Third Day Poster Session, 17 June 2010 - NanoTR-VI

Poster Session, Thursday, June 17
Theme F686 - N1123
Hydrogen Chemisorption on Metal Loaded Carbon Nanotubes
Gülah Ozan 1* , Saadet Kayıran Beyaz 2 , Nalan Tekin 2 , M. Efkan Kibar 3
1 Gebze Institute of Technology, Department of Chemistry, 41400 Gebze / Kocaeli-TURKEY.
2 Kocaeli University, Faculty of Science and Arts, Department of Chemistry, 41380 Izmit / Kocaeli- TURKEY.
3 Kocaeli University, Faculty of Engineering, Department of Chemical Engineering, 41380 Izmit / Kocaeli- TURKEY.
Abstract— Metal doped or metal decorated carbon nanotubes (CNTs) are the most capable materials for hydrogen storage by
chemisorption. Using CNTs for hydrogen storage has been one of the hottest topics in science and technology. We have
developed nickel doped materials by wet chemistry method and measured the hydrogen absorption capacity of these materials.
The comparison of absorption capacities between materials is discussed in the light of characterization results.
Hydrogen storage is an essential prerequisite for the
widespread deployment of fuel cells, particularly in transport.
The US Department of Energy (DOE) has announced a 6.0
wt% target for hydrogen storage on-board automobiles [1, 2].
Sorption in solids is one of the way for increasing hydrogen
storage. Nanostructured carbons are being investigated as
potential hydrogen adsorbents since they are cheap, light and
porous materials. CNTs can easily and dependably accept and
release substantial quantities of hydrogen by physisorption and
chemisorption mechanisms [3]. Many works are devoted to
measure and calculate hydrogen adsorption capacity of carbon
nanomaterials. According to the works done by Monte Carlo
simulations, it is observed that hydrogen storage is less than
1% at room temperature when it is absorbed with various
carbon materials such as SWCNTs, MWCNTs, and GNFs.
These works show that the physisorption is not sufficent for
store the quantity of hydrogen given in DOE target [4-6]. For
this reason the researchers have tried to create more attractive
nanocarbons surface for creating strong interaction with
hydrogen. The chemisorption mechanism could provide the
hydrogen storage capacity which can fulfill the technological
necessity [3]. The aim of this work is to study the hydrogen
chemisorption on Ni doped materials.
In this study, three different Ni doped materials were
prepared using active carbon (AC), Al 2 O 3 and multi walled
carbon nanotubes (MWCNTs). MWCNTs were synthesized
by Chemical Vapor Deposition (CVD) method using acetylene
as a carbon source and nickel as catalyst. MWCNTs were
purified by thermal oxidation in air at temperature at 350 ºC
for 2h in order to remove amorphous carbon and were treated
with 3M HCl solution in order to remove metal catalyst.
Carboxylic acid functionalized MWCNTs (f-MWCNTs) have
been obtained by treatment of concentrated H 2 SO 4 /HNO 3 (v:v,
3:1). 15 % Ni doped f-MWNTs, Al 2 O 3 and AC were prepared
from Ni(NO 3 ) 2 .6H 2 O by wet chemistry method. Formerly, f-
MWNT, Al 2 O 3 and A.C. was ultrasonically dispersed in
ethanol for 3h and Ni(NO 3 ) 2 .6H 2 O solution was added and
ultrasonicated in order to obtain homogenous metal dispersion
on these materials. Ni doped materials were centrifuged and
dried at 60 ºC for 4 days in vacuum oven. The synthesized
MWCNTs, f-MWCNTs were characterized by TEM, SEM,
FT-IR, EDX, Raman, and BET techniques. The specific
surface area of the 15% Ni doped materials are 222 m2/g for f-
MWCNTs, 114m2/g for Al 2 O 3 and 362m2/g for AC. The
hydrogen chemisorptions capacity of obtained Ni doped
materials was measured using Micromeritics, ASAP 2020,
Surface Area and Porosity Analyzer. Figure clearly shows that
MWCNTs were successfully synthesized and doped with Ni
metal atoms.
a
c
Figure: (a) HRTEM image of MWCNTs, (b) Raman Spectrum of MWCNTs,
(c) SEM image of 15 % Ni doped f-MWCNT and (d) EDX result of 15 % Ni
doped f-MWCNT
In summary, we have successfully developed nickel
doped materials and measured the hydrogen absorption
capacity of these materials. The comparison of absorption
capacities between Ni doped materials are discussed in light of
characterization results. The absorption results will be
presented during the conference.
This work was partially supported by TUBITAK under
Grant No. 106T502, 109T619 and by Kocaeli University
under Grant No. BAP 2007/70. BET characterization and H 2
chemisorption studies were done at AYARGEB at Kocaeli
University Teknopark Inc.
*Corresponding Author: gozan@gyte.edu.tr
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d
6th Nanoscience and Nanotechnology Conference, zmir, 2010 767