Electroless plated Co-Ni-P-B/Ni foam catalyst for hydrogen generation from sodium borohydride

Article abstract of DOI:10.1166/jnn.2016.12010

Co-Ni-P-B catalyst supported on Ni foam was prepared using electroless plating for hydrogen generation from an alkaline NaBH₄ solution. Co-B, Co-P-B, and Co-Ni-B were prepared for comparison. Surface morphology of catalyst/Ni foams were observe

Full text of DOI:10.1166/jnn.2016.12010

Article
Journal of
Nanoscience and Nanotechnology
Vol. 16, 1740–1743, 2016
Copyright © 2016 American Scientific Publishers
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Electroless Plated Co–Ni–P–B/Ni Foam Catalyst for
Hydrogen Generation from Sodium Borohydride
∗
Daeil Park and Taegyu Kim
Department of Aerospace Engineering, Chosun University, Gwang-Ju 501-759, Republic of Korea
Co–Ni–P–B catalyst supported on Ni foam was prepared using electroless plating for hydrogen
generation from an alkaline NaBH solution. Co–B, Co–P–B, and Co–Ni–B were prepared for com-
4
parison. Surface morphology of catalyst/Ni foams were observed using SEM analysis. The Co–
Ni–P–B/Ni foam catalyst showed the superior performance on hydrogen generation rate due to
the uniform formation of catalyst particles on the surface of Ni foam. Characteristics of hydrogen
generation rate on the Co–N–P–B/Ni foam catalyst were investigated at the variety of NaBH and
4
NaOH concentrations. The hydrogen generation rate increased with decreasing NaBH concentra-
4
tion, while increasing NaOH concentration. Durability test was performed, resulting in the stable
hydrogen generation for 6 hours.
Keywords: Hydrogen, Co–Ni–P–B/Ni Foam, NaBH , Electroless Plating.
4
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up to 10.8 wt%. Also, it has some advantages; high hydro-
1
. INTRODUCTION
3
Unmanned aerial vehicles (UAV) utilizing electric motors
have various advantages for military and industrial appli-
cations. Electric motor is superior to an internal combus-
tion engine because they are quite and free of unwanted
vibrations. However, the electric motor powered by bat-
teries offers a shorter flight time due to the low energy
density. To solve this problem, various studies on fuel
cells are currently in progress, such as direct methanol
fuel cells (DMFC), and proton exchange membrane fuel
cells (PEMFC). However, DMFC involves a lot of prob-
lem, such as low cell voltage, and low fuel efficiency due
to methanol crossover. Compared to other types of fuel
cells, PEMFC generates more power for a fixed weight of
the fuel cell, leading to a longer operating life. In addition,
energy efficiency of PEMFC is higher than that of DMFC.
However, a hydrogen supply problem has been a handicap
gen density (110 kg-H
safe, easy to refuel, and ecofriendly material. NaBH
2
/m ꢀ, stable and nonflammable,
is
by a hydrolysis reaction as expressed in
4
converted to H
Eq. (1).
2
3
NaBH +2H O → 4H +NaBO +Heat
(1)
4
2
2
2
Noble metals, such as Pt and Ru, are mostly used as cat-
alysts for a hydrolysis reaction of NaBH . However, these
catalysts are very expensive. Recently, it was reported that
transition metals, such as Raney Ni and Co, Ni- and Co-
4
4
borides, are comparably reactive on the hydrolysis reaction
5
of NaBH . In general, catalysts were coated on a sup-
4
port though impregnation method. The Al O pellet has
2
3
been widely used as a catalyst support but it showed low
thermal dispersion and weak mechanical strength; thus, an
alternative catalyst support is required.
1
to the application of PEMFC for compact power sources.
Ni foam support has been widely studied because of its
higher thermal conductivity and mechanical strength than
those of the Al O pellet. NaBH hydrolysis is a highly
Hydrogen is storable in a form of compressed H , liq-
2
uefied H , metal hydrides, hydrocarbon reforming, and
chemical hydrides. Among them, chemical hydrides are
2
2
3
4
exothermic reaction generating the heat. Therefore, hot
spots are formed on the surface of the catalyst support
during the reaction, which makes the catalyst deactivated.
Thus, the catalyst support is a very important factor to
very attractive materials to supply pure hydrogen to
2
PEMFC, such as NaBH , KBH , LiH, NaH, etc. Sodium
4
4
borohydride (NaBH ꢀ is most attractive as hydrogen stor-
age material due to its high potential hydrogen capacity of
4
6
determine the performance of the reaction.
In this study, Co–Ni–P–B catalysts supported on Ni
foam were prepared using electroless plating. The surface
∗
Author to whom correspondence should be addressed.
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J. Nanosci. Nanotechnol. 2016, Vol. 16, No. 2
1533-4880/2016/16/1740/004
doi:10.1166/jnn.2016.12010

