Decoration of silver nanoparticles on activated graphite substrate and their electrocatalytic activity for methanol oxidation

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Original Article

Decoration of silver nanoparticles on activated graphite substrate and

their electrocatalytic activity for methanol oxidation

M.S. Shivakumar

, G. Krishnamurthy

b,**

, C.R. Ravikumar

c,*

, Aarti S. Bhatt

d
aResearch Centre, Dept. of Chemistry, ACS College of Engineering, Bangalore, 560074, India

bDOS in Chemistry, Bangalore University, Bangalore, 560001, India

cDept. of Chemistry, East West Institute of Technology, Bangalore, 560091, India
dDepartment of Chemistry, NMAM Institute of Technology, Nitte, 574110, India

a r t i c l e i n f o

Article history:

Received 21 December 2018
Received in revised form
31 May 2019

Accepted 3 June 2019
Available online 10 June 2019
Keywords:

Silver nanoparticles
Electro catalyst
Graphite powder
Electroless deposition
Methanol oxidation

a b s t r a c t

Silver nanoparticles (~30e70 nm) have been impregnated on the activated graphite powder by an
electroless plating method. The so prepared silver decorated graphite powders are characterized byﬁeld
emission scanning electron microscopy, powder X-ray diffraction, energy dispersive X-ray and X-ray
photoelectron spectroscopy. The activated graphite powder displays a high surface coverage with tin
which is essential, as this ensures a thorough and complete coating of the graphite powder with silver.
The electrochemical studies of Graphite, Sn/Graphite and successive decoration of AgeSn/Graphite
powder have been carried out using cyclic voltammetry in the potential range between1.2 and 0.0 V at
a sweep rate of 50 mV s1and their electrocatalytic activity for methanol oxidation has been examined in
alkaline medium. The effective active surface area of Graphite and AgeSn/Graphite electrode are
calculated to be 6.2479 105cm2and 6.7886 105cm2, respectively. The impedance spectrum of the

AgeSn/Graphite electrode displays a depressed semicircle in the high-frequency region which
corre-sponds to low charge resistance and high capacitance. The results highlight the electrocatalytic behavior
of the graphite supported silver nanoparticles, making them suitable for fuel cell applications.
© 2019 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi.

This is an open access article under the CC BY license ( />

1. Introduction

Electroless deposition of silver nanoparticles on various
sub-strates is a well-known technique, which generally employed for
this metal. This method involves pretreatment of the substrate
surface, sensitization and activation for increasing the rate of
metal ions reduction on the surface of carbon substrate [1e3].
The applications of silver nanoparticles (Ag NPs) thus obtained
according to their properties like electric conductivity, re
ﬂec-tivity and other surface properties such as their ability to absorb
as well as chemisorb, making them suitable candidates for

catalysis applications [4e8]. These properties also lend them
unique biological, chemical and physical properties matching up
to their macro-scaled counterparts. No wonder, Ag NPs have also

been used in variedﬁelds such as renewable energies, medicine
and environment[9,10].

An alternative for the reduction of silver nanoparticles is to
introduce organic functional groups, for instance, carboxyl and
hydroxyl groups onto the carbon surface [11,12]. These organic
functional groups act as binding sites to the metal ions which
un-dergo reduction to ultimately form a metal layer on the carbon
surface[13,14]. Carbon materials such as graphite are widely used
in industries and processing techniques due to their high
conduc-tivity and elevated speciﬁc surface area. Also, the low cost of
graphite adds to its preferences[15].

Electrocatalysts are generally employed in fuel cells as it helps in
improving the fuel oxidation. However, the high cost of fuel cells
and its low durability hinders its wide application. In order to make
these fuel cells affordable, research is being carried out to decrease
the cost by decreasing the amount of expensive elements used or
by substituting some of the expensive components with cheaper
but more durable materials. Simultaneously, an effort is being made
to improvise its durability by developing high durable catalyst
supports or it can also be done by using Pt alloys as electro catalysts
[16]. Carbon based materials make a better catalyst support; for

* Corresponding author.
** Corresponding author.

