effect of power on and electrochemical characteristic of ...power (80 w, 100 w, 120 w, and 140 w)....
TRANSCRIPT
2015 2nd International Conference on Material Engineering and Application (ICMEA 2015) ISBN: 978-1-60595-323-6
Effect of Sputtering Power on Microstucture and Electrochemical Characteristic of Nickel Films Deposited by Magnetron Sputtering
Yongping Luo, Shunjian Xu, Zonghu Xiao, Wei Zhong, Hui Ou & Yuan Xiao
Xinyu Institute of New Energy, Xinyu University, Xinyu, Jiangxi, China
ABSTRACT: Nickel (Ni) film electrodes were deposited onto FTO by the magnetron sputtering
method. The influence of sputtering power on the morphology and electrochemical perfor‐
mances of the as‐prepared films has been investigated in this work. The surface crystal struc‐
ture and morphology of the prepared films were investigated by using X‐ray diffraction (XRD)
and scanning electron microscope (SEM). The results have shown that with the increase of the
sputtering power from 80 W to 140 W, the increases of the film surface roughness and porosi‐
ty. The films deposited at sputtering power of 140 W possess the highest specific surface area
and abundant pore structure, leading to better electrochemical performance of Ni film.
1 INTRODUCTION
In recent years, Ni nanoparticles have become one of the interesting metallic nanomaterials in
many promising fields including chemical catalysis, electrocatalysis, conducting paints, magnet-
ic recording, rechargeable batteries, medical diagnosis, superconducting devices, and so on
(Gao et al., 2010; Chen et al., 2007). Ni particles were reported to be excellent catalysts for hy-
drogenation of nitrobenzene and nitrophenol, oxygen reduction, and oxidation of olefins (Zhu et
al., 2011). Besides this, cheaper nickel nanoparticles are also used as a component of the modi-
fied electrodes for alcohol sensing (Shibli et al., 2006) and fuel cell development (Suleimanov
et al., 2008) particularly in alkaline medium although electrocatalytic activity of bare Ni foil is
insignificant at low potential (Bagchi & Bhattacharya).
Up to now, several elegant methods have been established for the preparation of high-quality Ni
nanoparticles, such as polyol method (Couto et al., 2007), chemical reduction (Wu et al., 2010),
ball milling (Yue et al., 2011), electrodeposition (Li & Dai, 2005), decomposition of organome-
tallic precursors (de Caro & Bradley, 1997), chemical vapor deposition (Singjai et al., 2007),
thermal plasma (Choi et al., 2003), modified electroless plating (Wu et al., 2009), microwave-
assisted synthesis (Xu et al., 2008), and magnetron sputtering (Tkach et al., 2015). And so on.
Magnetron sputtering method shows remarkable advantages, such as method is simple, low
cost, easy to promote, and facilitate preparation of thin films.
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In the present study, the magnetron sputtering method was used to prepare Ni film under the
conditions of working pressure of 1.8 Pa, deposition time of 20 min, and different sputtering
power (80 W, 100 W, 120 W, and 140 W). XRD and SEM were used for the characterization of
the surface crystal structure and morphology of the prepared Ni films. The comprehensive study
of the electrochemical activity of Ni films under the different sputtering power was performed
by using cycle voltammetry (CV).
2 EXPERIMENTS
2.1 Film deposition Processing
The deposition of Ni films was carried out by using a magnetrons sputtering system come from
SKY technology development Co., Ltd (Shenyang, china), which was equipped with a rotary
vane pump as well as a turbo-molecular pump. Deposition was carried out by Ni targets used as
RF sources in an Ar atmosphere (gas flow: 30 sccm). Ni targets were obtained from Zhongnuo
Advanced Material Technology Co., Ltd. (Beijing, china), and had purity of 99.99%. FTO con-
ductive glass (25 × 20 mm) was obtained from CSG Holding Co. Ltd. (Shenzhen,china), and
used as substrate. Prior to Ni film deposition on FTO substrates, the target was sputter cleaned
for 20 min with shutter in a closed position. The films were deposited at a substrate temperature
of 300ºC. Working pressure of 1.8 Pa, deposition time of 20 min, sputtering power of 80 W, 100
W, 120 W and 140 W were applied.