Park and Kim
Electroless Plated Co–Ni–P–B/Ni Foam Catalyst for H Generation from Sodium Borohydride
2
morphology of the catalysts were observed using SEM
analysis. Characteristics of hydrogen generation with Co–
Ni–P–B/Ni foam catalyst were investigated at the variety
of NaBH and NaOH concentrations. The catalyst durabil-
4
ity was evaluated to verify the stable hydrogen generation.
2
. EXPERIMENTAL DETAILS
2
.1. Preparation of the Supported Catalyst
The catalysts were prepared by using eletroless plating
method. CoCl , NiCl and NaH PO were dissolved in dis-
2
2
2
2
tilled water. The solution containing 20 wt% NaBH and
4
1
0 wt% NaOH were employed as the reducing solution.
Ni foam was used as the support for the catalyst. Before
the catalyst coating, the Ni foam was washed in an ultra-
sonic bath into the HCl solution for 10 min. After the pre-
treatment, the Ni foam was cleaned and dried in an oven.
The Ni foam was immersed into the mixture solution of
CoCl , NiCl and NaH PO for 10 min and then reduced
Figure 2. Comparison of Co–B, Co–P–B, Co–Ni–B, and Co–Ni–P–B
supported catalysts.
2
2
2
2
in the reducing solution. When the reducing reaction was
terminated, the catalysts were washed with distilled water.
The electroless plating process was repeated to obtain the
desired weight fraction. The weight fraction of the catalyst
to the Ni foam support was adjusted to 20 wt%.
The SEM images of Co–B, Co–P–B and Co–Ni–B cat-
alysts show that the surface morphologies were similar
each other. However, particle size of Co–Ni–P–B was
smaller than that of other catalysts. In general, the increase
in the particle size implies the significant loss of cata-
lyst dispersion during the plating process. The catalyst
2
.2. Hydrolysis Reaction on the Catalyst
Activities of the catalysts to hydrolysis reaction of NaBH4
dispersion was a very important factor to determine the
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were examined in a batch reactor.
IP: 185.14.195.181 On: Su nr ,e a1 c2t i vJ iut yn o2 f0 t1h 6e 1c a1 t :a4 l 9y s: 3t .6Thus, Co–Ni–P–B/Ni foam cata-
The catalysts with the size of 2 cm×2 cm was inserted
Copyright: American Scientific Publishers
lyst is expected to show a much better performance on the
hydrolysis reaction of NaBH4.
into the reactor and hydrogen generation was initiated by
supplying 10 mL of the reactant solution containing 5 wt%
NaBH and 5 wt% NaOH into the reactor. The hydrogen
generation rate was measured using a mass flow meter
4
3
.2. Comparison of Catalysts
The performance of catalysts were determined by mea-
suring the hydrogen generation rate as function of time
(
MFM).
3
. RESULTS AND DISCUSSION
3
.1. Characterization of Catalyst
Figure 1 shows the SEM images of Co-based/Ni foam cat-
alysts, such as Co–B, Co–P–B, Co–Ni–B and Co–Ni–P–B.
Figure 1. SEM images of Co–B, Co–P–B, Co–Ni–B, and Co–Ni–P–B
Figure 3. Hydrogen generation rate of Co–Ni–P–B/Ni foam catalyst at
supported catalysts.
the different NaBH concentration.
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J. Nanosci. Nanotechnol. 16, 1740–1743, 2016
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Electroless Plated Co–Ni–P–B/Ni Foam Catalyst for H Generation from Sodium Borohydride
Park and Kim
2
Figure 4. SEM images of the Co–Ni–P–B/Ni foam catalyst: before and
after the reaction.
reacting with the mixture of 5 wt% NaBH and 5 wt%
4
NaOH solution as shown in Figure 2.
As expected from the catalyst characteristics, Co–Ni–
P–B/Ni foam catalyst shows the highest hydrogen gen-
eration rate as compared to other supported catalysts.
This enhancement was explained on the basis of synergic
