Hollow Pd-Sn Nanocrystals for Efficient Direct H2O2 Synthesis: The Critical Role of Sn on Structure Evolution and Catalytic Performance

Article abstract of DOI:10.1021/acscatal.8b00347

The development of efficient catalysts with high activity and selectivity for the direct synthesis of H₂O₂ from H₂ and O₂ is highly desirable yet challenging. Herein, a series of Pd-Sn bimetallic nanocrystals with hollow structure have been successfully created as highly active and selective catalysts for direct H₂O₂ synthesis. We found that the introduction of Sn played an important role on the morphology evolution and composition control of the hollow Pd-Sn nanocrystals. Significantly, after rapid thermal treatment, the obtained hollow Pd-Sn/TiO₂ catalysts can deliver complete inhibition of H₂O₂ decomposition/hydrogenation, resulting in a large activity enhancement for the H₂O₂ production. The H₂ selectivity could be further improved by using water as the reaction solvent. Further investigation showed that the large activity enhancement of hollow Pd-Sn/TiO₂ catalysts for the direct H₂O₂ synthesis can be attributed to the presence of PdO, the ensemble effect between the Pd and Sn, and the interface effect of Pd/SnO_x and PdO/SnO_x.

Full text of DOI:10.1021/acscatal.8b00347

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Hollow Pd-Sn Nanocrystals for Efficient Direct H2O2 Synthesis: The
Critical Role of Sn on Structure Evolution and Catalytic Performance
Fu-min Li, Qi Shao, Mancheng Hu, Yu Chen, and Xiaoqing Huang
ACS Catal., Just Accepted Manuscript • DOI: 10.1021/acscatal.8b00347 • Publication Date (Web): 19 Mar 2018
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ACS Catalysis
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Hollow Pd-Sn Nanocrystals for Efficient Direct H2O2 Synthesis: The
Critical Role of Sn on Structure Evolution and Catalytic Performance
Fumin Li,† Qi Shao,‡ Mancheng Hu,† Yu Chen,*,† and Xiaoqing Huang*,‡
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† Key Laboratory of Macromolecular Science of Shaanxi Province, Key Laboratory of Applied Surface and Colloid
Chemistry (Ministry of Education), School of Chemistry and Chemical Engineering, School of Materials Science and
Engineering, Shaanxi Normal University, Xi’an 710062, China
‡ College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Jiangsu 215123, China
ABSTRACT: The development of efficient catalysts with high activity and selectivity for the direct synthesis of H2O2 from
H2 and O2 is highly desirable yet challenging. Herein, a series of Pd-Sn bimetallic nanocrystals with hollow structure have
been successfully created as highly active and selective catalysts for direct H2O2 synthesis. We found that the introduction
of Sn played an important role on the morphology evolution and composition control of the hollow Pd-Sn nanocrystals.
Significantly, after rapid thermal treatment, the obtained hollow Pd-Sn/TiO2 catalysts can deliver complete inhibition of
H2O2 decomposition/hydrogenation, resulting in a large activity enhancement for the H2O2 production. The H2 selectivity
could be further improved by using water as the reaction solvent. Further investigation showed that the large activity
enhancement of hollow Pd-Sn/TiO2 catalysts for the direct H2O2 synthesis can be attributed to the presence of PdO, the
ensemble effect between the Pd and Sn as well as the interface effect of Pd/SnOx and PdO/SnOx.
KEYWORDS: H2O2 production, hollow structure, activity, selectivity, interface effect
purification, as well as high costs (i.e., Pd-Au bimetallic
INTRODUCTION
catalyst). Thus, it is still a challenge to achieve effecient
Pd-based catalysts for the direct H2O2 production.
Hydrogen peroxide (H2O2) is an important chemical
oxidizing reagent and disinfectant, which is widely used
Recently, Hutchings and co-workers have synthesized a
in medicine, military and industry.1-7 Currently, the main
series of Pd-Sn catalysts by the impregnation-reduction
synthetic methods of H2O2 include electrolysis,
method with enhanced activity and H2 selectivity for the
anthraquinone process, direct hydrogenation of oxygen
direct H2O2 production, promising to replace the
(O2), isopropanol oxidation method and so on. While the
expensive Pd-Au catalysts.18 However, their thermal
anthraquinone process is widely used in industrial
treatment process are multi-step and time-consuming,
production,6, 8-9 it requires abundant poisonous organic
and the activity remains to be further improved. Here, we
compounds.10 Recently, due to the simple process, low
reported the successful creation of hollow Pd-Sn
energy consumption as well as limited environment
bimetallic alloy nanocrystals supported on TiO2 with
pollution, the direct hydrogenation of O2 to H2O2 with
more efficient direct H2O2 synthesis. Through a simple
hydrogen (H2) has received increasing research
rapid thermal treatment process, the degradation of H2O2
interests.11-13 While palladium (Pd) is considered to be a
could be completely inhibited. When water was used as
superior catalyst for the H2O2 production by direct
the reaction medium, high H2 selectivity (80.1%) and
hydrogenation approach, it is also very active towards the
excellent activity (120.1 mol kgcat h–1) could be achieved
–1
H2O2 decomposition/hydrogenation and the H2
simultaneously.
