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

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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.