Hollow PtPd Nanorods with Mesoporous Shells as an Efficient Electrocatalyst for the Methanol-Oxidation Reaction

Article abstract of DOI:10.1002/asia.201900907

Tailoring the morphology and composition of platinum-based electrocatalysts is of significant importance for the development of highly efficient direct methanol fuel cells. Herein, we report a dual-templating method for the design of hollow PtPd nanorods with mesoporous shells (mPtPd HNRs). We found that F127 micelles favored the formation of mesoporous structures and that SiO₂ nanorods served as a hard template for the creation of cavities. The well-developed mesopores, hollow structures, and bimetallic composition of the mPtPd HNRs afforded a sufficient number of active sites to facilitate the electrochemical oxidation of methanol, thereby leading to enhanced activity and stability. This strategy allowed for the reliable preparation of mesoporous hollow platinum-based electrocatalysts with desired compositions and morphologies for catalytic applications.

Full text of DOI:10.1002/asia.201900907

CHEMISTRY
AN ASIAN JOURNAL
www.chemasianj.org
Accepted Article
Title: Hollow PtPd Nanorods with Mesoporous Shells as an Efficient
Electrocatalyst for Methanol Oxidation Reaction
Authors: Hongjing Wang, Xiaoqian Qian, Songliang Liu, Shuli Yin,
Hongjie Yu, You Xu, Xiaonian Li, Ziqiang Wang, and Liang
Wang
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10.1002/asia.201900907
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Hollow PtPd Nanorods with Mesoporous Shells as an Efficient
Electrocatalyst for Methanol Oxidation Reaction
Hongjing Wang, Xiaoqian Qian, Songliang Liu, Shuli Yin, Hongjie Yu, You Xu, Xiaonian Li, Ziqiang
Wang* and Liang Wang*
Abstract: Tailoring the morphology and composition of Pt-based
electrocatalysts is of significant importance for the development of
highly efficient direct methanol fuel cells. Herein, we present a dual-
templating method to design hollow PtPd nanorods with mesoporous
shells (mPtPd HNRs), in which F127 micelles favor the formation of
mesoporous structure and SiO2 nanorods serve as hard template to
create cavity. The well-developed mesopore, hollow structure, and
bimetallic composition of the mPtPd HNRs offers sufficient active
sites and facilitated channels for methanol electro-oxidation, leading
to enhanced activity and stability. Our present strategy allows the
reliable preparation of mesoporous hollow Pt-based electrocatalysts
with desired composition and morphology for catalysis applications.
bimetallic nanocrystals have been explored to promote the
electrocatalytic performance for the MOR.
Given that the catalytic performance of catalysts is highly
related to their morphology, the shape-controlled synthesis of
efficient catalysts has been widely developed for various
electrocatalytic applications.[5] Among investigated candidates,
hollow nanomaterials with low density can provide high interior
surfaces and large pore space to adsorb and interact with
reactants.[6] In generally, the hard-templating approach using
silica is an effective method for preparing hollow materials due
to the facile control of template morphology and cavity size.[7]
However, most hollow nanostructures lack porous structures on
the surface. Porous structures not only provide sufficient active
sites and facilitated channels for catalytic reactions, but also
effectively mitigate dissolution, Ostwald ripening, and
aggregation of catalysts.[8] Therefore, engineering hollow
nanocrystals with porous shells, which allow the effective
utilization of internal and external surfaces of catalysts, is
expected to an attractive strategy for further improvement of
catalytic performance.
Herein, hollow PtPd nanorods with mesoporous shells
(mPtPd HNRs) have been synthesized through a dual-
templating approach and investigated the catalytic
performance for the MOR. During the synthesis process,
F127 micelles direct the formation of mesopores on the
surface and SiO2 NRs act as sacrificial templates to
generate hollow structures. Owing to well-developed
mesopore, hollow structure, and bimetallic composition, the
obtained mPtPd HNRs show excellent MOR activity and
Introduction
Direct methanol fuel cells (DMFCs) as sustainable energy
conversion devices have received intensive attention in
powering portable electronic systems due to their high energy
density, low operation temperature, and easy storage and
transportation of methanol.[1] The development of high-
performance electrocatalysts for methanol oxidation reaction
(MOR) is crucial to fulfill the commercial applications of DMFCs.
