Environmental Engineering Reference
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(b)
5.0
100 °C
75 °C
50 °C
25 °C
Desor, 25 °C
4.0
3.0
2.0
1.0
0.0
(a)
1.5
1.0
0.5
0.0
0
1
2
3
4
Pressure (MPa)
FIGURE 7.3 Pressure−composition isotherms of (a) N-doped hydrogen exfoliated graphene (N-HEG)
and (b) Pd-decorated H-HEG (Pd-N-HEG) in the temperature range 25−100°C and 0.1−4 MPa pressure.
Source : Reproduced with permission from Parambhath et al. [15].
at 450°C [14]. In particular, recent experimental studies have found that
doping or composite structures of graphene or graphene oxide (GO) with
metal or nonmetal elements or nanoparticles can substantially improve their
hydrogen storage capacity [15-17]. For instance, a high hydrogen storage
capacity for Pd decorated, N-doped hydrogen exfoliated graphene nanocom-
posite is demonstrated under moderate temperature and pressure [15].
Figure 7.3 shows pressure−composition isotherms of N-doped hydrogen
exfoliated graphene (N-HEG) and Pd-decorated H-HEG (Pd-N-HEG) in the
temperature range 25−100°C and 0.1−4 MPa pressure. An increase of 66%
is achieved by N-doping in the hydrogen uptake capacity of hydrogen exfoli-
ated graphene at room temperature and 2  MPa pressure, with a further
enhancement by 124% attained in the hydrogen uptake capacity by Pd
nanoparticle decoration over N-doped graphene. The high hydrogen uptake
capacities obtained was attributed to interplay between the catalyst support
and catalyst particles. Similarly, enhanced hydrogen storage capacity of
pristine graphene nanoplatelets has been found by others and attributed to
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