Carbon-modified MgH2: Experimental and ab-initio Investigations

The results of experimental and theoretical investigations of carbon-modified MgH2 for improving its sorption performances in hydrogen storage devices are reported. Large changes on its absorption/desorption capacities have been found. The following aspects are considered: size effects where finer particles obtained by energetic ball milling enable easier penetration, catalytic effects of carbon at the surface, and entrance of small quantities of C interstitially into the MgH2 structure. The energies and charge densities as studied by DFT suggest the activation of MgH2 through a decrease of the cohesive energy of the pristine hydride and a reduced ionic charge on hydrogen.

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Cohesive properties of metals as determined from atomic charge densities

Canadian Journal of Chemistry ◽

10.1139/v96-095 ◽

1996 ◽

Vol 74 (6) ◽

pp. 870-874 ◽

Cited By ~ 4

Author(s):

Yoram Tal

Keyword(s):

Charge Density ◽

Ab Initio ◽

Cohesive Energy ◽

Atomic Charge ◽

Metallic Elements ◽

Transition Elements ◽

Charge Densities ◽

Cohesive Properties ◽

Metallic Charge ◽

Cohesive Energies

A direct relation between the charge density of a free atom, ρa(r), and the cohesive energy of the corresponding metal is proposed. This relation is based on an approximation for the metallic charge density, ρm(r), that is constructed from ρa(r) through [Formula: see text] being the atomic volume of the metallic atom, and R0 the corresponding Wigner–Seitz radius. The cohesive energy Ecoh is then related to [Formula: see text] through [Formula: see text] A systematic study of 29 metallic elements including the 3d and 4d transition elements shows that the proposed relation is, in general, at least as accurate as recent ab initio results. In the same fashion, an expression for the metallic bulk modulus is derived. This expression requires, in addition to [Formula: see text], the values of ρa(R0) and its first derivative ρ′a(R0). The computed bulk moduli are, again, at least as good as the ab initio ones for the set of metallic elements studied. Key words: cohesive energies, bulk moduli, charge density, transition elements.

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Enhanced hydrogen storage properties of LiAlH4 catalyzed by CoFe2O4 nanoparticles

RSC Advances ◽

10.1039/c4ra00841c ◽

2014 ◽

Vol 4 (36) ◽

pp. 18989-18997 ◽

Cited By ~ 21

Author(s):

Ziliang Li ◽

Fuqiang Zhai ◽

Qi Wan ◽

Zhaojiang Liu ◽

Jiawei Shan ◽

...

Keyword(s):

Hydrogen Storage ◽

Ball Milling ◽

Cofe2o4 Nanoparticles ◽

Hydrogen Storage Properties ◽

Catalytic Effects ◽

Storage Properties

The catalytic effects of CoFe2O4 nanoparticles on the hydrogen storage properties of LiAlH4 prepared by ball milling were investigated.

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Li Uptake in Carbon Nanotube Systems: A First Principles Investigation

MRS Proceedings ◽

10.1557/proc-706-z8.8.1 ◽

2001 ◽

Vol 706 ◽

Author(s):

Vincent Meunier ◽

Jeremy Kephart ◽

Christopher Roland ◽

Jerry Bernholc

Keyword(s):

Carbon Nanotube ◽

Ab Initio ◽

Ball Milling ◽

First Principles ◽

Topological Defects ◽

Ion Bombardment ◽

Ion Uptake ◽

Li Ion ◽

Pass Through ◽

Non Equilibrium

AbstractCarbon nanotube systems can substantially increase their capacity for Li ion uptake, provided that the nanotube interiors become accessible to the ions. We examine theoretically, with ab initio simulations, the ability of Li ions to enter a nanotube interior. While our calculations show that it is quite unlikely for the ions to pass through pristine nanotubes, they are much more likely to enter via large-sized topological defects consisting of at least 9- or more membered rings. It is unlikely that such defects are formed spontaneously, but it may be possible to induce such topological defects by violent non-equilibrium means such as ball milling, chemical means and/or ion bombardment. Indeed, recent experiments on ball milled nanotube samples do report an important increase in the Li ion uptake.

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