Electrochemistry Communications 6 (2004) 242–244

www.elsevier.com/locate/elecom

Ni-fluorinated vapor growth carbon fiber (VGCF) compositefilms prepared by an electrochemical deposition process

Feng Wang a, Susumu Arai a,*, Shingo Morimoto b, Morinobu Endo c

a Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University,

4-17-1 Wakasato, Nagano-shi, Nagano 380-8553, Japanb Nagano Techno Foundation, 1-18-1 Wakasato, Nagano-shi, Nagano 380-0928, Japan

c Department of Electrical and Electronic Engineering, Faculty of Engineering, Shinshu University,

4-17-1 Wakasato, Nagano-shi, Nagano 380-8553, Japan

Received 2 December 2003; received in revised form 16 December 2003; accepted 17 December 2003

Published online: 15 January 2004

Abstract

Nickel-fluorinated vapor growth carbon fiber (VGCF) composite films have been fabricated by using electrochemical deposition

method from the plating bath containing a cationic fluorocarbon surfactant as the dispersing agent of fluorinated VGCF. The ESCA

result confirmed the existence of metallic Ni and the fluorinated VGCF with C–F covalent bond structure in the composite film,

while the SEM and TEM results showed that the fluorinated VGCFs embedded into the Ni-fluorinated VGCF composite film

obtained from the plating bath at a dispersion concentration of 2.5 g dm�3 VGCF. The results clearly proved that the bath con-

centration and deposition conditions, which were designed in the present study, are effective on preparing the Ni-fluorinated VGCF

composite film.

� 2003 Elsevier B.V. All rights reserved.

Keywords: Nickel; Fluorinated vapor growth carbon fiber; Composite film; Electrochemical; Deposition; Microstructure

1. Introduction

As a creative chemical method for surface modifica-

tion, the fluorination treatment of vapor growth carbon

fibers (VGCF) has received much attention [1,2]. The

fluorinated VGCF has an extremely low surface free

energy and then its surface is repellent to water, even to

oil. So far, the application of fluorinated VGCF is still

difficult relative to the application of traditional VGCF[3,4] due to this unique surface feature. Recently, con-

sidering its favorable super water-repellency, solid lu-

brication as well as thermal conductivity, the one

application of fluorinated VGCF is to fabricate its

composite material with metal matrix by using electro-

chemical deposition method since the co-deposition of

* Corresponding author. Tel.: +81-26-269-5413; fax: +81-26-269-

5208.

E-mail address: araisun@gipwc.shinshu-u.ac.jp (S. Arai).

1388-2481/$ - see front matter � 2003 Elsevier B.V. All rights reserved.

doi:10.1016/j.elecom.2003.12.007

the fibers can be considered to provide the compositefilms an opportunity to gain the properties of the fibers

according to Musiani [5]. However, the fluorinated

VGCF can hardly uniformly disperse in the plating bath

without any modification onto its surface due to its su-

perior water-repellency. In general, one of way to get rid

of this difficulty is by adding certain surface-active agent

to the electrolyte.

The intent of the present study is to design a novelplating bath containing a cationic fluorocarbon surfac-

tant as a dispersing agent of fluorinated VGCF for

preparing the Ni-fluorinated VGCF composite film by

using electrochemical deposition method. The chemical

states of Ni-fluorinated VGCF composite films are de-

termined by using electron spectroscope for chemical

analysis (ESCA). The microstructures of Ni-fluorinated

VGCF composite film are characterized by using field-emission scanning electron microscope (FE-SEM) and

transmission electron microscope (TEM).

848852856860864868872876880

Binding Energy (eV)

Inte

nsity

(C

PS)

Ni 2p 2p3/2

280285290295

680685690695700

Binding Energy (eV)

Binding Energy (eV)

Inte

nsity

(C

PS)

Inte

nsity

(C

PS)

C 1s

F 1s

peak 1

peak 2

(a)

(b)

(c)

Fig. 1. Ni 2p (a) C 1s (b) and F 1s (c) ESCA spectra of Ni-fluorinated

VGCF composite film. (Current density: 10 Adm�2, 2.5 g dm�3 fluo-

rinated VGCF in the plating bath.)

