Confined Ultrathin Pd-Ce Nanowires with Outstanding Moisture and SO2 Tolerance in Methane Combustion

Article abstract of DOI:10.1002/anie.201803393

An efficient strategy (enhanced metal oxide interaction and core–shell confinement to inhibit the sintering of noble metal) is presented confined ultrathin Pd-CeO_x nanowire (2.4 nm) catalysts for methane combustion, which enable CH₄ total oxidation at a low temperature of 350 °C, much lower than that of a commercial Pd/Al₂O₃ catalyst (425 °C). Importantly, unexpected stability was observed even under harsh conditions (800 °C, water vapor, and SO₂), owing to the confinement and shielding effect of the porous silica shell together with the promotion of CeO₂. Pd-CeO_x solid solution nanowires (Pd-Ce NW) as cores and porous silica as shells (Pd-CeNW@SiO₂) were rationally prepared by a facile and direct self-assembly strategy for the first time. This strategy is expected to inspire more active and stable catalysts for use under severe conditions (vehicle emissions control, reforming, and water–gas shift reaction).

Full text of DOI:10.1002/anie.201803393

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
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Accepted Article
Title: Confined Ultrathin Pd-Ce Nanowires with Outstanding Moisture-
and SO2- Tolerance in Methane Combustion
Authors: Honggen Peng, Cheng Rao, Ning Zhang, Xiang Wang,
Wenming Liu, Wenting Mao, Lu Han, Pengfei Zhang, and
Sheng Dai
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201803393
Angew. Chem. 10.1002/ange.201803393
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10.1002/anie.201803393
Angewandte Chemie International Edition
COMMUNICATION
Confined Ultrathin Pd-Ce Nanowires with Outstanding Moisture-
and SO2- Tolerance in Methane Combustion
Honggen Peng,a, b† Cheng Rao,a† Ning Zhang,a Xiang Wang, a Wenming Liu,a Wenting Mao,c Lu Han,c
Pengfei Zhang c, d, * and Sheng Dai b, d, *
Abstract: Pd-CeOx solid solutions have demonstrated promising
performance in industrial and environmental catalysis. However,
challenges such as severe growth and aggregation of Pd and ther-
mal-, vapor- or SO2-induced poisoning still obstruct their path toward
real-world applications. Herein we develop an efficient strategy (en-
hanced metal-oxide interaction and core-shell confinement to inhibit
the sintering of noble metal) for design and synthesis of confined ul-
trathin Pd-CeOx nanowire (2.4 nm) catalysts for methane combustion,
which enable CH4 total oxidation at a low temperature of 350C,
much lower than that (425C) of a commercial Pd/Al2O3 catalyst. Im-
portantly, unexpected stability was observed even under harsh con-
ditions (e.g., 800C, water vapor, and SO2), owing to the confinement
and shielding effect of the porous silica shell together with the pro-
motion of CeO2. Pd-CeOx solid solution nanowires (Pd-Ce NW) as
cores and porous silica as shells (Pd-CeNW@SiO2) were rationally
prepared by a facile and direct self-assembly strategy for the first
time. This strategy is expected to inspire more active and stable cat-
alysts for use under severe conditions (e.g., vehicle emissions con-
trol, reforming, and water gas shift reaction).