combustion due to the low reaction selectivity, which
largely reduces the utilization of H2 and the efficiency of
RESULTS AND DISCUSSION
the catalysts.14-15 To this end, a great deal of attentions
have been directed to improve the activity and H2
selectivity of Pd-based catalysts for the H2O2 production.
Several conventional strategies, including controlling the
Pd oxidation state, adding H+ and/or halogen ions to the
reaction medium, and forming Pd-based bimetallic
catalysts, have been developed to boost the direct H2O2
synthesis catalysis.16-17 Nevertheless, these approaches are
still not very efficient, since they can also lead to new
problems, such as low catalytic stability, difficult product
Hollow Pd-Sn nanocrystals were obtained through a
facile solvent-thermal method. Their composition and
morphology were readily controlled by tuning the
amount of SnCl2 supplied and the reaction temperature.
Specifically, hollow Pd2Sn, Pd4Sn, and Pd5Sn nanocrystals
were synthesized at 140 °C by using different amounts of
SnCl2. As a contrast, the solid Pd6Sn nanocrystals were
obtained under the same synthetic condition of hollow
Pd2Sn except for a lower reaction temperature of 120 °C.
The ratio of Pd to Sn was determined by the scanning
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electron microscope energy-dispersive X-ray spectroscopy
Page 2 of 7
nanocrystals have a lattice spacing of 0.229 nm, which
corresponds to (013) lattice spacing of intermetallic Pd2Sn
crystal (JCPDS: 89-2057, Figure 1F). In addition, solid
products have a lattice spacing of 0.236 nm that matches
(210) lattice spacing of intermetallic Pd2Sn crystal (JCPDS:
89-2057, Figure 1G). High-angle annular dark-field
scanning TEM (HAADF-STEM) image and EDX elemental
mapping patterns, in consistenting with the PXRD result,
demonstrate that the Pd element and the Sn element
have even distributions (Figure 1H), which confirms the
formation of Pd2Sn intermetallic nanomaterials. The EDX
line scanning of the hollow Pd2Sn nanocrystals displays
the characteristics of the hollow structure (Figure 1I),
which can improve the utilization of Pd.19-23
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(SEM-EDX) and inductively coupled plasma atomic
emission spectroscopy (ICP-AES) (Figure S1 and Table S1).
The typical transmission electron microscopy (TEM)
images of four Pd-Sn nanocrystals show their particle
sizes are about 10~15 nm (Figure 1A-D). It reveals that the
Pd2Sn, Pd4Sn, and Pd5Sn nanocrystals have bright center
and dark edge, suggesting the presence of hollow
structure (yield > 60%), while the Pd6Sn nanocrystals are
solid. The powder X-ray diffraction (PXRD) patterns
exhibit that the Pd4Sn, Pd5Sn, and Pd6Sn nanocrystals
have four distinct diffraction peaks, which can be readily
indexed to the (111), (200), (220), and (311) reflections of
face-centered cubic (fcc) crystal (Figure 1E). Compared
with standard fcc Pd diffraction data (JCPDS: 87-0643),
these diffraction peaks shift towards the lower angle,
which can be attributed to the insertion of Sn with the
larger atomic radius into the Pd lattice. The lattice
expansion indicates the successful formation of Pd-Sn
alloy. Meanwhile, the shift of diffraction peaks increases
with increasing Sn content, which is evident at the high
angle. Moreover, the hollow Pd2Sn nanocrystals with
intermetallic phase (JCPDS: 89-2057) has been obtained,
as revealed by the PXRD pattern (Figure 1E).
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To explore the formation process of hollow Pd2Sn
intermetallic compound, the intermediate products
obtained at different reaction times were investigated.
The time-dependent TEM images and PXRD patterns
were collected and analyzed (Figure 2A and B). Based on
these TEM images, it reveals that hollow nanocrystals
appear in the reaction time between 40 and 80 min, and
the proportion of these hollow nanocrystals increases
during
the
subsequent
reaction.