Until now, Pt is considered as the most efficient electrocatalyst
for the MOR due to its outstanding catalytic activity.[2] However,
the high cost and poor stability of Pt heavily limit the large-scale
commercialization of DMFCs. There is an urgent need to
develop alternative Pt-based catalysts to enhance their catalytic
performance and utilization efficiency of Pt.
To this end, abundant efforts have been devoted to fine
control of the composition and morphology of Pt-based catalysts.
Alloying Pt with other metals can generate strain and electronic
effects, which is considered as an attractive strategy to improve
catalytic activity and stability.[3] Among investigated metals, Pd is
regarded as one of most promising candidates because Pd
possesses excellent stability toward the MOR. Meanwhile, the
similar electronic configuration and lattice constant between Pt
and Pd favors the formation of single-crystallinity PtPd alloys
with particular functionalities.[4] Therefore, various PtPd
stability.
The
mPtPd
HNRs
achieve
a
large
electrochemically active surface area of 92.7 m2 g−1, high
−1
mass activity of 0.71 A mgPt and high specific activity of
1.5 mA cm−2, which are superior to the values of the
counterpart catalyst and commercial Pt/C.
Results and Discussion
The mPtPd HNRs with uniform size are synthesized via a
dual-templating approach, in which tri-block copolymer
F127 and SiO2 NRs act as soft template and hard template,
respectively (Scheme 1). In our strategy, the combination of
the self-assembly of surfactant micelles and moderate
chemical reduction of metal species is critical to generate
mesoporous structures. Scanning electron microscopy
(SEM) image clearly shows that the obtained silica has
Dr. H. Wang, X. Qian, S. Liu, S. Yin, H. Yu, Dr. Y. Xu, Prof. X. L, Dr. Z.
Wang and Prof. L. Wang
State Key Laboratory Breeding Base of Green-Chemical Synthesis
Technology, College of Chemical Engineering
Zhejiang University of Technology
Hangzhou 310014, P. R. China
E-mail: zqwang@zjut.edu.cn; wangliang@zjut.edu.cn
uniform nanorod morphology in
possesses the length of ca. 200 nm and the diameter of ca.
100 nm (Figure S1). The SiO2 NRs are served as the hard
a high yield, which
Supporting information for this article is given via a link at the end of the
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one mesoporous hollow PtPd nanorod and its corresponding
EDX line-scanning profiles and elemental mapping images
confirm the hollow structure and the uniform distribution of Pt
and Pd elements in the shell of the nanorod (Figure 2). The
atomic ratio of Pt/Pd is calculated to around 74/26 by inductively
coupled plasma-atomic emission spectroscopy (ICP-AES),
similar to the initial ratio of the metal precursors. The crystal
structure of the mPtPd HNRs is characterized by X-ray
diffraction (XRD). The XRD pattern of the mPtPd HNRs exhibits
four diffraction peaks at 39.9°, 46.5°, 67.8°, and 81.7°, which are
indexed to the (111), (200), (220), and (311) facets of the fcc
metallic structure, respectively (Figure 3). Interestingly, their
diffraction peaks have a slight shift to higher angle compared
with those of pure Pt (JCPDS card No: 04-0802), indicating
decreased lattice constant due to the incorporation of smaller Pd
atoms into Pt atoms. The above results demonstrate the
successful synthesis of bimetallic hollow PtPd nanorods.