effects caused by Ni atom in the supported catalyst. The
role of Ni is to create a high number of active sites on the
Figure 6. Cycle performance of the Co–Ni–P–B catalyst.
support surface.
3
.3. Effect of NaBH and NaOH Concentration
4
For this reason, the higher the NaBH concentration, the
4
Figure 3 shows the hydrogen yield of Co–Ni–P–B/Ni foam
catalyst as function of time at the different NaBH concen-
tration varying from 5 to 15 wt%. The NaOH was fixed
to 5 wt%. The hydrogen generation was initiated immedi-
ately and reached the hydrogen yield of 100% regardless
7
more NaBO was formed on the catalyst surface.
2
4
Figure 5 shows the effect of the concentration of NaOH
in the NaBH solution on the hydrogen yield of the Co–
4
Ni–P–B catalyst. The NaOH concentration varied from
3
to 7 wt%. As a result, the hydrogen generation rate
of the concentration. The hydrogen generation rate, which
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increased with increasing NaOH concentration. At the high
is the slope of the plot, was ma iI nP t a: i1n 8e d5 . 1t h 4r .o 1u 9g 5h . 1t h8 e1r Oe a nc :- Sun, 12 Jun 2016 11:49:36
concentration of NaOH, the positive effect on hydrogen
generation was probably because of suppression of hydro-
gen formation by hydroxide ions.
Copyright: American Scientific Publishers
tion time but rapidly dropped at the end of the reaction as
the hydrogen was produced during the hydrolysis reaction.
The hydrogen generation rate decreased with the increase
of the NaBH concentration due to the partial inactivation
4
3
.4. Cyclic Performance of Co–Ni–P–B/Ni
Foam Catalyst
caused by the NaBO formation on the surface of catalyst
2
during the reaction, as shown in Figure 4.
The cycle performance of the Co–Ni–P–B/Ni foam cata-
lyst was performed in 15 wt% and 5 wt% NaOH solution
of 25 mL (1 mL/min for 25 min) at room temperature. The
hydrogen volume generated of the Co–Ni–P–B/Ni foam
catalyst as a function of cycle is shown in Figure 6. It is
clearly observed that after each cycle, the hydrogen vol-
ume decreased. The decrease in catalytic performance may
be due to the NaBO formation on the catalyst surface
2
during the reaction.
4
. CONCLUSION
Co–Ni–P–B catalyst was synthesized on Ni foam substrate
by using electroless plating. The performance of Co–Ni–
P–B/Ni foam catalyst was evaluated under the hydroly-
sis of NaBH for hydrogen generation. Co–B, Co–P–B,
4
and Co–Ni–B/Ni foam catalysts were prepared for com-
parison. The Co–Ni–P–B/Ni foam catalyst showed much
superior hydrogen generation rate as compared to other
supported catalysts. In addition, hydrogen yield of Co–
Ni–P–B/Ni foam catalyst was measured at the different
Figure 5. Hydrogen generation rate of Co–Ni–P–B/Ni foam catalyst
with different NaOH concentration.
NaBH and NaOH concentration. The hydrogen generation
4
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J. Nanosci. Nanotechnol. 16, 1740–1743, 2016

Park and Kim
Electroless Plated Co–Ni–P–B/Ni Foam Catalyst for H Generation from Sodium Borohydride
2
rate increased with decreasing NaBH concentration and
increasing NaOH concentration.
3. H. I. Schlesigner, H. C. Brown, A. E. Finholt, J. R. Gilbreath, H. R.
Hockstra, and E. K. Hyde, J. Am. Chem. Soc. 75, 215 (1953).
4
4. S. C. Amendola, S. L. Sharp-Goldman, M. S. Janjua, M. T. Kelly,
P. J. Petillo, and M. Binder, J. Power Sources 85, 186 (2000).
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Received: 20 March 2015. Accepted: 16 April 2015.
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J. Nanosci. Nanotechnol. 16, 1740–1743, 2016
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