Electrocatalytic performance of Pt-Ni nanoparticles supported on an activated graphite electrode for ethanol and 2-propanol oxidation

Article abstract of DOI:10.1039/d0ra07331h

Platinum (Pt) and platinum-nickel (Pt-Ni) electrocatalysts were prepared on activated graphite electrodes by an electrochemical deposition process. The electrocatalysts were analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The electrocatalytic activity of the prepared electrocatalysts, their stability, and the effect of temperature toward ethanol and 2-propanol oxidation were evaluated by cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS). The results showed that the Pt-Ni/C exhibited higher catalytic activity, better stability and better tolerance to poisoning by ethanol and 2-propanol oxidation intermediate species compared to Pt/C, which was interpreted as synergistic and electronic effects between Pt and Ni. A study of the temperature dependence of ethanol and 2-propanol oxidation in the temperature range of 298-318 K, shows that the apparent activation energy for ethanol and 2-propanol oxidation on Pt-Ni/C was lower than on Pt/C. The results also revealed that the electro-oxidation of ethanol and 2-propanol on Pt/C were improved by raising the temperature and Ni modification.

Full text of DOI:10.1039/d0ra07331h

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Electrocatalytic performance of Pt–Ni
nanoparticles supported on an activated graphite
Cite this: RSC Adv., 2020, 10, 36941
electrode for ethanol and 2-propanol oxidation†
a
M. Nacef,a H. Fisli,b A. M. Affoune,a M. Pontie,c A. Makhlouf,d
*
M. L. Chelaghmia,
´
T. Derabla,a O. Khelifia and F. Aissate
Platinum (Pt) and platinum–nickel (Pt–Ni) electrocatalysts were prepared on activated graphite electrodes
by an electrochemical deposition process. The electrocatalysts were analyzed by scanning electron
microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The
electrocatalytic activity of the prepared electrocatalysts, their stability, and the effect of temperature
toward ethanol and 2-propanol oxidation were evaluated by cyclic voltammetry (CV),
chronoamperometry and electrochemical impedance spectroscopy (EIS). The results showed that the
Pt–Ni/C exhibited higher catalytic activity, better stability and better tolerance to poisoning by ethanol
and 2-propanol oxidation intermediate species compared to Pt/C, which was interpreted as synergistic
and electronic effects between Pt and Ni. A study of the temperature dependence of ethanol and 2-
propanol oxidation in the temperature range of 298–318 K, shows that the apparent activation energy
for ethanol and 2-propanol oxidation on Pt–Ni/C was lower than on Pt/C. The results also revealed that
the electro-oxidation of ethanol and 2-propanol on Pt/C were improved by raising the temperature and
Ni modification.
Received 26th August 2020
Accepted 26th September 2020
DOI: 10.1039/d0ra07331h
rsc.li/rsc-advances
for methanol). Furthermore, it's considered as a safe and green
fuel, and it can be obtained from materials containing sugar.8–11
1. Introduction
Another alcohol, 2-propanol is reported to have a promising
future for DAFCs due to no CO formation, lower crossover effect
and also less toxicity comparing to methanol.12–16
Direct alcohol fuel cells (DAFCs) have been recognized as one of
the most promising power sources for portable devices and
transportation applications.1–3 Most of the research in the fuel
cell eld is focused on direct methanol fuel cells (DMFCs) on
account of their merits of large energy conversion efficiency and
moderate operating temperature.4–7
However, some drawbacks of methanol such as toxicity and its
easier crossover through ionomeric membranes are the key
reasons to select other liquid fuels rather than methanol.8 For two
decades, ethanol has emerged as the rst choice, mostly thanks to
its high energy density (7.44 kW h kgꢀ1 compared to 6 kW h kg ꢀ1
Carbon supported Pt electrocatalysts are well-known to be
active for the electrochemical oxidation of ethanol and 2-propanol
in acid media. However, Pt is easily poisoned by strongly adsorbed
residues of alcohol electro-oxidation.12 To overcome this drawback,
various metals have been studied in several combinations with Pt,
resulting on binary or ternary metallic electrocatalysts, such as Pt–
Ru,17 Pt–Sn,18 Pt–Rh 19 and Pt–Sn–Mo.20 The promoting effect of
second or third elements has been attributed to the synergistic and
electronic effects. In the synergistic mechanism, secondary
element could adsorb hydroxyl species at lower potentials than Pt
and supplies oxygen to oxidize the blocking intermediate, and
consequently liberate Pt active sites.
a
´
´
´
´
Laboratoire d'Analyses Industrielles et Genie des Materiaux, Departement de Genie
´ ´
´
des Procedes, Universite 8 Mai 1945 Guelma, BP 401, Guelma 24000, Algeria.
