Ethanol electrooxidation on highly active palladium/graphene oxide aerogel catalysts

Article abstract of DOI:10.1016/j.chemphys.2020.110753

In this work, the low-loading (3 wt%) palladium/graphene oxide (Pd/GO) aerogels are facilely prepared via the lyophilisation, vacuum and reduction treatments. The Pd/GO aerogels display enhanced activity and stability in comparison to the commercial Pd/C. The enhancement of electrocatalytic performance can be attributed to the functional groups on the surfaces of the GO support, such as carbonyl and carboxyl groups, which can be tuned to interact with palladium to form active phases for the reaction. In addition, Pd nanoparticles (NPs) remain dispersed in nanoscale on the reacted catalyst.

Full text of DOI:10.1016/j.chemphys.2020.110753

Chemical Physics 534 (2020) 110753
Contents lists available at ScienceDirect
Chemical Physics
journal homepage: www.elsevier.com/locate/chemphys
Ethanol electrooxidation on highly active palladium/graphene oxide aerogel
catalysts
a
a
a
b
a,⁎
a
c
Jing Zhang , Zhiliang Zhao , Yongzhao Wang , Juan Wang , Dengchao Peng , Baiyu Li ,
a
a
a
a,⁎
b,⁎
Tingting Bo , Kang Zheng , Zhiyuan Zhou , Lin Lv , Zhiling Xin , Bingsen Zhang
,
a,⁎
Lidong Shao
a
Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, 2103 Pingliang Road, Shanghai
00090, China
2
b
Shenyang National Laboratory for Materials Science Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China
Nantong Vocational University, 89 Qingnian Road, Nantong 226006, China
c
A R T I C L E I N F O
A B S T R A C T
Keywords:
In this work, the low-loading (3 wt%) palladium/graphene oxide (Pd/GO) aerogels are facilely prepared via the
lyophilisation, vacuum and reduction treatments. The Pd/GO aerogels display enhanced activity and stability in
comparison to the commercial Pd/C. The enhancement of electrocatalytic performance can be attributed to the
functional groups on the surfaces of the GO support, such as carbonyl and carboxyl groups, which can be tuned
to interact with palladium to form active phases for the reaction. In addition, Pd nanoparticles (NPs) remain
dispersed in nanoscale on the reacted catalyst.
Pd nanoparticles
Ethanol oxidation reaction
Graphene oxide
Aerogels
Functional groups
1
. Introduction
chemistry of carbon is also a significant aspect to consider when de-
signing highly active catalysts [20–22]. The functional groups on the
Fuel cells are widely studied for environmentally friendly power
support materials can promote the catalytic reaction by affecting the
electronic structure of the loaded metal particles. The outer surface of
graphene can be chemically modified by introducing oxygen-containing
functional groups such as carboxyl, carbonyl, and hydroxyl by an oxi-
dation treatment. Based on interaction between the metal and support
[23–24], Pd nanostructures can be anchored on the oxygen-containing
functional groups by effectively forming a stable metal bond through
electrostatic interaction.
generation because they are capable of directly and conveniently con-
verting chemical energy into electrical energy. Direct ethanol fuel cells
(
DEFCs) are remarkable due to their high current density and the fact
that ethanol is an abundant and low-cost liquid fuel [1]. Thus, the
design and preparation of a superior electrocatalyst has become vital
for producing DEFCs [2]. In the current DEFCs, the anode catalysts are
generally based on either Pd or Pt. The Pd-based electrocatalysts are not
only low-cost, but also display higher ethanol oxidation reaction (EOR)
activity [3–9] and superior anti-CO poisoning characteristics [10–11]
than the Pt-based catalysts in an alkaline medium.
In this work, the low-loading (3 wt%) Pd/GO aerogels, with large
surface areas and enrich functionalities, are prepared by the lyophili-
sation, vacuum and reduction treatments. Functional groups on the GO
surface can help anchor Pd nanoparticles (NPs) and inhibit particle
aggregation, thereby achieving nanoscale uniform dispersion of Pd NPs.
The Pd/GO aerogels displayed higher activity and stability than the
commercial Pd/C in EOR. The fresh and reacted catalysts were analyzed
to study the correlation between structure and performance.
The support materials play a key role in the design of the catalysts
for the EOR. Carbon materials with excellent physicochemical proper-
ties and unique structures are very attractive as supports for DEFCs
palladium-containing electrocatalysts [12–17]. Among the numerous
2
carbon materials, graphene with the atomic layer of sp C-bonded two-
dimensional (2D) nanosheets is universally considered to be a pro-
spective catalyst supporting material due to its high conductivity
2. Experimental
[
18–19]. This not only helps to maximise the electron transfer rate on
the surface of the nanoelectrocatalyst, but also provides better mass
transfer of reactants to the electrocatalyst. Furthermore, the surface
The graphene oxide (GO) is from Tanyuan Co. Ltd (Shanghai). The
Pd(NO
3
)
2
(10 wt% in 10 wt% HNO ), Pd/C (3 wt%) and Nafion (5 wt%)
3
⁎
Corresponding authors.