The
phase
transformation was decoded by the PXRD patterns. In the
initial stage of the reaction (20 min), the Pd(II) precursor
is reduced to Pd nanocrystals. Then, the Sn(II) precursor
is reduced and Pd nanocrystals begin to transform into
Pd-Sn nanocrystals at 40 min, which can be evidenced by
a significant shift of diffraction peak. In the subsequent
reaction time (from 80 to 240 min), Pd-Sn nanocrystals
gradually evolve into intermetallic Pd2Sn nanocrystals.
Therefore, it can be found that 40 min is an important
reaction time node.
To
clarify
the
formation
mechanism,
the
crystallographic texture of intermediate products
obtained at 40 min was further investigated by PXRD
(Figure 2C). After deconvolving the strongest (111)
diffraction peak, two small diffraction peaks were
revealed, indicating two kinds of intermediate Pd-Sn
products, including Sn-deficient and Sn-riched Pd-Sn
alloys. Previous literatures demonstrated that Pd could be
etched by halogen ions and oxygen in reaction system,
followed by the formation of corrosion site.24-26
Meanwhile, the reduction of Sn2+ ions occured at the
corrosion site, which would expand into a hole and
eventually form a hollow structure.24 In other words, the
oxidative etching process of Pd and the reduction of Sn2+
ions synergistically led to the formation of hollow
structure. Based on the PXRD results, we can conclude
that the Sn-deficient Pd-Sn alloy intermediate products
eventually transformed into hollow Pd2Sn intermetallic
nanocrystals because of the subsequent reduction of Sn2+
ions. In contrast, the Sn-riched Pd-Sn alloy intermediate
products will evolve into solid nanocrystals owing to the
lack of Sn2+ reduction process. In addition, a high
temperature (140 °C) and more SnCl2 feed can provide
Figure 1. TEM images of (A) Pd2Sn, (B) Pd4Sn, (C) Pd5Sn,
and (D) Pd6Sn nanocrystals. (E) PXRD patterns of these
four Pd-Sn nanocrystals. HRTEM images of the typical (F)
hollow and (G) solid Pd2Sn nanocrystals. (H)
HAADF-STEM image and EDX elemental mappings of
Pd2Sn nanocrystals. Pd: green, Sn: red. (I) EDX line
scannings of Pd2Sn nanocrystals.
The in-depth characterizations and discussions were
implemented on hollow Pd2Sn nanocrystals as
a
sufficient energy and raw materials for the oxidative
etching process, respectively.25,
Therefore, when the
27
representative sample. High resolution transmission
electron microscopy (HRTEM) image shows the hollow
lower temperature (120 °C) or less SnCl2 feed is applied,
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only solid products can be obtained (Figure 1D and Figure
conversion of H2O2 to H2O, a thermal treatment process
was applied to these catalysts, and hollow Pd5Sn/TiO2
catalyst was selected as the candidate due to its highest
activity. Since the long time thermal treatment leads to
the particle aggregation (Figure S6), the treatment
process was carried out at high temperature (350 °C) for a
short time so as to largely maintain the morphology and
composition of these nanocrystals (Figure S7). With the
increase of treatment time, the reaction of H2O2 to H2O is
effectively inhibited, while the rate of H2O2 production
increases gradually (Figure 3D). When the treatment time
is 6 min, the degradation rate of H2O2 is decreased to 0
mol kgcat–1 h–1, and the activity of H2O2 production reaches
to 160.2 mol kgcat–1 h–1.
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Figure 2. Time-dependent morphology and composition
evolution of Pd2Sn nanocrystals based on (A) TEM images
and (B) PXRD patterns. (C) Enlarged PXRD pattern
obtained at 40 min.
The hollow Pd2Sn nanocrystals supported on TiO2
nanocrystals
(Pd2Sn/TiO2)
were
chosen
as
a
Figure 3. (A) H2O2 productivity of Pd2Sn/TiO2 in different
reaction media. (B) H2O2 productivity of Pd2Sn supported
on different carriers. (C) H2O2 productivity and
degradation of different catalysts under optimized
conditions. (D) H2O2 productivity and degradation of
Pd5Sn/TiO2 under different processing times.