Scheme 1. Schematic illustration of the formation of the mPtPd HNRs.
template to grow PtPd shells using ascorbic acid (AA) as
reductant. As shown in Figure S2, the uniform PtPd
mesoporous structures are gradually formed on the
surfaces of the SiO2 NRs (SiO2@mPtPd NRs). After HF
etching, mesoporous PtPd shells are still maintained
without any changes (Figure 1a and Figure S3). The well-
defined mesoporous structures possess uniform pore size
of around 14.5 nm (Figure S4a). The small angle X-ray
scattering (SAXS) profile also confirms the presence of
mesepores, as illustrated by the broad peak in the q range
of 0.4 and 0.5 nm−1 (Figure S5). The hollow structure is
illustrated by a strong contrast in a transmission electron
microscope (TEM) image (Figure 1b), and the shell
thickness of the hollow structure is measured to
approximately 25 nm (Figure S4b). High-resolution TEM
(HRTEM) image (Figure 1c) displays clear lattice fringes on
the edge of the mPtPd HNRs, which reveals a d-spacing
distance of 0.225 nm (Figure 1d), corresponding to the (111)
facet of face-centered cubic (fcc) metallic structure. The d-
spacing distance of the mPtPd HNRs is smaller than that of pure
Pt (0.227 nm), revealing the formation of bimetallic structure.
Figure 2. (a) HAADF-STEM image and compositional line profiles and (b-d)
EDX elemental mapping images of one hollow PtPd nanorod.
The formation process of the mPtPd HNRs is investigated by
some control experiments. In the absence of HCl, abundant
small mesoporous spheres except few mesoporous nanorods
are obtained (Figure S6a) because the reduction rate of AA is
too fast to grow mesoporous structures on the silica surface.
When HCl is increased to 0.1 mL, the reducing capability of AA
is greatly decreased, resulting in very slow reduction kinetics,
making the difficulty in the formation of mesoporous structures
(Figure S6b). The results indicate the significant effect of HCl on
the morphology of products by tailoring nucleation and crystal
growth of metals. In addition, hollow Pt nanorods with poor
mesoporous structures (mPt HNRs) are formed when K2PtCl4
solution is used as the only precursor (Figure S7a). Without the
Pt precursor, abundant Pd nanoparticles are agglomerated on
the surface without porous structures (Figure S7b). The use of
F127 is vital for the formation of well-developed mesopores. In
Figure 1. SEM (a) and TEM (b) images of the mPtPd HNRs. (c) HRTEM
image of the mPtPd HNRs and (d) corresponding Fourier filtered lattice
fringe image of the square area in (c).
In order to explore element component in the products, we
perform energy-dispersive X-ray (EDX) spectroscopy. A high-
angle annular dark field scanning TEM (HAADF-STEM) image of
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the absence of F127 under the typical synthetic process, the
products exhibit solid surface without porous structures (Figure
S8). With increasing reduction time, well-defined mesoporous
structures could be gradually developed, resulting in robust
mesoporous nanorods (Figure S9). The synthesis of the uniform
mPtPd HNRs is dependent on the balance between nucleation
and crystal growth by precise control of the reduction kinetics of
various metal precursors with the assistance of micelles.
commercial Pt/C (65.0 m2 g−1), and recently reported Pt-based
electrocatalysts such as Pt hierarchical nanowire arrays (60 m2
g−1),[11] PtRuTe mesoporous nanotubes (50.2 m2 g−1),[12] and
AgAu@Pt nanoframes (24.6 m2 g−1).[3a] The results reveal that
the mPtPd HNRs can provide sufficient active sites to react with
species, which is of great significance for the electrocatalytic
applications.