E-mail addresses: wangjuan@shiep.edu.cn (J. Wang), xinzhiling@126.com (Z. Xin), bszhang@imr.ac.cn (B. Zhang), lidong.shao@shiep.edu.cn (L. Shao).
https://doi.org/10.1016/j.chemphys.2020.110753
Received 27 January 2020; Received in revised form 10 March 2020; Accepted 11 March 2020
Available online 12 March 2020
0301-0104/ © 2020 Elsevier B.V. All rights reserved.

J. Zhang, et al.
Chemical Physics 534 (2020) 110753
Fig. 1. Schematic diagram of the preparation of the Pd/GO aerogels.
are purchased from Sigma Aldrich. The ethanol (> 99.7%) and KOH
are supplied by Sinopharm Co. Ltd (China). The hydrogen (H
particle size distribution of the Pd NPs. From statistical analysis, the
average diameter of Pd NPs is ca. 2.95 nm. However, in the case of the
Pd/C (shown in Fig. S1), the mean size of metal particles is ca. 3.53 nm.
The TEM image of the well-dispersed Pd/GO aerogels is shown in
Fig. 2b. From the energy-dispersive X-ray spectroscopy (EDX) elemental
mapping images (Fig. 2e-g), it can be seen that there is a homogeneous
distribution of Pd and O over the surfaces of the Pd/GO aerogel cata-
lysts. In order to demonstrate the fine structure of the samples, high-
resolution transmission electron microscopy (HRTEM) was performed
with corresponding local Fast Fourier Transformation (FFT). As shown
in Fig. 2h, the lattice fringes Pd (1 1 1) and Pd (2 0 0) with d-spacing of
2.24 and 1.94 Å can be identified in the Pd/GO aerogel samples re-
ferring to JCPDS NO. 65–6174. Fig. 2i shows the SEM image of the Pd/
GO aerogels, which evidences the two-dimensional sheet morphology
of the Pd/GO aerogels.
2
,
9
9.99%), helium (He, 99.99%) and nitrogen (N , 99.99%) are pur-
2
chased from Weichuang Co. Ltd (Shanghai). The experimental water is
Millipore ultrapure water.
Fig. 1 is a schematic diagram of the preparation of the Pd/GO
aerogels. Firstly, the raw GO solution was stirred for 2 h while under-
going sonication, PdNO solution was then added whilst undergoing
3
sonication for 0.5 h. After 2.5 h of sonication, the cations were de-
posited on the surface of the support meanwhile the interlayer spacing
of the raw GO increased. Subsequently, the mixed solution was dried by
lyophilisation (freeze drying) to maintain the integrity of the mor-
phology. The interlayer spacing was further expanded after vacuum
treatment at 500 °C at a heating rate of 10 °C/min for 0.5 h. Finally, the
cations were reduced by H through an annealing treatment at 250 °C at
2
a heating rate of 3 °C/min for 1 h to form Pd nanocrystals. Notably, as
shown in Fig. 2, the Pd/GO aerogels obtained after the vacuum and
hydrogen reduction treatment still maintained a good two-dimensional
morphology. Supporting Information provides experimental details in-
formation for sample preparation and electrochemical measurements.
Field emission transmission electron microscopy (TEM, FEI Tecnai
G2 F20) images were employed in scanning TEM (STEM) mode to
characterise the morphologies and microstructures of the catalysts. The
morphology of the catalysts was characterised using scanning electron
microscopy (SEM, JSM 6701F). X-ray photoelectron spectroscopy (XPS)
was carried out by a Thermo ESCALAB 250 instrument using an Al Kα
radiation source. X-ray diffraction (XRD) analyses were performed on a
Bruker D8 Advance instrument employing Cu Ka radiation. Raman
spectra were performed on a HORIBA LabRAM HR Evolution Raman
spectrometer at an excitation wavelength of 633 nm with an Ar-ion
laser.
Fig. 3A shows the XRD of the (a) Pd/C and (b) Pd/GO aerogels and
provides information on the crystallographic structures. The broad
diffraction peak at 24.46° is consistent with the (0 0 2) plane of a
carbonaceous structure. Meanwhile, the characteristic diffraction peaks
located at 40.00°, 46.53°, 67.92°, and 81.85° correspond, respectively,
to the (1 1 1), (2 0 0), (2 2 0), and (3 1 1) crystalline planes of the
metallic Pd (JCPDS No. 88–2235). For the Pd/GO aerogels, the strength
of the Pd peaks is not obvious due to the NPs size of the metal was too
tiny [25], which is consistent with the TEM results.
