Cu single-atoms embedded in porous carbon nitride for selective oxidation of methane to oxygenates

Article abstract of DOI:10.1039/d0cc06492k

Cu single atoms embedded in the C3N4 (Cu-SAs/C3N4) matrix exhibited high activity with 95% oxygenate selectivity for the direct conversion of methane at ambient temperature. The presence of abundant anchoring sites in C3N4 led to highly dispersed Cu-N4 mo

Full text of DOI:10.1039/d0cc06492k

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Cu single-atoms embedded in porous carbon
nitride for selective oxidation of methane to
Cite this: Chem. Commun., 2020,
6, 14677
oxygenates†
ab
5
Received 28th September 2020,
Accepted 31st October 2020
c
a
a
ab
ad
ab
Bo Wu, Ruoou Yang, Lei Shi, Tiejun Lin, Xing Yu, Min Huang, Kun Gong,
c
ce
ad
ad
Fanfei Sun, Zheng Jiang,
Shenggang Li,
Liangshu Zhong
*
and
DOI: 10.1039/d0cc06492k
ad
Yuhan Sun*
rsc.li/chemcomm
3 4 3 4
3
Cu single atoms embedded in the C N (Cu-SAs/C N ) matrix CH OOH in aqueous solution with an oxygenate selectivity of 78%
18
exhibited high activity with 95% oxygenate selectivity for the direct at 70 1C. Wu and co-workers synthesized atomically dispersed
conversion of methane at ambient temperature. The presence of CNT@PNC/Ni SA catalysts for the direct conversion of methane
À1
19
abundant anchoring sites in C
moieties, which were suggested to be the underlying active sites for on TiO
methane conversion. methane conversion with a turnover frequency (TOF) of 2.89 h
3
N
4
led to highly dispersed Cu–N
4
with a TOF value of 1.4 h at 50 1C. Cr single atoms supported
2
(Cr/TiO ) reported by Song et al. were also investigated for
2
À1
15
and 93% oxygenate selectivity at 50 1C. To achieve the activation
Direct conversion of methane has been considered to be the of methane at ambient temperature, Bao and co-workers devel-
‘
‘holy grail’’ of catalysis research in both industrial and academic oped Fe single-atom catalysts (FeN /GN) with an O–FeN –O
4
4
1,2
À1
community, which has attracted much attention in recent years.
The strong C–H bonds (434 kJ mol ), weak adsorption capacity, selectivity at 25 1C, while single Cu atom counterparts were
structure that exhibited a TOF of 0.47 h with 94% oxygenate
À1
À40
2
2
À1
and a rather small polarizability (2.84 Â 10
C m J ) of simultaneously observed to show no catalytic activity under
20
methane make it difficult for methane activation and harsh similar reaction conditions. The high catalytic activity of the
3,4
reaction conditions are always needed. It is highly desirable to target products is not always aligned with excellent selectivity for
develop efficient catalysts for the direct conversion of methane many catalytic systems. The direct conversion of methane to
under mild conditions. However, for catalysts using metal nano- oxygenates with both high catalytic activity and high oxygenate
particles (NPs), the metal utilization efficiency is low. Recently, selectivity under ambient temperature still remains a great bottle-
single-atom catalysts (SACs) have been proposed as an ideal neck for the reported single-atom catalysts. It is highly desirable to
platform to enhance the utilization efficiency of metals with develop new catalysts for selective oxidation of methane to further
5
6–9
10–14
unique catalytic performance for many catalytic reactions.
improve the catalytic activity and the oxygenate selectivity
There are also some studies on using single-atom catalysts to simultaneously.
15–17
catalyze direct methane conversion.