is somewhat limited, and the high surface energy of Pd nano-
species often leads to the sintering and growth of Pd during high-
temperature process.[1b, 3]
Cerium oxide has been used in catalytic methane combustion
as a robust support material.[4] It exhibits excellent redox proper-
ties as well as outstanding oxygen storage capacity.[4b, 5] The Pd-
CeO2 catalytic system is especially attractive for its high activity
and stability in CH4 combustion, which is contributed by not only
the active component (PdOx) but also the strong Pd-CeO2 inter-
action.[6] Considering the similar radius of the Pd2+ ion (0.86 Å)
and the Ce4+ ion (0.87 Å), the formation of the solid solution or
highly dispersed Pd-Ce-O mixed oxide is considerably enhanced,
which can generate more surface oxygen vacancies and under-
coordinated oxygen atoms.[7] Accordingly, the catalytic activity
and the thermal stability of ceria supported noble metal catalysts
for methane combustion can be greatly improved.[8] Encapsula-
tion of metal nanoparticles (NPs) into a nanoporous shell to as-
semble a core@shell structure is an effective strategy to resist
particle aggregation and to protect active centers from poisoning
species.[9] It could restrain the contact between metal NPs to
keep active sites stable even under harsh conditions, meanwhile
allowing the free diffusion of reactant molecules into and out of
the shells.[9c] Cargnello et al. reported a catalyst with PdO encap-
sulated in small cerium oxide NPs, which showed high thermal
stability for inhibiting the sintering of Pd nanoparticles in methane
combustion.[2c] However, the pure CeO2 shell was not stable at
high reaction temperatures and was subjected to sintering.[1c]
Natural gas is widely used in power generation and other heating
applications on account of its abundance worldwide and its high
hydrogen/carbon ratio. Methane, the main component of natural
gas, is known to be a serious greenhouse gas with an effect
about 20 times that of CO2.[1] Catalytic total combustion of me-
thane at low temperature is an effective method of preventing it
from polluting the atmosphere. It is widely acknowledged that
palladium (Pd)-based catalysts are the most active ones for me-
thane combustion.[2] However, the catalytic activity of Pd alone
[a]
[b]
Dr. H.-G. Peng, C. Rao, Prof. N. Zhang, W. Liu and X. Wang
Institute of Applied Chemistry, College of Chemistry
Nanchang University
Nanchang 330031 (P.R. China)
Dr. H.-G. Peng and Prof. S. Dai
Chemical Sciences Division
Oak Ridge National Laboratory
Oak Ridge, TN 37830 (United States)
E-mail: dais@ornl.gov
[c]
[d]
Prof. P.-F. Zhang and L. Han, W. T. Mao
School of Chemistry and Chemical Engineering
Shanghai Jiao Tong University
Shanghai 200240 (P.R. China)
E-mail: chemistryzpf@sjtu.edu.cn
Dr. P.-F. Zhang, Prof. S. Dai
Scheme 1 Formation process and catalytic application of Pd-CeNW@SiO2.
Department of Chemistry
University of Tennessee
To combine the unique characteristics of the Pd-CeO2 solid
solution or highly dispersed Pd-Ce mixed oxide with the en-
hanced metal-oxide interaction and the confinement effect of
Knoxville, TN 37996 (United States)
School of Chemistry and Chemical Engineering
Shanghai Jiao Tong University
†
These authors contributed equally to this work
This artiTchleis aisrticplerios tperoctetcetedd bbyycocpoyrpigyhtr.iAglhl rtig.hAtslrlersiegrvhedts. reserved.

10.1002/anie.201803393
Angewandte Chemie International Edition
COMMUNICATION
core-shell structured materials, in this communication, we devel-
oped an all-in-one versatile strategy to design high-performance
catalysts for CH4 total combustion (Scheme 1). Briefly, the aque-
ous solution of Pd(NH3)4(NO3)2 and Ce(NO3)3 was added into cy-
clohexane mixed with the surfactant NP-5 (polyethylene glycol
mono-4-nonylphenyl ether) solvent to form the micro-emulsion
system and then ammonia added to form the ultrathin Pd-Ce-
O(H)x nanowires. Lastly, the silica source tetraethoxysilane
(TEOS) was introduced to grow around the initially formed Pd-
Ce nanowires to form the elongated morphology (Scheme S1).
The as-prepared product was calcined at 600 °C in air to obtain
the final Pd-CeNW@SiO2 catalyst. The detailed synthesis proto-
col was presented in the supporting information (Experimental
section). The Pd-CeNW@SiO2 catalyst with untrathin Pd-Ce-O
solid solution nanowire (2.4 nm in width) as the core and mi-
croporous silica as the shell showed excellent performance in
methane combustion due to the microporous shell protected the
active sites from sintering, and the strong Pd-CeO2 interaction
played a significant role in the remarkable performance for me-
thane catalytic combustion.
