Towards safe hydrogen storage in vehicles The world is keen to transition from fossil fuel-powered vehicles to greener transport and hydrogen-powered fuel cell vehicles are highly promising in this respect. However, their extensive uptake is hampered by issues with cost, safety and performance. Energy © Thinkstock To improve cost and safety, use of high-pressure and cryogenic tanks, reversible adsorbents and metal hydride for on-board vehicle hydrogen storage has been attempted. These measures have been unsuccessful. The EU-funded project 'Computational study of hydrogen storage in metal-doped materials' (COMHMAT) worked on developing alternative techniques for cost-effective hydrogen storage utilising 'hydrogen spillover'. Hydrogen spillover involves the use of a transition-metal–doped sorbent to bind hydrogen in atomic form using a catalytic pathway with metal nanoparticles. Project members worked closely with experimental groups to develop novel materials for hydrogen storage. For this purpose, existing and model-designed materials were used. This included metal-doped graphene and functionalised graphitic materials, graphite oxides, metal–organic frameworks, oxidised carbon foam, graphdiyne, and defected graphitic materials with substitutional single-metal adatoms. Graphdiyne are 2D carbon allotropes of graphene with honeycomb structures. Adatoms are adsorbed atoms that lie on a crystal surface. Consortium members' expertise in quantum chemical simulations stood them in good stead when it came to performing in silico experiments. Functional hydrogen spillover materials with improved hydrogen storage capacities were successfully identified thereafter. Project activities led to eight publications in top-quality scientific journals. Promising outcomes have laid the foundation for further experimental and theoretical research worldwide. Success would increase the market uptake of hydrogen-based transport systems that are safe and emission free. Keywords Hydrogen storage, vehicles, fuel cell, metal-doped, hydrogen spillover, graphene, transport system
