Gas storage – Nanocarbon Laboratory

3 Settembre 202019 Febbraio 2021

Nickel addition to optimize the hydrogen storage performance of lithium intercalated fullerides

The addition of transition metals to alkali intercalated fullerides proved to enhance their already good hydrogen absorption properties. Herein we present a study based on two different synthetic strategies, allowing the addition of nickel as aggregates with different size to the lithium fulleride Li₆C₆₀: the former is based on the metathesis of nickel chloride, while the latter on the thermal decomposition of nickel carbonyl clusters. The hydrogen-storage properties of the obtained materials have been investigated with manometric and calorimetric measurements, which indicated a clear enhancement of the final absorption value and kinetics with respect to pristine Li₆C₆₀, as a consequence of nickel surface catalytic activity towards hydrogen molecules dissociation. We found up to 10 % increase of the total H₂ weight % absorbed (5.5 wt% H₂) in presence of Ni aggregates. Furthermore, the control of the transition metal particles size distribution allowed reducing the hydrogen desorption enthalpy of the systems.

29 Settembre 201919 Febbraio 2021

Neutron scattering study of nickel decorated thermally exfoliated graphite oxide

Surface decoration of graphene-based nanostructures with metals has been predicted to be an efficient way towards the development of resistant catalysts and novel materials for energy applications, such as hydrogen production and storage. We report on an extensive neutron scattering study of a defective graphene-based material decorated with nickel nanoparticles, obtained via the chemical decoration of thermally exfoliated graphite oxide. The combination of neutron diffraction and inelastic neutron scattering measurements has been used to characterize the low-dimensional carbon backbone and the presence of the nickel nanoparticles, organized at the nanometer scale on the graphene plane. The structural features of this system, along with the nickel capability of dissociating the hydrogen molecule upon hydrogen treatment, are herein discussed.

10 Settembre 201919 Febbraio 2021

Platinum carbonyl clusters decomposition on defective graphene surface

Having single atoms or small clusters docked onto a single layer graphene represents a charming feature for energy-storage and catalysis. Unfortunately, the large cohesion energy of transition metals often prevents the isolation of nanoscopic clusters, which invariably tend to aggregate. The decoration of defective graphene layers with single Pt atoms and sub-nanometric clusters is herein achieved by exploiting metal carbonyl clusters, as precursor, and investigated by means of transmission electron microscopy and X-ray photoemission spectroscopy. Unexpectedly, the process of aggregation of Pt into larger clusters is inhibited onto the surface of defective graphene, where the Pt-clusters are found to fragment even into single metal atoms.