E-mail: chelaghmia.mohamedlyamine@univ-guelma.dz; amine_chelaghmia@yahoo.
Among, different techniques of synthesizing used to prepare
platinum and its alloys onto substrates base carbon, the simple
electrodeposition has been proven as a powerful tool for the
fabrication of efficient electrocatalysts.21
fr
b
´
´
`
´
Laboratoire de Chimie Appliquee, Departement des Sciences de la Matiere, Universite
8 Mai 1945 Guelma, BP 401, Guelma 24000, Algeria
c
´
´
´ ´
Universite d'Angers, Faculte des Sciences, Groupe Analyses et Procedes (GAP), 2 Bd.
Lavoisier, 49045 Angers 01, France
Many authors have reported that the catalytic activity of Pt–
Ni for the electrooxidation of methanol is higher to that of Pt
alone.15,22–26 However, few studies, have demonstrated that Ni
tends to improve the catalytic activity of the Pt electrode for
ethanol and 2-propanol electrooxidation.27–30 Furthermore, one
of the most important factors is the temperature at which the
d
´
´
Laboratoire des Silicates, Polymeres et Nanocomposites, Universite du 8 Mai 1945,
Algeria
eCentre de Recherche Scientique et Technique en Analyses Physico-chimiques
(CRAPC), Algeria
† Electronic supplementary information (ESI) available. See DOI:
10.1039/d0ra07331h
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cell is operated. Until now, only few researches discussed the solution and bidistilled water, the graphite carbon substrates
effect of temperature on the performance of Pt based ethanol were then activated employing an electrochemical method
and 2-propanol oxidation catalysts.31–33
according to the previous work.27
To the best of authors' knowledge there are no reports on the
The Pt and Pt–Ni microparticles were electrodeposited from
temperature effect on the anodic oxidation of ethanol and 2- electrolytes consisting of 16 mM H2PtCl6, and 16 mM H2PtCl6 +
propanol in acidic medium on activated graphite supported Pt– 128 mM NiSO4 solutions, respectively, in 1.0 M H2SO4 by using
Ni. In the study reported herein, the electrocatalytic activity and amperometric i–t at ꢀ0.6 potential for just 600 s. Finally the
the effect of temperature on the electrooxidation of ethanol and prepared electrodes were cleaned thoroughly with deionized
2-propanol on activated graphite supported Pt and Pt–Ni elec- water and dried at room temperature.
trodes is studied and the resulting activation energy is derived
from experimental data. Furthermore a durability investigation
of these electrocatalysts was done.
2.3 Physical and electrochemical characterization
All electrochemical measurements were carried out using
a potentiostat (AMETEK, USA). A conventional three electrode
cell was used with, a smooth Pt, activated graphite, Pt/C and Pt–
2. Experimental
2.1 Chemicals and materials
Ni/C as the working electrode, a SCE (saturated KCl) electrode as
the reference electrode, and platinum foil as the counter
electrode.
Chloroplatinic acid (H2PtCl6$6H2O) and nickel sulfate (NiSO4-
$6H2O) were procured from Sigma-Aldrich. Sulfuric acid
(H2SO4), ethanol (C2H6O) and 2-propanol (C3H8O) were
purchased from Merck. Commercial graphite bare was obtained
from Union Carbide. All chemicals were of analytical grade and
used as received. All solutions were prepared by bidistillated
water.
The morphological features were examined using Field
Emission Scanning Electron Microscope (FESEM) (JEOL, 6301F,
Japan.). The temperature of the working aqueous solution was
thermostated within the range of 298–353 K using a hot plate
and monitored by a thermocouple inside the solution.
Electrochemical reactivity of the Pt/C and Pt–Ni/C electrodes
were investigated in 0.1 M H2SO4 + 1.0 M ethanol or 1.0 M 2-
propanol aqueous solutions by CV and chronoamperometry. All
2.2 Preparation of the Pt/C and Pt–Ni/C electrocatalysts
Prior to deposition, the graphite carbon substrates were current densities were normalized to the electrochemical
mechanically polished using metallurgical papers of different surface area (ECSA) obtained by hydrogen desorption integrals
grades. Aer successive sonication in acetone, 2.0 M H2SO4 according to the following equation: ECSA ¼ QH/(210 ꢁ m),
Fig. 1 FE-SEM images of Pt–Ni/C (a, b and c), EDX spectrum of Pt–Ni/C (d).
