Electrochemical growth of Au architectures on glassy carbon and their evaluation toward glucose oxidation reaction

Article abstract of DOI:10.1039/c2nj40666g

Arrow-like, flower, splintery flower-like and pin wheel Au architectures were obtained using cyclic voltammetry (I), differential pulse amperometry (II), square wave voltammetry (III) and second harmonic AC voltammetry (IV) as electrochemical methods of synthesis, named systems I, II, III and IV respectively. Architecture sizes were 610, 380, 590 and 480 nm, meanwhile crystal sizes were 48, 76, 120 and 210 nm, respectively. XRD patterns showed that systems I, III and IV preferentially exhibited the (111) plane and system II preferentially exhibited the (200) plane. The catalytic properties of the architectures were tested employing D-(+)-glucose at 10, 50 and 100 mM, where the results showed that two processes occur in the glucose electrooxidation: at ～-0.2 V vs. NHE, glucose is oxidized to gluconolactone, and after at ～0.3 V vs. NHE the successive oxidation of the gluconolactone by-product were carried out. Systems with the (111) preferential plane favor gluconolactone oxidation; while system II with the (200) plane enhanced glucose oxidation toward the gluconolactone by-product. Also, system II showed a higher current density with 26.4 mA cm^-2 at 100 mM glucose. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012.

Full text of DOI:10.1039/c2nj40666g

View Article Online / Journal Homepage / Table of Contents for this issue
Dynamic Article Links
NJC
Cite this: New J. Chem., 2012, 36, 2555–2561
www.rsc.org/njc
PAPER
Electrochemical growth of Au architectures on glassy carbon and their
evaluation toward glucose oxidation reactionw
a
b
a
b
´
´
N. Arjona, M. Guerra-Balcazar, G. Trejo, J. Ledesma-Garcıa* and
L. G. Arriaga*a
Received (in Montpellier, France) 25th May 2012, Accepted 11th September 2012
DOI: 10.1039/c2nj40666g
Arrow-like, flower, splintery flower-like and pin wheel Au architectures were obtained using cyclic
voltammetry (I), differential pulse amperometry (II), square wave voltammetry (III) and second
harmonic AC voltammetry (IV) as electrochemical methods of synthesis, named systems I, II, III
and IV respectively. Architecture sizes were 610, 380, 590 and 480 nm, meanwhile crystal sizes
were 48, 76, 120 and 210 nm, respectively. XRD patterns showed that systems I, III and IV
preferentially exhibited the (111) plane and system II preferentially exhibited the (200) plane.
The catalytic properties of the architectures were tested employing D-(+)-glucose at 10, 50 and
100 mM, where the results showed that two processes occur in the glucose electrooxidation:
at BÀ0.2 V vs. NHE, glucose is oxidized to gluconolactone, and after at B0.3 V vs. NHE the
successive oxidation of the gluconolactone by-product were carried out. Systems with the (111)
preferential plane favor gluconolactone oxidation; while system II with the (200) plane enhanced
glucose oxidation toward the gluconolactone by-product. Also, system II showed a higher current
density with 26.4 mA cmÀ2 at 100 mM glucose.
