Journal of The Electrochemical Society, D193 0013-4651

Journal of The Electrochemical Society, 153 �12� D193-D198 �2006� D193

Electrochemically Controlling the Size of Gold NanoparticlesChien-Jung Huang,a,z Pin-Hsiang Chiu,b Yeong-Her Wang,b,c Kan-Lin Chen,d

Jing-Jenn Linn,d and Cheng-Fu Yange

aDepartment of Applied Physics, National University of Kaohsiung, Nan-Tzu, Kaohsiung, TaiwanbInstitute of Electro-Optical Science and Engineering, cInstitute of Microelectronics, Department ofElectrical Engineering, National Cheng-Kung University, Tainan, TaiwandDepartment of Electronic Engineering, Fortune Institute of Technology, Kaohsiung, TaiwaneDepartment of Chemical and Materials Engineering, National University of Kaohsiung, Na-Tzu,Kaohsiung, Taiwan

This work demonstrates the electrochemical synthesis of nanoscale gold particles using a surfactant solution. Tetradodecylammo-nium bromide �TTAB� surfactant was applied to stabilize the gold clusters. Experimental results reveal that the size of theproduced gold nanoparticles is controlled by the amount of TTAB surfactant, the current density, and the growth temperature. Thesize of the gold nanoparticles can be controlled in the range 58.3–8.3 nm. The particle size decreases as the amount of TTABincreases from 1 to 90 mg. The optimal current density in this study was 3 mA/cm2. The size of the produced nanoparticlesincreases linearly with the growth temperature from 25 to 60°C. The gold nanoparticles were observed by transmission electronmicroscopy, ultraviolet-visible spectrometry, and X-ray photoelectron spectroscopy. A mechanism for electrochemically control-ling the size of the gold nanoparticles is presented.© 2006 The Electrochemical Society. �DOI: 10.1149/1.2358103� All rights reserved.

Manuscript submitted January 11, 2006; revised manuscript received July 11, 2006. Available electronically October 11, 2006.

0013-4651/2006/153�12�/D193/6/$20.00 © The Electrochemical Society

Nanoscale materials are of great interest due to their unique op-tical, electrical, and magnetic properties. Extensive investigations ofgold nanoparticles in biology, nonlinear optical switching, the for-mation of modified surfaces for surface-enhanced Raman scattering,immunoassay labeling, optical contrast agents, and catalysis re-vealed that the size and shape of the particles strongly determinetheir physical and chemical properties.1-6 Hence, controlling the par-ticle size is very important. The electrochemical production of nano-particles has been widely studied since the early work of Reetz et al.in 1994.7,8 Their studies indicated that size-selective nanosized tran-sition metal particles could be prepared electrochemically using tet-raalkylammonium salts as stabilizers of metal clusters in a nonaque-ous medium. The electrochemical method has been demonstrated tobe superior to other nanoparticle production approaches because ofits lower processing temperature, modest equipment, ease of con-trolling the yield, low cost, and high quality.9-14 A recent study syn-thesized gold nanorods electrochemically by introducing a shape-inducing cosurfactant.15 Yin et al.16 developed a novelelectrochemical technique for the size-controlled synthesis ofspherical nanoparticles in poly�N-vinylpyrrolidone� solution. Bart-lett et al.17 and Wiley et al.18 reported the deposition of metal usingother electrochemical approaches. The authors’ research group de-veloped the electrochemical method proposed herein to formcrooked gold nanocrystals with a novel structure, using micelle tem-plates formed from two surfactants with isopropanol addition.19,20 Inaddition, carefully controlling the amount of acetone solvent addedto the solution of surfactants changes the shape of the gold nanopar-ticles from spherical to cubic.21

This work experimentally studies the synthesis of gold nanopar-ticles using a two-electrode electrochemical cell in surfactant solu-tion, with special emphasis on the characteristics of the gold nano-particles produced. The amount of surfactant, the current density,and the growth temperature are also investigated. Furthermore, amechanism for controlling the size of gold nanoparticles using anelectrochemical method is presented.