Kwon et al. reported
Herein, we developed a green and facile strategy for the
that atomically dispersed Rh species stabilized on a tetragonal synthesis of atomically dispersed Cu atoms embedded in a
ZrO surface (Rh/ZrO ) could catalyze methane to CH OH and porous C N matrix (Cu-SAs/C N ) using H O as a solvent. The
2
2
3
3
4
3
4
2
as-obtained single Cu atom catalyst can be effectively used to
catalyze the methane conversion to C1 oxygenated products
with a very high TOF (11 h ) and oxygenate selectivity (95%) at
a
CAS Key Laboratory of Low-Carbon Conversion Science and Engineering,
Shanghai Advanced Research Institute, Chinese Academy of Sciences,
Shanghai 201203, China. E-mail: zhongls@sari.ac.cn, sunyh@sari.ac.cn
University of Chinese Academy of Sciences, 19 Yuquan Road, Shijingshan,
Beijing, 100049, China
À1
25 1C, which is much higher than those of most reported
b
c
catalysts. Various advanced characterization techniques and
DFT calculations were applied to elucidate the fine-structure
of active sites, and it was confirmed that Cu-SAs/C N in the
3 4
Shanghai Synchrotron Radiation Facility, Zhangjiang National Lab,
Shanghai Advanced Research Institute, Chinese Academy of Sciences,
Shanghai, 201204, China
form of a Cu–N moiety structure constituted the underlying active
4
d
e
School of Physical Science and Technology, ShanghaiTech University,
Shanghai 201203, China
sites, which contributed to the superior catalytic performance for
methane conversion at ambient temperature.
Shanghai Institute of Applied Physics, Chinese Academy of Sciences,
Shanghai, 201800, China
The methods for the synthesis and characterization of Cu-
3 4
SAs/C N are detailed in the Experimental section. Typically,
†
Electronic supplementary information (ESI) available. See DOI: 10.1039/
d0cc06492k
copper salts, melamine and cyanuric acid were used to produce
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Fig. 1 (a) SEM and (b) TEM images. (c) AC-HAADF-STEM image. The
representative Cu single atoms are highlighted in red cycles. (d) Element
3 4
mapping images of the Cu-SAs/C N catalyst.
Fig. 2 (a) XRD patterns. (b) FT-IR spectra of C
K-edge XANES. (d) Fourier transform (FT) of the Cu K-edge EXAFS spectra of
, Cu foil, Cu O and CuO. (e) Corresponding EXAFS fitting curve
in r space. (f) Cu K-edge XANES experimental spectra for Cu-SAs/C (red)
(black), Cu (orange
3 4 3 4
N and Cu-SAs/C N . (c) Cu
a Cu–melamine–cyanuric complex using H
2
O as the solvent. The Cu-SAs/C
N
3 4
2
3 4
N
as-obtained complex was then calcined under an Ar atmosphere
at 550 1C for 4 h to decompose the metal precursor and anchor
the metal atoms onto C N . For this synthetic strategy, water as a
and the calculated spectra for the proposed Cu–N
pink), N (blue), C (gray) and H (white).
4
3
4
cheap and green solvent was adopted without the usage of
alcohol or toxic organic solvents, such as methanol and dimethyl (FT-IR) of the samples revealed that embedding of the Cu
sulfoxide (DMSO). In addition, no surfactants were added during species had brought negligible structural changes in the CN
2
4
the preparation process. The content of Cu in Cu-SAs/C
measured by inductively coupled plasma optical emission spectro- area of Cu-SAs/C
3
N
4
heterocycles and heptazine rings (Fig. 2b). The specific surface
2
À1
3 4
N was 89.8 m g based on the multipoint
metry (ICP-OES) was 1.0%. The morphology and composition BET method (Fig. S4 and Table S1, ESI†). The N adsorption–
2
distribution of Cu-SAs/C N were then investigated using scanning desorption isotherm of Cu-SAs/C N belonged to type IV (based
3
4
3 4
electron microscopy (SEM), transmission electron microscopy on the IUPAC classification) with a hysteresis loop, indicating
TEM) and aberration corrected high angle annual dark field the existence of mesopores.
scanning transmission electron microscopy (AC-HAADF-STEM). X-Ray absorption spectroscopy was performed to investigate
(
The SEM (Fig. 1a) and TEM images (Fig. 1b) revealed two- the chemical nature and coordination environment of the Cu
dimensional nanosheet structures with abundant nanopores species on the atomic scale. Fig. 2c shows the Cu K-edge X-ray
(
ca. 15–40 nm) of Cu-SAs/C
accommodate a large number of exposed active sites with foil, Cu O and CuO. The XANES spectrum of Cu-SAs/C N
3 4
3 4 3 4
N . The highly porous support might absorption near-edge structure (XANES) of Cu-SAs/C N , Cu
2
enhanced mass-transfer to facilitate the adsorption of methane exhibited similar edge shapes to those of the Cu O and CuO
2
2
1,22
and desorption of the oxygenated products.