Raman spectroscopy was used to rapidly detect the structural fea-
tures of the carbonaceous catalysts and qualitatively characterise them.
Fig. 3B shows the Raman spectra of (a) Pd/GO aerogels and (b) Pd/C,
which demonstrates the disorder and defects of the carbon structure.
Both catalysts have two evident bands, namely the G and the D band at
−1
1598 and 1325 cm . The D-band originates from defects in the gra-
phite plane [26], and the G-band corresponds to the vibration of the
2
sp -bonded carbon domains [27]. The intense G band in the Pd/GO
aerogels indicates that the catalyst remains in the graphite structure
3
. Results and discussion
after vacuum annealing at 500 °C. The value of I
D
/I is generally used
G
to reveal the amount of in-plane and edge flaws of the catalysts [28].
The I /I value (1.28) for Pd/GO aerogels is slightly higher than the
value for Pd/C (1.13), suggesting that there are planar lattice defects in
Fig. 2a shows the typical STEM images of Pd/GO aerogels, the Pd
D
G
NPs are uniformly and well dispersed on the support, indicating the
anchoring effect from the graphene oxide. The inset of Fig. 2a shows the
2

J. Zhang, et al.
Chemical Physics 534 (2020) 110753
Fig. 2. (a) Typical STEM image of the Pd/GO aerogels with the inset shows the Pd particle size distribution. (b) TEM image of the Pd/GO aerogels. (c)-(g) EDX
elemental maps of (e) C, (f) O and (g) Pd in the Pd/GO aerogels. (h) HRTEM image of the Pd/GO aerogels with FFT. (i) SEM image of the Pd/GO aerogels.
the Pd/GO aerogels.
OH), 287.12 eV corresponds to carbonyl (C]O), and 290.12 eV cor-
responds to carboxyl (COOH) [32–34]. Based on the deconvolution of
the C 1 s peak, the percentage of total oxygen-containing groups of the
Pd/GO aerogels is estimated to exceed 37%, which is higher than 19%
of the Pd/C (as shown in Fig. S2).
XPS was utilised to inspect the valence of the elements and the
properties of the Pd/GO aerogels at the surface and subsurface regions.
In the fitted Pd 3d spectrum of the Pd/GO aerogels (Fig. 4a), the Pd 3d5/
0
2
(335.68 eV) and Pd 3d3/2 (340.86 eV) peaks are assigned to Pd , while
the Pd 3d5/2 (337.16 eV) and Pd 3d3/2 (342.36 eV) peaks are both as-
Fig. 5A illustrates the cyclic voltammograms (CVs) of the Pd/GO
2
+
−1
cribed to Pd [29–30]. The remaining two peaks at 338.13 and
aerogels and Pd/C conducted between −0.8 V and 0.6 V at 50 mV s
3
43.35 eV are ascribed to the bivalent polynuclear Pd-hydroxo com-
in 1 M KOH + 1 M ethanol solution while purging with nitrogen. Both
catalysts show forward and backward peaks and the lower onset po-
tential of the Pd/GO aerogels indicates that it is easier to achieve an
EOR. As the CVs show, the EOR performance of the Pd/GO aerogels
plexes due to the imcomplete reduction of the palladium salt [31]. As
illustrated in Fig. 4b, the C 1 s spectrum of the Pd/GO aerogels is fitted
to four independent peaks that represent different functional groups.
3
The intense peak of 284.78 eV is attributed to the sp hybrid CeC. The
features a forward peak current density (I
f
) around −0.2 V to ethanol
) around −0.5 V to
binding energy peak located at 285.69 eV corresponds to hydroxyl (C-
oxidation, and the backward current density (I
b
3

J. Zhang, et al.
Chemical Physics 534 (2020) 110753
Fig. 3. (A) XRD patterns of (a) Pd/C and (b) Pd/GO aerogels. (B) Raman spectra
of (a) Pd/GO aerogels and (b) Pd/C.
Fig. 4. (a) XPS spectrum of the Pd/GO aerogels in Pd 3d region. (b) XPS
remove residual carbonaceous materials that were not totally oxidised.
