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Influence of different amounts of FeCl3 ondecomposition and hydrogen sorption kinetics ofMgH2
M. Ismail*
Department of Physical Sciences, Faculty of Science and Technology, Universiti Malaysia Terengganu,
21030 Kuala Terengganu, Malaysia
a r t i c l e i n f o
Article history:
Received 20 August 2013
Received in revised form
31 October 2013
Accepted 18 November 2013
Available online 6 January 2014
Keywords:
Magnesium hydride
Iron chloride
Catalytic effect
De/rehydrogenation
a b s t r a c t
In the present work, the hydrogen storage properties of MgH2-X wt.% FeCl3 (X ¼ 5, 10, 15
and 20) are investigated experimentally. It is found that the MgH2 þ 10 wt.% FeCl3 sample
exhibits the best comprehensive hydrogen storage properties, in terms of the onset
dehydrogenation temperature, the hydrogen amounts de/reabsorbed as well as the relative
de/rehydrogenation rates. The onset dehydrogenation temperature of the 10 wt.% FeCl3-
doped MgH2 sample is reduced by about 90 �C compared to the as-milled MgH2, and the
sorption kinetics measurements indicate that the FeCl3-doped sample displays an average
dehydrogenation rate 5e6 times faster than that of the undoped MgH2 sample. Higher
levels of doping introduce negative effects, such as lower capacity and slower absorption/
desorption rates compared to samples with lower FeCl3 doping levels. The apparent acti-
vation energy for hydrogen desorption is decreased from 166 kJ�mol�1 for as-milled MgH2
to 130 kJ�mol�1 by the addition of 10 wt.% FeCl3. It is believed that the improvement of the
MgH2 sorption properties in the MgH2/FeCl3 composite is due to the catalytic effects of the
in-situ generated Fe species and MgCl2 that are formed during the heating process.
Copyright ª 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights
reserved.
1. Introduction
Its large gravimetric density (7.6wt.%H2), abundant resources,
low cost and good reversibility are advantages of MgH2
compared with other metal hydrides or complex hydrides
such as LaNi5 [1] and LiAlH4 [2e5]. These advantages make
MgH2 an attractive material as a potential candidate for solid-
state hydrogen storage. Nevertheless, the high decomposition
temperature and slow desorption/absorption kinetics are two
problems that limit the use of MgH2 as a hydrogen storage
material. Many extensive efforts have been carried out to
overcome these problems, including the use of a catalyst [6,7],
mechanical treatment to produce nanocomposites [8e10] and
combination with other metal/complex hydrides (destabili-
sation systems) [11e20]. Among them, the introduction of
catalysts into MgH2 has produced a significant effect on the
hydrogen sorption properties of MgH2. Various catalysts have
been doped into MgH2 by mechanical milling such as metal
[21e27], metal oxide [28e36], metal halide [7,37e47], carbon
materials [48e55] and alloys [56e59].
Previous studies have shown that the addition of a
transition-metal compound on MgH2 significantly improved
the hydrogen sorption properties. This enhancement can be
* Tel.: þ609 6683336; fax: þ60 9 6694660.E-mail address: [email protected].
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associatedwith the catalytic role of transitionmetal cations to
the dissociation process of hydrogen molecules. Liang et al.
[23] reported that the added 5 wt.% transitionmetal (Ti, V, Mn,
Fe, Ni) improved the de/rehydrogenation kinetics of MgH2
compared to undopedMgH2. Meanwhile, the addition ofmetal
halides as catalysts significantly improved the hydrogen
storage properties of MgH2 [7,37,38]. Like the other additive
group, the real catalytic mechanism of metal halides on MgH2
is still an open question. Jin et al. [37] studied the effects of
NbF5 on the hydrogenation properties of MgH2 and concluded
that the actual catalyst was Nb hydride, not NbF5. It was
suggested that NbF5 melts during high-energy ball milling and
this promotes the formation of extremely fine, film-like Nb
hydride preferentially along the grain boundaries of nano-
crystalline MgH2 by a liquid/solid reaction and suppresses the
grain growth of MgH2 quite effectively. Ma et al. [41,42]
compared the catalytic effects of TiF3 and TiCl3, and found
that TiF3 showed a superior catalytic effect over TiCl3 in
improving the hydrogen sorption kinetics of MgH2, which was
attributed to the catalytic effects of the F anion. From com-
bined XPS examination and designed experiments, Ma et al.
suggested that a considerable amount of F participated in the
generation of a metastable active TieFeMg species. Recently,
Mao et al. [7] studied the catalytic effect of NiCl2 and CoCl2 on
the hydrogen sorption of MgH2 and suggested that besides the
catalytic effect of Mg2Ni and Mg2Co as a dehydrogenation
product, the chlorine-based product, MgCl2, may also play an
important role in improving the hydrogen sorption kinetic
properties of MgH2.