2.2 Ni film Characterization
The morphology of as-prepared Ni films was characterized by using EVO MA 10 (Zeiss, Ger-
many) equipped with energy dispersive spectroscopy (EDS). X-ray diffraction (XRD) was car-
ried out by a Bruker D8 (German) X-ray diffractometer using Cu Kα radiation source and λ =
1.5406 Å at 30 kV and 30 mA. Electrochemical measurements were performed on an electro-
chemical analyzer (CHI660A, Shanghai, China) in deaerated aqueous solution containing 1 M
NaOH with a three-electrode configuration, in which Ni film as working electrode, a Pt wire as
the counter electrode and a Ag/AgCl electrode as reference electrode. All measurements were
carried out at ambient temperature.
3 RESULT AND DISCUSSION
3.1 XRD analysis of Ni films
The as-prepared Ni/FTO samples show almost the same XRD patterns as shown in Figure 1.
The peaks located at 44.4º, 51.7º and 76.4º attributed to the (111), (200), and (220) reflections of
the Ni phase (PDF 65-0380), respectively. The peaks of FTO and NiOOH can be seen in the
samples.
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20 30 40 50 60 70 80
FTO
111
200
220 * NiOOH
*
2θ / deg.
Inte
nsity
/ α.
u.
a
b
c
d
Figure 1. XRD of Ti films under the conditions of working pressure of 1.8 Pa, deposition time of 20 min
and different sputtering power: (a) 80 W, (b) 100 W, (c) 120 W, (d) 140 W.
3.2 Effect of sputtering power on the morphology of Ni films
Figure 2 shows SEMs of Ni films obtained under the conditions of working pressure of 1.8 Pa,
deposition time of 20 min, and different sputtering power (80 W, 100 W, 120 W, and 140 W). It
can be seen from Figure 1(A) to (D), the increases of the film surface roughness and porosity
with the increase of the sputtering power. The film is thicker at relatively higher sputtering
power.
It is mainly attributed to the increase of the sputtering power increases the current between sub-
strate and target, ionized argon ion will be increasing. The bombardment of argon ion to the tar-
get surface becomes more intensified, the target atom will be more stripped from the target sur-
face. With the increase of the deposition rate, the particles sputter from the target will be
depositied on the particle cluster of NiO. The formation of island growth promotes a large of
pores were produced on the film surface.
Figure 2. SEMs of Ni film with different sputtering power: (A) 80 W, (B) 100 W, (C) 120 W, (D) 140 W.
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3.3 Effect of technology parameters on the electrochemical characteristic of Ni films
Figure 3 shows the CVs of Ti film with different sputtering power in 1 M NaOH solution at the
scan rate of 50 mV s-1. From the CVs, a pair of redox peaks was observed at 250 mV and 400
mV, which attributed to the Ni2+/Ni3+ redox couple. The redox peak current is biggest at the
sputtering power of 140 W, which probably due to the large specific surface area and abundant
porous microstructure of the Ni film prepared on the condition of the sputtering power of 140
W.
100 200 300 400 500 600-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
E /V vs. Ag/AgCl
a
I / m
A
d
Figure 3. CVs of Ni film with different sputtering power: (a) 80 W, (b) 100 W, (c) 120 W, (d) 140 W.
4 SUMMARY
In this study, it was investigated that the effect of sputtering power on the morphology and elec-
trochemical properties of Ni films. The Ni films were prepared by using magnetron sputtering
on FTO substrates under sputtering power from 80 W to 140 W. The film deposited at a higher
sputtering power possessed a higher specific surface area and abundant pore structure, leading
to better electrochemical performance of Ni film.
ACKNOWLEDGEMENTS
This work was financially supported by Natural Science Foundation of China (51263021), Nat-
ural Science Foundation of Jiangxi (20141521050002).
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