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where QH is the coulombic charge according to the integrated
area of hydrogen adsorption and desorption in CV curve, m
represents the loading of Pt on graphite electrode.27
3. Results and discussion
3.1 Physical and electrochemical characteristics of Pt/C and
Pt–Ni/C electrocatalysts
FE-SEM images of the obtained deposits Pt/C and Pt–Ni/C
electrocatalysts surfaces are shown in Fig. 1. As can be seen,
the surface morphology of activated graphite was affected by the
incorporation of homogeneous distribution Pt and Ni micro-
particles (Fig. 1a–c). Pt microparticles were deposited as small
particles in the range from 80 to 200 nanometers, while the Ni
was in the form of clusters. The elemental compositions of the
catalysts were identied from the EDX spectrum as shown in
Fig. 1d. The peaks corresponding to Pt, Ni, and C were clearly
observed conrming the presence of Pt microparticles and Ni
onto the activated graphite electrodes surface.
Fig. 3 CVs of Pt–Ni/C and Pt/C electrocatalysts in 0.1 M H2SO4
solution at a scan rate of 50 mV sꢀ1 and 298 K. The inset is the CV of
smooth Pt electrode in 1.0 M H2SO4 solution.
adsorption of the oxygen species on Pt–Ni/C electrocatalyst
during the anodic scan aer 0.6 V is more pronounced than that
on Pt/C alone. Consequently the peak current density of Pt oxide
reduction is enhanced on Pt–Ni/C.
XRD patterns of Pt–Ni/C electrocatalysts in comparison with
that of Pt/C and Ni/C were displayed in Fig. 2.
C (002) plane of crystalline graphite structure was observed
in all studied electrocatalysts at 26ꢂ. The XRD spectra of Pt/C
and Ni/C agreed well with the standard patterns of the Pt
(JCPDS no. 01-087-0646) and Ni (JCPDS no. 89-2838).
3.2 Ethanol and 2-propanol electrooxidation on Pt/C and Pt–
Ni/C in acidic medium
The electrocatalytic activity of the Pt/C and Pt–Ni/C electro-
catalysts towards ethanol and 2-propanol oxidation was studied
using CV. The observed cyclic voltammograms are shown in
Fig. 4. It shows that both ethanol and 2-propanol trans-
formation are characterized by three oxidation peaks; two peaks
appear during the positive going potential scan (PGPS), peaks (I)
and (II), while the third one (R) is recorded on the negative
going potential scan (NGPS). The change in the current values
indicates that the Ni contribution increases the anodic oxida-
tion kinetic during the whole potential range.
For Pt/C three characteristic peaks were observed at 2q ¼
39.91ꢂ, 46.31ꢂ, and 67.68ꢂ, and indexed well to the (111), (200),
and (220) crystal planes of face-centered cubic of pure Pt
respectively. In the same gure, for Ni/C another three charac-
teristic diffraction peaks located at 2q ¼ 44.8ꢂ, 52.1ꢂ, and 76.6ꢂ,
are associated with the (111), (200), and (220), crystal planes
respectively indicate the formation of pure Ni. The XRD pattern
of Pt–Ni/C show the corresponding diffraction peaks of Pt/C and
Ni/C indicating that the Pt and Ni are separated phases in their
metallic state.
These features have been already observed on different
electrocatalysts; such as Pt/C, Pt–Rh, Pt–Ni/C and Pt–Sn/C.13–20
The rst oxidation peak (peak I) corresponds mainly to the
formation of CO2 for ethanol and to the formation of CO2 and
acetone for 2-propanol whereas the second oxidation peak
(peak II) is caused by other products as acetic acid and acetal-
dehyde for ethanol and to the oxidation of acetone for 2-prop-
anol. The mechanism of ethanol electrooxidation in acid
solution has been summarized as the following scheme of
parallel reactions:
The electrochemical behavior of the obtained deposits was
studied in 0.1 M H2SO4 solution at a scan rate of 50 mV sꢀ1
(Fig. 3). As can be seen in Fig. 3, the voltammetric features of the
Pt/C and Pt–Ni/C are similar to that observed on the smooth Pt
electrode: typical hydrogen and oxygen adsorption/desorption
regions with the presence of a strong double layer region were
observed in all electrocatalysts. However, it seems that the
CH3CH2OHsol / [CH3CH2OH]ads / C1ads
;
C2ads / CO2 (total oxidation)
(1)
(2)
CH3CH2OHsol / [CH3CH2OH]ads / CH3CHO
/ CH3COOH (partial oxidation)
and the mechanism of 2-propanol electrooxidation in acid
solution has been summarized as the following scheme of
parallel reactions:
[CH3CH(O–H)CH3]sol / [CH3CH(O–H)CH3]ads
Fig. 2 XRD spectra of different modified graphite electrodes.