E-mail addresses:(G. Krishnamurthy),Ravicr128@
gmail.com(C.R. Ravikumar).

Peer review under responsibility of Vietnam National University, Hanoi.

Contents lists available atScienceDirect

Journal of Science: Advanced Materials and Devices

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j s a m d

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instance XC-72 Vulcan carbon powder is a widely used support in
the electrodes of several modern fuel cells. The graphite submicron
particles on the catalyst support aids in the oxidation of fuel cells
application.

Our present work employs the electroless plating method to
reduce silver nanoparticles by introducing organic functional
groups on the activated graphite powder with electrocatalytic
surfaces. This serves as a better platform to obtain decorated silver
nanoparticles on sensitized and activated graphite powders. The
oxidized graphite powders have been treated with reducing agent
and immersed in Ag bath solution (pH 11) to obtain silver
nano-particles on graphite powders [17]. The so-prepared decorated
silver nanoparticles on sensitized and activated graphite have been
tested for their electrocatalytic activity of methanol oxidation in
alkaline solution by cyclic voltammetry (CV) and electrochemical
impedance spectroscopy (EIS). The surface morphology, structure,
composition have been characterized by Field emission scanning

electron microscopy (FESEM), Energy dispersive X-ray analysis
(EDX), powder X-ray diffraction (PXRD) and X-Ray photoelectron
spectroscopy (XPES).

2. Materials and methods

All the chemicals have been procured from SigmaeAldrich and
have been used without any further puriﬁcation. Graphite powder,
silver nitrate, stannous chloride, polyethylene glycol, glucose,
po-tassium hydroxide and methanol used have99.99% purity. The
solvents sulphuric acid, nitric acid and aqueous ammonium
hy-droxide solution are of AR grade.

2.1. Functionalization of graphite powder

About 1 g of graphite powder was treated in 200 cm3of an acid
mixture of conc. HNO3and conc. H2SO4(1:3 v/v) and reﬂuxed at

110C for 8 h to produceeOH and eCOOH functionalized graphite
powder. The samples were then ﬁltered, washed with distilled
water and dried at 95± 3C for about 6 h. Thus, the functionalized

graphite powder was obtained.

2.2. Decoration of silver nanoparticles on graphite powder

To obtain decorated silver nanoparticles on graphite by
elec-troless plating, 2 g of oxidized graphite powder (<20

m

m) was
treated with 50 cm3 of 20% SnCl2, stirred for 10 min and then

ﬁltered. The obtained graphite powder was then treated with
30 cm3of glucose solution, 20 cm3of methanol and 1 g of
poly-ethylene glycol, stirred for 10 min, ﬁltered and transferred to a
250 cm3of silver bath solution (3 g of AgNO3in 250 cm3of water)

along with 0.6 g NaOH. To this, ammonia solution was added
dropwise to get a clear solution, stirred for 45 min,ﬁltered and
dried[17].

2.3. Characterization

The samples were characterized by powder X-ray diffraction
studies using a high-resolution X-ray diffractometer (Shimadzu
7000S) at a scanning rate of 2 min1using CuK

a

radiation. It was
operated at 45 kV and 40 mA. The surface morphology of the metal

coating and the extent of coverage were analyzed using a Carl Zeiss
Ultra 55 FESEM. The elemental analysis was done using Axis Ultra
X-Ray Photoelectron spectroscopy. The electrochemical studies
were carried out using an Auto lab PGSTAT30 model with pilot
integration controlled by GPES 4.9 software in a
three-compartment cell. The measurements were carried in the
fre-quency range of 1 Hz to 1 MHz. The experimentally obtained
real and imaginary components were analyzed using the CH608E
instrument.

2.4. Preparation of working electrode

For the preparation of carbon paste electrode, 500 mg of silver
decorated graphite powder was thoroughly mixed with 20% of

silicone oil. The resulting paste was packed into a Teﬂon tube and a
copper wire was inserted for external electric contact. The surface
was polished by butter paper. When necessary, a fresh surface was
obtained by pushing an excess and polishing the electrode surface
mechanically using steel rod.