STEM image of Cu-SAs/C
in Fig. 1c shows the existence of (Cu , 1 o d o 2) in Cu-SAs/C N . The chemical state of Cu
isolated bright spots corresponding to the Cu single-atoms in Cu-SAs/C N was further investigated by X-ray photoelectron
The AC-HAADF- references, revealing the existence of the Cu oxidized state
d+
3 4
N
3
4
3
4
(
highlighted in red circles) on the C
were detected. The elemental mapping images of Cu-SAs/C
Fig. 1d further confirmed that the Cu species were distributed to Cu .
homogeneously in the C N matrix. For comparison, C N and (EXAFS) spectra of the Cu-SAs/C N catalyst (Fig. 2d) were
3
N
4
matrix, and no Cu NPs spectroscopy (XPS). The Cu 2p3/2 peak located at 932.1 eV and
3 4
N
in the Cu LM2 auger peak at 571.1 eV (Fig. S5, ESI†) were assigned
+
25–27
The extended X-ray absorption fine structure
3
4
3
4
3 4
Cu-NPs/C N4 were prepared using similar processes (Experi- significantly different from those of the bulk references of Cu
3
mental section and Fig. S3, ESI†).
No Cu-containing crystal phases were detected in the X-ray Fig. 2e. No Cu–Cu coordination peak at around 2.2 Å could be
diffraction (XRD) patterns of Cu-SAs/C (Fig. 2a). The two detected, indicating that the Cu atoms were atomically dispersed
peaks located at 131 and 271 were ascribed to the (100) and in the C
2
foil, Cu O and CuO, and the related fitting curves are shown in
3 4
N
2
5
N
3 4
matrix. Cu-SAs/C
3 4
N exhibited a prominent peak at
The Fourier transform infrared spectra 1.5 Å, corresponding to the first shell of Cu–N contribution.
2
3
3 4
(002) planes of C N .
14678 | Chem. Commun., 2020, 56, 14677--14680
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EXAFS fitting was conducted to obtain the quantitative structural as shown in Fig. S8d (ESI†). The chemical state of Cu increased
configuration of Cu in Cu-SAs/C (Table S2, ESI†). The coordi- with the increasing Cu loadings from 0.2% to 1.0%, and the
3 4
N
2
7
À1
nation number (CN) was 4 for the fitted first shell (Cu–N). The TOF value increased from 5.4 to 6.7 h , suggesting that Cu–N4
XANES spectrum of Cu-SAs/C N could be produced by the with a higher Cu chemical state benefits this reaction. As
3
4
corresponding Cu–N4 structure modeled by DFT calculations shown in Table S3 (ESI†), the TOF values for Fe-SAs/C N and
3
4
À1
À1
with the Cu atoms coordinated by four N atoms (Fig. 2f), which Co-SAs/C
3
N
4
were 1.2 h and 1.3 h , respectively. In addition,
À1
almost overlapped with the experimental spectra. In addition, the activity of Mn-SAs/C
the XPS peak in the N 1s region located at 399.1 eV (Fig. S6, ESI†) The conversion of H
All methane oxidation were calculated for various catalysts. As
the above analyses demonstrated the atomically dispersed Cu shown in Fig. S10 (ESI†), Cu-SAs/C exhibited the highest
species embedded in the C N matrix for Cu-SAs/C N , while Cu- H O conversion (14.0%), much higher than those of Fe-SAs/
3
N
4
was very low with a TOF of 0.3 h
.
2 2
O and the gain (G) factor during
2
7,28
4
was attributed to the nitrogen bonded to copper (Cu–N ).
3 4
N
3
4
3
4
2 2
NPs/C N4 exhibited a Cu–N peak and a strong Cu–Cu peak C N (6.7%), Co-SAs/C N (2.8%) and Mn-SAs/C N4 (3.4%),
3
3
4
3
4
3
located at 1.5 Å and 2.2 Å, respectively (Fig. S7, ESI†).