/ CH3(C]O)CH3 + 2H+ + 2eꢀ
(3)
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Fig. 4 CVs of ethanol electrooxidation on Pt/C (black) and Pt–Ni/C
(red) and 2-propanol electrooxidation on Pt/C (green) and Pt–Ni/C
(blue) in 0.1 M H2SO4 at a scan rate of 50 mV sꢀ1 and 298 K.
[CH3CH(O–H)CH3]sol + 5OHads / 13H+ + 13eꢀ + 3CO2 (4)
During the NGPS, the Pt oxides are reduced at 0.6 V and
subsequently, the catalyst surface is re-activated and hence the
oxidation of both alcohols and/or the oxidation of intermediate
molecules take place again (peak R).
According to Fig. 4, the current densities of the two oxidation
peaks of both alcohols recorded on Pt–Ni/C are higher than that
Fig. 5 (a) Tafel plot of Pt/C and Pt–Ni/C during of ethanol or 2-
propanol electro-oxidation, (b) Nyquist plots of 0.5 m ethanol/2-
on the Pt/C (1.5 and 1.7 times higher in the case of ethanol and propanol in 0.1 M H2SO4 at Pt/C and Pt–Ni/C [inset: the equivalent
circuit model describes the electrochemical process at Pt/C and Pt–
Ni/C].
2-propanol, respectively). The ratio of the current densities
between the rst anodic peak (II) and the reverse anodic peak
(IR) is used to evaluate the conversion extent from alcohol to
CO2.15
kinetics, electrochemical impedance spectroscopy (EIS) was
performed at an overpotential of 0.7 V in 0.1 M H2SO4 and 0.5 M
ethanol/2-propanol in the frequency ranging from 10 kHz to
0.01 Hz (Fig. 5b). The equivalent circuit model (inset of Fig. 5b)
contains resistance of solution (Rs), the charge transfer resis-
tance (Rct), the Warburg element (W), and constant phase
element (CPE). Rct is related to the electrocatalytic kinetics at
the electrocatalyst/electrolyte interface and a small value
corresponds to a fast electron transfer capacity. The tted values
of charge transfer resistance Rct for the, Pt–Ni/C and Pt/C were
285.98 U and 312.33 U during ethanol electro-oxidation and
142.93 U and 207.03 U during 2-propanol electro-oxidation
respectively. The low Rct value obtained for Pt–Ni/C suggests
that the charge-transfer process is faster when compared with
the Pt/C during ethanol and 2-propanol electro-oxidation. These
ndings conrm the benecial effect of Ni addition to Pt in
ethanol and 2-propanol electrooxidation catalysis.
A large ratio represents more effective removal of the
poisoning substances produced among ethanol and 2-propanol
electro-oxidation. Thus the II/IR equal to 1.08 and 0.71 for Pt–Ni/
C and Pt/C electrocatalysts in the case of ethanol electro-
oxidation and 1.0 and 0.6 in the case of 2-propanol electro-
oxidation. The higher peak ratio for the Pt–Ni/C electro-
catalyst suggests that the introduction of Ni can improve cata-
lyst performance through increasing the poisoning tolerance to
the intermediate carbonaceous species formed during ethanol
or 2-propanol electrooxidation.
