H and Li dynamics in Li 12 C 60 and Li 12 C 60 H y

Abstract

Lithium and hydrogen dynamics in Li 12 C 60 and Li 12 C 60 H y are investigated by means of 7 Li and 1 H solid state Nuclear Magnetic Resonance (NMR) in the temperature range 80-550 K. Differential scanning calorimeter characterization on the hydrogen sorption and desorption and X-rays structural analysis are also reported. In the pure phase, the 7 Li results show a thermally activated dynamic that can be associated to Li motions within the crystal interstices. Upon hydrogenation, Li ionic motion is considerably hindered by the presence of hydrofullerene molecules. The 1 H measurements show that C-H bonds are stable on the local scale up to 400-450 K. The NMR results at higher temperatures are compatible with a H diffusion mechanism which anticipates the H desorption process.

Induced Magnetic Field of Fullerenes: Role of σ- and π- Contributions to Spherical Aromatic, Nonaromatic, and Antiaromatic Character in C60q (q = +10, 0, −6, −12), and Related Alkali-Metal Decorated Building Blocks, Li12C60 and Na6C60

“…The fascinating spherical structure of buckminsterfullerene, C 60 , , has delighted the scientific community in the few past decades, resulting in extensive and continuous growth leading to interdisciplinary applications of technological interest in a wide variety of fields. − Its icosahedral cage composed of 12 pentagonal and 20 hexagonal faces is the smallest example of fullerenes obeying the isolated-pentagon rule (IPR). , Owing to its unsaturated π-orbital system, C 60 exhibits noticeable chemical and physical properties, − where several efforts has been devoted to the understanding of the structural-stability relationship and related features. ,− In addition, charged fullerene ions found in alkali-metal fullerene phases (A n C 60 ) in varying stoichiometry exhibits metal–insulator transitions and superconductivity properties, − where A 6 C 60 and A 12 C 60 bearing C 60 6– and C 60 12– fullerides appear to be particularly stable building blocks with further applications. − Moreover, lithium-doped fullerenes have been found to display increased reactivity with regard to pristine C 60 …”

“…Moreover, the analysis of the induced magnetic field at the molecular surroundings is able to recover the long-range characteristics of the shielding cone in three-dimensional structures, , where the external field is applied from a specific orientation. In addition, the magnetic behavior of the C 60 6– and C 60 12– fullerides is of interest, owing to its further application as charged building blocks in the formation of extended networks and their application as hydrogen-storage materials. − …”

“…To explore different electronic shell scenarios, ranging from a closed-shell situation to an incomplete or partially filled shell structure, C 60 10+ , C 60 , C 60 6– , and C 60 12‑ were studied via density functional theory (DFT) calculations, as relevant fullerene charged ions accounting for a SPDFG closed-shell configuration, an incomplete H shell, and incomplete H and I shells. The analysis of the induced magnetic field was extended to related alkali-metal decorated fullerenes Li 12 C 60 and Na 6 C 60 characterized as relevant building blocks in A n C 60 phases. − The global response, and its further deconstruction into σ-, π-, and core-electrons unravels the changes that govern the particular induced field features from different charged fullerenes, in order to extend our understanding of the magnetic behavior of such prominent spherical structures by varying the electron population of different electronic shells, contributing to further characterization and design of spherical/nonaromatic and antiaromatic spherical structures.…”

Synthesis and characterization of mixed sodium and lithium fullerides for hydrogen storage

“…For such high doping levels, the number of alkali ions exceeds the maximum amount of electrons that can virtually populate the lowest degenerate unoccupied molecular orbital (LUMO) on fullerene, the latter being able to host six electrons, but the metal clustering can overcome this instability. Na 10 C 60 and Li 12 C 60 can reversibly absorb up to 3.0 and 5.2 wt% H 2 with a relative dehydrogenation enthalpy of about 66 and 52 kJ/mol H 2 , respectively 8,9 . The absorption process leads to a partial segregation of NaH or LiH, achieved after hydrogenation of the fullerene molecule.…”

Solid-State Hydrogen Storage Systems and the Relevance of a Gender Perspective

“…Below, a brief introduction of the selected materials for solid-state hydrogen storage is reported (i.e., pure metals, intermetallic compounds, and complex hydrides) to introduce and discuss realized tanks or integrated system applications. Hydrogen storage by physisorption is also possible in MOFs, nanotubes, graphene, and similar materials as recently summarized in comprehensive reviews and articles on the topic [40][41][42][43][44][45][46][47][48][49][50][51]; however, these materials were investigated at a research level and never tested in larger prototypes.…”