3. Results and discussion

3.1. The mechanism of Ag deposition on Sn/graphite

The mechanism of deposition of silver on graphite substrate
involves,ﬁrstly, the sensitization of graphite surface in the SnCl2

solution to enhance the absorption of silver ions in the subsequent
activation process. The stannous ions adsorbed on to the surface of
functionalized graphite surface during sensitization act as seeds for
the nuclei of the Ag nanoparticles growth during activation process.
The initial formation of the silver nanoparticles is based on the
application of reducing and oxidizing agents on the graphite
sub-strate surface, namely Sn2ỵand Agỵ. This redox reaction proceeds as
[8,18e20].

Sn2ỵỵ 2Agỵ/Sn4ỵỵ 2Ag (1)

In this method, which is a form of polyol method, ethylene
glycol acts as a reducing agent. Silver nanoparticles are synthesized
during the reduction of silver ions while the hydroxyl groups of
poly (ethylene glycol) are oxidized to aldehyde groups.

2AgNO3 ỵ 2NaOH /Ag2Osị ỵ 2NaNO3ỵ H2O (2)

Ag2Osị / 2Agỵỵ O2 (3)

HOCH2CH2OH/ CH3CHOỵ H2O (4)

CH3CHOaqị ỵ 3OH/CH

3CHOOỵ 2H2O ỵ 2e (5)

Agỵỵ e/Ag0 (6)

2AgNH3ị2NO3aqị þ CH3CHO/2Ag0 þ CH3COOHþ 4NH3

þ HNO3

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The above equations (eqs.(2)e(8)) depict the possible proposed
mechanism of the in situ synthesis of silver nanoparticles under alkali
conditions. On coming in contact with the alkali solution, silver nitrate
gets converted to anhydrated Agỵ; a reaction between OHions with
silver ions leads to the formation of silver oxide (Ag2O). In presence of

a highly alkaline environment (pH 13), Ag2O dissociates into silver

ions bonded to the hydroxyl and carboxylate moieties on the surfaces
of graphite through ionic interactions (eq.(1)).

Simultaneously, polyethylene glycol undergoes alkaline
hy-drolysis to produce aldehyde which oxidizes releasing electrons.
As a result, silver ions reduce to silver nanoparticles, resulting in
a transparent clear solution (eq.(5)(8)). Similar to silver ions,

the resulting silver nanoparticles also remain bonded onto the
graphite surface. Finally, a nano layer of silver nanoparticles is
deposited on the graphite surface by treating it with alkali in
presence of ammonia solution. As shown in equation(2), silver
nitrate in presence of alkali oxidizes to silver oxide, leading to
the formation of Agỵions. Some of the Agỵions produced are
reduced to Ag0 whereas the remaining form a diammine silver
(I) complex on addition of ammonia; the complex so formed is
Tollen's reagent. Tollen's reagent is a commonly used source to
synthesize silver nanoparticles, as it readily undergoes reduction
to form Ag0 in presence of aldehyde which in turn oxidizes to
carboxyl group. Being positively charged, [Ag(NH3)2]ỵalso gets

easily absorbed onto the graphite surface via eCOO and eOH
functional groups[21e23].

3.2. Powder X-ray diffraction studies

The diffraction pattern of the silver decorated graphite powder
was studied on a PXRD. FromFig. 1(a) it can be seen that PXRD

patterns of graphite showed very strong peaks at 2

q

of 26.66and
54.81 which matches very well with that of graphite powder.
The PXRD also exhibited diffraction peaks at 38.26, 44.23, 64.8,
74.7 and 76.6 corresponding to (111), (200), (220), (222) and
(311) planes of silver as well as diffraction peaks at27.7, 32.46,
57 and 67.8 for tin. The average crystallite size (D) of
nano-particles was estimated from diffraction planes along the
direc-tion normal to the (h k l) plane applying Scherrer's formula and
was found to be around 34 nm. The PXRD peaks further

conﬁrmed the crystalline nature of silver nanoparticles[24], this
indicates a uniform and good decoration of silver nanoparticles on
graphite.