carbon nanotubes have been employed.15,16 Some disadvan-
tages of chemical synthesis are the increase of the process cost
due to the use of additives and surfactants, high reaction times
and the necessary use of purification methods.17 Besides, the use
of supports could reduce the mechanical stability of the film and
exhibit an extra process which is the incorporation of the
electrocatalytic materials into some substrate by spray method.18
Surfactantless and additiveless electrochemical synthesis has
been proposed as an alternative method of synthesis.19,20 The
advantages of electrochemical methods are the use of
less amount of precursors, shorter reaction times and the
versatility to modify the shape and size of particles directly in
the substrate.17 Tian et al. have prepared pyramidal, rod-like and
spherical Au nanostructures by chronoamperometry varying the
bath conditions.21 Wang et al. have prepared hierarchical flower-
like Au microstructures using square wave voltammetry at
different run times.18 In general, electrochemical techniques
such as square wave voltammetry (SWV), chronoamperometry
(CA) and cyclic voltammetry (CV) as well as different bath
conditions such as salt concentration, pH and temperature have
been used to modify the shape and size of Au particles.22
The lab-on-a-chip technologies combine functions of sensing and
actuation in miniaturized devices such as micro-electromechanical
systems (MEMs).23 MEMs have gained attention because of
their numerous applications such as biological and chemical
analysis, point-of-care testing, clinical and forensic analysis,
molecular and medical diagnostics.24–26 Different deposition
methods like chemical vapor deposition (CVD), supercritical
1
Introduction
In the last few years, great interest in nanostructured Au
particles has emerged, because of their unique physical and
chemical properties different from bulk metals.1 The properties of
Au materials can be tuned by the size, shape and crystal orienta-
tion of Au particles.2,3 Au materials are biocompatible and exhibit
high catalytic activities toward glucose electrooxidation, allowing
their use in a broad range of applications from glucose sensors to
fuel cells/bio-fuel cells.4–9
Several chemical syntheses have been proposed for the
development of Au particles with different shape or size; where
in general, the use of different surfactants such as thiols or
ethylene glycol or reducing agents such as ascorbic acid and
sodium borohydride has been proposed.10–14 Furthermore, in
order to increase the electroactive surface area (ESA) of Au
nanoparticles, supports such as vulcan carbon, polyaniline or
a
´
Centro de Investigacion y Desarrollo Tecnologico en Electroquımica,
76703 Queretaro, Mexico. E-mail: larriaga@cideteq.mx;
´
´
´
´
Fax: +52 442 2116007; Tel: +52 442 211 6069
´
Division de Investigacion y Posgrado, Facultad de Ingenierıa,
Universidad Autonoma de Queretaro, 76010 Queretaro, Mexico.
b
´
´
´
´
´
E-mail: janet.ledesma@uaq.mx; Tel: +52 442 192 12 00 ext. 65411
w Electronic supplementary information (ESI) available: Fig. S1:
XRD patterns of system II. Fig. S2 to S5: XRD patterns for the 1st
and 10th voltammetric cycle in 100 mM glucose electrooxidation for
systems I to IV, respectively. Fig. S6 to S9: AFM images for the 1st
and 10th voltammetric cycle in 100 mM glucose electrooxidation for
systems I to IV, respectively. See DOI: 10.1039/c2nj40666g
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012
New J. Chem., 2012, 36, 2555–2561 2555

View Article Online
fluid deposition and electrodeposition are used to fill masks of
high-aspect-ratio.27 Besides simplicity and low cost, the most
advantageous property of electrodeposition is the ability to
provide spatially selective growth in conductive or catalytic
regions.28 The importance of the present work lies in the
application of electrochemically synthesized materials in the
miniaturization of electrochemical energy systems. In this
context, a series of Au architectures were easily prepared using
different electrochemical methods: cyclic voltammetry (CV),
differential pulse amperometry (DPA), square wave voltam-
metry (SWV) and second harmonic voltammetry (2nd HV).
Bath conditions such as concentration of Au salt and the
temperature were kept constant for each Au architecture, the
evaluation of its catalytic activity toward the glucose oxidation
reaction was tested at 10, 50 and 100 mM. These results open
the possibility to employ the different Au architectures in
MEMs such as microfluidic glucose fuel cells and/or micro-
fluidic glucose sensors.
XC-72 on graphite was used as a substrate due to the high
amorphous part of the glassy carbon which inhibited all Au
characteristic crystallographic planes. The morphology of Au
structures was investigated using an AFM-STM Digital
Instruments Nanoscope IIIs (AFM).
2.3 Electrochemical evaluation of the electrocatalytic
properties of Au structures
Three concentrations of D-(+)-glucose (ACS reagent, Sigma-
Aldrich) 10, 50 and 100 mM were used in order to evaluate the
electrocatalytic properties of the different architectures toward
the glucose electrooxidation in 0.3 M KOH (87%, J. T.
