Post on 23-Jan-2018
EXPERIMENTAL
RESULTS AND DICUSSIONS (CONTrsquoD)
3 intense peaks (200) peak was larger than
expected for a random
polycrystalline sample
Cu NANOWIRE ARRAYS PREPARED BY A SIMPLE REDOX DEPOSITION METHOD
Leong Feng Ping Angela
INTRODUCTION Metallic nanowires possess high functionality due to their multiple attractive properties and
characteristics with potential applications in various fields like nanoscale electronics and
magnetic devices Cu is particularly desirable due to its electrical properties and low cost Yet the
fabrication of Cu nanowires remains largely limited popular template-based methods of
electrodeposition and electroless deposition are energy-consuming environmentally
unfriendly non-facile and difficult to control
PURPOSE To report the synthesis of Cu nanowires in anodic aluminum oxide (AAO) templates using a
simple metal displacement deposition method which combines the template deposition and
metal displacement reaction This method is based on galvanic contact between the sputtered
noble metal film covering the bottom of the template and a less noble metal partially exposed
to the solution
REFERENCES 1 A Huczko App Phy A 70 (2000) 365-376
2 R Inguanta S Piazza C Sunseri Electrochem Commun 11 (2009) 1385-1388
3 S L Xu X Sun H Ye T You X Y Song S X Sun Mater Chem and Phy 120 (2010) 1-5
4 G Kartopu O Yalcin Electrodeposited Nanowires and Their Applications ISBN 978-953-
7619-88-6 pp228 2000
5 ZH Yang ZW Li L Liu LB Kong J Magn Magn Mater 323 (2011) 2674-2677
6 Q L Xu G W Meng X B Wu Q Wei M G Kong X G Zhu Z Q Chu Chem
Mater 21 (2009) 2397-2402
7 Chowdhury D P Casey J F Rohan Electrochem Commun 11 (2009) 1203-1206
8 W Lee R Ji U Gosele and K Nielsch Nat Mater 5 (2006) 741-747
9 A Santos L Vojkuvka J Pallares J Ferre-Borrull L F Marsal J Electroanal Chem
632 (2009) 139-142
10 S S Djokic J Electrochem Soc 143 (1996) 1300
11 AJ Bard R Parsons J Jordan J Standard Potentials in Aqueous Solution Marcel
Dekker New York 1985
CONCLUSION bull Regular and uniform arrays of Cu nanowires were successfully synthesized by a simple metal
displacement deposition method
bull This fabrication technique is easy to control and low-cost as the deposition can be carried out
at room temperature without requiring energy organic surfactants specific equipment or
modification on the pore walls
bull Considering copper is one of the most important metals in modern electronic technology this
process can be useful for industrial manufacture of copper nanowires
RESULTS AND DISCUSSIONS
AAO Template Characterisation
FUTURE WORK bull Extension of method to fabrication of nanowires of other metals and heterogeneous alloys
since the Al3+Al redox pair has a lower standard reduction potential than many metallic ions
bull Study potential factors affecting the redox deposition to investigate optimal conditions for this
fabrication method
XRD Results
Properties of Cu nanowires
bull Face-centered cubic
crystal structures
bull Strong texturing
bull Preferred growth direction in the (200)
crystal plane
(200) peak was larger
than expected for a random
polycrystalline sample
3 intense peaks
SEM images of Cu nanowire arrays after template removal
Redox Deposition Scheme
3 intense peaks 3 intense peaks
Stage 1
Foil DC anodized in
05M H2C2O4(aq) at
40V for 10-15min
9999
pure Al foil Annealed at 500degC in
air for 5h and
cleaned with acetone
Immersed in 6 wt
H3PO4(aq) for ~40min
to widen pores
Al-surrounded AAO
floated on 6 wt H3PO4(aq)
to dissolve barrier layer
100nm Pt layer
sputtered on one side
of template to form
conductive layer
Sample
sputtered
with Pt thin
layer in
vacuum
Alumina film on
surface partially
dissolved by
05ml of 1M
NaOH(aq)
bull Morphology of AAO template
and Cu nanowire arrays examined
by Field Emission SEM
bull Crystalline structures of
nanowires identified by XRD
Pre
par
atio
n o
f A
AO
Te
mp
late
s D
ep
osi
tio
n o
f C
u
Nan
ow
ire
Arr
ays
Ch
arac
teri
sati
on
Orderly upstanding Cu nanowires with bases inside AAO templates
0141 μm
0136 μm
0136 μm
0151 μm
(2a) Top-view (2b) Side-view
Islands consisting of bundles of Cu nanowires
(2d) Low magnification
1359 nm
1070 nm
1163 nm
(2e) High magnification
Alumina matrix of AAO template has almost been dissolved away
Cu Nanowires Characterisation
(1a) Top-view (1b) Cross-sectional view
6988 microm 7183 microm
SEM images of blank AAO templates after pore widening SEM image of cross-section of AAO template after infiltration with Cu nanowires embedded in pores
bull Pore center distance 160 nm
bull Pore diameter 120 nm
bull Thickness of AAO template 70 μm
bull Pores are distributed in perfect hexagonal
order in defect-free area
ACKNOWLEDGEMENTS This work was supported by the Young Defence Scientists Programme (YDSP) Ministry of Defence Singapore I would like to thank Mr Yang Zhihong from Temasek Laboratories NUS for guiding me through the
experiments instructing me in the background knowledge and clarifying my doubts as well as Mr Murali Krishnaswamy for his guidance during the editing of the report and aiding with administrative details
At cathode
Cu2+ + 2e- Cu
At anode
Al Al3+ + 3e-
Cl- ions in solution etch away the
alumina layer on Al foil exposing pure Al
Cu2+
Cu2+
(1c)
Average diameter of nanowires is 120 nm
(2c)
Remaining
Al on back
of template
etched with
1M CuCl2(aq)
100nm Pt layer sputtered on
one side of template to
form conductive layer
Template
infiltrated by
01M CuCl2(aq)
for 4h
Cut into
Stage 2
Voltage
increased to
60V at 06Vs-1
and
maintained
for 2h
Image taken from httpmediadigikeycomphotos3M20Photos1170-775EX105Ejpg
All images and graphs are self-taken and self-drawn unless otherwise stated
Image taken from Microstructure and magnetic properties of Co-Cu nanowire arrays fabricated by galvanic displacement deposition ZH Yang ZW Li L Liu LB Kong J Magn Magn Mater 323 (2011) 2674-2677