Understanding the mechanism of electroxidation of ethanol in detail is
essential for the anode design of Pd-based DEFCs. Zhao et al. [35] has
explored the mechanism of electroxidation of ethanol on palladium
electrodes. It was found that the dissociative adsorption of ethanol
proceeded quite quickly, and the rate-determining step was to remove
the adsorbed ethoxy groups through the hydroxyl groups adsorbed on
the surface of the Pd electrode (Eqs. (1)–(3)).
spectrum of the Pd/GO aerogels in C 1s region.
the Pd/GO aerogels have an ESCA that is 2.5 times larger than that for
commercial Pd/C, thus increasing the electrochemical activity of the
electrocatalyst. Furthermore, the peak current ratio of the forward scan
(I ) to backward scan (I ), I /I , is usually used to investigate the ability
f
b
f
b
of catalysts to withstand the poisoning of carbonaceous materials [37].
The I
f
/I ratios of Pd/GO aerogels and Pd/C equal 1.96 and 0.58, re-
b
–
−
Pd + OH → Pd-OHads + e
(1)
(2)
(3)
spectively, which demonstrates that the Pd/GO aerogels have a stronger
–
O + 3e−
Pd-(CH
3
CH
2
OH)ads + 3OH → Pd-(COCH
3
)
ads + 3H
2
anti-poisoning ability.
In order to assess the stability of the Pd/GO aerogels, 3600 s
chronoamperometric curves were acquired in 1 M KOH + 1 M ethanol
at a potential of −0.2 V. As shown in Fig. 5B, the Pd/GO aerogel cat-
alysts exhibit higher current densities both in the initial and final
measurements, indicating that the performance of the Pd/GO aerogels
in the EOR is superior to Pd/C. At first, the current density of the EOR
on both catalysts decrease sharply, possibly owing to the accumulation
of toxic intermediates and adsorption on the catalyst surface, which
tends to stabilise after a certain period of time. In terms of the Pd/GO
Pd-(COCH
3
)
ads + Pd-OHads → Pd-CH COOH + Pd
3
As demonstrated in Fig. 5A, the Pd/GO aerogels have a visible mass
−
1
−1
activity of 1300 A g , which is 2.7 times higher than the 480 A g for
commercial Pd/C. The electrochemical active surface area (ECSA) was
generally used to investigate the electrochemical active sites. The
ECSAs of the Pd-based electrocatalysts are calculated as follows:
ECSA = Q/(0.405 × m), where Q (mC) is the Coulomb charge defined
−1
by integrating the PdO reduction peak area, 0.405 (mC cm ) re-
presents the charge required to reduce a PdO monolayer, and m (g) is
the Pd loading on the glassy carbon electrode [36]. Fig. S3 shows the
CV measurements in 1 M KOH, the calculated ECSAs for the Pd/GO
−1
aerogels, in the first 1000 s, the mass activity is 132.1 A g , and in the
−1
following 1000 s, the mass activity is 95.2 A g . After 3600 s of the
−
1
stability test, the mass activity of the Pd/GO aerogels is 71.6 A g
,
which is higher than the Pd/C (17.4 A g−1). These observations
2
−1
aerogels and Pd/C equal 97.43 and 38.41 m g , respectively. Clearly,
4

J. Zhang, et al.
Chemical Physics 534 (2020) 110753
after the reaction and a favourable distribution of particles was pre-
served. The inset of Fig. 6b shows the particle size distribution of the Pd
NPs. The average dimension of the Pd NPs on the used catalysts in-
creased slightly to ca. 3.79 nm, indicating that the Pd/GO aerogels had
no significant particle agglomeration and metal leaching during the
reaction.
Generally, graphene aerogels (GAs) can be prepared either by the
polymerisation of an organogel or by assembling primary carbon na-
nomaterials [38]. Due to their excellent chemical durability and par-
ticular architecture, graphene aerogels have many extraordinary char-
acteristics. GAs usually have an ultra-low density, their adjustable pore
structures ensure a large internal surface area and low mass transfer
resistance, and their carbon-based supports are an excellent way of
transferring electrons. GAs also exhibit surprising catalytic activity
[
39]. In our work, the lyophilisation connected with the vacuum an-
nealing ensures the integrity of the Pd/GO aerogels morphology and the
uniform distribution of Pd NPs on the surface, the catalyst is free of
surfactant formation process.
The elemental components of the Pd/GO aerogels and Pd/C de-
termined using XPS are illustrated in Table S1. As can be seen from
Table S1, the C 1s/O 1s ratio of the Pd/GO aerogels and Pd/C are 8.00
0
2+
and 12.86, and the Pd /Pd
ratios are 1.04 and 3.64, respectively.