Baker). The same working electrode was employed at three
glucose concentrations, where the loss of material was tested
by the decrement of electroactive surface area (ESA) in 0.5 M
H2SO4 (99.7%, J. T. Baker). Briefly, this procedure was
conducted as follows: first, ESA was estimated by a voltam-
perometric profile obtained in acid media for each Au struc-
ture. After that, cyclic voltammetry, linear sweep voltammetry
and chronoamperometry in basic media were performed in
order to evaluate the glucose electrooxidation using different
Au architecture. Finally, the voltamperometric profile in acid
media was obtained and the ESA value was newly estimated
and compared with the initial value. This procedure was
Performed for 10, 50 and 100 mM glucose.
2
Experimental
2.1 Synthesis of Au architectures
Electrochemical synthesis of Au architectures was carried out
in a standard three-electrode glass cell with an electrode
separation of 1 cm, using an AutoLab PGSTAT-30 potentio-
stat/galvanostat. The cell configuration for all synthesis
processes was: glassy carbon plates (SPIs instruments, a
geometrical area of 1.56 cm2) as a working electrode, a
saturated calomel electrode (BASs) and Pt wires as reference
and counter electrodes, respectively. The working electrode,
which was used as a substrate, was prepared by polishing
until mirror-finished with 0.05 mm alumina powder followed
by washing in deionized water in an ultrasonic bath for 30
minutes. After that, the plates were cycled 50 times in 0.5 M
H2SO4 (97.5% J. T. Baker).
3
Results and discussion
3.1 Physicochemical characterization
Fig. 1 shows the X-ray diffraction patterns collected from four
Au architectures. The characteristic planes of Au with a single
face-centered-cubic (fcc) crystallographic structure can be
observed for all cases, corresponding to the planes (111),
(200), (220), (311) and (222) located at 381, 451, 651, 781 and
821 respectively. The peaks located approximately at 421, 541,
601 and 871 could be attributed to the graphite.
Preferential planes were obtained according to the synthesis
procedure, for method I (CV) there exists competition between
(111) and (200) planes (Fig. 1(I)). Method II (DPA) exhibits
the (200) plane preferentially (Fig. 1(II)). Methods III (SWV)
and IV (2nd HV) show preferentially the (111) plane
(Fig. 1(III) and (IV)). The average crystal size was estimated
from diffractograms applied to the (311) plane. The results are
presented in Table 1, where the values obtained from AFM
images are compared.
Electrodeposition of Au structures was performed from 4
mM HAuCl4Á3H2O ( Z 99.9%, Aldrich) as a precursor in
0.1 M perchloric acid (69.8%, J. T. Baker) in the presence of
N2 (99.999%, Infra) at 298.15 K. Four alternative electro-
chemical methods were conducted under the same bath
conditions (salt concentration and temperature): (I) cyclic
voltammetry (CV) with 20 cycles between 0.183 and 1.583 V
vs. NHE at 0.1 V sÀ1; (II) differential pulse amperometry
(DPA) at 0.783 and 1.238 V vs. NHE as lower (EL) and upper
(EU) pulse potential, respectively, for 500 s; (III) square wave
voltammetry (SWV) by scanning the potential 1.283 to 0.283 V
vs. NHE at 8 Hz frequency and 0.001 V amplitude for 6 run
times; (IV) second harmonic voltammetry (2nd HV) by applying
a potential of 0.783 V vs. NHE for 30 s. After that, a potential
range from 1.283 to 0.283 V vs. NHE at 1 Hz and 0.001 V
amplitude was applied for one run time, with 2 seconds of
modulation time with 4 seconds of time interval (Fig. S1, ESIw).
AFM images of Au architectures are illustrated in Fig. 2.
Arrow-type architecture (obtained under the system I condi-
tions) is observed in Fig. 2(Ia), where the structure sizes are in
the order of hundreds of nanometers (670 nm, approximately);
meanwhile, the average crystal size is tens of nanometers
(48 nm, approximately). Flower (system II conditions) and
splintery flower-type (system III conditions) are shown in
Fig. 2(IIa) and (IIIa), respectively. A flower size is approxi-
mately 380 nm and the average crystal size is around 76 nm. A
splintery flower size is approximately 590 nm and an average
crystal size is around 120 nm. Pinwheel-type architecture was
obtained under the conditions of system IV, and is presented
in Fig. 2(IVa), the size is approximately 480 nm and the
2.2 Physicochemical characterization of Au with different
micro/nano-structures
The obtained architectures were characterized by X-ray
diffraction (XRD) measurements using a Bruker D8 Advance
diffractometer operated at 30 kV and 30 mA. Vulcan carbon
c
2556 New J. Chem., 2012, 36, 2555–2561
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012

View Article Online
Fig. 1 XRD patterns of Au structures synthesized by (I) cyclic
voltammetry (CV), (II) differential pulse amperometry (DPA), (III)
square wave voltammetry (SWV) and (IV) second harmonic AC
voltammetry (2nd HV).