Experimental

The gold nanoparticles were prepared electrochemically using asimple two-electrode cell, with oxidation of the anode and reductionof the cathode. Figure 1 schematically depicts the electrochemicalapparatus. The experimental cell was housed in a conventional 20� 80 mm glass test tube. With dimensions of 30 � 10 � 0.5 mm, a

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gold plate and platinum plates were cut to form the anode and thecathode, respectively. Both electrodes were initially cleaned usingfine sandpaper and further cleaned using aqua regia and deionizedwater for 5 min each. They were then dried using nitrogen gas.Electrodes in the cell were spaced 5 mm apart and held in placeusing Teflon spacers.

A growth solution of 0.08 M cetyltrimethylammonium bromide�C19H42Br−N+, CTAB, Fluka, 98%� was prepared following the pro-cedure presented in our previous work.19-21 The cationic CTAB sur-factant served as the electrolyte. 3 mL of growth solution was put ina glass test tube. Then, a measured amount of powdered auxiliarysurfactant �tetradodecylammonium bromide �C48H100Br−N+�;TTAB, Fluka, 99%� was added to the tube, where it floated on the

Figure 1. �Color online� Schematic diagram of the electrochemical appara-tus for synthesizing gold nanoparticles.

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70, and �f� 90 mg; scale bar represents 100 nm.

D194 Journal of The Electrochemical Society, 153 �12� D193-D198 �2006�D194

growth solution. The test tube was then sonicated �ELMA T710DH,Germany� at 100 kHz for 5 min. The cationic TTAB surfactant,which also acts as an electrolyte, stabilized the resulting small par-ticles. A series of samples of TTAB were made, with masses of1–10, 30, 50, 70, and 90 mg, to determine whether the amount ofTTAB has any effect on the particle size distribution. Appliedvoltage-controlled electrolysis was used throughout the process. Ex-periments were performed at three current densities �1, 2, and3 mA/cm2� and at three temperatures �25, 40, and 60°C�. Experi-mental runs were made under sonication at 100 kHz for 25 min perrun. This work is a careful and systematic study of the effect of thesurfactant, the applied voltage, and the growth temperature. All ofthese parameters must be considered to obtain synthetically usefulresults in a simple and reproducible manner.

The microstructural characteristics of the produced nanoparticleswere observed by field-emission-gun transmission electron micros-copy �FEG-TEM, Philips Tecnai G2 F20� at an accelerating voltageof 200 kV. TEM specimens for both microscopes were prepared bytaking �7 �L from the cell after an experimental run and mixing itwith 2 mL of ethyl alcohol �99.8%�, and then putting a drop of theresulting mixture on a standard 200-mesh 3 mm copper grid coatedwith a thin carbon film �Agar Scientific, England� and letting it dryin an electronic drying cabinet �Jow Ruey Technical DRY-70, Tai-wan� for 3 days at room temperature ��25°C�. The histograms ofthe distributions of particle diameters �Di� for each sample weredetermined by making manual measurements of over 100 particlesin the TEM images. The standard deviation �� is given by thefollowing relationship22

� = �� N�Di − daverage�2� � �N − 1�2�1/2

where daverage is the average diameter and N is the number of par-ticles.

The optical properties of the produced gold nanoparticles wereevaluated using an ultraviolet visible �UV/vis� spectrometer �Hitachi3310, Japan�. X-ray photoelectron spectroscopy �XPS, Escalab-210,VG Scientific� was employed to study the electron spectra and per-form the elemental analysis. The sample for XPS characterizationwas prepared by drop-casting a single drop of growth solution ontoa clean glass slide �1 � 1 cm� and then drying it in air.

Results and Discussion

Influence of the amount of surfactant on particle size.— In theelectrochemical process, the bulk metal at the anode is oxidized tometal cations, which migrate to the cathode where reduction occurswith the formation of adatoms. Such clusters are trapped by thesurfactant. The cationic TTAB �C48H100Br−N+� surfactant is basedon nitrogen atoms that carry the cationic charges and is adsorbedstrongly onto most solid surfaces. This surfactant is seen as theelectrolyte and a stabilizer in the growth solution, as shown in Fig.1. The process was repeated using 1, 10, 30, 50, 70, and 90 mg ofTTAB under otherwise identical conditions �40°C, 2 mA/cm2� todetermine whether the amount of TTAB surfactant affects particlesize and optical properties. The TEM images of gold nanoparticlesproduced from the different amounts of TTAB, shown in Fig. 2a-f,all have the same scale bar. These TEM micrographs clearly showthat the particle size can be controlled by the selection of the appro-priate amount of TTAB. Figure 2f shows the smallest particles. Fig-ure 3 presents a typical average diameter �daverage� and standarddeviation �� of the gold nanoparticles. Statistical counting of morethan 100 particles revealed that the average diameters of the goldnanoparticles were 58.3 ± 12.6, 44.6 ± 18.1, 36.7 ± 19.6,25.3 ± 11.7, 17.2 ± 10.2, and 10.6 ± 6.5 nm. Notably, the particlesize was inversely proportional to the amount of TTAB between 1and 90 mg.

