Y.-S. Ko, Y.-U. Kwon / Electrochimica Acta 55 (2010) 7276–7281
7281
Table 1
Particle density (N), size, surface area, and morphology of electrochemically deposited Pt for 60 s from a 10 mM K2PtCl4 solution under different applied potentials.
Applied potential vs. (Ag/AgCl)/V
−0.050
−0.10
1.9 0.7
158 62
0.72 0.1
−0.15
−0.20
a
N (× 108 cm−2
)
1.3 0.4
201 87
0.59 0.08
2.4 0.7
138 51
1.1 0.1
2.6 0.1
131 44
1.1 0.05
Particle size (nm)a
Surface area (mC cm−2
Morphologya
b
)
The surface of Pt particles gets rougher on moving left to right
a
The particle density, size, and morphology were determined by the observations of SEM images.
The surface area of Pt particles was calculated by the integration of the hydrogen ions-desorbed region on cyclic voltammograms.
b
cyclic voltammetry of electrodeposited Pt particles in 0.5 M H2SO4
aqueous solution. The scan rate was 0.1 V/s. The electrochemical
data including the surface area as well as the particle density, size,
and morphology are summarized in Table 1. As the overpotential
increases, the surface area also increases due to the increased par-
ticle density and the rougher surface. However, the surface areas
at the applied potentials of −0.15 V and −0.20 V are the same with
each other. This phenomenon can be explained by the fact that the
particle density is saturated and the particle size gets smaller when
the overpotential is high although the surface of Pt particles seems
to be rougher at −0.20 V than at −0.15 V.
Acknowledgements
This work was supported by grants NRF-20090094024 (Prior-
ity Research Center Program), NRF-2010-0015035 (Basic Science
Research Program NCRC), and KETEP 2009-3021010030-11-1
(Research Center of Break-through Program CIGS). We thank CCRF
for the SEM data.
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4. Conclusions
We investigated the nucleation and growth mechanisms of elec-
trochemical deposition process of Pt particles on the FTO electrode
2−
by varying the concentration of PtCl4
ions and the overpoten-
tials within the mass-transfer-limited region. Based on the results
obtained by analyses of SEM images and current–time transients
with the SH theory, the nucleation mechanism changes from pro-
gressive to instantaneous as the overpotential and concentration
increase. The increase in these two parameters also enhances the
particle density. In particular, the morphology of the particle sur-
face becomes rougher when the overpotential increases rather than
the concentration does. Thus, the surface area of the platinized
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the high overpotentials probably due to the saturation of the par-
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overpotential and the concentration are the important parameters
to easily control those properties that affect the catalytic activity.
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electrochemical deposition of Pt on the FTO electrode.
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