This paper introduces the use of FeCl3 to prepare an MgH2-
metal chloride system aiming at combining the functions of
both transition metal cations and chlorine anions. Different
amounts of MgH2 and FeCl3 were ball milled together to pre-
pare a set of MgH2/FeCl3 mixtures and their hydrogen storage
properties and reaction mechanisms were investigated by a
Sievert-type pressure-composition-temperature (PCT) appa-
ratus, differential scanning calorimetry (DSC) and X-ray
diffraction (XRD). The catalytic effect of FeCl3 on the hydrogen
sorption properties of MgH2 was investigated.
2. Experimental details
Pure MgH2 (hydrogen storage grade), FeCl3 (reagent grade,
97%) and MgCl2 (anhydrous, �98%) were purchased from
SigmaeAldrich. Iron powder (�200 mesh, 99þ% (metal basis))
were purchased from Alfa Aesar. All materials were used as
received with no further purification. The MgH2 and additives
were respectively loaded into a sealed stainless steel vial
together with hardened stainless steel balls in an argon at-
mosphere MBraun UNIlab glove box. The ratio of the weight of
the balls to the weight of the powder was 40:1. The samples
were then milled in a planetary ball mill (NQM-0.4) for 1 h, by
first milling for 0.5 h, resting for 6 min, and then milling for
another 0.5 h in a different direction at the rate of 400 rpm.
The experiments on de/rehydrogenation were performed
in a Sievert-type PCT apparatus (Advanced Materials Corpo-
ration). The sample was loaded into a sample vessel in the
glove box. For the temperature-programmed desorption (TPD)
measurements, all the samples were heated in a vacuum
chamber, and the amount of desorbed hydrogen was
measured to determine the lowest decomposition tempera-
ture. The heating rate for the TPD experiment was 5 �Cmin�1,
and samples were heated from room temperature to 450 �C.The de/rehydrogenation kinetics measurements were con-
ducted at the desired temperature with initial hydrogen
pressures of 0.1 MPa and 3.0 MPa, respectively.
XRD analysis was performed using a RigakuMiniFlex X-ray
diffractometer with Cu Ka radiation. q�2q scans were carried
out over diffraction angles from 20� to 80� with a speed of
2.00� min�1. Before the measurement, a small amount of
sample was spread uniformly on the sample holder, which
was wrapped with plastic wrap to prevent oxidation.
DSC analysis of the dehydrogenation process was carried
out on a Mettler Toledo thermogravimetric analysis/differ-
ential scanning calorimetry (TGA/DSC) 1. The sample was
loaded into an alumina crucible in the glove box. The crucible
was then placed in a sealed glass bottle in order to prevent
oxidation during transportation from the glove box to the DSC
apparatus. An empty alumina crucible was used for reference.
The samples were heated from room temperature to 550 �Cunder an argon flow of 30 ml min�1, and different heating
rates were used.
3. Results and discussion
3.1. Dehydrogenation temperature
Fig. 1 presents the TPD performances of the as-received MgH2,
the as-milled MgH2, and the MgH2 doped with 5 wt.%, 10 wt.%,
15 wt.% and 20 wt.% FeCl3. From the TPD curves, it is clear that
raising the dopant percentage from 5 wt.% to 20 wt.% resulted
in a decrease of the onset desorption temperature compared
to the undopedMgH2. The as-received MgH2 started to release
hydrogen at about 410 �C, with a total dehydrogenation ca-
pacity of 7.0 wt.% H2 by 430 �C. After milling, the onset
desorption temperature of MgH2 was reduced to about 340 �C,indicating that the milling process also influenced the onset
Fig. 1 e TPD patterns for the dehydrogenation of as-
received MgH2, as-milled MgH2 and the MgH2 doped with
5 wt.%, 10 wt.%, 15 wt.% and 20 wt.% FeCl3.