Figure 4 shows the UV/vis absorption spectra data for solutionsin experimental runs with various amounts of TTAB. Each sampleappeared cloudy red to the human eye. Figure 4 shows that the gold


Figure 2. Transmission electron micrographs of gold nanoparticles preparedusing different amounts of TTAB surfactant; �a� 1, �b� 10, �c� 30, �d� 50, �e�

Figure 3. Histogram of the average diameter �daverage� in the distributionwith standard deviation ��, for gold nanoparticles formed by adding �a� 1,�b� 10, �c� 30, �d� 50, �e� 70, and �f� 90 mg of TTAB.


D195Journal of The Electrochemical Society, 153 �12� D193-D198 �2006� D195

nanoparticles had a maximum absorbance band at around 540 nm, avalue which agrees very well with the values in the literature, from500 and 560 nm for the surface plasmon resonance �SPR� band ofspherical gold nanoparticles.23,24 The optical absorption and scatter-ing of a spherical metal nanoparticle whose diameter is muchsmaller than the wavelength can be described using the quasistaticapproximation. Based on the assumption that the surroundings arean isotropic matrix with dielectric constant �m, the actual absorptionof light by the solution is given by the following equation25

Qabs =18�NV�m

3/2

��

�2

��1 + 2�m�2 + �22 �1�

where Qabs is the absorption cross section of the particle, N is thenumber of nanoparticles per unit volume, V is the volume of nano-particles, and � is the wavelength of the absorbing radiation. �1 and�2 represent the real and imaginary parts of the material dielectricfunction, respectively �� = �1 + i�2�. Use of Eq. 1 assumes that thespherical metal nanoparticles are far enough apart to scatter inde-pendently and that no multiple scattering occurs. The condition formaximum absorption of the SPR band is given by the followingexpression

�1 = − 2�m �2�provided that damping is weak. The metal is taken to have thesimple dielectric function

�1 = �� −�2

�p2 �3�

and the peak position of the SPR band obeys

�position2 = �p

2�� + 2�m� �4�

where �� is the high frequency value of the dielectric function. Thevalue of �� about 13.2 for gold� is determined by all of the transi-tions within the metal at UV and higher frequencies. �p is theplasma wavelength of the bulk metal and is given by

�p2 = 4�2c2m�0/ne2 �5�

where n is the concentration of free electrons in the metal, m is theeffective mass of the conduction electrons, c is the velocity of lightin vacuum, e is the electron charge, and �0 is the vacuum permittiv-ity. As is clear from Eq. 4, the peak position of the SPR band issensitive to the solvent dielectric constant ��m� and the plasmawavelength of the bulk metal ��p�. �p varies inversely with thesquare root of n. The most important parameter that affects � is n,

Figure 4. �Color online� UV/vis absorption spectra of aqueous dispersionsof gold nanoparticles with various amounts of TTAB and the dependence ofthe maximum SPR band on the amount of TTAB.

