Nanointerface Engineering of Metal Hydrides for Advanced Hydrogen Storages

With global efforts to relieve the formidable impact of climate change, hydrogen is considered a viable replacement for fossil fuels without intermittency concerns of other renewable sources. Hydrogen storage plays a pivotal role in the implementation of hydrogen economy, coupling hydrogen production with fuel cell technologies. Storing hydrogen in the form of solid-state hydride materials has been studied as a future hydrogen storage technology for enabling a safe, energy-efficient, and high-energy-density system. However, hostile thermodynamic and kinetic properties of each hydride material result in insufficient hydrogen storage performance for practical applications, such as sluggish hydrogen absorption or desorption, high dehydrogenation temperatures, and sometimes limited reversibility; thus, these kinetic and thermodynamic characteristics need to be thoroughly understood depending on each hydride material. Among various strategies, nanostructuring has been regarded as a general approach to tackling such limitations regarding thermodynamic and kinetic characteristics of hydride materials. In particular, the formation of nanosized hydrides within a nanostructured scaffold -also known as nanoconfinement-is of great potential for advanced hydrogen storage because it can additionally leverage host-guest interactions at the nanointerfaces of hydride materials and scaffolds. In this context, the active tuning of such nanointerfaces brings about additional thermodynamic or kinetic changes in hydrogen sorption reactions compared to the unmodified nanoconfined hydride composites, holding great promise for tailored strategies for each metal hydride. In this Perspective, we summarize the major thermodynamic and kinetic barriers of each metal hydride and highlight the recent progress in overcoming such limits, mainly focusing on nanointerface engineering in nanoconfined metal hydrides. Further, we provide our insight and current challenges in understanding the underlying mechanisms of the interaction at the nanointerface, whereby the noticeable technological leaps can be emulated in practical systems.