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desorption temperature of MgH2 [8,60]. The curve shows that
there was no reduction in the hydrogen desorption capacity of
MgH2 after milling. The addition of FeCl3 markedly improved
the onset desorption temperature for MgH2. All the samples
doped with FeCl3 started to decompose below 300 �C. For the5 wt.% doped sample, the dehydrogenation process was
initiated at 290 �C, which was a decrease in the desorption
onset of about 50 �C, with a total dehydrogenation capacity of
7.0 wt.% H2, which was the same as the hydrogen desorption
capacity of the as-received and as-milled MgH2. A further in-
crease of the additives up to 10 wt.% reduced the dehydroge-
nation temperatures to about 250 �C. The addition of 10 wt.%
FeCl3 caused decreases in the desorption onset of about 90 �C,but the amount of hydrogen released slightly dropped to about
6.5 wt.% H2. Further raising the doping amounts to 15 wt.%
and 20 wt.% reduced the desorption temperature to 245 �C but
at the cost of more loss of hydrogen release content. The
overall hydrogen release content was 6 wt.% H2. We assume
the reduction of hydrogen capacity in the 15 wt.% and 20 wt.%
added samples was due to the excessive catalytic effect
brought about by the relatively high level of the added FeCl3.
3.2. De/rehydrogenation kinetics
Isothermal desorption kinetics curves for the as-milled MgH2
and theMgH2 dopedwith 5 wt.%, 10 wt.%, 15 wt.% and 20 wt.%
FeCl3 samples were measured at 300 �C under 0.1 MPa pres-
sure. Fig. 2 shows that the samples doped with 5 wt.%,
10 wt.%, 15 wt.% and 20 wt.% FeCl3 released 5.06 wt.%,
5.75 wt.%, 4.77 wt.% and 4.06 wt.% hydrogen at 300 �C in
30 min under 0.1 MPa pressure, respectively. In contrast, the
undoped MgH2 sample desorbed just 0.88 wt.% hydrogen over
the same time. The doped samples showed a significant
improvement with respect to desorption kinetics. Fig. 3 shows
the isothermal absorption kinetics measurements for the as-
milled MgH2 and FeCl3-doped MgH2 samples. The samples
were soaked at a constant temperature of 300 �C and under
3.0 MPa hydrogen pressure. The hydrogen absorbed by the
5 wt.%, 10 wt.%, 15 wt.% and 20 wt.% FeCl3-doped MgH2
samples at 300 �C reached 4.65 wt.%, 5.21 wt.%, 4.74 wt.% and
4.02 wt.% hydrogen within 2 min. The as-milled MgH2 sample
absorbed 4.06 wt.% hydrogen over the same period. Analysis
of the isothermal de/absorption kinetics shows that a signifi-
cant improvement of MgH2 de/rehydrogenation kinetics can
be achieved by adding 10 wt.% FeCl3.
The result shows that the 10 wt.% doping amount can be
considered as the best compromise between the dehydroge-
nation temperature, isothermal de/absorption kinetics and
hydrogen yield, considering that a large amount of FeCl3 is
detrimental in terms of gravimetrical hydrogen density. Thus,
identification of the optimal 10wt.% amount of FeCl3 led to the
analysis of the FeCl3 mechanism and the catalytic effect in the
subsequent test.
In addition, to further analyse the hydrogen desorption
kinetics of the MgH2/FeCl3 composite, isothermal dehydroge-
nation measurements were performed at different
Fig. 2 e Isothermal desorption kinetics curves for as-milled
MgH2 and MgH2 doped with 5 wt.%, 10 wt.%, 15 wt.% and
20 wt.% FeCl3.
Fig. 3 e Isothermal absorption kinetics measurement of as-
milled MgH2 andMgH2 doped with 5 wt.%, 10 wt.%, 15 wt.%
and 20 wt.% FeCl3.
Fig. 4 e Isothermal dehydrogenation curves of as-milled
MgH2 and 10 wt.% FeCl3-doped MgH2 at 280 �C (a, d), 300 �C(b, e) and 320 �C (c, f).