representative sample to investigate the activity and
selectivity of Pd-Sn nanocrystals for the direct H2O2
production (Figure S3A). Detailed procedures for the
direct H2O2 production are shown in the experimental
section. Herein, a mixed solution of methanol and water
was used as the reaction medium. By regulating the ratio
of methanol to water, the highest reactivity is achieved at
a methanol/water ratio of 8 : 2 (Figure 3A). After that,
hollow Pd2Sn nanocrystals loaded on different supports
were also prepared (Figure S4) and invsetiaged for their
catalytic activities. The expermential results show that
hollow Pd2Sn/TiO2 catalyst has the best catalytic activity
(Figure 3B), which can be attributed to the promoting
effect of TiO2 for the direct H2O2 production,28-32 such as
the improved charge transport, owing to Ti3+ species and
Ovacancy defects in bulky TiO2.33 Under this optimized
synthesis condition, the performances of a series of
Pd-Sn/TiO2 catalysts (Figure S3B-D), commercial Pd/C
and Pd/TiO2 catalysts (Figure S5) were also evaluated,
where the hollow Pd5Sn/TiO2 exhibits the highest activity
of 98.4 mol kgcat–1 h–1 (Figure 3C). Compared with Pd/TiO2
catalyst, the enhanced activity of Pd-Sn/TiO2 indicates
that the introduction of Sn improves the activity of Pd for
the the direct H2O2 production. The rate of H2O2
degradation (i.e., the decomposition and hydrogenation
of H2O2) on various catalysts was further investigated,
which showed that all catalysts exhibited high activity for
the conversion of H2O2 to H2O (Figure 3C), which is
detrimental to the H2 selectivity. In order to inhibit the
Although all Pd-Sn/TiO2 catalysts can also exhibit
similar activity change (i.e., the H2O2 production
enhancement and H2O2 degradation inhibition) after the
rapid thermal treatment (Figure 4A), all Pd-Sn/TiO2
catalysts show low H2 selectivity of about 15% (Figure S8).
Considering the complete inhibition of H2O2 degradation
on these catalysts, the low H2 selectivity must be
attributed to the combustion of H2. To improve the H2
selectivity, the ratio of water to methanol was
reconsidered. The results show that the H2 selectivity can
reach to 80.1% in pure water medium with the H2O2
–1
production of 120.1 mol kgcat h–1 at hollow Pd5Sn/TiO2
catalyst (Figure 4B), which is superior to most of the
reported values (Table S2).12, 18, 34-36 Compared with the
mixed medium, the pure water solvent improves the
reaction selectivity, but the catalytic activity is also
reduced. Previous reports showed that the solubility of H2
and O2 in water is far less than that in methanol.37 As a
result, the reduced reactant concentration loses some
catalytic activity but also changes reactive mode of H2 and
O2 with active sites, resuluting in the selectivity
ehancement. Moreover, hollow Pd5Sn/TiO2 catalyst can
exhibit promising stability in both the methanol/water
mixture and pure water (Figure 4C). After 5 reaction
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rounds, the catalytic activity remains more than 80% of
the initial activity. Since TEM image and EDX analysis
show no obvious changes in the morphology and
composition of Pd5Sn nanocrystals (Figure S9), the
deactivation may originate from the mass loss of catalysts
due to the multiple centrifugation.
Page 4 of 7
scission,45-47 a reasonable interface effect is established to
explain the enhanced performance (Figure 5D).
Specifically, Pd or PdO can activate both H2 and O2, but
its high activity often results in O2 splitting, which is not
beneficial for producing H2O2. The SnOx can achieve weak
activation of O2 without breaking the O-O bond.
Therefore, when SnOx adsorbs an O2 and Pd or PdO near
SnOx activate a H2, H2O2 will rapidly generate at Pd/SnOx
and PdO/SnOx interfaces. In this work, CTAB is used in
Pd-Sn nanocrystals synthesis, and Br– has been identified
to enhance catalytic performance for the H2O2
production.37 Therefore, XPS analysis was used to detect
the presence of Br–. The results show that there is no Br
on the surface of Pd5Sn/TiO2 (Figure S11), which also
proves once again that Sn plays a key role in improving
catalytic performance of Pd-Sn/TiO2 catalysts for the
H2O2 production.
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Figure 4. (A) H2O2 productivity and degradation of
different catalysts after rapid thermal treatment at 350°C
for 6 min. (B) H2 selectivity and H2O2 productivity of
Pd5Sn/TiO2 in different reaction media. (C) Recycling
performance of Pd5Sn/TiO2 in the methanol/water
mixture and pure water.
Since the H2O2 generation reaction occurred on the
surface of catalyst, the surface-sensitive X-ray
photoelectron spectroscopy (XPS) was used to reveal the
structure-activity relationship of these Pd-Sn/TiO2
catalysts.38-43 Considering Pd atoms were the main active
sites for the the direct H2O2 production, Pd 3d XPS signal
was analyzed firstly. For Pd5Sn/TiO2, the proportion of
Pd(0) drastically reduces after the thermal treatment
(Figure 5A), which has a major contribution for the H2O2
degradation inhibition.13 The evolution of the Pd chemical
state is also observed in other Pd-Sn/TiO2 (Figure 5B).