Table 1 Determination of the average crystal sizes of Au architec-
tures by XRD patterns and AFM images
Architecture size/nm Crystal size/nm Crystal size/nm
(AFM)
Architecture (AFM)
(XRD)
Arrow (I)
Flower (II)
Splintery
670 10
385 5
592 8
48 4
76 2
120 11
42
41
35
flower (III)
Pin wheel (IV) 488 17
210 20
37
average crystal size is around 210 nm. Also, in Fig. 2(Ib)–(IVb)
the distribution of the architectures can be observed. Film of
the arrow-type structures is almost uniform, whereas those of
flower, splintery flower and pinwheel-type structures are
dispersed throughout the glassy carbon surface. Pinwheel
structures, also exhibit a localized growth on the plate
imperfections. The architecture thicknesses are not uniform;
however were estimated by AFM images, whose approximate
values are 99, 210, 146 and 216 nm, for the synthesis methods I
to IV, respectively.
Fig. 2 AFM images of different Au structures obtained by (I) cyclic
voltammetry (CV), (II) differential pulse amperometry (DPA), (III)
square wave voltammetry (SWV) and (IV) second harmonic AC
voltammetry (2nd HV).
3.2 Electrochemical evaluation of the electrocatalytic
properties of Au structures
Fig. 3a shows the electrochemical responses of different Au
architectures supported on glassy carbon in 0.5 M H2SO4 in a
range of potential of 0.55 to 1.65 V vs. NHE at 50 mV sÀ1. In
Fig. 3b (inset) the oxidation region of Au materials (1.3 to
1.6 V vs. NHE) is illustrated. According to Hamelin the Au
facets show different electrochemical profiles in acid media.29
In Fig. 3b, different behaviors are seen in the corresponding
region of the Au species oxidation (1.3–1.6 V vs. NHE), where
three peaks can be observed at 1.34, 1.46 and 1.55 V vs. NHE.
The first peak can be attributed to the strong electro-adsorption
of OHÀ ions;30,31 furthermore, the intensity depends on the
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012
New J. Chem., 2012, 36, 2555–2561 2557

View Article Online
Table 2 Electroactive surface area (ESA) values
System
ESA initial (A) (cm2) ESA final (B) (cm2) % ESA loss
I (CV)
II (DPA)
III (SWV)
0.8601
0.2761
0.7676
0.6471
0.1849
0.6140
1.5673
24.7
33.1
20.0
2.0
IV (2nd HV) 1.5991
Electroactive surface area was estimated as follows: (A) before to
accomplish the cyclic, linear and chronoamperometric experiments in
10 mM glucose and (B) after the experiments in 100 mM glucose.
usually different, and a general sequence may hold l(111) o
l(100) o l(110). In this regard it is expected that (200)-
dominant facets like system II show a lower stability compared
to (111)-dominant facets (system IV) due to their highest
surface energy.
Cyclic voltammetry was employed to evaluate the effect of
the changes on the Au surface in the presence of 10 mM glucose
at the beginning (first cycle) and at the tenth cycle (Fig. 4).
Three oxidation peaks can be seen in Fig. 4. The first peak
corresponds to glucose oxidation to gluconolactone; the second
and third peaks are attributed to further oxidation of adsorbed
lactone to gluconic acid and the Au surface, respectively.37 The
changes in the potential value for the glucose oxidation between
first and tenth cycles were negligible for systems I and III, only
changes in the current densities were observed. In Au architec-
tures obtained by methods II and IV, the potential value
between the tenth and the first cycle at the maximum current
density was modified, showing a negative shift at around À0.3
and À0.13 V, respectively (Fig. S2 to S9, ESIw).