indicating that Cu single atoms were more efficient than Fe,
. In addition, Cu-SAs/
also exhibited the highest G value (0.015). The G values for
XPS, XANES and FT-EXAFS results (Fig. S8 and Table S2, ESI†) Fe-SAs/C , Co-SAs/C and Mn-SAs/C were only 0.011,
showed that Cu was four-fold coordinated with N atoms. In 0.010 and 0.004, respectively. As the Cu-SAs/C catalyst
addition, this strategy could be facilely applied for the prepara- showed the best capability for activating and utilizing H
Moreover, Cu-SAs/C
3 4 2 2
N catalysts with different Cu loadings Co and Mn single atoms to activate H O
(0.2% and 0.5%) were also prepared for comparison, and the
3 4
C N
3
N
4
3
N
4
3 4
N
3 4
N
2 2
O
tion of other 3d transition metal elements including Fe, Co and compared to the other metal single atom catalysts, it exhibited
Mn (Table S3, ESI†) by replacing the Cu source with other metal the highest catalytic activity for the oxidation of methane. With
precursors. The XANES and EXAFS results of the other M-SAs/ the decreasing reaction time from 5 h to 2 h, the oxygenate
C
3
N
4
catalysts also demonstrated the existence of isolated production was still up to 100 mmol over Cu-SAs/C
3
N
4
, and the
À1
metal single-atoms embedded in the C
3
N
4
matrix (Fig. S9, corresponding TOF was as high as 11 h , which largely out-
ESI†).
performed the reported catalysts (Table S4, ESI†).
The conversion of methane with H
2
O
2
as the oxidant was
The role of supports was also studied. Cu supported on
evaluated at ambient temperature (25 1C) in a stainless-steel Al
2 3 2
O and SiO with a similar Cu loading amount were prepared
autoclave with a Teflon linear vessel. The partially oxygenated by a wetness impregnation method for a comparison study. It
products included CH OOH, CH OH and HCOOH in the liquid was found that both 1% Cu/Al O and 1% Cu/SiO2 showed
3
3
2 3
phase (Fig. 3a). C N could not catalyze the methane conver- much lower activity than Cu-SAs/C N (Table S3, ESI†). In
3
4
3 4
sion, and no C1 oxygenates were observed. Among the various addition, when Cu NPs supported on C
kinds of metals including Cu, Fe, Co and Mn, Cu-SAs/C used as a catalyst, only 65 mmol C1 oxygenated products
exhibited the highest yield for the C1 products (153 mmol) with (CH OH and HCOOH) were obtained, suggesting that the
3 4 3 4
N (Cu-NPs/C N ) was
3 4
N
3
a reaction time of 5 h. The calculated TOF was as high as activity of Cu-SAs was much higher than that of Cu-NPs. The
À1
6
9
.7 h , and the C1 oxygenated production selectivity was up to effect of CH
4
partial pressure on the catalytic performance was
5%. A relation between Cu loading and TOF was established, studied (Fig. 3b). The selectivity to CO (CO and CO ) showed
x
2
no obvious change, while the yield of the oxygenated products
increased from 88 mmol to 153 mmol when the methane partial
pressure increased from 0.5 MPa to 3 MPa. The influence of the
amount of H
gated. As shown in Fig. S11 (ESI†), the oxygenate selectivity was
always higher than 95% for different H added amounts. In
2 2
O on the catalytic performance was also investi-
2 2
O
addition, the product yields first increased with the increase of
the H O added amount and reached the highest when the
2
2
H O added amount was 5 mL. A further increase of the H O
2 2
2
2
amount to 8.0 mL would result in significant decay in the
oxygenate production.
Furthermore, the recyclability of Cu-SAs/C
3 4
N and Cu-NPs/
C
3
N
4
was investigated as shown in Fig. 3c. For the Cu-SAs/C N
3 4
catalyst, there was no obvious decrease in the yield of the
oxygenated products, while the yield of the oxygenated products
dramatically decreased by 41.4% over Cu-NPs/C N4 for the
3
second run. The AC-HAADF-STEM image of the spent Cu-SAs/
C N confirmed that no Cu NPs and clusters could be observed
Fig. 3 (a) Catalytic results over C
of methane partial pressure on the Cu-SAs/C
over Cu-SAs/C and Cu-NPs/C catalysts. Reaction conditions: 5 h, 15 mL
O, 5 mL 40 wt% H , 3 MPa and catalyst, 30 mg. (d) EPR experiments over
Cu-SAs/C in the liquid phase.
