Design, fabrication and testing of porous material-metal hydride composites for hydrogen storage

氢被广泛认为是一种很有前途的替代石油的可再生燃料。目前的储存方法主要是通过压缩或冷却来增加氢的密度。然而，这些通常需要低温或高压条件，实现和维护成本高昂。或者，氢可以通过吸附在固体纳米孔支架上或可逆地形成金属氢化物来储存。这两种技术都有各自的优缺点，两种方法都不能同时满足实际储氢的所有标准。实现固态储氢是工程和化学领域的一个重要目标，也是实现以氢为中心的安全、经济、环境友好的燃料的关键。制备纳米级的金属氢化物颗粒曾被用来通过最大化比表面积、增加表面能和减少内扩散路径来提高各种金属氢化物的储氢能力。通常，这些纳米材料是通过机械研磨合成的，这会产生容易受到污染的不一致的材料。最近，将金属氢化物引入多孔网络已被证明是控制纳米金属氢化物合成的一种实用途径。孔径仅为几纳米的纳米多孔材料显示出良好的合成多孔材料-金属氢化物复合材料的潜力，并表现出一些有益的性质，包括减少暴露在水中，降低形成热，提高稳定性。来自多孔支架的限制效应可以进一步改变客体材料的相图，稳定在相同压力和温度条件下可能不稳定的相。纳米多孔材料-金属氢化物复合材料提供了一条令人兴奋的途径，以克服目前在氢气存储方面的挑战，并产生具有独特性质的限制相。在本项目中，将探索碳质微介孔主体材料的性质，以确定支架对包裹的客体金属氢化物的行为的影响。设计纳米多孔材料-金属氢化物复合材料需要几个步骤，包括：-系统地探索主体属性，如孔大小和孔几何形状，以确定对受限材料排列的影响。-确定多孔支架对受限金属氢化物晶格的形成/分解和物理性质的影响程度。-了解纳米多孔材料-金属氢化物系统中的相成核以及客体材料在整个复合材料中如何变化。-研究不同制造技术和条件对最终复合材料系统的影响。-执行计算模拟以了解材料中的潜在机制，以预测客体结构和复合材料性能。本项目的总体目标是合理设计和制备新型纳米多孔材料-金属氢化物复合材料，以在商业上可以达到的温度和压力条件下开发出理想的储氢性能。此外，了解和制造纳米约束复合材料可能会导致催化剂、电子学和储能材料的发展。

Hydrogen is widely acknowledged to be a promising renewable fuel for replacing petroleum. Current methods of storage focus on compression or cooling to increase the density of hydrogen. However, these often require cryogenic or high-pressure conditions which are costly to achieve and maintain. Alternatively, hydrogen can be stored via adsorption onto a solid nanoporous scaffold, or reversibly forming a metallic hydride. Both techniques have their own sets of advantages and disadvantages with neither method meeting all criteria for practical hydrogen storage simultaneously. Achieving solid-state hydrogen storage is an important goal within engineering and chemistry, and is the key to realising a safe, cost-effective, environmentally friendly fuel centred around hydrogen.Producing metal-hydride particles at the nanometre scale has previously been used to improve the hydrogen storage capabilities of various metal hydrides through maximising the surface area, increasing surface energies, and reducing internal diffusion paths. Typically, these nanosized materials are synthesised through mechanical milling, which produces inconsistent materials that are prone to contamination. Recently, incorporating the metal hydride within a porous network has proven to be a practical pathway to control the synthesis of nanosized metal hydrides. Nanoporous materials with pore diameters of only several nanometres demonstrate good potential for synthesising porous material-metal hydride composites, and show several beneficial properties, including reduced exposure to moisture, reduced formation enthalpies, and improved stability. Confinement effects from the porous scaffolds can further alter the phase diagram of the guest material, stabilising phases which may otherwise be unstable under the same pressure and temperature conditions.Nanoporous material-metal hydride composites provide an exciting avenue to overcoming the current challenges in hydrogen storage and producing confined phases with unique properties. In this project, carbonaceous micro-mesoporous host material properties will be explored to identify the effect the scaffold has on the behaviour of the encapsulated guest metallic hydride.Several steps are required to be able to design nanoporous material-metal hydride composites, including: - Systematically explore host properties such as pore size and pore geometry to determine the effect on the confined material arrangement. - Identify the extent to which the porous scaffold affects the formation/decomposition and physical properties of the confined metal hydride lattice.- Understand phase nucleation within the nanoporous material-metal hydride system and how the guest materials can vary throughout the composite. - Investigate the effect of different manufacturing techniques and conditions on the final composite system. - Perform computational simulations to understand underlying mechanisms within the material to predict the guest structure and composite properties. The overarching goal of this project is to rationally design and fabricate novel nanoporous material-metal hydride composites to exploit desirable properties for hydrogen storage at commercially achievable temperature and pressure conditions. Furthermore, understanding and manufacturing of nanoconfinement composites may lead to developments in catalysts, electronics, and energy storage materials.