Fig. 3 Cyclic voltammograms of Au architectures synthesized by (I)
CV, (II) DPA, (III) SWV and (IV) 2nd HV in 0.5 M H2SO4. Fig. 3A
shows the full scale of the electrochemical response of different Au
architectures. Fig. 3B exhibits the Au oxidation zone (1.3–1.6 V vs.
NHE). Scan rate 50 mV sÀ1 at 298.15 K in the presence of saturated N2.
The decrement in the current density could be related to the
inhibition of glucose oxidation reaction due to the formation
of byproducts which are accumulated at the Au surface,
causing a blocking effect of electroactive sites.7 Shifts in
potential values of the glucose oxidation are attributed to
the cleaning of the Au surface carried out after the first cycle,
which could be explained in terms of the number of AuOH
sites. In the first cycle at negative potentials the AuOH species
are formed; this species interacts with one glucose molecule to
give gluconolactone by the two-electron oxidation.38 At the
tenth cycle, the quantity of AuOH is increased, which could
facilitate the glucose oxidation reaction; this is reflected in
more negative potential values.
preferential Au crystallographic plane.30 The second peak is
related to the exchange of OHads to form a 3D lattice of
AuO.32 The third peak is related to the formation of a compact
Au2O3 oxide layer.33 In the case of systems I, III and IV (Fig. 3b),
the first peak (1.3 V vs. NHE) presents higher intensity in terms of
current density than second and third peaks, besides the third
peak exhibits higher intensity in system II. Higher intensities of
the first oxidation peak were found in systems with preferentially
the (111) plane. Meanwhile, the high intensity of the third peak
was found in the system with preferentially the (200) plane, which
is consistent with the results of XRD patterns of Au materials on
graphite substrates.
Linear sweep voltammetry was used in order to evaluate the
electrocatalytic properties of the Au material toward the glu-
cose oxidation reaction at 10, 50 and 100 mM (Fig. 5). Table 3
summarizes the current density and potential values of Fig. 5.
The current density in all systems (Fig. 5(I)–(IV)) is
enhanced by the increment of glucose concentration, which
means that the byproducts of glucose are not blocking
completely the electroactive sites of Au architectures. Further-
more, the gluconolactone oxidation is carried out preferen-
tially in systems I, III and IV. In Fig. 5(II) is observed that the
oxidation of D-(+)-glucose is carried out preferentially in
architectures synthesized by method II, which could mean
that systems with preferentially (111) planes promote the
oxidation of glucose byproducts as gluconolactone, and
the system with preferentially the (200) plane promotes the
glucose oxidation.
Electroactive surface area (ESA) of different Au structures
was estimated through electrochemical profiles in 0.5 M
H2SO4 from charge density associated with the reduction of
a full monolayer of Au oxides,34 using the theoretical values of
444 and 384 mC cmÀ2 for the systems with (111) and (200)
preferential planes, respectively (Table 2).35 According to
Table 2, the highest ESA is obtained with method IV (2nd
HV), following the order: method IV 4 I 4 III 4 II. Also
in Table 2, high percentages of loss of ESA are observed;
in general these losses occurred due to the formation of
bubbles in the surface which made the film detach from the
substrate. According to the literature surface energies reported
by Wang,36 those of different crystallographic planes are
c
2558 New J. Chem., 2012, 36, 2555–2561
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012

View Article Online
Fig. 5 Linear sweep voltammograms of Au architectures at
(a) 10 mM, (b) 50 mM and (c) 100 mM glucose + 0.3 M KOH for
the synthesis method: (I) CV, (II) DPA, (III) SWV and (IV) 2nd HV at
20 mV sÀ1 and 298.15 K in the presence of saturated N2.
Fig. 4 Cyclic voltammograms of Au architectures at (a) 1 cycle and
(b) ten cycles for each synthesis method: (I) CV, (II) DPA, (III) SWV
and (IV) 2nd HV in 10 mM glucose + 0.3 M KOH aqueous solution
at 20 mV sÀ1 and 298.15 K in the presence of saturated N2.
