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可替代石油的可再生燃料。目前的储存方法侧重于压缩或冷却，以增加氢的密度。然而，这些通常需要低温或高压条件，这是昂贵的实现和维护。另外，氢可以通过吸附到固体纳米孔支架上来储存，或者可逆地形成金属氢化物。这两种技术都有各自的优点和缺点，没有一种方法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、环保燃料的关键。在纳米尺度上生产金属氢化物颗粒已经被用来通过最大化表面积、增加表面能和减少内部扩散路径来提高各种金属氢化物的储氢能力。通常，这些纳米级材料是通过机械研磨合成的，这产生了不一致的材料，容易受到污染。最近，将金属氢化物结合在多孔网络中已被证明是控制纳米金属氢化物合成的实用途径。孔径仅为几纳米的纳米多孔材料显示出合成多孔材料-金属氢化物复合材料的良好潜力，并显示出一些有益的特性，包括减少暴露于水分、降低形成焓和提高稳定性。多孔支架的约束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为克服当前储氢挑战和生产具有独特性能的约束相提供了一条令人兴奋的途径。在这个项目中，碳质微介孔宿主材料的特性将被探索，以确定支架对被封装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：-系统地探索基质性质，如孔隙大小和孔隙几何形状，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-金属氢化物体系中的相成核，以及客体材料在整个复合材料中如何变化。-研究不同的制造工艺和条件对最终复合系统的影响。-进行计算模拟，了解材料内部的潜在机制，以预测客体结构和复合材料的性能。该项目的总体目标是合理设计和制造新型纳米多孔材料-金属氢化物复合材料，以在商业上可实现的温度和压力条件下开发理想的储氢性能。此外，纳米约束复合材料的理解和制造可能会导致催化剂、电子和储能材料的发展。

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.