Since the thermal treatment induces that the bonding of
both O and Sn atoms on Pd surface, the electronic
structure of Pd will be changed. Considering that the
difference between the electronegativity of O (X=3.44)
and Pd (X=2.20) is much greater than that of Sn (X=1.96)
and Pd (X=2.20),44 the influence of Sn on the Pd
electronic structure may be very weak. Combined with
previous experimental results, it could be found that the
introduction of Sn further strengthens the inhibition,
which should be attributed to the ensemble effect of
Pd-Sn alloy.16 Benefiting from this inhibition, the H2O2
production rate on all the catalysts is improved after the
thermal treatment. The XPS data of Sn element show that
Sn exists mainly in the form of SnOx in the original
Pd5Sn/TiO2 (Figure 5C). Subsequent thermal treatment
results in the increased proportion of SnOx. This
evolution also occurs on other Pd-Sn/TiO2 (Figure S10).
Compared to Pd/TiO2, the introduction of SnOx
fundamentally enhances the activity of Pd-based catalysts
for the H2O2 production. Furthermore, considering that
SnOx is active in adsorbing O2 but inefficient in O O bond
Figure 5. (A) XPS patterns of Pd 3d of Pd5Sn/TiO2 before
and after a thermal treatment within a short time. (B) The
proportion of Pd(0) based on XPS results for several
Pd-Sn/TiO2 before and after a thermal treatment within a
short time. (C) XPS patterns of Sn 3d of Pd5Sn/TiO2
before and after a thermal treatment within a short time.
(D) The illustration of the interface effect in Pd-Sn
catalysts.
CONCLUSIONS
To summarize, we have successfully synthesized a
series of Pd-Sn bimetallic nanocrystals with hollow or
solid structure, which closely related to the amount of
SnCl2 supplied and the reaction temperature. Through a
facile rapid thermal treatment, the complete inhibition of
H2O2 degradation has been achieved on these
Pd-Sn/TiO2; among them, hollow Pd5Sn/TiO2 exhibited
the highest activity for the direct H2O2 production. By
controlling the reaction medium, 80.1% H2 selectivity and
–1
120.1 mol kgcat h–1 activity could be obtained for the
hollow Pd5Sn/TiO2. The enhanced activity of hollow
Pd-Sn/TiO2 can be attributed to the existance of PdO, the
ensemble effect of hollow Pd-Sn, as well as the interface
effect of Pd/SnOx and PdO/SnOx interfaces. Our study
presents a promising Pd-based nanostructure for direct
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Peroxide Using a Novel Membrane Catalyst. Angew. Chem.
Int. Ed. 2001, 40, 1776-1779.
H2O2 synthesis catalysis with excellent activity and
selectivity.
1
(11) Kanungo, S.; Paunovic, V.; Schouten, J. C.; Neira D’Angelo,
M. F., Facile Synthesis of Catalytic AuPd Nanoparticles
within Capillary Microreactors Using Polyelectrolyte
Multilayers for the Direct Synthesis of H2O2. Nano Lett.
2017.
(12) Lari, G. M.; Puertolas, B.; Shahrokhi, M.; Lopez, N.;
Perez-Ramirez, J., Hybrid Palladium Nanoparticles for
Direct Hydrogen Peroxide Synthesis: The Key Role of the
Ligand. Angew. Chem. Int. Ed. 2017, 129, 1801-1805.
(13) Plauck, A.; Stangland, E. E.; Dumesic, J. A.; Mavrikakis, M.,
Active Sites and Mechanisms for H2O2 Decomposition over
Pd Catalysts. Proc. Natl. Acad. Sci. USA 2016, 113, E1973.
(14) Liu, Q.; Bauer, J. C.; Schaak, R. E.; Lunsford, J. H., Supported
Palladium Nanoparticles: An Efficient Catalyst for the Direct
Formation of H2O2 from H2 and O2. Angew. Chem. Int. Ed.
2008, 120, 6317-6320.
(15) Teranishi, M.; Naya, S.-i.; Tada, H., In Situ Liquid Phase
Synthesis of Hydrogen Peroxide from Molecular Oxygen
Using Gold Nanoparticle-Loaded Titanium(IV) Dioxide
Photocatalyst. J. Am. Chem. Soc. 2010, 132, 7850-7851.