(a)
(b)
Dwidth,core=2.40 nm
d=0.31 nm
d=0.26 nm
50 nm 0 1 2 3 4 5 6 7 8
5 nm
Core Width (nm)
100 (d)
(c)
Si
80
O
60
40
20
0
Pd
Ce
0
10 20 30 40 50 60
Position (nm)
The morphologies of Pd-CeNW@SiO2 were initially identified
by transmission electron microscopy (TEM); the results are
shown in Figure 1a. It can be seen that worm-like Pd-Ce nan-
owires are encapsulated inside the microporous silica shell to
form the special elongated morphology and the average width of
a nanowire is approximately 2.40 nm (Figure 1a inset), which is
one of the smallest Ce based nanowires. For comparison, Pd-
Ce supported on silica spheres as a reference catalyst was also
prepared via the conventional wet impregnation method (Pd-
Ce/SiO2). The Pd-Ce-O composite oxides spread out on the sil-
ica surface and were much larger, with a mean particle size of
5.35 nm (Figure S1). From the high resolution TEM (HRTEM)
image of Pd-CeNW@SiO2 (Figure 1b and S2), the lattice spac-
ings derived from Fast Fourier Transform (FFT) of 0.31 nm and
0.26 nm can be clearly observed. For the lattice spacing of 0.31
nm, it is difficult to distinguish whether it belongs to CeO2 (111)
or PdO (100); and for the other lattice spacing of 0.26 nm is also
difficult to distinguish whether it belongs to PdO (101) or CeO2
(200) due to the highly dispersed Pd-Ce mixed oxide or solid so-
lution structure. High-angle annular dark field scanning TEM
(HAADF-STEM) image and line scanning profiles of Pd-
CeNW@SiO2 are displayed in Figure 1 (c, d). The Pd and ce-
rium (Ce) signals have the same intensity in the same position,
demonstrating that Pd and Ce atoms are evenly dispersed in the
center of the particle. It is evidently verified that the highly dis-
persed Pd-Ce mixed oxides were formed. Moreover, silicon and
oxygen have a stronger intensity than the Pd and Ce signals,
evidencing the formation of the Pd-Ce nanowire core and SiO2
shell structures.
Pd 3d
Ce3d
(f)
(e)
Pd 3d
5/2
337.28
Pd 3d
3/2
342.58
Pd-Ce/SiO2
Pd-Ce/SiO2
Enlarged signals of Pd-CeNW@SiO2
Pd-CeNW@SiO2
Pd-CeNW@SiO2
345
340
335
330
920
900
880
Binding Energy (eV)
Binding Energy (eV)
Figure 1 (a) TEM (inset is the width distribution of Pd-Ce-O nanowires); (b)
HRTEM images; (c) HAADF-STEM image; (d) line scan and (e, f) XPS profiles
of Pd-CeNW@SiO2 and related catalysts.
The X-ray photoelectron spectroscopy (XPS) spectra of Pd-
CeNW@SiO2 and Pd-Ce/SiO2 samples were collected, as the
results shown in Figure 1 (e, f), to study their surface composi-
tion. The compositions of both samples were subjected to quan-
tification analysis (XPS and inductively coupled plasma spec-
troscopy [ICP]); the results are summarized in Table S1. ICP re-
sults showed that Pd and Ce bulk contents were similar in Pd-
CeNW@SiO2 and Pd-Ce/SiO2 samples. However, the XPS re-
sults showed a great difference. The surface content measured
by XPS is lower than that measured by ICP, indicating that Pd
and Ce are mainly distributed in the center of Pd-CeNW@SiO2
core-shell sample, which matches well with the results of TEM
and line scanning analysis. Compared with the Pd-Ce/SiO2 sam-
ple, the Pd-CeNW@SiO2 sample showed weaker Pd 3d and Ce
3d signals. Peaks with binding energy at 342.58 eV (Pd 3d3/2
)
and 337.28 eV (Pd 3d5/2) were assigned to the oxidized Pd spe-
cies (Pd(II)).[9b, 10]
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10.1002/anie.201803393
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COMMUNICATION
same broad peaks as the amorphous silica, and a strong diffrac-
tion peak at 33.8 is attributed to the PdO (JCPDS NO.41-1445),
meaning that the sample has larger PdO crystalline sizes than
Pd-CeNW@SiO2 and Pd@SiO2, which is well in line with TEM
results.
(a)
(b)
(d)
Pd-L
The N2 adsorption-desorption isotherm curves are shown in
Figure 2e and the quantification results are listed in Table S2.
Pd-CeNW@SiO2 displays typical type IV isotherms with H1 hys-
teresis loops, which are evidenced by the presence of the capil-
lary condensation step at P/P0 = 0.8 -1.0. The pore size distribu-
tion (Figure 2f) showed the sample possessing both mesopores
(36.3 nm) and some intraparticle micropores (1.4 nm). The mi-
cropores attributed to the structure directing agent (NP-5) were
also existed in the SiO2 and Pd@SiO2 samples (Figure S4). The
reactants (CH4 and O2) and products (CO2 and H2O) were able
to easily access and leave the active Pd-Ce-O sites through
these micropores. The mesopores resulting from the accumula-
tion of the silica nanospheres show a slight difference, which
may be due to the addition of Pd or Ce precursors that changed
the size and morphology of the silica shell.