According to Tables 2 and 3, system IV exhibited the
highest ESA (1.5991 cm2); however it is the system with the
lowest current density related to glucose electrooxidation
(0.39, 2.14 and 3.71 mA cmÀ2 for 10, 50 and 100 mM glucose,
respectively). Liu et al. observed a similar case, when the
surface area of Au nanostructures increases, the current
density associated with the glucose oxidation decreases. This
process could be related with successive oxidation of Au
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012
New J. Chem., 2012, 36, 2555–2561 2559

View Article Online
Table 3 Determination of the potential and current density asso-
ciated with the glucose oxidation at 10, 50 and 100 mM
Table 4 Comparison of the glucose oxidation reaction for different
Au systems
j/mA
E/V j/mA
Glucose
concentration density
(mM)
(mA cmÀ2
Current
E/V
cmÀ2
10 mM 10 mM 50 mM 50 mM
E/V
j/mA cmÀ2 100
cmÀ2
mM 100 mM
System
Material
Electrolyte
)
Ref.
I (CV)
II (DPA)
III (SWV)
IV (2nd HV) À0.46 0.39
À0.28 0.94
À0.30 2.00
À0.28 0.83
À0.23
3.49
À0.21 8.75
À0.16 26.40
À0.27 7.91
À0.35 3.71
Au/GC
Au/C tip
Au/GC
0.3 M KOH 10
0.1 M KOH 10
0.1 M NaOH 10
2.0
1.7
0.25
2.1
This work
À0.23 11.25
43
37
42
À0.25
4.85
2.14
À0.26
AuNPs/Au 0.3 M NaOH 10
Where E is the potential at the maximum peak associated with the
glucose oxidation and j is the current density associated with the same
peak.
GC is referred to glassy carbon, AuNPs/Au are gold nanoparticles on
gold polycrystalline.
demonstrates that the Au architectures have electrocatalytic
stability for the glucose oxidation. Nevertheless, the four
systems exhibited the evolution of bubbles, which could be
related to the presence of Au–OHads on the Au surface. This
species interacts with glucose or the gluconolactone byproduct
to give products of more than two-electron oxidation.38
Comparison of the current densities associated with the 10 mM
glucose oxidation reaction in alkaline media is shown in Table 4.
System II exhibited a lower density current compared with gold
nanoparticles prepared by C. Jin and I. Taniguchi;42 despite that,
Au particles synthesized under the conditions of system II were
obtained faster, easily and with a lower cost due to avoidance of
the use of surfactants and reductive agents.
surfaces.39,40 Also in Table 3, system II presents the highest
current densities for the different glucose concentrations (2.00,
11.25 and 26.40 mA cmÀ2). Since the point of view of the
glucose oxidation potential, system IV presents the more
negative potential for 10, 50 and 100 mM glucose (À0.46,
À0.26 and À0.35 V vs. NHE, respectively). This indicates that
the pinwheel Au architecture favors the glucose oxidation as
compared to arrow, flower and splintery flower-like Au archi-
tectures. The electrocatalytic activity of Au based materials in
alkaline media could be explained in terms of hydrous surface
oxide formation.41 Thus, the most negative redox potential of
the (111)-dominant in structure IV could be related to the
easiest formation of hydrous oxide species on the surface.
Also, it is possible that the characteristics such as orientation
and morphology, of this material facilitate the glucose oxida-
tion process.
4
Conclusions
In summary arrow like, flower, splintery flower-like and pin-
wheel Au structures were prepared under the same concen-
tration of an Au precursor at room temperature using
templateless, surfactantless electrochemical methods. Average
crystal sizes estimated by AFM images were 48, 76, 120 and
210 nm, respectively. XRD patterns showed that arrow, splintery
flower-like and pinwheel architectures present preferentially a
(111) plane, meanwhile flower architecture exhibited preferen-
tially a (200) plane. The electrocatalytic properties toward
glucose electrooxidation reaction were evaluated. Flower
Au architecture exhibited the highest current density of
B26.4 mA cmÀ2 at 100 mM glucose and good stability for
glucose electrooxidation. Pinwheel Au architecture presented the
more negative anodic potential (À0.46 V vs. NHE at 10 mM
glucose) associated with glucose oxidation reaction. In this con-
text, Au architectures prepared by electrochemical techniques,
could be excellent candidates as catalysts in the miniaturization of
devices with on chip applications that use glucose as fuel.44
Furthermore, in order to evaluate the stability of the Au
architectures toward the glucose oxidation reaction, chron-
oamperometry experiments at the oxidation potential value
(presented in Table 3) in the presence of 10, 50 and 100 mM
glucose in 0.3 M KOH for 30 minutes were accomplished.