(16) Edwards, J. K.; Freakley, S. J.; Carley, A. F.; Kiely, C. J.;
Hutchings, G. J., Strategies for Designing Supported
Gold-Palladium Bimetallic Catalysts for the Direct Synthesis
of Hydrogen Peroxide. Acc. Chem. Res. 2014, 47, 845-854.
(17) Xu, H.; Cheng, D.; Gao, Y., Design of High-Performance
Pd-Based Alloy Nanocatalysts for Direct Synthesis of H2O2.
ACS Catal. 2017, 7, 2164-2170.
(18) Freakley, S. J.; He, Q.; Harrhy, J. H.; Lu, L.; Crole, D. A.;
Morgan, D. J.; Ntainjua, E. N.; Edwards, J. K.; Carley, A. F.;
Borisevich, A. Y., Palladium-tin Catalysts for the Direct
Synthesis of H₂O₂ with High Selectivity. Science 2016, 351,
965-968.
(19) Xia, X.; Wang, Y.; Ruditskiy, A.; Xia, Y., 25th Anniversary
Article: Galvanic Replacement: A Simple and Versatile
Route to Hollow Nanostructures with Tunable and
Well-Controlled Properties. Adv. Mater. 2013, 25, 6313-6333.
(20) Zhu, Y. P.; Ma, T. Y.; Jaroniec, M.; Qiao, S. Z.,
Self-Templating Synthesis of Hollow Co3O4 Microtube
Arrays for Highly Efficient Water Electrolysis. Angew. Chem.
Int. Ed. 2017, 56, 1324-1328.
(21) Huang, H.; Li, K.; Chen, Z.; Luo, L.; Gu, Y.; Zhang, D.; Ma, C.;
Si, R.; Yang, J.; Peng, Z.; Zeng, J., Achieving Remarkable
Activity and Durability toward Oxygen Reduction Reaction
Based on Ultrathin Rh-Doped Pt Nanowires. J. Am. Chem.
Soc. 2017, 139, 8152-8159.
(22) Yu, L.; Wu, H. B.; Lou, X. W. D., Self-Templated Formation
of Hollow Structures for Electrochemical Energy
Applications. Acc. Chem. Res. 2017, 50, 293-301.
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AUTHOR INFORMATION
Corresponding Authors
*E-mail: ndchenyu@gmail.com (Y. C.)
*E-mail: hxq006@suda.edu.cn (X. H.)
Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENT
This work was financially supported by the Ministry of
Science
and
Technology
(2016YFA0204100,
2017YFA0208200), the National Natural Science Foundation
of China (21571135), Young Thousand Talented Program, the
start-up supports from Soochow University, the Priority
Academic Program Development of Jiangsu Higher
Education Institutions (PAPD), Fundamental Research Funds
for the Central Universities (GK201602002 and 2016TS044).
Supporting Information.
This material is available free of charge via the Internet at
http://pubs.acs.org. Experimental details, results of TEM,
EDX, selectivity, XPS, and ICP-AES, and comparison of
performances.
REFERENCES
(1) Bryliakov, K. P., Catalytic Asymmetric Oxygenations with the
Environmentally Benign Oxidants H2O2 and O2. Chem. Rev.
2017, 117, 11406-11459.
(2) Lane, B. S.; Burgess, K., Metal-Catalyzed Epoxidations of
Alkenes with Hydrogen Peroxide. Chem. Rev. 2003, 103,
2457-2474.
(3) Zheng, Z.; Ng, Y. H.; Wang, D.-W.; Amal, R., Epitaxial Growth
of Au-Pt-Ni Nanorods for Direct High Selectivity H2O2
Production. Adv. Mater. 2016, 28, 9949-9955.
(4) Fellinger, T.-P.; Hasché, F.; Strasser, P.; Antonietti, M.,
Mesoporous
Nitrogen-Doped
Carbon
for
the
Electrocatalytic Synthesis of Hydrogen Peroxide. J. Am.
Chem. Soc. 2012, 134, 4072-4075.
(5) Wilson, N. M.; Flaherty, D. W., Mechanism for the Direct
Synthesis of H2O2 on Pd Clusters: Heterolytic Reaction
Pathways at the Liquid-Solid Interface. J. Am. Chem. Soc.
2016, 138, 574-586.
(6) Zhao, S.; Zhao, X.; Zhang, H.; Li, J.; Zhu, Y., Covalent
Combination of Polyoxometalate and Graphitic Carbon
Nitride for Light-driven Hydrogen Peroxide Production.
Nano Energy 2017, 35, 405-414.