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temperatures. Fig. 4 shows the isothermal dehydrogenation
curves of the as-milledMgH2 and 10wt.% FeCl3-dopedMgH2 at
280 �C, 300 �C and 320 �C, respectively. As expected, the
dehydrogenation rate was lower for the pureMgH2 (Fig. 4(c)) at
320 �C; however, the desorption kinetics increased dramati-
cally after the FeCl3 was added. The 10wt.% FeCl3-dopedMgH2
sample could release 5.45 wt.% hydrogen within 10 min at
320 �C (Fig. 4(f)); under the same temperature, only 0.33 wt.%
hydrogen was detected after 10 min for the pure MgH2, and
even after 30 min only 2.06 wt.% hydrogen release was ach-
ieved. Further investigation of the FeCl3-doped MgH2 sample
at lower temperatures revealed a similar result (Fig. 4(a)e(e)),
in which the 10 wt.% FeCl3-doped MgH2 sample exhibited
better dehydrogenation kinetics than the un-doped MgH2.
This kinetic enhancement is related to the energy barrier for
H2 release from MgH2. The activation energy for decomposi-
tion of the MgH2 has been reduced by adding FeCl3. To
calculate the activation energy of the as-milled MgH2 and
FeCl3-added MgH2, the Arrhenius equation was used as
follows:
k ¼ k0 expð � EA=RTÞ (1)
where k is the rate of dehydrogenation, k0 is a temperature-
independent coefficient, EA is the apparent activation energy
for hydride decomposition, R is the gas constant, and T is the
absolute temperature. As shown in Fig. 5, by plotting ln(k) vs.
1/T, the apparent activation energy, EA, for H2 release from the
as-milled MgH2 sample and the FeCl3-doped MgH2 sample,
can be identified. From the calculation, the apparent activa-
tion energy of dehydrogenation, EA, for the as-milled MgH2
was 166 kJ mol�1. This value was lowered by 36 kJ/mol after
adding 10 wt.% FeCl3 (EA w 130 kJ mol�1 for the FeCl3-added
MgH2). Owing to this lowering of the activation energy, the
decomposition of the MgH2 was improved significantly.
3.3. Differential scanning calorimetry
The thermal properties of the as-received and as-milled MgH2
and the FeCl3-doped MgH2 samples were further investigated
by DSC within the 30e550 �C temperature range (10 �C min�1
heating rate), as shown in Fig. 6. The DSC curve of as-received
MgH2 displayed only one strong endothermic peak at
approximately 440.79 �C, corresponding to the decomposition
of the MgH2. The hydrogen desorption temperature for the as-
milled MgH2 and MgH2 with added FeCl3 decreased by
approximately 55 �C and 145 �C compared to that for pure
MgH2. The DSC curves for the as-milled MgH2 and 10 wt.%
FeCl3-doped MgH2 samples had strong endothermic peaks at
424.62 �C and 353.35 �C, respectively. The notable reduction of
the peak temperature in the DSC results revealed that the
dehydrogenation properties of MgH2 were significantly
improved by adding FeCl3. However, it could be seen that the
onset decomposition temperatures of the samples in the DSC
were slightly higher than in the TPD (Fig. 1). These differences
may have resulted from the fact that the dehydrogenation
was conducted under different heating rates and there were
different heating atmospheres in the two types of
measurements.
To determine the enthalpy (DHdec) of MgH2 decomposition,
the DSC curves were analysed by STARe software. From the
integrated peak areas, the hydrogen desorption enthalpy was
obtained. For the as-milled MgH2, the hydrogen desorption
enthalpy can be calculated as 75.7 kJ mol�1 H2. This value is
almost the same as the theoretical value (76 kJmol�1 H2). After
the addition of FeCl3, the enthalpy of hydrogen desorption
fromMgH2was similar to that of undopedMgH2. These results
indicated that the additive investigated in this work acted as
catalysts, and did not change the thermodynamics of the
systems. This phenomenon is similar to Malka et al.’s report
on ZrF4, NbF5, TaF5, and TiCl3 doped MgH2 [44].
In order to compare the value of activation energy calcu-
lated by desorption kinetics analysis (Arrhenius plot, Fig. 5)
and DSC curve (Kissinger analysis) for hydrogen released from
MgH2, DSC traces for the as-received and as-milled MgH2 and
10 wt.% FeCl3-doped MgH2 composite at different heating
rates were measured as shown in Fig. 7(a)e(c). The activation
energy, EA, for the hydrogen desorption was obtained by per-
forming a Kissinger analysis [61], according to the following
equation:
Fig. 5 e Arrhenius plots of ln(k) vs. 1/T for as-milled MgH2
and MgH2 D 10 wt.% FeCl3.
