Current research trends and perspectives on materials-based hydrogen storage solutions: A critical review

Effective hydrogen storage solutions have been pursued for decades, and materials-based hydrogen storage is a research frontier of much current interest. Yet, no researched materials to date have come close to the DOE 2020 targets for hydrogen storage at ambient conditions, although some good results have been reported at cryogenic temperature. This paper critically reviews the current research trends and perspectives on materials-based hydrogen storage including both materials-based physical storage and materials-based chemical storage. In the case of physical storage, the efforts on exploring new porous materials with extra larger surface/pore volume, inducing hydrogen spillover effect, and tailoring reaction enthalpies are discussed. Meanwhile, for chemical storage, approaches to improve the kinetics and/or thermodynamics such as the development of composite hydride systems, nanoconfinement of hydride materials as well as the usage of ionic liquids as hydrogen storage materials or useful additives are discussed. Furthermore, the applied techniques on solid-state materials towards system integration such as shaping and electrospinning processes are introduced. Finally, the concept of storing hydrogen in para form for long-term hydrogen storage is discussed, and a converter packed with catalysts to process the normal hydrogen to para-hydrogen is highlighted.