The widespread adoption of hydrogen as an energy carrier could bring significant benefits, but only if a number of currently intractable problems can be overcome. Not the least of these is the problem of storage, particularly when aimed at use onboard light-vehicles. The aim of this overview is to look in depth at a number of areas linked by the recently concluded HYDROGEN research network, representing an intentionally multi-faceted selection with the goal of advancing the field on a number of fronts simultaneously. For the general reader we provide a concise outline of the main approaches to storing hydrogen before moving on to detailed reviews of recent research in the solid chemical storage of hydrogen, and so provide an entry point for the interested reader on these diverse topics. The subjects covered include: the mechanisms of Ti catalysis in alanates; the kinetics of the borohydrides and the resulting limitations; novel transition metal catalysts for use with complex hydrides; less common borohydrides; protic-hydridic stores; metal ammines and novel approaches to nano-confined metal hydrides.

assembled and non-assembled systems and offer a robust set of independent tools to highlight atomic details in self-organized structures.

Distinct Raman spectroscopic signatures of the metal core of atomically precise, ligand‐protected noble metal nanoclusters are reported using Au38(PET)24 and Au38−xAgx(PET)24 (PET = 2‐phenylethanethiolate, ‐SC2H4C6H5) as model systems. The fingerprint Raman features (occurring <200 cm−1) of these clusters arise due to the vibrations involving metal atoms of their Au23 or Au23−xAgx cores. A distinct core breathing vibrational mode of the Au23 core has been observed at 90 cm−1. Whereas the breathing mode shifts to higher frequencies with increasing Ag content of the cluster, the vibrational signatures due to the outer metal‐ligand staple motifs (between 200 and 500 cm−1) do not shift significantly. DFT calculations furthermore reveal weak Raman bands at higher frequencies compared to the breathing mode, which are associated mostly with the rattling of two central gold atoms of the bi‐icosahedral Au23 core. These vibrations are also observed in the experimental spectrum. The study indicates that low‐frequency Raman spectra are a characteristic fingerprint of atomically precise clusters, just as electronic absorption spectroscopy, in contrast to the spectrum associated with the ligand shell, which is observed at higher frequencies.

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