The MOR performance of samples is measured by CVs in N2-
saturated 1.0 M CH3OH + 0.5 M H2SO4 solution. The current
densities normalized to the mass loading of Pt and ECSA stand
for mass activity and specific activity, respectively (Figure 4a
and 4b). The CVs exhibit two-peak profiles, in which forward
peaks are assigned to the methanol oxidation and backward
peaks correspond to the oxidation of generated intermediates
during the MOR process. It is noted that the mPtPd HNRs
possess higher current density than that of the mPt HNRs and
commercial Pt/C, indicative of their enhanced activity for the
electro-oxidation of methanol due to the unique structure. The
specific activity (1.50 mA cm−2) of the mPtPd HNRs is 1.1 and
2.8 times that of the mPt HNRs (1.32 mA cm−2) and Pt/C (0.54
mA cm−2), respectively, indicating the high intrinsic activity of the
mPtPd HNRs (Figure 4c). Moreover, the mPtPd HNRs possess
a high mass activity of 0.71 A mgPt−1, superior to the mPt HNRs
−1
(0.58
A mgPt ) and commercial Pt/C (0.21 A
mgPt−1),
respectively. They are superior to recently reported Pt-based
electrocatalysts under the same conditions (Table S1), such as
Pd nanohollows/Pt nanorods nanocomposites (0.50 A mgpt−1),[13]
PtPdTe nanowire (0.59 A mgpt−1),[14] and Au-Pt nanodendrites
(0.45 A mgpt−1).[15] The superb mass activity reveals that the
mPtPd HNRs can effectively reduce the Pt usage while still
maintaining high activity. As shown in linear sweep voltammetry
(LSV) curves (Figure 4d), the onset potential of the mPtPd
HNRs is smaller than that of the mPt HNRs and commercial Pt/C,
suggesting that it is more favorable to catalyze the MOR on the
mPtPd HNRs.
Figure 3. XRD pattern of the mPtPd HNRs.
According to above results, a possible formation mechanism
would be inferred. In the present synthetic strategy, the
concentration of F127 (ca. 0.9 wt%) exceeds the critical micelle
concentration, resulting in the formation of spherical micelles.[9]
The metal precursors are easily coordinated with water to form
metal-aqua complexes that can combine with hydrophilic
ethylene oxide groups in F127,[10] leading to sufficient coverage
of metal species on the micelle surface. After addition of AA, Pt
and Pd species are reduced to PtPd seeds covering on the silica
surface owing to strong affinity between its amino groups and
PtPd seeds. As the crystal growth proceeds, surfactant
molecules are gradually self-assembled into an ordered array at
the solid-liquid interface. After the removal of the micelles and
silica, well-developed mesoporous shells and hollow structure
are formed.
Given the mesoporous hollow structure and bimetallic
compositions, the mPtPd HNRs are considered as effective
MOR electrocatalysts for investigating their catalytic activity,
compared with the counterpart mPt HNRs and commercial Pt/C.
All potentials are converted to reversible hydrogen electrode
(RHE) for electrochemical measurements. The typical cyclic
voltammograms (CVs) are conducted in N2-saturated H2SO4 (0.5
M) at the scan rate of 50 mV s−1 (Figure S10), which can be
employed to calculate the electrochemically active surface area
(ECSA) by integrating the charge passing the electrode during
hydrogen adsorption/desorption process after double-layer
correction. The ECSA of the mPtPd HNRs is calculated to be
92.7 m2 g−1, superior to that of the Pt HNRs (44.2 m2 g−1),
Figure 4. (a) Mass-normalized and (b) ECSA-normalized CVs in 1.0 M CH3OH
+ 0.5 M H2SO4. (c) Comparisons of mass activity and specific activity for
different catalysts. (d) LSV curves of different catalysts.
The MOR kinetics of the catalysts is studied by CVs
under different scan rates. As shown in Figure 5a, we can
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see that the current density increases and the peak
potential has a positive shift with the increase of the scan
rate (v). Furthermore, a linear relationship is observed
hollow structure in the mPtPd HNRs not only facilitates diffusion
of guest species due to the uniform mesopores in the shells as
well as the large hollow interiors, but also improves the effective
utilization of active surfaces from both the interior and exterior
surfaces of the mesoporous shells, making them superior
electrocatalytic activity. Moreover, the mesoporous hollow
structure greatly suppresses the dissolution, Ostwald ripening,
and aggregation of catalysts, leading to excellent catalytic
stability.
between the forward peak current density (jm) and v1/2
,
suggesting the diffusion-controlled process for the MOR.[5g]
The slope of the mPtPd HNRs (0.04) is higher than that of
the mPt HNRs (0.025) and the Pt/C (0.0085), confirming
more favorable kinetics of methanol oxidation on the mPtPd
HNRs (inset of Figure 5a, Figure S11 and Figure S12). The
electrocatalytic stability of the MOR is a critical factor for
practical applications, which is evaluated by accelerated
durability tests. After measurements at the potential range
of 0.22 and 1.22 V in 1.0 M CH3OH + 0.5 M H2SO4 solution,
the current densities of all the catalysts have degradation
with the increase of CV cycles (Figure 5b and Figure S13).