(7) Cao, X.; Zeng, Z.; Shi, W.; Yep, P.; Yan, Q.; Zhang, H.,
Three-Dimensional Graphene Network Composites for
Detection of Hydrogen Peroxide. Small 2013, 9, 1703-1707.
(8) Liu, Y.; Quan, X.; Fan, X.; Wang, H.; Chen, S., High-Yield
Electrosynthesis of Hydrogen Peroxide from Oxygen
Reduction by Hierarchically Porous Carbon. Angew. Chem.
Int. Ed. 2015, 54, 6837-6841.
(9) Campos-Martin, J. M.; Blanco-Brieva, G.; Fierro, J. L. G.,
Hydrogen Peroxide Synthesis: An Outlook beyond the
Anthraquinone Process. Angew. Chem. Int. Ed. 2006, 45,
6962-6984.
(23) Li, F.-M.; Zhai, Y.-N.; Wu, Z.-Q.; Li, S.-N.; Lee, J.-M., A Facile
Self-Templated Approach for the Synthesis of Pt Hollow
Nanospheres with Enhanced Electrocatalytic Activity. Adv.
Mater. Interfaces 2016, 3, 1600563-n/a.
(24) Liu, X.; Li, X.; Wang, D.; Yu, R.; Cui, Y.; Peng, Q.; Li, Y.,
Palladium/tin
Bimetallic
Single-crystalline
Hollow
Nanospheres. Chem. Commun. 2012, 48, 1683-1685.
(25) Xiong, Y.; Wiley, B.; Chen, J.; Li, Z.-Y.; Yin, Y.; Xia, Y.,
Corrosion-Based Synthesis of Single-Crystal Pd Nanoboxes
and Nanocages and Their Surface Plasmon Properties.
Angew. Chem. Int. Ed. 2005, 44, 7913-7917.
(26) Fu, G.; Gong, M.; Tang, Y.; Xu, L.; Sun, D.; Lee, J. M., Hollow
and Porous Palladium Nanocrystals: Synthesis and
Electrocatalytic Application. J. Mater. Chem. A 2015, 3,
21995-21999.
(10) Choudhary, V. R.; Gaikwad, A. G.; Sansare, S. D.,
Nonhazardous Direct Oxidation of Hydrogen to Hydrogen
(27) Long, R.; Zhou, S.; Wiley, B. J.; Xiong, Y., Oxidative Etching
for Controlled Synthesis of Metal Nanocrystals: Atomic
ACS Paragon Plus Environment

ACS Catalysis
Page 6 of 7
Addition and Subtraction. Chem. Soc. Rev. 2014, 43,
6288-6310.
(28) Huang, X.; Tan, C.; Yin, Z.; Zhang, H., 25th Anniversary
Article: Hybrid Nanostructures Based on Two-Dimensional
Nanomaterials. Adv. Mater. 2014, 26, 2185-2204.
(38) Ran, J.; Zhu, B.; Qiao, S.-Z., Phosphorene Co-catalyst
Advancing Highly Efficient Visible-Light Photocatalytic
Hydrogen Production. Angew. Chem. Int. Ed. 2017, 56,
10373-10377.
1
2
3
(39) Chen, Y.; Fan, Z.; Luo, Z.; Liu, X.; Lai, Z.; Li, B.; Zong, Y.; Gu,
4
5
6
7
8
9
(29) Wang, L.; Ge, J.; Wang, A.; Deng, M.; Wang, X.; Bai, S.; Li,
R.; Jiang, J.; Zhang, Q.; Luo, Y.; Xiong, Y., Designing p-Type
Semiconductor-Metal Hybrid Structures for Improved
Photocatalysis. Angew. Chem. Int. Ed. 2014, 126, 5207-5211.
(30) Zhou, B.; Song, J.; Zhou, H.; Wu, T.; Han, B., Using the
Hydrogen and Oxygen in Water Directly for Hydrogenation
Reactions and Glucose Oxidation by Photocatalysis. Chem.
Sci. 2016, 7, 463-468.
(31) Zhou, H.; Han, B.; Liu, T.; Zhong, X.; Zhuang, G.; Wang, J.,
Selective Phenol Hydrogenation to Cyclohexanone over
Alkali-metal-promoted Pd/TiO2 in Aqueous Media. Green
Chem. 2017, 19, 3585-3594.
(32) Zhang, J.; Wang, B.; Nikolla, E.; Medlin, J. W., Directing
Reaction Pathways through Controlled Reactant Binding at
Pd-TiO2 Interfaces. Angew. Chem. Int. Ed. 2017, 56,
6594-6598.