50 nm
(c)
Ce-L
Pd-Ce overlapped
600
500
400
300
200
100
0
2.2
2.0
1.8
36.3
60
40
20
0
(e)
(f)
(a)100
10.0
(b)
Pd-Ce NW@SiO2
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
50
100
50
1.36
Pd@SiO2
P
d-Ce
0.0 0.2 0.4
P
d@S
1.0
0.1
C
N
ommerci
W@SiO
i
O
2
0.49
1.4
100
50
Pd/Al
Commercial catalyst
Pd/Al2O3
al
2
Pd-CeNW@SiO2
0.6 0.8 1.0
catalyst
O
3
2
0.13
0.0
0.2
0.4
1
10
100
0
1.6
1.7
1.8
1.9
2.0
200 300 400 500 600 700 800
Temperature (oC)
Relative pressure (P/P0)
Pore Diameter(nm)
1/T (10-3K-1)
800 o
C
(c)
445 o
C
(d)
100
80
60
40
20
0
100
Figure 2. (a) HAADF-STEM image; (b, c and d) EDX mapping and (e, f) N2
310 o
C
80
60
40
20
0
375 o
C
adsorption/desorption isotherm and pore size distribution of Pd-CeNW@SiO2.
without adding water vapour
with 5 vol. % water vapour
Further information about the spatial distribution of Pd and
Ce in Pd-CeNW@SiO2 catalyst was provided by HAADF-STEM
and EDX-mapping images. Figure 2b-d show the Pd and Ce
mappings and their overlap, respectively. These mappings give
direct evidence of the homogeneous distribution of Pd and Ce
atoms in every particle in the same position. All of the Pd-Ce
nanowires are totally encapsulated in silica nanoshells, as can
be clearly witnessed in the HAADF-STEM image (Figure 2a).
The mapping pictures (Figure 2b, c and d) show clearly that Pd
is mixed and coexists closely with Ce, which is further verified
that the sample with highly dispersed Pd-Ce-O oxides or solid
solution nanowire as a core and microporous silica as a shell
was successfully prepared.
To obtain the phase composition and crystal structure of the
Pd-CeNW@SiO2 sample, X-ray diffraction (XRD) technique was
chosen. As shown in Figure S3, Pd-CeNW@SiO2 displays a
broad peak in the 2θ range of 15 - 35, which was assigned to
the amorphous silica. No diffraction peaks related to Pd species
were detected, which was similar to that of Pd@SiO2. The result
is consistent with the TEM images showing the particle size of
PdOx or Pd-Ce-O is ultra-small. The Pd-Ce/SiO2 sample has the
0
5
10
15
20
25
0
10
20
30
50
Time on stream (h) 40
Time on stream (h)
Figure 3. (a) Heating and cooling (5C min-1) light-off curves of CH4 conversion
against temperature for Pd-CeNW@SiO2 (1.5 wt.Pd%), Pd@SiO2 (1.5
wt.Pd%), and a commercial Pd/Al2O3 catalyst (2.0 wt.Pd%); (b) Arrhenius plots,
(c) high-temperature stability, and (d) water resistance of Pd-CeNW@SiO2.
Conditions: 1% CH4, 21% O2, balanced with N2, WHSV = 36000 mL gcat.-1 h-1.
PdOx is a high-performance catalyst for the CH4 combustion
reaction,[3b, 11] and CeOx has been used successfully as a sup-
port for PdOx to enhance catalytic performance owing to its high
oxygen storage capacity.[2c, 4a, 10] These features motivated us to
explore the CH4 combustion application by current Pd-
CeNW@SiO2 catalyst. For comparison, Pd@SiO2, Pd/Al2O3 (a
commercial catalyst with 2.0 wt.% Pd), and Pd-Ce/SiO2 were
also studied; the results are shown in Figure 3a and Figure S5.