p


which is directly related to the particle size26 and the simple phe-nomenological description of the adsorbate effect.27 When smallnanoparticles are either positively or negatively charged, this is sen-sitively reflected as either a decrease or an increase in n because theparticle volume is small.28,29 Additionally, some molecules such asthiols, surfactants, or polar solvents are intimately bound to the par-ticle surface, and they may provide or withdraw additional electrondensity at the interface.30-32 Equation 4 clearly states that changes inthe particle charge density and solution dielectric constant alter theplasma frequency and can cause a shift in the peak position of theSPR band. In this study, the inset in Fig. 4 plots the relationshipbetween the peak position of the maximum absorption SPR band forvarious amounts of surfactant TTAB and average particle size. Thepeak position of the SPR band decreases with a blue shifting from540 to 522 nm as the particle size decreases from 58.3 to 10.6 nm.The peak with the shortest SPR band is observed for particles pro-duced by 90 mg of TTAB, indicating the presence of particles of theminimum size. For very small particles, the SPR absorption peak isbroadened so much that it disappears, which is consistent with otherreports.33,34 Furthermore, the intensity of the SPR band decreased asthe amount of TTAB increased. This relation is explained by Eq. 1,which states that the intensity of the SPR band depends strongly onN and V. During an electrochemical process, the bulk gold at theanode is oxidized to yield gold cations, which then migrate to thecathode where reduction yields gold adatoms. These gold adatomsare trapped by the surfactant to form gold nanoparticles. Surfactantmolecules form a bilayer structure around the gold nanoparticles, inwhich the inner layer is bound to the gold surface via the surfactantheadgroups.35 Therefore, the surfactant is usually considered to be astabilizer or a micelle-template, which controls the size of the goldnanoparticles �Fig. 1�. The surfactant around the cathode graduallychanged in color from off-white at the beginning of the reaction to aruby red at the end of the reaction; the red substance diffused slowlyfrom the cathode surface to the surfactant solution during electroly-sis. The appearance of the red color reveals the formation of goldnanoparticles. Under the given experimental conditions, the amountof gold nanoparticles decreases as the amount of TTAB increases.Deposition of gold ions on the cathode surface decreased as theamount of TTAB increased, because the number of gold ions de-creased from the anode to the cathode. The large amount of surfac-tant is well known to reduce the conductivity of the electrolyte,reducing the rate of deposition. Therefore, increasing the amount ofTTAB reduced the gold deposition rate on the cathode and consid-erably reduced the formation of gold nanoparticles. The role ofTTAB surfactant in the electrochemical reaction was considered asfollows. First, under fixed conditions of current density, time, andelectrode area in the electrochemical reaction, the electrolyte �sur-factant� concentration influenced the amount of gold oxidized/reduced �number of adatoms�. Second, the amount of TTAB alsoinfluenced the particle size. In this work, although the particle sizedecreased as the TTAB amount increased, the amount of goldoxidized/reduced decreased as the amount of TTAB increased be-cause of the drop in deposition rate. In this study, more TTAB sur-factant synthesized smaller particles �Fig. 2� and fewer gold nano-particles. However, the intensity of the SPR band is determined bythe larger amount of TTAB, which is responsible for the lower con-centration of smaller gold nanoparticles.

Figure 5 shows the XPS analysis of gold nanoparticles producedusing various amounts of TTAB to elucidate their composition. TheXPS spectra exhibited no material other than gold or the surfactant.Figure 5 shows the spectra of Au 4f, Br 3d, C 1s, N 1s, and O 1score levels of gold nanoparticles and the surfactant. Additionally, aslight Si 2p core level spectrum appears at a binding energy of about103 eV, because the samples are prepared on a glass slide. The284.5 eV binding energy is a C 1s core level peak, from the tail ofthe surfactant hydrophobic group. The Br 3d5/2 and Br 3d3/2 corelevel spectra peaks are at 186.8 and 180.2 eV, respectively, indicat-ing the presence of the hydrophilic portion of the surfactant. The O



1s core level peak is observed at 531.3 eV. An N 1s peak from thefront of the surfactant hydrophobic group is observed at a bindingenergy of 420.2 eV.

Figure 5 shows a magnified Au 4f core-level spectrum with vari-ous amounts of TTAB surfactant. The Au 4f core-level can be char-acterized by two pairs of peaks associated with Au 4f7/2 and Au4f5/2 spin-orbit coupling. These are characteristic values for elementAu�0�. Au is in 0 valence. The results also clearly show that thebinding energy of the Au 4f peak can be changed by altering theamount of TTAB surfactant. When the amount of TTAB surfactantis 10 mg, as in image �a�, the binding energies of Au 4f7/2 and Au4f5/2 are 84.0 and 87.8 eV, respectively. When the amount of theTTAB surfactant is increased from 30 to 90 mg, the binding ener-gies of Au 4f7/2 and Au 4f5/2 peaks change slightly from 84.2 to84.5 and 88.0 to 88.3 eV, respectively. Notably, the binding ener-gies of Au 4f7/2 and Au 4f5/2 peaks increased with the amount ofTTAB surfactant. The difference between the binding energies of theAu 4f7/2 and Au 4f5/2 peaks for all samples is 3.8 eV, a value simi-lar to that of bulk gold. The typical Au 4f7/2 and Au 4f5/2 peaks forthe bulk gold binding energy are at 83.9 and 87.6 eV, respectively,36

probably because of a shift in the Fermi level as the particles be-come smaller. Such shifts have been reported elsewhere.37-39

