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vs. chemisorption) as well as the carbon structural changes have been
discussed in Ref. [30]. In Ref. [28] the chemisorption contributions
have been detected by Fourier transform infrared spectroscopic
analysis. Some different models are considered and discussed
[36, 37]. It should be noted that a negligible spillover effect, i.e., about
one order less than in Refs. [27-35], has been found in Ref. [37] for
hydrogen uptake by Pt-doped graphite nanofibers; this result has
been “surprising” for the authors themselves [37]. As mentioned in
Refs. [27-37], the spillover enhancement mechanisms are not well
understood and further studies are needed.
There is ground to suppose [3,4] that the micro mechanisms of
the observed phenomenon [27-37] can be, at some extent, related
to the results of specific intercalation and chemisorption of atomic
hydrogen into the graphene layers, and also to the results discussed
below [17, 38, 39] on the hydrogen intercalation through graphene
layers, induced by chemisorption.
2.3.4 On the Hydrogen Intercalation (Multilayer Physical
Adsorption) in GNFs and SWNT Bundles Initiated
by Monolayer Chemisorptions
Analysis [3] of a number of related studies has revealed a real
possibility of hydrogen intercalation, a multilayer physical
adsorption, in graphite nanofibers and carbon SWNT bundles,
induced by the monolayer chemisorption of I-III types (Table 2.1).
In particular, it has been shown [3] that the reported
distinguished data [17] (Fig. 2.16) can be related to the hydrogen
intercalation (multilayer physical adsorption or hydrogen
liquefaction) initiated by the monolayer chemisorption of
type I (Table 2.1). It should be noted that the nonconventional
adsorption isotherms of Fig. 2.16 are, at some extent, similar to
the isotherms in Fig. 2.25; hence, some similarity in the adsorption
micromechanisms can be supposed.
As reported in Part I and Ref. [3], a direct experimental proof
of multilayer hydrogen intercalation between graphene sheets in
bundles of GNFs with Pd catalyst (Fig. 2.20) has been obtained in Ref.
[38]. The anomalously high value of the hydrogen storage capacity
declared by the authors was 17 wt% (hydrogen weight to the sum
of carbon and hydrogen weights), charging the H
gas at 300 K and
8 MPa. From these data (Fig. 2.20) a rather high value of the adsorbed
2