Further calculations (Table S2) show that the oxygen-containing func-
tional groups hydroxyl (C-OH), carbonyl (C]O), and carboxyl (COOH)
groups of the Pd/GO aerogels account for 17.78%, 10.16%, and 9.08%,
respectively, which are higher than 7.86%, 4.59% and 6.55% of the Pd/
C. The percentage of total oxygen-containing groups of the Pd/GO
aerogels is 37.13%, which is nearly double the Pd/C (19.00%). It is well
known that functional groups can affect interactions with supported
metal nanoparticles [40]. Here, we concluded that the O-containing
functional groups, such as carbonyl and carboxyl, on the surface of GO
are vital for the interaction of Pd with the support. It was reported that
the lone pair of electrons around the C]O bond in the anhydride or
carboxylic acid can be shared with the 4d orbital of Pd [41], which may
result in an intense interaction between the Pd and GO. This possibly
facilitates the anchoring of the Pd NPs, while also limiting the growth of
the Pd NPs. Meanwhile, the particle size effects in Pd catalysis are
closely related to the electrocatalytic performance [29,42]. The smaller
particle size may contribute to relatively higher specific surface area
and high exposed surface atoms density of Pd [43,44], which is of great
significance for low-loading Pd-catalyzed ethanol oxidation. Moreover,
the TEM images after the stability reaction further demonstrated the
stability of the Pd/GO aerogels that we prepared. The Pd/GO aerogels
still maintained the original morphology, while the size of Pd NPs did
not increase significantly after the reaction, and still showed improved
stability and dispersity, further confirming the intense interaction
−
1
Fig. 5. (A) CV curves in 1 M KOH + 1 M ethanol at a scan rate of 50 mV s
.
(
B) chronoamperometric curves in 1 M KOH + 1 M Ethanol at a potential of
−
0.2 V vs. SCE, (a for Pd/GO aerogels and b for Pd/C).
indicate that Pd/GO aerogels have a relatively good stability towards
EOR.
Fig. 6a and 6b show the representative TEM images of used Pd/GO
aerogels, at different measurement scales. After 3600 s of the stability
reaction, no significant morphological differences were observed. The
Pd/GO aerogels still maintained a good two-dimensional morphology,
meanwhile there was no obvious growth in the dimension of the Pd NPs
Fig. 6. (a), (b) TEM images of used Pd/GO aerogels with the inset of (b) shows the Pd particle size distribution.
5

J. Zhang, et al.
Chemical Physics 534 (2020) 110753
between the Pd NPs and GO.
oxidation, Electrochim. Acta 244 (2017) 16–25, https://doi.org/10.1016/j.
electacta.2017.05.078.
[
[
[
7] H. Yang, S. Li, S. Shen, Z. Jin, J. Jin, J. Ma, Unraveling the cooperative synergy of
palladium/tin oxide/aniline-functionalized carbon nanotubes enabled by layer-by-
layer synthetic strategy for ethanol electrooxidation, ACS Sustainable Chem. Eng. 7
4
. Conclusion
(
2019) 10008–10015, https://doi.org/10.1021/acssuschemeng.9b01197.
In summary, the low-loading (3 wt%) Pd/GO aerogels, with large
8] S. Li, H. Yang, H. Zou, M. Yang, X. Liu, J. Jin, J. Ma, Palladium nanoparticles
anchored on the NCNTs@NGS with a three-dimensional sandwich-stacked frame-
work as an advanced electrocatalyst for ethanol oxidation, J. Mater. Chem. A 6
(2018) 14717–14724, https://doi.org/10.1039/C8TA04471F.
surface areas and enrich functionalities, have been obtained aided by a
relatively facile way combining the lyophilisation, vacuum, and re-
duction processing. The Pd/GO aerogels exhibit enhanced activity and
stability compared with the commercial Pd/C. The GO with large sur-
face provided a platform for immobilizing Pd NPs, on which the surface
carbonyl and carboxyl groups promote the formation of active sites by
forming the interaction between palladium and support. Due to the
metal-support interaction, nanoscale Pd NPs on GO showed improved
stability and dispersity after 3600 s reaction. Such a facile synthesis
method can be used for a general catalyst development which exploits
the role of enriched surface chemistry of aerogels in influencing cata-
lysis.
9] H. Yang, Z. Yu, S. Li, Q. Zhang, J. Jin, J. Ma, Ultrafine palladium-gold-phosphorus
ternary alloyed nanoparticles anchored on ionic liquids-noncovalently functiona-
lized carbon nanotubes with excellent electrocatalytic property for ethanol oxida-
tion reaction in alkaline media, J. Catal. 353 (2017) 256–264, https://doi.org/10.
1
016/j.jcat.2017.07.025.
[
[
10] L. Chen, L. Lu, H. Zhu, Y. Chen, Y. Huang, Y. Li, L. Wang, Improved ethanol elec-
trooxidation performance by shortening Pd-Ni active site distance in Pd-Ni-P na-
nocatalysts, Nat. Commun. 8 (2017) 14136.