Fig. 6 e DSC traces of as-received and as-milled MgH2 and
MgH2 D 10 wt.% FeCl3 (Heating rate: 10 �C minL1, argon
flow: 30 mlminL1).
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ln�b=Tp2
� ¼ �EA=RTp þA (2)
where b is the heating rate, Tp is the peak temperature in the
DSC curve, R is the gas constant, and A is a linear constant.
Thus, the activation energy, EA, can be obtained from the slope
in a plot of ln[b/Tp2] versus 1000/Tp. Fig. 8 shows the Kissinger
plot of the dehydrogenation for the 10 wt.% FeCl3-doped MgH2
composite as compared with the as-received and as-milled
MgH2. The apparent activation energy, EA, estimated from
the Kissinger analysis for the 10 wt.% FeCl3-doped MgH2
compositewas found to be 130 kJmol�1, whichwas lower than
for the as-received and as-milled MgH2 (186 and 166 kJ mol�1,
respectively). The values obtained indicate that doping with
FeCl3 reduced the activation energy and thus improved the
dehydrogenation behaviour of MgH2. The activation energy
obtained from the Kissinger analysis was similar to that value
obtained from the Arrhenius plot. So, we systematically
proved that both the Kissinger analysis and Arrhenius plot
were appropriate methods to calculate the activation energy
of hydrogen releases from MgH2.
3.4. X-ray diffraction
In order to determine the phase structure of the doped
samples, XRD scans were performed on the 10 wt.% FeCl3-
doped MgH2 sample after milling, after dehydrogenation at
450 �C, and after rehydrogenation at 300 �C under 3.0 MPa
hydrogen pressure, as shown in Fig. 9. The results show
that neither FeCl3 nor any secondary FeCl-containing phase
was detected after milling, which was probably due to the
fact that the FeCl3 grains were too small to be detectable in
the MgH2 matrix by XRD, or because the FeCl-containing
phases may have existed in an amorphous state directly
after ball milling. In the dehydrogenation spectra, there
were distinct peaks of Mg, which indicates that the dehy-
drogenation of MgH2 was completed. A small amount of
MgO was also detected in the dehydrogenation spectra due
to slight oxygen contamination. In addition, some peaks of
the MgCl2 and Fe appeared after dehydrogenation,
Fig. 7 e DSC traces at different heating rates for (a) as-received MgH2, (b) as-milled MgH2, and (c) MgH2 D 10 wt.% FeCl3.
Fig. 8 e Kissinger plot of dehydrogenation for 10 wt.%
FeCl3-doped MgH2 composite compared with as-received
and as-milled MgH2.
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suggesting that the reactions of MgH2 þ FeCl3 may have
occurred as follows:
3MgH2 þ 2FeCl3/3MgCl2 þ 2Feþ 3H2 (3)
The standard Gibbs free energy, DG�f of MgH2, MgCl2 and
FeCl3 are�35.98,�592.12 and�334.05 kJ/mol [62], respectively,
thus the total change DG associated with reaction (3) will be
�1000.31 kJ/mol of MgH2. This confirms the possibility of re-
action (3) from the thermodynamic potentials. For the rehy-
drogenated sample, it can be seen that Mg was largely
transformed into MgH2. The peaks of MgCl2 and Fe remained
unchanged, together with a small amount of MgO.
XRD examination of the dehydrogenated FeCl3-doped MgH2
samples identified the formation of MgCl2 and Fe, and this
product still remained after rehydrogenation. The formation of
MgCl2 and Fe encouraged us to speculate thatMgCl2 and Femay
have been acting as a real catalyst. Therefore, in order to
examine the effects of MgCl2 and Fe onMgH2, samples of MgH2
doped with 10 wt.% MgCl2, Fe and (MgCl2 þ Fe) were prepared,
as shown in Fig. 10. For comparison, the as-received and as-
milled MgH2 and the MgH2 þ 10 wt.% FeCl3 are also shown in
this figure. It is clear that the dehydrogenation kinetics of MgH2
were improved by doping with MgCl2 (Fe þ MgCl2), and Fe
compared to the as-milled MgH2, but their performance was
not as significant as that in the MgH2/FeCl3 composite. This
indicates that in-situ generated Fe species may have played an
important role and that the significantly improved dehydro-
genation performance of the MgH2/FeCl3 system was more
likely to be a synergistic effect. This phenomenon may have
arisen because, during the heating process, FeCl3 would react
with MgH2 as shown in reaction (3) and the subsequently
precipitated Fe particles might achievemuch higher dispersion
on theMgH2 surface andmore compact phase segregation than
the as-milled MgH2eFe. This would be likely to lead to
enhanced de/rehydrogenation kinetics.