Controlling the size of particles by changing the currentdensity.— During the operation of our electrochemical cell, bulkgold is ionized and then travels as gold ions from the anode to thecathode �anode-oxidation/cathode-reduction�. The reduction of thegold ions at the cathode affords so-called adatoms. These adatomsaggregate in the presence of the surfactants to form the nanopar-ticles. The current flows through the electrolyte as moving gold ions.Thus, the current density is the current flow per cross-sectional areanormal to the flow of current. The rate of removal of gold ions canalso be described in terms of current density. The current density is,however, determined by the applied electric field. In this study, todetermine whether the current density has any effect upon the size ofgold nanoparticle, a series of preparations was carried out usingcurrent densities varying from 1 to 3 mA/cm2. At the highest cur-rent density of 3 mA/cm2, the cathode was strongly gold-coloredand so was electroplated in gold. At 1 mA/cm2, the cathode was itsoriginal color; the color of the solution had changed only slightly. Ata given amount of surfactant and temperature, a change in currentdensity alone visibly affected the color of the reacted solution. Ex-

Figure 5. �Color online� XPS electron spectra of gold nanoparticles forvarious amounts of TTAB surfactant; inset also shows a typical XPS spec-trum of the Au-4f core level.


perimental runs were performed at current densities of 1, 2, and3 mA/cm2 to test the effect of current density on the production ofgold nanoparticles. The results show that the particle size decreasedas the current density increased, as revealed by TEM analysis �Fig.6�.

The average diameters of the gold nanoparticles were53.7 ± 17.2, 32.1 ± 11.1, and 12.2 ± 7.3 nm, respectively. There-fore, smaller particles are formed at higher current density. Figure 7shows the UV/vis absorption spectra obtained in this series of ex-periments. The peak of the SPR band is blueshifted from538 to 523 nm as the particle size decreases from 58.3 to 10.6 nm,as shown in the inset in Fig. 7. This relationship between the currentdensity and the particle size from the free energy of formation of agold cluster, G�N�, has two terms, as follows40

G�N� = − Nze + ��N� �6�

where N is the number of ions in the gold cluster, is the overpo-tential, z is the ion charge, e is the charge of the electron, and � isthe electrostatic potential. The first term is related to the number, N,of gold ions that move from the solution to the crystal phase on thesurface of the cathode and the second term is related to the increasein the surface energy associated with the creation of the surface of agold cluster. This increase in the surface energy equals the differ-ence between the binding energies of the N bulk gold ions and thoseof the N gold ions arranged on the surface of the gold crystal. Bothterms in Eq. 6 are functions of the size of the gold cluster, N. Thesize of the critical nucleus in two dimensions is given by

Figure 6. Transmission electron micrographs of gold nanoparticles preparedat current densities of �a� 1, �b� 2, and �c� 3 mA/cm2; scale bar represents100 nm.


D197Journal of The Electrochemical Society, 153 �12� D193-D198 �2006� D197

Nc =bs�2

�ze�2 �7�

where Nc is the number of atoms in the gold cluster, b is the factorthat relates the surface area S of the nucleus to its perimeter P �b= P2/4S; b = � for a circular nucleus�, s is the area occupied by oneatom on the surface of the gold nucleus, and � is the edge energy.Therefore, Nc strongly depends on the overpotential and is inverselyproportional to 2. The critical radius of the surface nucleus rc is afunction of the overpotential

rc =s�

ze�8�

Therefore, rc is inversely proportional to the overpotential ��, andthe electron transfer overpotential may be defined as the rate ofchange of electrode potential with the current associated with thelimiting rate of electron transfer across the phase boundary betweenthe electrically conducting electrode and the ionic conductingsolution.41,42 The overpotential is directly related to the current den-sity. Both experimental and theoretical results show that changingthe current density in the electrochemical cell controls the size of thegold nanoparticles, revealing that a larger current density is associ-ated with smaller particles.