3.3. Energy dispersive X-ray analysis

EDX analysis was carried out to conﬁrm the deposition of silver
on the graphite layer. This is evident fromFig. 1(b) which displays
the EDX pattern of silver deposited graphite powder. Theﬁgure
clearly hows prominent peaks corresponding to silver and tin along
with the carbon peak.

3.4. Field emission scanning electron microscopy

The surface morphology of the silver coating and uniformity
in distribution were analyzed by a FESEM.Fig. 2shows the
im-ages of as obtained silver nanoparticles deposited graphite
powder. The powder seems to have a rod like structure and the
average size of the silver nanoparticles on the surface of
acti-vated graphite is approximately in the range between 30 and
70 nm. This agrees well with the crystallite size calculated via
PXRD in section3.2.

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3.5. X-ray photoelectron spectroscopy

Fig. 3 shows the wide angle spectra for silver deposited on
graphite powder and also the individual binding energy spectrum
of silver, tin and carbon. The Ag3d5/2and Ag3d3/2peaks at 367.5 eV

and 373 eV are attributed to silver. The peaks at 486.5 eV and

495 eV correspond to tin and the peak at 284.2 eV corresponds to
carbon 1Cs of graphite. The characteristic XPES spectrum with
appropriate binding energies and intensities further conﬁrmed the
deposition of silver and tin on graphite[25e27].

3.6. Electrochemical characterization of electrode
3.6.1. Cyclic voltammetry studies

Fig. 4(a) represents the CV for the AgeSn/Graphite carbon paste
electrode in 0.5M KOH with increasingly varying methanol
con-centrations such as 0.025e1 M. During the course of the study, the
CV exhibited a signiﬁcant change in its response and also anodic
peak current (Ipa) value for methanol oxidation. The values are

tabulated in Table 1. It can be observed that in the presence of
CH3OH anodic peak current appears at 0.75 V, which is in

Fig. 2. FESEM images of silver nanoparticles deposited on Graphite powder: (a) 5000 X and (b) 50,000 X.

0 200 400 600 800 1000 1200

0
40000
80000
120000
160000

Intensity(cps)

Binding Energy(eV)

(a)

480 490 500 510

2000
4000
6000
8000

Intensity(cps)

Binding Energy(eV)

Tin

486.5eV

(

c

)

495.2eV

275 280 285 290 295 300

0
500
1000
1500
2000
2500
3000

Intensity(cps)

Binding Energy(eV)

Carbon

284.2eV

(b)

355 360 365 370 375 380

0
2000
4000
6000
8000

Intensity(cps)

Binding Energy(eV)

Silver

367.5eV

(d)

373.6eV

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accordance with the oxidation of CH3OH at crystalline Ag NPs. With

an increase in the methanol concentration, the peak response
in-creases initially up to 1M methanol, followed by a decrease in the
peak response. It is also noteworthy that above 1 M of methanol
concentration, the oxidation current decreases. This is probably due

to the adsorption of methanol molecules on the electrocatalyst
leading to the blockage of active sites[28].

If we examine the electrocatalyst performance (Table 2), for all
the three systems the onset potential for CH3OH oxidation remains

constant. However, anodic peak current and anodic peak potential

-1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0

-2.0x10-4

-1.5x10-4

-1.0x10-4

-5.0x10-5

0.0

5.0x10-5

1.0x10-4

Current (A)

Potential (V)

0.025 M CH3OH

0.05 M CH3OH

0.07 M CH3OH

0.1 M CH3OH

1 M CH3OH

0.025 M CH3OH
1 M CH3OH
Ag-Sn/Graphite electrode

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5

0.0

2.0x10-3

4.0x10-3

Current (A)

Potential (V)
Graphite (a)

Sn/Graphite (b)
Ag-Sn/Graphite (c)

(a)
(b)

(c)

1M CH3OH + 0.5 M KOH

-1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0

-3.0x10-4

-2.0x10-4

-1.0x10-4

0.0

1.0x10-4

2.0x10-4

Current (A)

Potential (V)