11] E.A. Monyoncho, S. Ntais, N. Brazeau, J.J. Wu, C.L. Sun, E.A. Baranova, Role of the
metal-oxide support in the catalytic activity of Pd nanoparticles for ethanol elec-
trooxidation in alkaline media, ChemElectroChem 3 (2) (2016) 218–227, https://
doi.org/10.1002/celc.201500432.
[
12] G. Hu, F. Nitze, H.R. Barzegar, T. Sharifi, A. Mikołajczuk, C.W. Tai, A. Borodzinski,
T. Wågberg, Palladium nanocrystals supported on helical carbon nanofibers for
highly efficient electro-oxidation of formic acid, methanol and ethanol in alkaline
electrolytes, J. Power Sources 209 (2012) 236–242, https://doi.org/10.1016/j.
jpowsour.2012.02.080.
CRediT authorship contribution statement
Jing Zhang: Writing
- review & editing, Formal analysis,
[
[
13] A.L. Wang, X.J. He, X.F. Lu, H. Xu, Y.X. Tong, G.R. Li, Palladium-cobalt nanotube
arrays supported on carbon fiber cloth as high-performance flexible electrocatalysts
for ethanol oxidation, Angew. Chem. Int. Ed. Engl. 54 (12) (2015) 1–6, https://doi.
org/10.1002/anie.201410792.
Investigation. Zhiliang Zhao: Data curation. Yongzhao Wang: Data
curation, Software. Juan Wang: Writing - review & editing. Dengchao
Peng: Visualization. Baiyu Li: Supervision. Tingting Bo: Data curation.
Kang Zheng: Validation. Zhiyuan Zhou: Software. Lin Lv: Validation.
Zhiling Xin: Supervision. : . Bingsen Zhang: Supervision, Funding
acquisition. Lidong Shao: Conceptualization, Resources, Funding ac-
quisition.
14] L. Wang, Y. Wang, A. Li, Y. Yang, Q. Tang, H. Cao, T. Qi, C. Li, Electrocatalysis of
carbon black- or poly(diallyldimethylammonium chloride)-functionalized activated
carbon nanotubes-supported Pd-Tb towards methanol oxidation in alkaline media,
J. Power Sources 257 (2014) 138–146, https://doi.org/10.1016/j.jpowsour.2014.
0
1.109.
[
[
15] L.X. Ding, A.L. Wang, G.R. Li, Z.Q. Liu, W.X. Zhao, C.Y. Su, Y.X. Tong, Porous Pt-Ni-
P composite nanotube arrays: highly electroactive and durable catalysts for me-
thanol electrooxidation, J. Am. Chem. Soc. 134 (13) (2012) 5730–5733, https://
doi.org/10.1021/ja212206m.
Declaration of Competing Interest
16] V. Celorrio, M.G. Montes de Oca, D. Plana, R. Moliner, D.J. Fermín, M.J. Lázaro,
Electrochemical performance of Pd and Au-Pd core-shell nanoparticles on surface
tailored carbon black as catalyst support, Int. J. Hydrogen Energ. 37 (8) (2012)
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influ-
ence the work reported in this paper.
7
152–7160, https://doi.org/10.1016/j.ijhydene.2011.12.014.
[
[
17] A.K. Geim, K.S. Novoselov, The rise of graphene, Nanosci. Tech. (2009) 11–19,
https://doi.org/10.1142/9789814287005_0002.
18] L. Shao, T.W. Lin, G. Tobias, M.L.H. Green, A simple method for the containment
and purification of filled open-ended single wall carbon nanotubes using C60 mo-
lecules, Chem. Commun. 18 (2008) 2164–2166.
Acknowledgements
This work was supported by the Science and Technology
Commission of Shanghai Municipality (No. 14DZ2261000) and
National Natural Science Foundation of China (No. 51802190).
Dr. Bingsen Zhang acknowledges the financial support provided by
the National Natural Science Foundation of China (No. 51932005) and
Liao Ning Revitalization.
[19] H. Zhang, Ultrathin two-dimensional nanomaterials, ACS Nano 9 (2015)
9439–9451, https://doi.org/10.1021/acsnano.5b05040.
[
20] B. Zhang, X. Ni, W. Zhang, L. Shao, Q. Zhang, F. Girgsdies, C. Liang, R. Schlögl,
D.S. Su, Structural rearrangements of Ru nanoparticles supported on carbon na-
notubes under microwave irradiation, Chem. Commun. 47 (2011) 10716–10718.
