系的Driess小组进行电催化活性的研究。

A number of important chemical processes are electrolytic, meaning that they are driven by passing electricity through the reaction mixture. Often, materials which increase the rate of these processes (electrocatalysts) are used to improve the energy efficiency and capacity of the process, but these materials commonly contain so-called 'noble metals' such as palladium or iridium. Noble metals are scarce and expensive, and so it can be challenging to carry out these processes at the large scales required industrially. One such process is the electrolytic conversion of water to hydrogen and oxygen. Hydrogen gas is an important product due to its viability as a 'green' fuel, and so its efficient production is becoming ever more crucial as we seek to move away from traditional carbon-based fuels. It is therefore necessary to find effective new electrocatalysts which contain cheaper and more abundant metals so that hydrogen production may more easily be carried out at the large scales required.One potential class of materials are alloys (metals containing a mixture of elements) of aluminium (the most abundant metal in the earth's crust) with base metals (such as iron or manganese). These alloys are challenging to synthesise due to aluminium's very low melting point, so alternative routes are required. One option is to synthesise molecular compounds containing an Al-M bond which decompose at high temperatures to form the desired alloy. Such compounds (referred to as Single Source Precursors or SSPs) allow us to generate otherwise inaccessible materials.One challenge this approach poses is in finding a systematic means of synthesising a range of Al-M bonded compounds for a variety of metals. Such compounds exist for a few select metals, but their syntheses isn't readily generalisable (so fewer possible electrocatalyst materials can be made and tested), and the Al-M bonds are often weak, so they may not be suitable for thermal generation of an alloy. The recent discovery of a new class of compound, aluminyls, which feature an anionic (negatively charged) aluminium atom supported by an organic scaffold, offers a solution. This type of compound is suitable for reaction with a large range of other metal compounds, and so offers a general route to a wide range of SSPs containing strong (covalent) Al-M bonds.The aim of this project is therefore to use these aluminyl compounds (and potentially related gallium and indium analogues) to synthesise a broad library of SSPs containing a variety of base metals. These compounds will be studied to provide insight into their chemical behaviour, before exploring their conversion into aluminium containing alloys by thermal decomposition. These alloys will be analysed to determine their exact composition and surface structure, and finally tested as electrocatalysts to compare their performances with those of traditional noble metal materials.The use of aluminyl and related systems as a means of accessing this class of compound, as well as their subsequent conversion into potentially active alloys, is a novel approach within this field.This project falls within the EPSRC manufacturing the future research area.This project will involve collaboration with both the Moody group from the Department of Materials at the University of Oxford (for the analysis and characterisation of alloy material) and with the Driess group from the Department of Chemistry at TU Berlin for the investigation of electrocatalytic activity.