10 mv/s
20m v/s
50 mv/s
100 mv/s
150 mv/s
200 mv/s
250 mv/s
 Ag-Sn/Graphite electrode in 1M MeOH+0.5M KOH

10 mV S-1

250 mV S-1

(a)

(b)

(c)

Fig. 4. (a). Cyclic voltammogram of AgeSn/Graphite electrode in different concentration methanol in 0.5M KOH. (b). Cyclic voltammogram of Graphite (a), Sn/Graphite (b) and
AgeSn/Graphite (c) in 1 M CH3OH containing 0.5 M KOH at the sweep rate of 50 mV/s. (c). Cyclic voltammogram of AgeSn/Graphite electrode in a mixture of 1MCH3OHỵ0.5M KOH
solution at different scan rates (10, 20, 30, 50,100, 150, 200 and 250 mV/s).

Table 1

Electrocatalytic activity of AgeSn/Graphite electrode at different concentrations of methanol in 0.5 M KOH.

Concentration of CH3OH (M) Epa(V) Ipa(A) Epc(V) Ipc(A)

0.025 0.76 4.595 105 0.8319 9.025 105

0.05 0.77 5.545 105 0.8355 1.081 104

0.07 0.76 7.329 105 0.9179 1.388 104

0.1 0.76 8.154 105 0.9628 1.377 104

1 0.75 9.814 105 0.9291 1.554 104

Table 2

Comparative electrochemical performance of methanol oxidation on Graphite (a), Sn/Graphite (b) and AgeSn/Graphite (c) electrode measured in a solution of 1M CH3OH in

0.5M KOH at a sweep rate of 50 mV/s.

Electrocatalytic Performance Data

Electrodes If(A) Eonset(V) Epa(V)

Graphite (a) 1.549 104 0.71 ± 0.04 0.71

Sn/Graphite (b) 1.096 104 0.71 ± 0.04 0.74

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(Epc) values vary; with the AgeSn/Graphite being the most

favor-able catalyst system. It displays a higher current density when
compared to the other intermediate states (Sn/Graphite and
Graphite) as shown inFig. 4(b).

The silver nanoparticles on graphite are thus capable of
cata-lyzing the oxidation of methanol. Theﬁrst step of the oxidation is
the adsorption of methanol on the surface of Ag NPs acting as
catalyst. This results in a step by step removal of hydrogen in the
form of hydrogen cations toﬁnally form a silver-carbon residue.
The latter reacts with dissociated water toﬁnally release carbon
dioxide. In the process, along with the removal of each hydrogen
ion, an electron gets released giving rise to methanol oxidation
current. The mechanism can be understood by the following
re-actions[16,29].

CH3OHỵ H2/CO2ỵ 6Hỵỵ 6e (9)

CH3OHỵ Ag/Ag CH2OHỵ Hỵỵ e (10)

Ag CH2OHỵ Ag/Ag2 CHOH ỵ Hỵỵ e (11)

Ag2 CHOH ỵ Ag/Ag3 COH ỵ Hỵỵ e (12)

Ag3 COH /Ag CO ỵ 2Agsị ỵ Hỵỵ e (13)

H2O/ OHỵ Hỵ (14)

Ag CO ỵ OH/Agsị ỵ CO

2ỵ Hỵỵ e (15)

Fig. 4(c) represents the cyclic voltammogram, corresponding
to AgeSn/Graphite electrode in 1M CH3OH in 0.5M KOH solution

at various scan rates (v¼ 10e250 mV/s). In the present case, the

0.1

0.2

0.3

0.4

0.5

0.6

-1.0x10

-3

-5.0x10

-4

0.0

5.0x10

-4

1.0x10

-3

0.1

0.2

0.3

0.4

0.5

0.6

-6.0x10

-4

-4.0x10

-4

-2.0x10

-4

0.0

2.0x10

-4

4.0x10

-4

C

u

rre

n

t (

A

)

Potential (V)

10mV/S
20mV/S

30mV/S
40mV/S
50mV/S
60mV/S
70mV/S
80mV/S
90mV/S
100mV/S

10 mV/S

100 mV/S

Graphite electrode in 10 mM of Fe

2+

/Fe

3+

in 0.5 M KCl

(a)

C

u

rre

n

t (

A

)

Potential (V)

10mV/S
20mV/S
30mV/S
40mV/S
50mV/S
60mV/S
70mV/S
80mV/S
90mV/S
100mV/S

10 mV/S

100 mV/S

Ag-Sn/Graphite electrode in 10 mM of Fe2+

/Fe3+

in 0.5 M KCl

(b)

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Ipa showed an increase while the cathodic peak current (Ipc)

decreased. The peak currents are proportional to the sweep rate,
indicating that the surface reaction of the electrode is conﬁned.