Fig. 6 shows the current density behavior for the glucose
oxidation at higher concentration as a function of the time.
The results obtained in the presence of 10 and 50 mM glucose
are similar (data not shown).
It can be observed that all experiments exhibit an exponen-
tial decrement and remain practically constant, which means
that the processes are controlled by diffusion. Also, the result
Acknowledgements
The authors gratefully acknowledge financial support from the
Mexican Council for Science and Technology (CONACyT)
through SEP-CONACYT (Grant 154263), ANR-CONACYT
2011 (Grant 163114) and PROMEP-74 2012.
Notes and references
Fig. 6 Chronoamperometric curves of Au architectures at 100 mM
glucose + 0.3 M KOH for the methods of synthesis: (I) CV, (II) DPA,
(III) SWV and (IV) 2nd HV at 20 mV sÀ1 and 298.15 K in the presence
of saturated N2. The applied potentials are provided in the figure.
1 M. C. Daniel and D. Astruc, Chem. Rev., 2004, 104, 293–346.
2 R. Sardar, A. M. Funston, P. Mulvaney and R. W. Murray,
Langmuir, 2009, 25, 13840.
3 L. M. Liz-Marzan, Langmuir, 2006, 22, 32.
´
c
2560 New J. Chem., 2012, 36, 2555–2561
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012

View Article Online
4 D. Basu and S. Basu, Int. J. Hydrogen Energy, 2011, 36,
14923–14929.
5 Y. Bai, W. Yang, Y. Sun and C. Sun, Sens. Actuators, B, 2008, 134,
471–476.
6 Y. Xia, W. Huang, J. Zheng, Z. Niu and Z. Li, Biosens. Bioelectron.,
2011, 26, 3555–3561.
7 S. Cherevko and C. H. Chung, Sens. Actuators, B, 2009, 142,
216–223.
23 M. J. Madou, Fundamentals of Microfabrication, CRC Press,
Boca Raton, 2nd edn, 2002.
24 O. Ordeig, P. Ortiz, X. Munoz-Berbel, S. Demming,
S. Buttgenbach, C. Ferna
´
Chem., 2012, 84, 3546–3553.
´
ndez-Sanchez and A. Llobera, Anal.
¨
25 N. R. Beer, E. K. Wheeler, L. Lee-Houghton, N. Watkins,
S. Nasarabadi, N. Hebert, P. Leung, D. W. Arnold, C. G. Bailey
and B. W. Colston, Anal. Chem., 2008, 80, 1854–1858.
26 J. Wang and M. P. Chatrathi, Anal. Chem., 2003, 75, 525–529.
27 J. M. Blackburn, D. P. Long, A. Cabanas and J. J. Watkins,
Science, 2001, 294, 141–145.
28 G. Zangari, in Modern Electroplating, ed. M. Schlesinger and
M. Paunovic, Wiley, New Jersey, 5th edn, 2010, pp. 617–636.
29 A. Hamelin, J. Electroanal. Chem., 1996, 1–11.
8 W. Wang, C. Yang, X. Q. Cui, Q. L. Bao and C. M. Li, Microfluid.
Nanofluid., 2010, 9, 1175–1183.
9 M. Guerra-Balca
J. Ledesma-Garcıa and L. G. Arriaga, Electrochem. Commun.,
2010, 12, 864–867.
´
zar, D. Morales-Acosta, F. Castaneda,
´
10 C. Cao, S. Park and S. J. Sim, J. Colloid Interface Sci., 2008, 322,
152–157.
´ ´ ´
11 S. Goy-Lopez, P. Taboada, A. Cambon, J. Juarez, C. Alvarez-
Lorenzo, A. Concheiro and V. Mosquera, J. Phys. Chem. B, 2010,
114, 66–76.