We can see from the Figure 5c that the mPtPd HNRs
maintain 66% of the initial mass activity, which is much
higher than the mPt HNRs (35%) and commercial Pt/C
(32%). Furthermore, chronoamperometric measurements
are further performed to estimate the stability of catalysts
(Figure 5d). After tests at 0.92 V for 5000 s, the mPtPd
HNRs retain a higher current density with slower decay
than the mPt HNRs and commercial Pt/C, indicating the
excellent stability of the mPtPd HNRs for the MOR.
Figure 6. Schematic illustration of the MOR pathway on the mPtPd HNRs.
Conclusions
In summary, we have successfully developed a reliable
approach to prepare the mPtPd HNRs using F127 and SiO2
NRs as soft template and hard template, respectively. Due
to the well-developed mesoporous structure, large hollow
cavity, and synergistic effect on the mPtPd HNRs, they
display excellent electrocatalytic activity and stability toward
MOR. This synthetic approach is a universal strategy, which
can be extended to prepare many other Pt-based alloys
with well-developed mesoporous structure by choosing
appropriate precursors. Moreover, by tuning morphology of
templates, more complicated mesoporous hollow structures
with versatile functions will be obtained in the future.
Figure 5. (a) CVs of the mPtPd HNRs at different scan rates and
corresponding fitted plot of the jm vs. the v1/2. (b) Mass activities of samples
before and after 1000 cycles, and (c) corresponding mass activity changes
under different cycles. (d) Chronoamperometric curves of samples at 0.92 V.
Experimental Section
Materials and Chemicals
Potassium tetrachloroplatinate (K2PtCl4), sodium tetrachloropalladate
(Na2PdCl4), Pluronic F127 (poly (ethylene oxide)100–poly (propylene
The excellent electrocatalytic MOR performance of the
mPtPd HNRs can be explained by their well-defined
mesoporous hollow structure and bimetallic component
(Figure 6). The alloy structure of Pt and Pd can tailor their
electronic structures and generate synergistic effect derived
from the Pt−Pd interaction, thus modifying the d-band
center of Pt and weakening the electronic interaction
between Pt atoms and adsorbates, which favors enhanced
intrinsic MOR activity. On the other hand, the mesoporous
oxide)65–poly (ethylene oxide)100) and 3-aminopropyltrimethoxysilane
(APTMS) were purchased from Sigma-Aldrich. Tetraethyl orthosilicate
(TEOS, ≥99.8%), hexadecyltrimethyl-ammonium bromide (CTAB,
≥99.8%), ascorbic acid (AA), hydrochloric acid (HCl, 36.0–38.0%),
aqueous ammonia (28 wt%), isopropanol, and ethanol were purchased
from Sinopharm Chemical Reagent Co., Ltd.
Synthesis of SiO2 NRs
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The SiO2 NRs were synthesized based on the previous report with minor
modification.[16] Typically, F127 (1.26 g), CTAB (100 mL, 40 mM) and
ammonia solution (120 mL, 2.5 wt%) were mixed under stirring at room
temperature, followed by adding TEOS (4.8 mL). After the solution was
stirred at room temperature for 6 h, the products were collected by
centrifugation and washed three times with ethanol and water, and they
were further immersed in HCl at 90 °C for 20 h to remove the surfactant.
Finally, the SiO2 NRs were washed with ethanol and dried in a vacuum
oven for 24 h. For modification of amino groups on silica surface, the
obtained SiO2 NRs (50 mg) were mixed with isopropanol (10 mL) and
APTMS (200 μL), and the solution was heated at 80 °C for 12 h under
reflux. After that, the modified SiO2 NRs were thoroughly washed with
ethanol and dried at 60 °C.