Tafel plots of ethanol and 2-propanol electro-oxidation on
the Pt–Ni/C catalysts, derived from the CV grams in 0.1 M H2SO4
with 1.0 M ethanol or 2-propanol at a scanning rate of 10 mV
sꢀ1, are shown in Fig. 5a. The value of Tafel slope represents the
two reaction mechanism for ethanol and 2-propanol electro-
oxidation in the two region of CV grams. The Tafel slope is in
the range of 85.3 (for ethanol) and 92.4 mV decꢀ1 (for 2-prop-
anol) at low potentials (below 0.7 V), which means that the
ethanol and 2-propanol electro-oxidation dehydrogenation as
the rate determining step (r.d.s). When the over-potential is
above 0.7 V, the generated intermediates and their adsorption
at the Pt–Ni sites become dominant and the second Tafel slope
is in the range of 435 and 886 mV decꢀ1. As a result, the r.d.s
may change to the intermediates oxidation during of ethanol
and 2-propanol electro-oxidation at higher electrode potentials.
To understand the electron transfer rate of the elaborated
electrocatalyst on ethanol and 2-propanol electro-oxidation
3.3 Effects of forward potential scan limits on the
electrooxidation process
To get more information about catalytic oxidation process of the
modied electrodes, we examined the effect of the forward
potential scan limits on the voltammetric curves. The CVs for
ethanol and 2-propanol oxidation on Pt–Ni/C electrocatalyst
with different forward potential scan limits are shown in Fig. 6.
As given in Fig. 6a, by increasing the nal anodic limit in the
forward scan, the forward scan peak current density of ethanol
remains unchanged, but oxidation current density in the
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negative scan (R) was decreased. This indicated that the
decrease in the adsorbed CO, as previously observed on Pt–Ru.17
The presence of Ni facilitates the oxidation of freshly chem-
isorbed species and serves as anti-poison sites by catalyzing
oxidation of CO at lower potentials. However, in the case of 2-
propanol, Fig. 6b, the oxidation current density peak in the
reverse scan remains at the same value when the forward
potential scan limits are changed. This is, probably due to the
absence of CO as reaction intermediate as observed previously
14
´
by Gojkovic on Pt. Comparison between some ethanol and 2-
propanol electrocatalysts are presented in Table 1S.† It can be
seen that the proposed Pt–Ni/C electrode had a high electro-
catalytic activity for ethanol and 2-propanol electroxidation.34–36
3.4 The scan rate effect
The inuence of the scan rate on the electrocatalytic oxidation
of ethanol and 2-propanol at Pt–Ni/C were investigated using
CV. Fig. 7a and b show the CVs of the Pt–Ni/C recorded in 0.1 M
H2SO4 solution in the presence of 1.0 M ethanol/1.0 M 2-prop-
anol at different scan rates respectively. The current densities
peaks in PGPS, peak (I) and peak (II) are linearly proportional to
the square root of scan rate (v1/2), as shown in the insets of
Fig. 7a and b, suggesting that the electrocatalytic oxidation of
ethanol and 2-propanol on Pt–Ni/C electrocatalyst and their
intermediates were controlled by diffusion process.
Fig. 7 CVs of Pt–Ni/C electrocatalyst in 0.1 M H2SO4 and 1.0 M
ethanol (a) or 1.0 M 2-propanol (b) at various scan rates and 298 K. The
inset represents dependence of the peak on the square root of scan
Additionally, the peaks (I) and (II) shi positively with the rate.
increasing of scan rates while peak (R) shis negatively. This
phenomenon indicates an irreversible charge transfer on the
electrode surface during alcohol electrooxidation process.
Furthermore, it can be seen that voltammograms are super-
imposed during the beginning of the potential scan rate which
indicates a controlled charge transfer kinetic.
In addition the small negative current due to the reduction
of the surface Pt oxides which is formed at higher potentials in
the PGPS, was observed in the range of potential 0.45 V.
3.5 The temperature effect
The effect of temperature on the electrocatalytic activities of Pt/
C and Pt–Ni/C is shown in Fig. 8. Electrodes activities for both
alcohols oxidation are markedly enhanced as it can be expected
due to the temperature contribution. On the Pt/C electro-
catalyst, the way of increasing current densities of two peaks, (I)
and (II), is almost the same for both alcohols (inset of Fig. 8a
and b). However, a signicant difference between the voltam-
mograms recorded on Pt–Ni/C electrocatalyst can be noted
(Fig. 8a and b). For ethanol, the increase in the current densities
of peak (I) is much greater than that in peak (II), which could be
attributed to better conversion of ethanol to CO2 reducing the
amount of CO to be oxidized subsequently. In the case of 2-
propanol, the oxidation does not lead to the formation of CO.
However the amount of intermediates generated during its
oxidation increases resulting on a rise in the current densities of
peak (I). In addition as shown in Fig. 6c and d the II/IR ratio of
Pt–Ni/C is higher than that of Pt/C, which shows that the
temperature has better catalytic efficiency on Pt–Ni/C than on
Pt/C.