Cyclic voltammogram of different sweep rates were performed
with Graphite and AgeSn/Graphite carbon paste electrodes in the

ferro/ferri system[30]. From the cyclic voltammogram of Graphite

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

-3.0x10

-4

-2.0x10

-4

-1.0x10

-4

0.0

1.0x10

-4

2.0x10

-4

C

u

rre

n

t (A

)

Potential (V)

23

0

C

30

0

C

40

0

C

50

0

C

60

0

C

23

0

C

60

0

C

Ag-Sn/Graphite Electrode in 1M CH

3

OH + 0.5 M KOH

Fig. 6. Effect of temperature on cyclic voltammogram of methanol oxidation on of AgeSn/Graphite electrode in the temperature range of 25Ce60C with a potential sweep rate of

50 mV s1.

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and AgeSn/Graphite carbon paste electrodes (Fig. 4(b)), the active
surface area of Graphite and AgeSn/Graphite was estimated using
the RandleseSevecik equation of a reversible process[31].

Ip¼ 2:69 105 n3

2 A D
1
2 C

0 v
1

2 (16)

where Ip is the peak current of active surface area, D is diffusion
coefﬁcient, C0 is concentration of electro active species, A is

active surface area, n is number of electrons involved in the

re-action and

n

is sweep rate. The active surface area of Graphite
and AgeSn/Graphite was calculated to be 6.2479 105cm2and

6.7886 105cm2, respectively. On plotting Ip

aas a function of

sweep rate, a linear graph was obtained. The linearity was more
profound in the scan rate range from 10 to 100 mV/s (Fig. 5). The
correlation coefﬁcient (r2) of AgeSn/Graphite was calculated to

be 0.99. The results clearly suggest an adsorption-controlled
process[32].

The temperature dependence on oxidation of 1M methanol in
0.5M KOH, on AgeSn/Graphite electrode was investigated in the
temperature range of 23e60C by cyclic voltammetry (Fig. 6). In
this temperature range, the shift in the current and potential of
methanol oxidation is not drastic. Nevertheless, it does suggest a
deﬁnite kinetic enhancement with increase in temperature from 23
to 60C[30].

3.6.2. Electrochemical impedance studies

EIS is employed to study the electron transfer between the
electrode surface and electrolyte. The impedance spectra for the
AgeSn/Graphite, Sn/Graphite and graphite electrodes system are
represented inFig. 7. For the impedance measurement, all
elec-trodes were immersed in 5 mM of [Fe(CN)6]3/4and 0.5 M KCl

solution. The analysis was carried out in the frequency range 1 Hz to
1 MHz[33,34]. The electroactivity is governed by the following
equation.

ẵFeCNị6

4/ ẵFeCNị
6

ỵ e (17)

FromFig. 7it can be observed that the impedance plot of the
AgeSn/Graphite electrode displays a depressed semicircle for
charge transfer resistance in the high-frequency region, while a
slope related to Warburg impedance in the low-frequency region.
The low impedance of AgeSn/Graphite electrode implies a lower
charge transfer resistance, suggesting an easy electrochemical
re-action on this electrode[35e37].Fig. 7 also gives the equivalent
circuit of the system in the inset; wherein W is the Warburg
impedance at lower frequency range, which is in series with the
charge transfer resistance (Rct) and parallel to capacitance (C). The

order of charge transfer resistance and corresponding capacitance
for Graphite, Sn/Graphite and AgeSn/Graphite electrodes have
been obtained by ﬁtting experimental data according to the
equivalent circuit[38]and tabulated inTable 3. It can be observed
from the values that a minimum Rctand maximum Cdlis obtained

for AgeSn/Graphite electrode. The following result can be
sum-marized from the experiment: Graphite (2.198 108 F) > Sn/