(33) Hoang, S.; Berglund, S. P.; Hahn, N. T.; Bard, A. J.; Mullins,
C. B., Enhancing Visible Light Photo-oxidation of Water
with TiO2 Nanowire Arrays via Cotreatment with H2 and
NH3: Synergistic Effects between Ti3+ and N. J. Am. Chem.
Soc. 2012, 134, 3659-3662.
(34) Sankar, M.; He, Q.; Morad, M.; Pritchard, J.; Freakley, S. J.;
Edwards, J. K.; Taylor, S. H.; Morgan, D. J.; Carley, A. F.;
Knight, D. W.; Kiely, C. J.; Hutchings, G. J., Synthesis of
Stable Ligand-free Gold-Palladium Nanoparticles Using a
Simple Excess Anion Method. ACS Nano 2012, 6, 6600-6613.
(35) Ouyang, L.; Da, G.-j.; Tian, P.-f.; Chen, T.-y.; Liang, G.-d.;
Xu, J.; Han, Y.-F., Insight into Active Sites of Pd-Au/TiO2
Catalysts in Hydrogen Peroxide Synthesis Directly from H2
and O2. J. Catal. 2014, 311, 129-136.
(36) Edwards, J. K.; Hutchings, G. J., Palladium and
Gold-Palladium Catalysts for the Direct Synthesis of
Hydrogen Peroxide. Angew. Chem. Int. Ed. 2008, 47,
9192-9198.
L.;
Zhang,
H.,
High-Yield
Synthesis
of
Crystal-Phase-Heterostructured 4H/fcc Au@Pd Core–Shell
Nanorods for Electrocatalytic Ethanol Oxidation. Adv.
Mater. 2017, 29, 1701331.
(40) Hu, F.; Zhu, S.; Chen, S.; Li, Y.; Ma, L.; Wu, T.; Zhang, Y.;
Wang, C.; Liu, C.; Yang, X.; Song, L.; Yang, X.; Xiong, Y.,
Amorphous Metallic NiFeP: A Conductive Bulk Material
Achieving High Activity for Oxygen Evolution Reaction in
Both Alkaline and Acidic Media. Adv. Mater. 2017, 29,
1606570.
(41) Zhao, X.; Zhang, H.; Yan, Y.; Cao, J.; Li, X.; Zhou, S.; Peng, Z.;
Zeng, J., Engineering the Electrical Conductivity of Lamellar
Silver-Doped Cobalt(II) Selenide Nanobelts for Enhanced
Oxygen Evolution. Angew. Chem. Int. Ed. 2017, 56, 328-332.
(42) Gao, Z.; Ye, H.; Tang, D.; Tao, J.; Habibi, S.; Minerick, A.;
Tang, D.; Xia, X., Platinum-Decorated Gold Nanoparticles
with Dual Functionalities for Ultrasensitive Colorimetric in
Vitro Diagnostics. Nano Lett. 2017, 17, 5572-5579.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(43) Li, F.-M.; Gao, X.-Q.; Li, S.-N.; Chen, Y.; Lee, J.-M., Thermal
Decomposition Synthesis of Functionalized PdPt Alloy
Nanodendrites with High Selectivity for Oxygen Reduction
Reaction. NPG Asia Mater. 2015, 7, e219.
(44) Suresh, C. H.; Koga, N., A Molecular Electrostatic Potential
Bond Critical Point Model for Atomic and Group
Electronegativities. J. Am. Chem. Soc. 2002, 124, 1790-1797.
(45) Liu, Y.; Ishihara, A.; Mitsushima, S.; Kamiya, N.; Ota, K. I.,
Transition Metal Oxides as DMFC Cathodes Without
Platinum. J. Electrochem. Soc. 2007, 154, B664-B669.
(46) Punniyamurthy, T.; Velusamy, S.; Iqbal, J., Recent Advances
in Transition Metal Catalyzed Oxidation of Organic
Substrates with Molecular Oxygen. Chem. Rev. 2005, 105,
2329-2364.
(47) Garino, N.; Sacco, A.; Castellino, M.; Muñoz-Tabares, J. A.;
Chiodoni, A.; Agostino, V.; Margaria, V.; Gerosa, M.;
Massaglia, G.; Quaglio, M., Microwave-Assisted Synthesis of
Reduced Graphene Oxide/SnO2 Nanocomposite for Oxygen
Reduction Reaction in Microbial Fuel Cells. ACS Appl.
Mater. Interfaces 2016, 8, 4633-4643.
(37) Samanta, C., Direct Synthesis of Hydrogen Peroxide from
Hydrogen and Oxygen: An Overview of Recent
Developments in the Process. Appl. Catal. A-Gen. 2008, 350,
133-149.
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