This work was financially supported by the National Natural
Science Foundation of China (No. 21601154, 21776255,
21701141).
Keywords: PtPd nanorod • hollow structure • mesoporous shell
• electrocatalyst • methanol oxidation reaction
[1]
[2]
a) N. Kakati, J. Maiti, S. H. Lee, S. H. Jee, B. Viswanathan, Y. S. Yoon,
Chem. Rev. 2014, 114, 12397-12429; b) X. Zhao, M. Yin, L. Ma, L.
Liang, C. Liu, J. Liao, T. Lu, W. Xing, Energy Environ. Sci. 2011, 4,
2736-2753; c) Y. Feng, H. Liu, J. Yang, Sci. Adv. 2017, 3, 1700580; d)
J. Chang, L. Feng, C. Liu, W. Xing, X. Hu, Energy Environ. Sci. 2014, 7,
1628-1632.
Synthesis of the mPtPd HNRs
a) Z. Wu, Y. Lv, Y. Xia, P. A. Webley, D. Zhao, J. Am. Chem. Soc. 2012,
134, 2236-2245; b) S. Sakong, A. Gross, ACS Catal. 2016, 6, 5575-
5586; c) H. E. M. Hussein, H. Amari, J. V. Macpherson, ACS Catal.
2017, 7, 7388-7398; d) X. L. Tian, L. Wang, P. Deng, Y. Chen, B. Y. Xia,
J. Energy Chem. 2017, 26, 1067-1076; e) L. Tao, Y. Shi, Y.-C. Huang,
R. Chen, Y. Zhang, J. Huo, Y. Zou, G. Yu, J. Luo, C.-L. Dong, S. Wang,
Nano Energy 2018, 53, 604-612; f) X. Sun, X. Zhu, N. Zhang, J. Guo, S.
Guo, X. Huang, Chem. Commun. 2015, 51, 3529-3532.
In brief, K2PtCl4 (3 mL, 20 mM), Na2PdCl4 (1 mL, 20 mM), HCl (50 μL, 6
M) and modified SiO2 NRs (3 mg) were mixed, followed by adding F127
(40 mg) under sonication. Then, AA (4 mL, 0.1 M) was rapidly added to
the above solution, reacting for 4 h at room temperature. After the
reaction was finished, the products were collected by centrifugation and
washing with water several times, which were treated with HF (10 wt%)
for 12 h to remove SiO2 templates. Finally, the mPtPd HNRs were
obtained after centrifugation, washing and drying.
[3]
a) X. Yan, S. Yu, Y. Tang, D. Sun, L. Xu, C. Xue, Nanoscale 2018, 10,
2231-2235; b) L. Han, P. Cui, H. He, H. Liu, Z. Peng, J. Yang, J. Power
Sources 2015, 286, 488-494; c) Z. Wang, X. Ren, Y. Luo, L. Wang, G.
Cui, F. Xie, H. Wang, Y. Xie, X. Sun, Nanoscale 2018, 10, 12302-
12307; d) X. Qiu, T. Li, S. Deng, K. Cen, L. Xu, Y. Tang, Chem. Eur. J.
2018, 24, 1246-1252; e) H. Wang, S. Yin, Y. Xu, X. Li, A. A. Alshehri, Y.
Yamauchi, H. Xue, Y. V. Kaneti, L. Wang, J. Mater. Chem. A 2018, 6,
8662-8668.
Materials Characterization
The morphology of the synthesized samples was measured by SEM
(JCM-7000). TEM images and element mapping were carried out by a
JEM-2100F apparatus equipping with an EDX spectroscopy. XRD was
recorded on an X-ray diffractometer (Shimadzu, XRD-6000) with Cu Kα
radiation. SAXS experiment was conducted with a Rigaku D-Max 2550 X
instrument using Cu Kα as radiation The chemical composition of mPtPd
HNRs was analyzed by ICP-AES (Thermo Elemental IRIS Intrepid).