From the results, we speculate that the formation of the
fresh and fine Fe particle resulted from the reaction of the
MgH2 and FeCl3 during the dehydrogenation processmay play
an important role in enhancement of MgH2 sorption, since it is
well known that Fe is a good catalyst for MgH2 [22,23]. The
presence of the fresh and fine Fe metal may interact with
hydrogen molecules, which may lead to the dissociation of
hydrogen molecules and the improvement of the desorption/
absorption rate. Apart from the speculated catalytic effects of
Fe species, the function of Cl� may also introduce an extra
catalytic effect on MgH2 sorption properties. Mao et al. [7] has
suggested that besides the catalytic effect of Mg2Ni andMg2Co
as a dehydrogenation product the chlorine-based product,
MgCl2, may also play an important role in improving the
hydrogen sorption kinetic properties of NiCl2 and CoCl2-doped
MgH2. As shown in Fig. 10, MgCl2 also has a positive influence
on the dehydrogenation behaviour of MgH2. These finely
dispersed dehydrogenated products may contribute to kinetic
desorption improvement by serving as the active sites for
nucleation and creation of the dehydrogenated product by
shortening the diffusion distance of the reaction ions. The
catalytic effect of MgCl2 may further combine with the cata-
lytic function of Fe species to generate a synergetic effect.
According to Malka et al. [44], the catalytic effect of a metal
halides on the hydrogen sorption of MgH2 could also be
simultaneously influenced by several factors, such as the
formation of MgF2 and the catalytic influence of transition
metal halides (with different levels ofmetal oxidation state) or
pure transitionmetals. In addition, reaction (3) could generate
clean surfaces (without MgO at MgH2 surface) and, subse-
quently, increase the surface reactivity and the decomposi-
tion reaction. However, further work is necessary to clarify
more details on the exact role of FeCl3 when added to MgH2.
4. Conclusion
The research reported in this paper systematically investi-
gated the catalytic effect of varying proportions of FeCl3 on the
hydrogen storage properties of MgH2 synthesised by ball
milling. We observed that the FeCl3 catalyst decreased the
dehydrogenation temperature and enhanced the sorption
Fig. 9 e X-ray diffraction patterns of FeCl3-doped MgH2 (a)
after milling, (b) after dehydrogenation, and (c) after
rehydrogenation.
Fig. 10 e TPD patterns for the dehydrogenation of as-
received and as-milled MgH2, and MgH2 doped with
10 wt.% MgCl2, Fe, (MgCl2 D Fe) and FeCl3.
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kinetics of MgH2. The 10 wt.% FeCl3-doped MgH2 sample
exhibited optimal sorption performance, including the onset
dehydrogenation temperature, isothermal de/absorption ki-
netics, and the released hydrogen capacity. For example, the
dehydrogenation temperature of the 10 wt.% FeCl3-doped
MgH2 sample reduced by about 90 �C compared to the as-
milled MgH2, and the sorption kinetics measurements indi-
cated that the FeCl3-doped sample displayed an average
dehydrogenation rate that was 5e6 times faster than that of
the undoped MgH2 sample. The activation energy for
hydrogen desorption was also decreased from 166 kJ mol�1 for
the as-milled MgH2 to 130 kJ mol�1 by addition of 10 wt.%
FeCl3. However, heavy FeCl3 doping also introduced negative
effects, such as lower capacity and a decreased absorption/
desorption rate compared to the lightly doped sample. It is
believed that, upon heating, the fresh and fine Fe particle is in-
situ precipitated via the reaction of MgH2 and FeCl3, and this
may combine with the catalytic function of the MgCl2 species
to generate a synergetic effect, which in turn further improves
the hydrogen storage properties of MgH2.
Acknowledgements
The author is grateful to the University Malaysia Terengganu
for providing the facilities necessary to carry out this project.
The author also acknowledges the Malaysian Government for
financial support through the Research Acculturation Grant
Scheme (57087).
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