F. Wang et al. / Electrochemistry Communications 6 (2004) 242–244 243

2. Experimental

The vapor grown carbon fibers (VGCFs) used in the

present study were obtained via catalyst assisted CVD

(Showa Denko Co. Ltd) [6]. The fluorinated VGCFs

used was prepared through direct reaction with fluorine

gas with 0.1 MPa pressure at temperatures of 500 �C for

1 day [7]. The plating bath used contained 1 M

NiSO4 � 6H2O, 0.2 M NiCl2 � 6H2O and 0.5 M H3BO3.All solutions were prepared using deionized water and

reagent grade chemicals. The fluorinated VGCFs with

2.5 g dm�3 concentration were dispersed in deionized

water by mixing with a cationic fluorocarbon surfactant

(N-[3-(perfluorooctanesulfonamide) propyl]-N,N,N-tri-

methylammonium iodide) with ultrasonic agitation (ul-

trasonic generator 300-T, NIHONSEIKI Co. Ltd) for

60 min. The copper foil with internal dimensions of1� 2 cm was used as substrate and Ni plate was used as

anode material. The current density was ranged from 2.5

to 10 Adm�2 and all the deposition processes were

performed under the total electric charge of 36 C cm�2.

The plating cell was a beaker of 200 cm3 with magnetic

stirrer agitation and the electrochemical deposition

process was preformed at 40 �C. The chemical state of

composite film was determined by electron spectroscopefor chemical analysis (ESCA) (ESCA-3400, Shimadsu).

The surface morphologies of Ni-fluorinated VGCF

composite films were observed with the help of field

emission scanning electron microscope (FE-SEM) (S-

4100, HITACHI) and their crystallographic structures

were determined by transmission electron microscope

(TEM) (JEOL-2000, JEOL). The TEM sample was

prepared by using electrochemical etching method.

Fig. 2. TEM image and electron diffraction pattern of Ni-fluorinated

VGCF composite film. (Current density: 10 Adm� 2, 2.5 g dm�3

fluorinated VGCF in the plating bath.)

3. Results and discussion

ESCA has recently been widely used in the investi-

gation of elemental valence and the chemical state of

alloy element in thin metallic films. Fig. 1 shows the

ESCA spectra in the Ni 2p, C 1s and F 1s regions forNi-fluorinated VGCFs composite film. As shown in

Fig. 1(a), the Ni 2p spectrum shows the binding energy

of 852.7 eV (Ni 2p3=2) and 870.0 eV (Ni 2p1=2), indi-

cating that Ni in composite film is in metallic state. The

C 1s spectrum of Ni-fluorinated VGCFs (Fig. 1(b)) re-

veals the presence of 2 peaks corresponding to C–C or

C–H (peak 1: binding energy¼ 285.0 eV), C–F groups

(peak 2: binding energy¼ 288.5 eV). Moreover, Fig. 1(c)shows the F 1s spectrum (binding energy¼ 689.0 eV),

corresponding to C–F covalent bond structure. The

above results indicate that nickel in the composite film

exists in the metallic state and confirm that the VGCFs

with C–F covalent structure exist in the composite film.

Fig. 2 shows the TEM images and selected area dif-

fraction (SAD) pattern of Ni-fluorinated VGCFs com-

posite film deposited at the current density of 10

Adm�2. The fluorinated VGCFs in the diameter of 0.2

lm are present clearly as shown in bright image, re-

vealing that the fabric nature of the fluorinated VGCF.Moreover, no new phase could be observed in the in-

terface between the fluorinated VGCF and Ni matrix.

This means that the fluorinated VGCFs-Ni bond must

Fig. 3. SEM surface morphology of Ni-fluorinated VGCF composite

film. (Current density: 10 Adm�2, 2.5 g dm�3 fluorinated VGCF in the

plating bath.)

244 F. Wang et al. / Electrochemistry Communications 6 (2004) 242–244

have a physical or mechanical nature. The SAD patternas shown in Fig. 2 shows the typical diffused rings cor-

responding to Ni matrix with polycrystalline structure.

Fig. 3 shows a field-emission scanning electron mi-

crograph image of Ni-fluorinated VGCFs composite

film at the current density of 10 Adm�2. It can be seen

that the fluorinated VGCFs show uniform dispersion in

the nickel matrix. This indicates that the above methods

used to disperse fluorinated VGCFs into plating bathare effective. Also, the figure clearly shows that the

fluorinated VGCFs embedded in the nickel matrix cover

the surface of the composite film. Therefore, the Ni-

fluorinated VGCF composite film, obviously, may pro-

vide water-repellency and the aim of fibers protection

can be realized.

4. Conclusion

A new class of Ni-fluorinated VGCF composite ma-

terial has been fabricated by using electrochemical de-

position method. The ESCA, TEM as well as SEM

results confirm that Ni-fluorinated VCCFs composite

film with favorable VGCF dispersion in Ni matrix can

be prepared by using the plating bath containing a

cationic fluorocarbon surfactant as dispersing agent.These composite films provide proper opportunity in the

creation of new super water-repellent and wear-resistant

composite films.

Acknowledgements

This research was supported by the CLUSTER of the

Ministry of Education, Culture, Sports, Science andTechnology, Japan.

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