[21] S. Bai, C. Wang, W. Jiang, N. Du, J. Li, J. Du, R. Long, Z. Li, Y. Xiong, Etching
approach to hybrid structures of PtPd nanocages and graphene for efficient oxygen
reduction reaction catalysts, Nano Res. 8 (9) (2015) 2789–2799.
[
22] X. Huang, L. Shao, G.W. She, M. Wang, S. Chen, X.M. Meng, Catalyst-free synthesis
of single crystalline ZnO nanonails with ultra-thin caps, CrystEngComm 14 (2012)
Appendix A. Supplementary data
8
330–8334.
[
23] W. Zhang, W. Zheng, Single atom excels as the smallest functional material, Adv.
Func. Mater. 26 (2016) 2988–2993, https://doi.org/10.1002/adfm.201600240.
Supplementary data to this article can be found online at https://
doi.org/10.1016/j.chemphys.2020.110753.
[24] C. Zhang, W. Zhang, N.E. Drewett, X. Wang, S.J. Yoo, H. Wang, T. Deng, J. Kim,
H. Chen, K. Huang, S. Feng, W. Zheng, Integrating catalysis of methane decom-
O
position and electrocatalytic hydrogen evolution with Ni/Ce 2 for improved hy-
References
drogen production efficiency, ChemSusChem 12 (2019) 1000–1010, https://doi.
org/10.1002/cssc.201802618.
[
25] M.M. Demir, M.A. Gulgun, Y.Z. Menceloglu, B. Erman, S.S. Abramchuk,
E.E. Makhaeva, A.R. Khokhlov, V.G. Matveeva, M.G. Sulman, Palladium nano-
[
[
[
1] L. An, T.S. Zhao, Transport phenomena in alkaline direct ethanol fuel cells for
sustainable energy production, J. Power Sources 341 (2017) 199–211, https://doi.
org/10.1016/j.jpowsour.2016.11.117.
2
particles by electrospinning from Poly(acrylonitrile-co-acrylic acid)-PdCl solu-
tions. Relations between preparation conditions, particle Size, and catalytic ac-
tivity, Macromolecules 37 (2004) 1787–1792, https://doi.org/10.1021/
ma035163x.
2] E. Antolini, Pt-Ni and Pt-M-Ni (M=Ru, Sn) anode catalysts for low-temperature
acidic direct Alcohol Fuel Cells: A Review, Energies 10 (1) (2017) 1–20, https://doi.
org/10.3390/en10010042.
[
[
[
26] P. Wang, G. Zhang, H. Jiao, L. Liu, X. Deng, Y. Chen, X. Zheng, Pd/graphene na-
nocomposite as highly active catalyst for the Heck reactions, Appl. Catal. A 489
3] K. Jiang, P. Wang, S. Guo, X. Zhang, X. Shen, G. Lu, D. Su, X. Huang, Ordered PdCu-
based nanoparticles as bifunctional oxygen-reduction and ethanol-oxidation elec-
trocatalysts, Angew. Chem. Int. Ed. 55 (2016) 1–7, https://doi.org/10.1002/anie.
(
2015) 188–192, https://doi.org/10.1016/j.apcata.2014.10.044.
27] H. Gao, L. He, Y. Zhang, S. Zhang, L. Wang, Facile synthesis of Pt nanoparticles
supported on graphene/Vulcan XC-72 carbon and their application for methanol
oxidation, Ionics 23 (2) (2016) 435–442.
2
01603022.
[
4] C. Xu, Y. Liu, D. Yuan, Pt and Pd supported on carbon microspheres for alcohol
electrooxidation in alkaline media, Int. J. Electrochem. Sci. 2 (2007) 647–680
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.653.6378&rep=rep1
28] M.M. Lucchese, F. Stavale, E.H.M. Ferreira, C. Vilani, M.V.O. Moutinho, R.B. Capaz,
C.A. Achete, A. Jorio, Quantifying ion-induced defects and Raman relaxation length
in graphene, Carbon 48 (5) (2010) 1592–1597, https://doi.org/10.1016/j.carbon.
&type=pdf.
[
3
5] W. Wang, W. Jing, L. Sheng, D. Chai, Y. Kang, Z. Lei, Pd Cu coupling with nitrogen-
2
009.12.057.
doped mesoporous carbon to boost performance in glycerol oxidation, Appl. Catal.
A 538 (2017) 123–130, https://doi.org/10.1016/j.apcata.2017.03.027.