[4]
[5]
a) Y. Zhang, L. Bu, K. Jiang, S. Guo, X. Huang, Small 2016, 12, 706-
712; b) R. Zhao, Y. Liu, C. Liu, G. Xu, Y. Chen, Y. Tang, T. Lu, J. Mater.
Chem. A 2014, 2, 20855-20860; c) L.-N. Zhou, X.-T. Zhang, Z.-H.
Wang, S. Guo, Y.-J. Li, Chem. Commun. 2016, 52, 12737-12740.
a) H.-H. Li, S.-H. Yu, Adv. Mater. 2019, DOI: 10.1002/adma.201803503;
b) N. S. Porter, H. Wu, Z. Quan, J. Fang, Acc. Chem. Res. 2013, 46,
1867-1877; c) H. Wang, S. Yin, Y. Li, H. Yu, C. Li, K. Deng, Y. Xu, X. Li,
H. Xue, L. Wang, J. Mater. Chem. A 2018, 6, 3642-3648; d) L. Bu, N.
Zhang, S. Guo, X. Zhang, J. Li, J. Yao, T. Wu, G. Lu, J.-Y. Ma, D. Su, X.
Huang, Science 2016, 354, 1410-1414; e) G.-R. Xu, B. Wang, J.-Y. Zhu,
F.-Y. Liu, Y. Chen, J.-H. Zeng, J.-X. Jiang, Z.-H. Liu, Y.-W. Tang, J.-M.
Lee, ACS Catal. 2016, 6, 5260-5267; f) H. Wang, Y. Li, C. Li, K. Deng,
Z. Wang, Y. Xu, X. Li, H. Xue, L. Wang, J. Mater. Chem. A 2019, 7,
801-805; g) L. Huang, X. Zhang, Q. Wang, Y. Han, Y. Fang, S. Dong, J.
Am. Chem. Soc. 2018, 140, 1142-1147.
Electrochemical Measurements
Electrochemical measurements were conducted on
a CHI 842D
electrochemical workstation in a three-electrode system with Ag/AgCl (3
M KCl) electrode, Pt wire, and modified glassy carbon electrode (GCD, 3
mm in diameter) as reference electrode, counter electrode, and working
electrode, respectively. The working electrode was prepared as follows.
In brief, obtained catalyst (2 mg) was dispersed in water (1 mL) to form
the ink under ultrasonication for 30 min, and then the ink (5 μL) was
dropped on the surface of the clean GCD and dried in oven.
Subsequently, Nafion solution (5 μL, 0.05%) was further coated on the
surface and dried in an oven. The ECSA of electrocatalysts was
determined from CVs measured in a N2-saturated H2SO4 (0.5 M) at a
scan rate of 50 mV s−1. The ECSA of the catalysts can be estimated by
the equation (ECSA = Q/m × 210), where Q is the charge collected in the
underpotentially deposited hydrogen adsorption/desorption region after
double-layer correction, m is the mass loading of Pt on the electrode, and
210 μC cm−2 stands for the monolayer adsorption of hydrogen on Pt
surface. For MOR measurements, CVs and LSV curves were measured
in a mixed solution containing CH3OH (1.0 M) and H2SO4 (0.5 M) at a
scan rate of 50 mV s−1. Chronoamperometry measurements were
conducted at the potential of 0.92 V.
[6]
[7]
a) L. Yu, H. Hu, H. B. Wu, X. W. Lou, Adv. Mater. 2017, 29, 1604563; b)
X. Wang, J. Feng, Y. Bai, Q. Zhang, Y. Yin, Chem. Rev. 2016, 116,
10983-11060; c) F. Li, Q. Shao, M. Hu, Y. Chen, X. Huang, ACS Catal.
2018, 8, 3418-3423.
a) X. W. Lou, L. A. Archer, Z. Yang, Adv. Mater. 2008, 20, 3987-4019; b)
Q. Zhang, W. Wang, J. Goebl, Y. Yin, Nano Today 2009, 4, 494-507; c)
B. Y. Guan, L. Yu, X. W. Lou, Adv. Mater. 2016, 28, 9596-9601; d) K.
Lan, Y. Xia, R. Wang, Z. Zhao, W. Zhang, X. Zhang, A. Elzatahry, D.