Effect of growth temperature on particle size.— Finally, thepossible effect of growth temperature on the size of surfactant-stabilized gold colloids was experimentally studied. At a givenamount of TTAB surfactant, neither the current density nor thegrowth temperature visibly changed the color of the solution,but they did affect the cathode. At high temperature, the cathodewas more heavily gold-plated. However, a more detailed studyshowed a moderate and significant positive correlation betweenthe temperature and the size of the produced particles. Processtemperatures of 25, 40, and 60°C �30 mg, 2 mA/cm2� were applied.The results showed that the particle size increases with the growthtemperature, as shown by TEM analysis and shown in Fig. 8.Figure 8 shows the TEM images of gold nanoparticles producedat growth temperatures of 25, 40, and 60°C, which yieldedrespective particles of sizes 8.3 ± 2.2, 34.5 ± 12.3, and53.8 ± 18.3 nm. Figure 9 presents UV/vis absorption spectra ofgold nanoparticles grown at various temperatures. The inset inFig. 9 plots the relationship between the peak position of themaximally absorbing SPR band at different growth temperaturesand average particle sizes. The peak position of the SPR banddecreases as it is redshifted from 521 to 538 nm as the particlesize is increased from 8.3 to 53.8 nm, and the temperature falls

Figure 7. �Color online� UV/vis absorption spectra of aqueous dispersion ofgold nanoparticles produced at different current densities.


from 25 to 60°C. These results show that the particle size canalso be controlled by the growth temperature, to which it isproportional. The results can be explained by the higher diffusionand migration rates of surfactant intermediates at highertemperatures, the inhibition of the decrease in the viscosity of

Figure 8. Transmission electron micrographs of gold nanoparticles preparedat growth temperatures of �a� 25, �b� 40, and �c� 60°C; scale bar represents100 nm.

Figure 9. �Color online� UV/vis absorption spectra of aqueous dispersionsof gold nanoparticles produced at different growth temperatures.



the medium, which reduces the overpotential, and other changes.43

Other factors, such as the higher rate of desorption of the surfactantstabilizer from the particle surface at higher temperatures, mayalso play a role. Table I presents the basic characteristics ofgold nanoparticles synthesized under various conditions. Theexperimental results presented above clearly demonstrate thefabrication of good-quality gold nanoparticles using a simpleelectrochemical cell with a stabilizer that is composed of surfactant.The size of the produced nanoparticles is well controlled byvarying the amount of TTAB surfactant, the current density, andthe growth temperature.

Conclusions

This study reports the electrochemical production of gold nano-particles in surfactant solution. The size of the particles is controlledby varying the amount of TTAB surfactant, the current density, andthe growth temperature. Changing the amount of the TTAB moststrongly affected the particle size, and the SPR band is blueshiftedfrom 540 to 522 nm as the particle size decreases from58.3 to 10.6 nm. The peak of the SPR band is redshifted from521 to 538 nm as the particle size increases from 8.3 to 53.8 nmand the temperature falls from 25 to 60°C. For the range of vari-ables studied, the optimal parameters were a current density of3 mA/cm3 for a cell solution with 30 mg of TTAB and a growthtemperature of 25°C, which produced the smallest nanoparticles ofsize diameter 8.3 nm. Various characterizations, such as by UV/visabsorption spectroscopy, TEM, and XPS, indicated that the pro-duced gold nanoparticles are of good and stable character. The elec-trochemical method is confirmed to be appropriate for the low-cost,low-temperature, and rapid fabrication of gold nanoparticles.

Acknowledgment

This work was partially supported by the National Science Coun-cil �NSC� of Taiwan under contract no. NSC 94-2215-E-390-001.The authors thank the Department of Mechanical Engineering,Southern Taiwan University of Technology �STUT�, Taiwan, fortheir support in TEM sample preparation.

Table I. Properties of gold nanoparticles synthesized under vari-ous conditions.

Sample Size �nm� SPR �nm�

TTAB amount �mg�1 58.3 542

10 44.6 53630 36.7 53050 25.3 52870 17.2 52490 10.6 522Current density�mA/cm2�1 53.7 5382 32.1 5303 12.2 523

Temperature �°C�25 8.3 52140 34.5 53060 53.8 538


National University of Kaohsiung assisted in meeting the publicationcosts of this article.

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Journal of The Electrochemical Society, D193 0013-4651