12 M. P. Pileni, J. Phys. Chem. C, 2007, 111, 9019–9038.
13 C. Ye, Q. Kong, R. Wu, J. Hu, Z. Chen and A. Li, Mater. Lett.,
2010, 64, 1720–1723.
14 J. Zhou, J. Ralston, R. Sedev and D. A. Beattie, J. Colloid Interface
Sci., 2009, 331, 251–262.
15 F. M. Cuevas-Muniz, M. Guerra-Balcazar, F. Castaneda,
´
30 M. Pasta, F. La Mantia and Y. Cui, Electrochim. Acta, 2010, 55,
5561–5568.
31 H. Angerstein-Kozlowska, B. E. Conway, B. Barnett and
J. Mozota, J. Electroanal. Chem., 1979, 100, 417–446.
32 B. E. Conway, Prog. Surf. Sci., 1995, 49, 331–452.
33 B. Lertanantawong, A. P. O’Mullane, W. Surareungchai,
M. Somasundrum, L. D. Burke and A. M. Bond, Langmuir,
2008, 24, 2856–2868.
34 S. Trasatti and O. A. Petrii, Pure Appl. Chem., 1991, 63, 711–734.
35 W. Niu, S. Zheng, D. Wang, X. Liu, H. Li, S. Han, J. Chen,
Z. Tang and G. Xu, J. Am. Chem. Soc., 2009, 131, 697–703.
36 Z. L. Wang, J. Phys. Chem. B, 2000, 104, 1153–1175.
J. Ledesma-Garcı
196, 5853–5857.
16 M. Guerra-Balca
´
a and L. G. Arriaga, J. Power Sources, 2011,
´
zar, F. M. Cuevas-Muniz, F. Castaneda,
´
37 A. Habrioux, K. Servat, T. Girardeau, P. Guerin, T. W. Napporn
´
R. Ortega, L. Alvarez-Contreras, J. Ledesma-Garcı
´
a
and
and K. B. Kokoh, Curr. Appl. Phys., 2011, 11, 1149–1152.
38 S. B. Aoun, Z. Dursun, T. Koga, G. S. Bang, T. Sotomura and
I. Taniguchi, J. Electroanal. Chem., 2004, 567, 175–183.
39 R. R. Adzic, M. W. Hsiao and E. B. Yeager, J. Electroanal. Chem.,
1980, 260, 475–485.
L. G. Arriaga, Electrochim. Acta, 2011, 56, 8758–8762.
17 E. Antolini and J. Perez, J. Mater. Sci., 2011, 46, 4435–4457.
18 L. Wang, S. Guo, X. Hu and S. Dong, Electrochem. Commun.,
2008, 10, 95–99.
19 R. S. Jayashree, J. S. Spendelow, J. Yeom, C. Rastogi,
M. A. Shannon and P. J. A. Kenis, Electrochim. Acta, 2005, 50,
4674–4682.
20 J. Chai, F. Li, Y. Bao, S. Liu, Q. Zhang and L. Niu, J. Solid State
Electrochem., 2011, 16, 1203–1210.
21 Y. Tian, H. Liu, G. Zhao and T. Tatsuma, J. Phys. Chem. B, 2006,
110, 23478–23481.
22 A. P. O’Mullane, S. J. Ippolito, Y. M. Sabri, V. Bansal and
S. K. Bhargava, Langmuir, 2009, 25, 3845–3852.
40 A. Liu, Q. Ren, T. Xu, M. Yuan and W. Tang, Sens. Actuators, B,
2012, 162, 135–142.
41 L. D. Burke and T. G. Ryan, Electrochim. Acta, 1992, 37, 1363–1370.
42 C. Jin and I. Taniguchi, Chem. Eng. Technol., 2007, 30, 1298–1301.
43 M. Pasta, R. Ruffo, E. Falletta, C. M. Mari and C. Della Pina,
Gold Bull., 2010, 43, 57–64.
44 F. M. Cuevas-Muniz, M. Guerra-Balca
N. Sabate, L. G. Arriaga and J. Ledesma-Garcı
2012, 216, 297–303.
´
zar, J. P. Esquivel,
´
´
a, J. Power Sources,
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012
New J. Chem., 2012, 36, 2555–2561 2561