Zhao, Matter 2019, DOI: 10.1016/j.matt.2019.03.003; e) D. Niu, Z. Ma,
Y. Li, J. Shi, J. Am. Chem. Soc. 2010, 132, 15144-15147;
[8]
a) H. Wang, S. Yin, C. Li, K. Deng, Z. Wang, Y. Xu, X. Li, H. Xue, L.
Wang, J. Mater. Chem. A 2019, 7, 1711-1717; b) H. Wang, Y. Li, K.
Deng, C. Li, H. Xue, Z. Wang, X. Li, Y. Xu, L. Wang, ACS Appl. Mater.
Interfaces 2019, 11, 4252-4257; c) Z. Wang, C. Li, K. Deng, Y. Xu, H.
Xue, X. Li, L. Wang, H. Wang, ACS Sustainable Chem. Eng. 2019, 7,
2400-2405; d) H. Wang, H. Yu, Z. Wang, Y. Li, Y. Xu, X. Li, H. Xue, L.
Wang, Small 2019, 15, 1804769; e) Y. Xu, Y. Li, X. Qian, D. Yang, X.
Chai, Z. Wang, X. Li, L. Wang, H. Wang, Nanoscale 2019, 11, 4781-
4787; f) S.-H. Han, H.-M. Liu, P. Chen, J.-X. Jiang, Y. Chen, Adv.
Acknowledgements
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Energy Mater. 2018, 8, 1801326; g) B. Y. Guan, S. L. Zhang, X. W. D.
Lou, Angew. Chem. Int. Ed. 2018, 57, 6176-6180.
[13] S. Lai, C. Fu, Y. Chen, X. Yu, X. Lai, C. Ye, J. Hu, J. Power Sources
2015, 274, 604-610.
[9]
H. Ataee-Esfahani, J. Liu, M. Hu, N. Miyamoto, S. Tominaka, K. C. W.
[14] H.-H. Li, S. Zhao, M. Gong, C.-H. Cui, D. He, H.-W. Liang, L. Wu, S.-H.
Yu, Angew. Chem. Int. Ed. 2013, 52, 7472-7476.
[15] Y. Li, W. Ding, M. Li, H. Xia, D. Wang, X. Tao, J. Mater. Chem. A 2015,
3, 368-376.
Wu, Y. Yamauchi, Small 2013, 9, 1047-1051.
[10] H. J. Wang, H. J. Yu, S. L. Yin, Y. Xu, X. N. Li, Y. Yamauchi, H. R. Xue,
L. Wang, J. Mater. Chem. A 2018, 6, 12744-12750.
[11] C. Wang, Y. Zhang, Y. Zhang, P. Xu, C. Feng, T. Chen, T. Guo, F.
Yang, Q. Wang, J. Wang, M. Shi, L. Fan, S. Chen, ACS Appl. Mater.
Interfaces 2018, 10, 9444-9450.
[16] Y. Wang, B. Shang, F. Lin, Y. Chen, R. Ma, B. Peng, Z. Deng, Chem.
Commun. 2018, 54, 559-562.
[12] S. Yin, H. Wang, K. Deng, Z. Dai, Z. Wang, Y. Xu, X. Li, H. Xue, L.
Wang, Chem. Eur. J. 2019, 25, 5316-5321.
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Entry for the Table of Contents
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Hollow
PtPd nanorods
with
Hongjing Wang, Xiaoqian Qian,
mesoporous shells synthesized
through
approach
Songliang Liu, Shuli Yin, Hongjie Yu,
You Xu, Xiaonian Li, Ziqiang Wang*
and Liang Wang*
a
dual-templating
exhibit superior
electrocatalytic performance for
methanol oxidation reaction.
Page No. – Page No.
Hollow PtPd Nanorods with
Mesoporous Shells as an Efficient
Electrocatalyst
for
Methanol
Oxidation Reaction
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