Porous metal–organic frameworks for hydrogen storage

The high gravimetric energy density and environmental benefits place hydrogen as a promising alternative to the widely used fossil fuels, which is however impeded by the lack of safe, energy-saving and cost-effective H₂ storage systems. The use of solid adsorbents as candidate materials offers a less energy-intensive way of storing hydrogen. The exceptional diversity and tunability of the chemical composition, topological structure, and surface chemistry together with large surface area position porous metal–organic frameworks as promising hydrogen storage material candidates. In this review, we first introduce several classes of important metal–organic frameworks for hydrogen storage, and then highlight the progress associated with the key challenges to be addressed, including the improvement of hydrogen–framework interaction required for enhancing room-temperature hydrogen storage capacities, and the optimization/balance of both gravimetric and volumetric storage/working capacities. In particular, the strategies used to tune and enhance hydrogen binding energies have been comprehensively reviewed. Future development prospects and related challenges of using porous metal–organic frameworks as hydrogen storage materials are also outlined. This feature review provides a wide perspective and insightful thoughts and suggestions for hydrogen storage using metal–organic frameworks, and promotes the further development of hydrogen storage materials to realize a hydrogen economy.