8.2 Chemisorption of Hydrogen and Fullerenes
85
six boron atoms making it C 54 B 6 . The doped nanomaterial had D 3d symmetry. By
employing van’t Hoff–Arrhenius law and Polanyi–Wigner equation, it was optimized
that that the hydrogen will get adsorbed on boron-doped fullerenes and can undergo
dissociation without additional catalysts. The separation of the hydrogen takes place
at ∼0.5 picoseconds at 25 °C. The study reported the boron-doped fullerenes as a
good storage material for atomic hydrogen and poor for molecular hydrogen [8]. A
seemingly similar study reported the use of B and Be-doped fullerenes for hydrogen
adsorption [9]. The fabrication of boron-doped fullerene is reported by Ting el al.
They can be prepared by the laser vaporization treatment of a boron nitride and
graphite mixture. The mixture is used in the form of composite disk of both materials
bound with cement [10].
ZhiGang et al. have reported the barrierless physisorption to chemisorption of
hydrogen molecules on the fullerenes doped with lightweight elements. The study
employed local density approximation (LDA) within density functional theory (DFT)
as process. The DFT process is capable of large systems at low computational costs.
In practice, C 35 B fullerene is brought onto the space of C 35 B−H 2 stable system.
The two C 35 B molecules now behave like forceps with each attaching itself to the
opposite side of the small H 2 molecules resulting in its dissociation to H, H (with
one H with each of C 35 B). This is barrierless physisorption to chemisorption. The
study suggested that H–H bond breaking occurs because of energy discharge as C 35 B
gets near to the C 35 BH 2 . The evolved energy increased the bond length between H–H
ultimately leading to chemisorption of H 2 molecules in the hydrogen storage method.
Overall the energy decreases monotonously during this procedure [11].
Ni-dispersed fullerenes exhibited that they can be a promising alternative to
the reversible hydrogen storage. In a study, it is exhibited that fullerenes covered
with nickel on surface are capable of storing three molecules of hydrogen. Therefore, fullerenes with dense coating of Ni are thought of excellent storage medium
for hydrogen storage, with the ability to store ∼6.8 wt.% of hydrogen. 6.5 wt. %
of storage is the target that Department of Energy is trying to achieve for automotive purposes. The study reported that the Ni dispersed has 11.8 kcal/mol of
hydrogen desorption activation barrier, which is suitable for several practical H 2
storage purposes [12].
Charged fullerenes are also high-capacity hydrogen storage medium. In an investigation, the DFT was used for making first-principle calculations and the potential
of charged fullerenes for hydrogen storage was analyzed. It was found that both positively and negatively charged fullerenes depict remarkable increase (0.18−0.32 eV)
in H 2 storage capacity at 25 °C. The improved binding of the hydrogen is delocalized
and covered the whole surface of fullerene. When completely covered with hydrogen
the charged fullerene has ~ 8 wt.% hydrogen coverage. The study showed that the
enhancement in hydrogen storage of fullerenes due to metals is less as compared to
the charged fullerene because metals usually get trapped inside the fullerene cage,
and there is less charge distribution on outer surface [13].
A study conducted by HongJiang et al. has reported alkali metal-doped fullerene
for the chemisorption of hydrogen. Fullerene doped with Li (Li 6 C 60 ) and Na (Na 6 C 60 )
proved as promising hydrogen storage materials. However, the stabilities, structures,
85
six boron atoms making it C 54 B 6 . The doped nanomaterial had D 3d symmetry. By
employing van’t Hoff–Arrhenius law and Polanyi–Wigner equation, it was optimized
that that the hydrogen will get adsorbed on boron-doped fullerenes and can undergo
dissociation without additional catalysts. The separation of the hydrogen takes place
at ∼0.5 picoseconds at 25 °C. The study reported the boron-doped fullerenes as a
good storage material for atomic hydrogen and poor for molecular hydrogen [8]. A
seemingly similar study reported the use of B and Be-doped fullerenes for hydrogen
adsorption [9]. The fabrication of boron-doped fullerene is reported by Ting el al.
They can be prepared by the laser vaporization treatment of a boron nitride and
graphite mixture. The mixture is used in the form of composite disk of both materials
bound with cement [10].
ZhiGang et al. have reported the barrierless physisorption to chemisorption of
hydrogen molecules on the fullerenes doped with lightweight elements. The study
employed local density approximation (LDA) within density functional theory (DFT)
as process. The DFT process is capable of large systems at low computational costs.
In practice, C 35 B fullerene is brought onto the space of C 35 B−H 2 stable system.
The two C 35 B molecules now behave like forceps with each attaching itself to the
opposite side of the small H 2 molecules resulting in its dissociation to H, H (with
one H with each of C 35 B). This is barrierless physisorption to chemisorption. The
study suggested that H–H bond breaking occurs because of energy discharge as C 35 B
gets near to the C 35 BH 2 . The evolved energy increased the bond length between H–H
ultimately leading to chemisorption of H 2 molecules in the hydrogen storage method.
Overall the energy decreases monotonously during this procedure [11].
Ni-dispersed fullerenes exhibited that they can be a promising alternative to
the reversible hydrogen storage. In a study, it is exhibited that fullerenes covered
with nickel on surface are capable of storing three molecules of hydrogen. Therefore, fullerenes with dense coating of Ni are thought of excellent storage medium
for hydrogen storage, with the ability to store ∼6.8 wt.% of hydrogen. 6.5 wt. %
of storage is the target that Department of Energy is trying to achieve for automotive purposes. The study reported that the Ni dispersed has 11.8 kcal/mol of
hydrogen desorption activation barrier, which is suitable for several practical H 2
storage purposes [12].
Charged fullerenes are also high-capacity hydrogen storage medium. In an investigation, the DFT was used for making first-principle calculations and the potential
of charged fullerenes for hydrogen storage was analyzed. It was found that both positively and negatively charged fullerenes depict remarkable increase (0.18−0.32 eV)
in H 2 storage capacity at 25 °C. The improved binding of the hydrogen is delocalized
and covered the whole surface of fullerene. When completely covered with hydrogen
the charged fullerene has ~ 8 wt.% hydrogen coverage. The study showed that the
enhancement in hydrogen storage of fullerenes due to metals is less as compared to
the charged fullerene because metals usually get trapped inside the fullerene cage,
and there is less charge distribution on outer surface [13].
A study conducted by HongJiang et al. has reported alkali metal-doped fullerene
for the chemisorption of hydrogen. Fullerene doped with Li (Li 6 C 60 ) and Na (Na 6 C 60 )
proved as promising hydrogen storage materials. However, the stabilities, structures,