Fig. 6 CVs of Pt–Ni/C electrocatalyst in 0.1 M H2SO4 and 1.0 M
ethanol (a) or 1.0 M 2-propanol (b) recorded with different positive
potential limits at a scan rate of 50 mV sꢀ1 and 298 K.
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Fig. 8 CVs of Pt–Ni/C electrocatalyst in 0.1 M H2SO4 and 1.0 M ethanol (a) or 1.0 M 2-propanol (b) recorded at different temperatures. The insets
represent CVs of Pt/C electrocatalyst in 0.1 M H2SO4 and 1.0 M ethanol (a) or 1.0 M 2-propanol (b) recorded at different temperatures. II/IR
variation with temperature for ethanol (c) and 2-propanol (d) electrooxidation on Pt/C and Pt–Ni/C electrodes.
Arrhenius plots were drawn for different potentials at
The activation energy (Ea) values were calculated for different
different temperatures (Fig. 9a and b). Linear relationships potential values (Fig. 9c and d).
between log I and 1/T is noted in all cases, indicating that the
The lower apparent activation energy on Pt–Ni/C than that
reaction mechanism at each potential is not changed with on Pt/C indicates that temperature rise is the most benecial for
temperature.
ethanol and 2-propanol oxidation on Pt–Ni/C electrocatalyst
Fig. 9 Arrhenius plots for ethanol (a) and 2-propanol (b) electrooxidation at different potentials on Pt–Ni/C and Pt/C electrocatalysts. Variation in
activation energy for ethanol (c) and 2-propanol (d) electrooxidation with potentials on Pt/C and Pt–Ni/C electrocatalysts.
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The Pt–Ni/C electrocatalyst exhibited higher catalytic activity,
better stability and tolerance to poisoning by ethanol and 2-
propanol oxidation intermediate species compared to Pt/C
electrocatalyst which was interpreted by synergistic and elec-
tronic effect between Pt and Ni, porous structure and high
surface area. From the Arrhenius analysis, the apparent acti-
vation energies of ethanol and 2-propanol electrooxidation on
Pt–Ni/C electrocatalyst are lower than those on Pt/C electro-
catalyst under the same conditions. These results suggested
that Pt–Ni/C can be a promising anode electrocatalyst for direct
alcohol fuel cells in acidic medium.
Fig. 10 Chronoamperograms of Pt/C and Pt–Ni/C electrocatalysts in
0.1 M H2SO4 and 1.0 M ethanol or 1.0 M 2-propanol.
Conflicts of interest
There are no conicts to declare.
than that on Pt/C. All the above results of CV, Arrhenius plots
and apparent activation energy values indicate that Pt–Ni/C
exhibits higher catalytic activity for both alcohols oxidation
than Pt/C.
Acknowledgements
The authors wish to thank Dr Romain Mallet and SCIAM Angers
University, France, for the experiments conducted with FESEM
and EDX instruments.
3.6 Study of electrocatalysts' stability
In practice, long-term stability of an electrode is crucial. Thus
chronoamperograms were plotted at 0.6 V during 600 s (Fig. 10).
In this process, aer the initial current decay, Pt–Ni maintains
higher current densities than the Pt, revealing their long-term
stability for the oxidation of ethanol and 2-propanol.
In addition, CV cycling tests were further conducted. From
this prospect, 100 cycles of cyclic voltamogrammes were applied
on Pt–Ni/C in 1.0 M ethanol or 1.0 M 2-propanol + 0.1 M H2SO4
and compared to that on Pt/C (Fig. 1S†). It can be observed that
in the case of ethanol the peak current density decreases by
21.8% on Pt–Ni/C, and 44% on Pt/C if compared to that of the
rst cycles. For 2-propanol the peak current density decreases
by 24% on Pt–Ni/C, and 36% on Pt/C if compared to that of the
rst cycles. These results are consistent with the chro-
noamperometric curves in Fig. 10.
Moreover, the long-term stability of the electrocatalyst was
also evaluated by measuring its CV response every week for up
to 21 days (Fig. 2S†). The Pt–Ni/C electrocatalyst was stored at
room temperature when it was not in use. The peak current
density of both ethanol and 2-propanol retained their response
integrity up to 85% aer three weeks, reecting the good
stability of the electrocatalyst.
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