Pd-Ce/SiO2 shows the worst activity due to relatively large Pd or
Pd-Ce particle size; thus, the commercial catalyst (2 wt.%
Pd/Al2O3) was selected as the reference. In detail, the tempera-
tures corresponding to 100% conversion of CH4 to CO2 and H2O
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for Pd-CeNW@SiO2 (red curve), Pd@SiO2 (pink curve), and the
commercial Pd/Al2O3 catalyst (blue curve) catalysts were 350,
375, and 425 °C, respectively (Figure 3 a). Note that the tem-
perature of 50% methane conversion is only 290 °C for Pd-
CeNW@SiO2, which means that it is an excellent low-tempera-
ture methane combustion catalyst. The activity details are listed
in Table S3 and Figure S6. Pd-CeNW@SiO2 and the reference
samples showed stable activity for CH4 combustion over the en-
tire range of temperatures studied (200 - 800 °C) (Figure 3a),
with no decrease in activity during either heating or cooling
curves. By contrast, Pd-CeNW@SiO2 afforded better activity
than Pd@SiO2 and the commercial catalyst (2 wt.%Pd/Al2O3)
during the cooling stage. The enhanced activity of the Pd-
CeNW@SiO2 catalyst may be the result of the strong Pd-CeO2
interaction and the excellent oxygen donation capability of
CeO2.[6d, 6e]
For comparison, the catalytic performances of Pd-based cat-
alysts for CH4 total combustion compared with the state of the
art are presented in Table S4. It can be clearly observed that Pd-
CeNW@SiO2 is one of the best materials for CH4 combustion.
Kinetic rate data verified the very high intrinsic activity of the
catalyst compared with the related catalysts (Figure 3b); the
quantification results are listed in Table S3. The reaction rates
at 275 C on the Pd-CeNW@SiO2 sample were about 2.8 times
higher than those on Pd@SiO2 and 10.5 times higher than on
the commercial catalyst, under conditions of 1% CH4, 21% O2,
balanced with N2, WHSV = 36000 mL gcat.-1 h-1.
celerate CH4 oxidation.[14] In situ DRIFT spectra of CH4 combus-
tion on Pd-CeNW@SiO2 (Figures S11 and S12) showed that
the bands (1120 cm-1) assigning to bicarbonate[5d] increased af-
ter CH4 adsorption with time and disappeared after O2 introduc-
tion. Thus, it is clear that CO2 and H2O is produced from the in-
termediate of adsorbed bicarbonate.
High-temperature stability and water and SO2 tolerance are
crucial parameters for determining the application potential of a
methane combustion catalyst. Therefore, Pd-CeNW@SiO2 was
examined under conditions of high temperature, moisture or SO2
for an extended time, with the results shown in Figure 3 (c and
d) and Figures S18-19. The catalyst displayed outstanding long-
term stability at 310 or 800 C for 50 hours, during which the
methane conversion remained essentially unchanged. Thus, the
Pd-CeNW@SiO2 displayed superior high temperature thermal
stability. Interestingly, the TEM image (Figure S13) of the spent
catalyst at 800 C after 50 hours maintains the initial core-shell
structure, and the core Pd-Ce-O solid solution nanowire is not
sintered clearly. Moreover, the pore volume and pore size of the
catalyst barely changed under the harsh reaction conditions, as
shown by the N2 adsorption/desorption isotherm (Figure S14).
Even more exciting, Pd-CeNW@SiO2 also displayed a preferred
SO2 and water resistance. With 5 vol. % water vapor in methane,
for Pd-CeNW@SiO2, the temperature corresponding to total
conversion of CH4 was 450 C (Figure S15). No evident CH4
conversion decrease was observed during the 24 hours test at
375 or 445 C, indicating the catalyst was structurally stable with
excellent water tolerance (Figure 3d and Figure S16). The TEM
image (Figure S17) of the spent catalyst at 445 C after 24 hours
with 5 vol. % water vapor further proved the point.
Carbon monoxide temperature programmed desorption (CO-
TPD) tests (Figure S8) were used to quantify the metal disper-
sion and the number of exposed active sites on the Pd. The turn-
over-frequency (TOF) values derived from the dispersion of Pd
were listed in Table S3. The TOF values at 275 C for the Pd-
CeNW@SiO2 sample were 2.74 times higher than those for the
Pd@SiO2 sample without ceria.
