Hydrogen interaction with fullerenes: From C20 to graphene (original) (raw)
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Physical Review Letters, 2008
We explore theoretically the feasibility of functionalizing carbon nanostructures for hydrogen storage, focusing on the coating of C 60 fullerenes with light alkaline-earth metals. Our first-principles density functional theory studies show that both Ca and Sr can bind strongly to the C 60 surface, and highly prefer monolayer coating, thereby explaining existing experimental observations. The strong binding is attributed to an intriguing charge transfer mechanism involving the empty d levels of the metal elements. The charge redistribution, in turn, gives rise to electric fields surrounding the coated fullerenes, which can now function as ideal molecular hydrogen attractors. With a hydrogen uptake of >8:4 wt % on Ca 32 C 60 , Ca is superior to all the recently suggested metal coating elements.
Interaction of hydrogen with Pd- and co-decorated C24 fullerenes: Density functional theory study
Synthetic Metals, 2017
In this work, we have investigated the adsorption of a hydrogen atom and molecules on the Pd and Co-decorated C 24 fullerenes by means of density functional theory. The hydrogen interaction mechanism with host cages by regarding the adsorption energy and charge density variations was studied. It is found that both Pd and Co atoms have a significant role to increase the adsorption energy as an exothermal process. This energy change is strongly dependent on the electrostatic potential variations around the Pd and Co atoms doped on the C 24 fullerene. Also, the HOMO-LUMO gap (E g) for C 24 fullerene varies from 1.20 to 0.76 and 0.86 eV, after decorations of Co and Pd atoms, respectively. More consideration such as thermodynamics parameter, electronic density of states, and charge density analysis are discussed in the context.
Influence of Electron Doping on the Hydrogenation of Fullerene C60: A Theoretical Investigation
ChemPhysChem, 2011
The influence of electron attachment on the stability of the mono- and dihydrogenated buckminsterfullerene C(60) was studied using density functional theory and semiempirical molecular orbital techniques. We have also assessed the reliability of computationally accessible methods that are important for investigating the reactivity of graphenic species and surfaces in general. The B3LYP and M06L functionals with the 6-311+G(d,p) basis set and MNDO/c are found to be the best methods for describing the electron affinities of C(60) and C(60)H(2) . It is shown that simple frontier molecular orbital analyses at both the AM1 and B3LYP/6-31G(d) levels are useful for predicting the most favourable position of protonation of C(60)H(-) , that is, formation of the kinetically controlled product 1,9-dihydro[60]fullerene, which is also the thermodynamically controlled product, in agreement with experimental and previous theoretical studies. We have shown that reduction of exo- and endo-C(60)H makes them more stable in contrast to the reduction of the exo,exo-1,9-C(60)H(2) , reduced forms of which decompose more readily, in agreement with experimental electrochemical studies. However, most other dihydro[60]fullerenes are stabilized by reduction and the regioselectivity of addition is predicted to decrease as the less stable isomers are stabilized more by the addition of electrons than the two most stable ones (1,9 and 1,7).
Ni-dispersed fullerenes: Hydrogen storage and desorption properties
Applied Physics Letters, 2006
Our study shows that the H 2 storage media using Ni-dispersed fullerenes could be viable alternatives to reversible hydrogen storage. It is demonstrated that a single Ni coated on the fullerene surface can store up to three H 2 molecules. Consequently, at high Ni coverage, Ni-dispersed fullerenes are considered to be the novel hydrogen storage media capable of storing ϳ6.8 wt % H 2 , thus exceeding the Department of Energy target ͑6.5 wt %͒ for automobile applications. Moreover, the H 2 desorption activation barrier of 11.8 kcal/ mol H 2 is ideal for many practical hydrogen storage applications.
Applied Surface Science, 2021
Using first principles density functional theory simulations, we have observed that the scandium decorated C24 fullerene can adsorb up to six hydrogen molecules with an average adsorption energy of-0.35 eV per H2 and average desorption temperature of 451 K. The gravimetric wt % of hydrogen for the scandium decorated C24 fullerene system is 13.02%, which is sufficiently higher than the Department of Energy, United States demand. Electronic structure, orbital interactions, and charge transfer mechanisms are explained using the density of states, spatial charge density difference plots, and Bader charge analysis. A total amount of 1.44e charge transfer from the 3d and 4s orbitals of scandium to the 2p carbon orbitals of C24 fullerene. Hydrogen molecules are attached to scandium decorated C24 fullerene by Kubas type of interactions. Diffusion energy barrier calculations predict that the existence of a sufficient energy barrier will prevent metal-metal clustering. Ab-initio molecular dynamics (A.I.M.D.) simulations confirm the solidity of structure at the highest desorption temperature. Therefore, 2 we believe that the scandium decorated C24 fullerene system is a thermodynamically stable, promising reversible high-capacity hydrogen storage device.
Hydrogen-absorbing intermetallics generate very pure and chemically active hydrogen. In this communication we report on the use of this property for hydrogenation of fullerenes (C , C ) in solvent-free solid-phase systems. Fullerene hydrides with high contents of 6 0 70 hydrogen (24-26 H atoms per fullerene molecule) have been obtained by hydrogenation of solid-phase mixtures of fullerite with either intermetallic compounds LaNi , LaNi Mn , CeCo or V and Pd metals in relatively mild conditions, a hydrogen gas pressure of 5 4.65 0.35 3
Extending the hydrogen storage limit in fullerene
Carbon, 2017
Li 6 C 60 has been chosen as the most representative system to study the hydrogenation mechanism in alkali-cluster intercalated fullerides. We present here a muon spin relaxation (µSR) experiment that hints the chance to achieve a higher storage capacity on fullerene with respect to the values suggested in literature. Moreover, a linear relationship between the muonium adduct radical hyperfine frequency and the level of C 60 hydrogenation was found and it can be exploited to probe the C 60 hydrogenation level, giving more credit to this technique in the field of hydrogen storage materials.