Graphite (1.498 1010F)< AgeSn/Graphite (6.659 107F). This

indicates that AgeSn/Graphite electrode show better 
electro-catalytic activity when compared to Sn/Graphite electrode.
4. Conclusion

In this report, we have successfully prepared an efﬁcient
elec-trocatalyst by electroless deposition of silver nanoparticles on
activated graphite powder. The analytical techniques such as
FESEM, PXRD, EDX, and XPES have helped us to substantially infer
the supporting data. The electrochemical studies of oxidation of
methanol in alkaline medium were carried out using CV, while the
active surface area of Graphite and AgeSn/Graphite electrodes
were calculated using RandleseSevecik equation. The capacitance
improved and the charge transfer resistance decreased for AgeSn/
Graphite electrode as compared to Sn/Graphite electrode. This
in-dicates a superior surface catalytic activity of AgeSn/Graphite
electrodes. The obtained results are encouraging as the prepared
graphite supported silver nanoparticles have the potential to
deliver as an efﬁcient electrocatalyst for fuel cell applications.
Acknowledgements

The authors acknowledge the instrumental facilities of PXRD
and CV at the Department of Chemistry, Central College, Bangalore
University and EIS facility at Rajarajeshwari College of Engineering,
Research Centre, Department of Chemistry, Bangalore. The authors
would also like to extend their acknowledgement to Indian

Insti-tute of Science, Bangalore for providing XPES, FESEM and EDX
facilities.

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Electrodes Rs/U Rct/U Cdl/F W

</div>
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</div>

Decoration of silver nanoparticles on activated graphite substrate and their electrocatalytic activity for methanol oxidation

Original Article

Decoration of silver nanoparticles on activated graphite substrate and

their electrocatalytic activity for methanol oxidation

M.S. Shivakumar

, G. Krishnamurthy

, C.R. Ravikumar

, Aarti S. Bhatt

a r t i c l e i n f o

a b s t r a c t

Journal of Science: Advanced Materials and Devices

m

a

q

<b>(a)</b>

Tin

<b>(</b>

<b>c</b>

<b>)</b>

<b>Intensity(cps)</b>

<b>Carbon</b>

<b>(b)</b>

<b>Intensity(cps)</b>

<b>Silver</b>

<b>(d)</b>

<b>Current (A)</b>

<b>Potential (V)</b>

<b>Current (A)</b>

<b>Potential (V)</b>

<b>(a)</b>

<b><sub>(b)</sub></b>

<b>(c)</b>

<b>0.1</b>

<b>0.2</b>

<b>0.3</b>

<b>0.4</b>

<b>0.5</b>

<b>0.6</b>

<b>-1.0x10</b>

<b>-5.0x10</b>

<b>0.0</b>

<b>5.0x10</b>

<b>1.0x10</b>

<b>0.1</b>

<b>0.2</b>

<b>0.3</b>

<b>0.4</b>

<b>0.5</b>

<b>0.6</b>

<b>-6.0x10</b>

<b>-4.0x10</b>

<b>-2.0x10</b>

<b>0.0</b>

<b>2.0x10</b>

<b>4.0x10</b>

<b>C</b>

<b>u</b>

<b>rre</b>

<b>n</b>

<b>t (</b>

<b>A</b>

<b>)</b>

<b>Potential (V)</b>

<b>10 mV/S</b>

<b>100 mV/S</b>

<b>Graphite electrode in 10 mM of Fe</b>

<b>/Fe</b>

<b> in 0.5 M KCl</b>

<b>(a)</b>

<b>C</b>

<b>u</b>

<b>rre</b>

<b>n</b>

<b>t (</b>

<b>A</b>

<b>)</b>

<b>Potential (V)</b>

<b>10 mV/S</b>

<b>100 mV/S</b>

<b>(b)</b>