In the presence of 20 ppm SO2, the catalytic performance fol-
lowed the sequence of Pd-CeNW@SiO2 > Pd@SiO2 > Pd-
Ce/SiO2 (Figures S18 and S19). In situ DRIFT spectra of SO2
adsorption at 450 °C (Figures S20-S22) showed typical bands
at around 1255 and 1110 cm-1 corresponding to palladium sul-
fate[5c] on Pd-Ce/SiO2 and Pd@SiO2, which was the main factor
deactivating Pd-based catalysts when SO2 is contained in the
reaction gas. Obviously, the formation rate and amount of palla-
H2-TPR (temperature programmed reduction) experiments
(Figure S9) were performed to study the redox properties and
strong metal-oxide interactions of Pd-CeNW@SiO2. Pd@SiO2
showed a major reduction peak at 88 C, which was attributed to
the reduction of PdOx to metallic Pd.[12] This reduction peak ob-
served for the Pd-CeNW@SiO2 sample shifts to a higher tem-
perature (120 C) owing to the strong Pd-CeO2 interaction.[6d]
The Pd-CeNW@SiO2 sample showed two additional H2-con-
sumption peaks. These two peaks at 300-400 C and 700-900
oC can be assigned to the reduction of Ce4+ to Ce3+ of the surface
and lattice Ce species, respectively.[13] The H2-TPR of Pd-
Ce/SiO2 consists of two peaks at 60-120 C. The peak at 60 C
is attributed to the reduction of the individual PdO species, while
the peak at 105 C belongs to the reduction of the Pd species
interacting with CeOx. O2-TPD experiments (Figure S10) were
performed to further study the oxygen properties of Pd-
CeNW@SiO2 and Pd@SiO2. Pd-CeNW@SiO2 possessed more
active oxygen species than Pd@SiO2. In brief, the H2-TPR and
O2-TPD results demonstrated that both the activity and the
amount of active oxygen species were higher in Pd-
CeNW@SiO2. These factors are believed to be favorable to ac-
dium sulfate followed the sequence of Pd-CeNW@SiO2
<
Pd@SiO2 < Pd-Ce/SiO2, which is in agreement with SO2 re-
sistance sequence. Thus, it is clear that the porous shell has the
shielding effect for SO2 poison and a protective role for CeO2 on
Pd[15] leading to Pd-CeNW@SiO2 catalyst with excellent SO2 tol-
erance.
Even with simultaneous addition of SO2 and water vapor to
the feed gas at 450 C, methane conversion remained at 100%
during the 10 h test for Pd-CeNW@SiO2 (Figure S23). It seems
fair to say that the catalyst showed superior thermal, H2O stability
and sulfur tolerance. In addition, methane catalytic combustion
activity over Pd-CeNW@SiO2 at a higher weight hourly space
velocity (WHSV) was tested, and the CH4 conversion at 72000
mL gcat.-1 h-1 slightly decreased compared with that at 36000 mL
gcat.-1 h-1 (Figure S24).
In summary, a Pd-CeNW@SiO2 core-shell catalyst with ul-
trathin Pd-Ce-O solid solution or highly dispersed mixed oxide
nanowire as the core and microporous silica as the shell was
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This work is supported by the National Key R&D Program of
China (2016YFC0205900), the National Natural Science
Foundation of China (21503106, 21567016 and 21773106), the
Natural
Science
Foundation
of
Jiangxi
Province
(20171BCB23016 and 20171BAB203024), and the Foundation
of State Key Laboratory of Coal Clean Utilization and Ecological
Chemical Engineering (Grant No. 2016-15). The authors
gratefully acknowledge Dr. Yuan Wang from the University of
New South Wales and Duanjian Tao from the Jiangxi Normal
University for their constructive suggestions during revising this
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Keywords: solid solutions • core-shell • CH4 total oxidation •
strong metal-support interactions • thermal-, vapor- and SO2-
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10.1002/anie.201803393
Angewandte Chemie International Edition
COMMUNICATION
Entry for the Table of Contents
COMMUNICATION
Honggen Peng, Cheng Rao, Ning
Zhang, Xiang Wang, Wenming Liu,
Wenting Mao, Lu Han, Pengfei Zhang *
and Sheng Dai*
One plus one is greater than two.
Double confinement strategy was intro-
duced to design a methane combus-
tion catalyst with ultra-high water and
sulphur tolerance.
Page No. – Page No.
Confined Ultrathin Pd-Ce Nanowires
with Outstanding Moisture- and SO2-
tolerance in Methane Combustion
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This article is protected by copyright. All rights reserved.