[
[
29] W. Zhou, J. Lee, Particle size effects in Pd-catalyzed electrooxidation of formic acid,
J. Phys. Chem. C 112 (2008) 3789–3793, https://doi.org/10.1021/jp077068m.
30] H. Meng, S. Sun, J.P. Masse, J.P. Dodelet, Electrosynthesis of Pd single-crystal
[
6] W. Wang, Y. Dong, L. Xu, W. Dong, X. Niu, Z. Lei, Combining bimetallic-alloy with
selenium functionalized carbon to enhance electrocatalytic activity towards glucose
6

J. Zhang, et al.
nanothorns and their application in the oxidation of formic acid, Chem. Mater. 20
Chemical Physics 534 (2020) 110753
[38] H. Hu, Z. Zhao, W. Wan, Y. Gogotsi, J. Qiu, Ultralight and highly compressible
graphene aerogels, Adv. Mater. 25 (15) (2013) 2219–2223, https://doi.org/10.
1002/adma.201204530.
(
2008) 6998–7002, https://doi.org/10.1021/cm8014513.
[
31] H.F. Wang, W.E. Kaden, R. Dowler, M. Sterrer, H.J. Freund, Model oxide-supported
metal catalysts-comparison of ultrahigh vacuum and solution based preparation of
Pd nanoparticles on a single-crystalline oxide substrate, Phys. Chem. Chem. Phys.
[39] J. Mao, J. Iocozzia, J. Huang, K. Meng, Y. Lai, Z. Lin, Graphene aerogels for efficient
energy storage and conversion, Energ. Environ. Sci. 11 (4) (2018) 772–799.
[40] C. Batchelor-McAuley, L. Shao, G.G. Wildgoose, M.L.H. Green, R.G. Compton, An
electrochemical comparison of manganese dioxide microparticles versus α and β
manganese dioxide nanorods: mechanistic and electrocatalytic behaviour, New J.
Chem. 32 (2008) 1195–1203.
1
4 (32) (2012) 11525–11533.
[
[
[
[
[
[
32] W.H. Lee, P.J. Reucroft, Vapor adsorption on coal- and wood-based chemically
activated carbons: (I) Surface oxidation states and adsorption of H O, Carbon 37 (1)
2
(
2007) 7–14, https://doi.org/10.1016/S0008-6223(98)00181-X.
33] K.A. Wepasnick, B.A. Smith, J.L. Bitter, D. Howard Fairbrother, Chemical and
structural characterization of carbon nanotube surfaces, Anal. Bioanal. Chem. 396
[41] G.R. Zhang, B.Q. Xu, Surprisingly strong effect of stabilizer on the properties of Au
nanoparticles and Pt^Au nanostructures in electrocatalysis, Nanoscale 2 (12) (2010)
2798–2804.
(
3) (2010) 1003–1014.
34] K. Zhang, B.T. Ang, L.L. Zhang, X.S. Zhao, J. Wu, Pyrolyzed graphene oxide/re-
sorcinol-formaldehyde resin composites as high-performance supercapacitor elec-
trodes, J. Mater. Chem. 21 (8) (2011) 2663–2670.
[42] S. Kabir, A. Serov, K. Artyushkova, P. Atanassov, Design of novel graphene mate-
rials as a support for palladium nanoparticles: highly active catalysts towards
ethanol electrooxidation, Electrochim. Acta 203 (2016) 144–153, https://doi.org/
10.1016/j.electacta.2016.04.026.
35] Z.X. Liang, T.S. Zhao, J.B. Xu, L.D. Zhu, Mechanism study of the ethanol oxidation
reaction on palladium in alkaline media, Electrochimica Acta 54 (2009)
[43] J.C. Ng, C.Y. Tan, B.H. Ong, A. Matsuda, Effect of synthesis methods on methanol
oxidation reaction on reduced graphene oxide supported palladium electrocatalysts,
Procedia Eng. 184 (2017) 587–594, https://doi.org/10.1016/j.proeng.2017.04.
143.
2
203–2208, https://doi.org/10.1016/j.electacta.2008.10.034.
36] R. Pattabiraman, Electrochemical investigations on carbon supported palladium
catalysts, Appl. Catal. A 153 (1997) 9–20, https://doi.org/10.1016/S0926-860X
(
96)00327-4.
5
[44] Z. Zhuang, W. Chen, Ultra-low loading of Pd nanoclusters on carbon nanotubes as
37] X. Chen, B. Su, G. Wu, C.J. Yang, Z. Zhuang, X. Wang, X. Chen, Platinum nano-
flowers supported on graphene oxide nanosheets: their green synthesis, growth
mechanism, and advanced electrocatalytic properties for methanol oxidation, J.
Mater. Chem. 22 (2012) 11284–11289.
bifunctional electrocatalysts for the oxygen reduction reaction and the ethanol
oxidation reaction, J. Colloid Interface Sci. 538 (2019) 699–708, https://doi.org/
10.1016/j.jcis.2018.12.015.
7