3
N
4
and M/C
3
N
4
catalysts at 3 MPa. (b) Effect
3
4
3 4
N catalyst. (c) Recyclability tests
(Fig. S12, ESI†), and the XAFS results revealed that there was no
3
N
4
3 4
N
obvious change in the coordination environments and the
chemical state (Fig. S13 and Table S2, ESI†) of the Cu single
H
2
2 2
O
3
N
4
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atoms, confirming the excellent stability of Cu-SAs/C
ChemComm
3
N
4
. The
8 C. Hammond, M. M. Forde, M. H. Ab Rahim, A. Thetford, Q. He,
R. L. Jenkins, N. Dimitratos, J. A. Lopez-Sanchez, N. F. Dummer,
D. M. Murphy, A. F. Carley, S. H. Taylor, D. J. Willock,
E. E. Stangland, J. Kang, H. Hagen, C. J. Kiely and G. J. Hutchings,
Angew. Chem., Int. Ed., 2012, 51, 5129.
9 Z. Jin, L. Wang, E. Zuidema, K. Mondal, M. Zhang, J. Zhang,
C. T. Wang, X. J. Meng, H. Q. Yang, C. Mesters and F. S. Xiao,
Science, 2020, 367, 193.
0 L. Nie, D. H. Mei, H. F. Xiong, B. Peng, Z. B. Ren, X. I. P. Hernandez,
A. DeLaRiva, M. Wang, M. H. Engelhard, L. Kovarik, A. K. Datye and
Y. Wang, Science, 2017, 358, 1419.
1 J. Lin, A. Q. Wang, B. T. Qiao, X. Y. Liu, X. F. Yang, X. D. Wang,
J. X. Liang, J. Li, J. Y. Liu and T. Zhang, J. Am. Chem. Soc., 2013,
135, 15314.
ICP-OES study (Table S5, ESI†) on the spent sample after 3 cycles
of reaction showed that the Cu loading remained constant and
no obvious leakage was found, suggesting the high structure
stability of Cu-SAs/C N . Electron paramagnetic resonance (EPR)
3
4
spin-trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was
used to detect the radicals as shown in Fig. 3d. The presence of
1
ꢀ
ꢀ
ꢀ
OH, CH
3
and OOH radicals in the reaction mixture confirmed
in
solution was triggered by radicals with the participation
that the selective oxidation of methane over Cu-SAs/C
H
of CH .
3 4
N
1
O
2 2
ꢀ
29,30
3
In conclusion, a Cu-SAs/C N catalyst with Cu exclusively in 12 H. B. Zhang, J. Wei, J. C. Dong, G. G. Liu, L. Shi, P. F. An, G. X. Zhao,
3
4
J. T. Kong, X. J. Wang, X. G. Meng, J. Zhang and J. H. Ye,
Angew. Chem., Int. Ed., 2016, 55, 14310.
single atoms was prepared and tested for selective oxidation of
methane. The Cu-SAs/C catalyst exhibited remarkable catalytic
3 4
N
1
1
3 Y. Pan, R. Lin, Y. J. Chen, S. J. Liu, W. Zhu, X. Cao, W. X. Chen,
K. L. Wu, W. C. Cheong, Y. Wang, L. R. Zheng, J. Luo, Y. Lin,
Y. Q. Liu, C. G. Liu, J. Li, Q. Lu, X. Chen, D. S. Wang, Q. Peng,
C. Chen and Y. D. Li, J. Am. Chem. Soc., 2018, 140, 4218.
4 Y. Zheng, Y. Jiao, Y. H. Zhu, Q. R. Cai, A. Vasileff, L. H. Li, Y. Han,
Y. Chen and S. Z. Qiao, J. Am. Chem. Soc., 2017, 139, 3336.
performance when hydrogen peroxide was used as an oxidant,
À1
and presented a high TOF value of 11 h with 95% oxygenate
selectivity under ambient temperature. The presence of abundant
anchoring sites in C N led to highly dispersed Cu–N moieties, as
3 4 4
illustrated by AC-HAADF-STEM and EXAFS results and DFT 15 Q. K. Shen, C. Y. Cao, R. K. Huang, L. Zhu, X. Zhou, Q. H. Zhang,
L. Gu and W. G. Song, Angew. Chem., Int. Ed., 2020, 59, 1216.
calculations. The as-obtained Cu–N moieties coordinated in the
4
1
6 W. X. Huang, S. R. Zhang, Y. Tang, Y. T. Li, L. Nguyen, Y. Y. Li,
J. J. Shan, D. Q. Xiao, R. Gagne, A. I. Frenkel and F. F. Tao,
Angew. Chem., Int. Ed., 2016, 55, 13441.
C N matrix were suggested to be the underlying active sites for
3
4
methane conversion.
This work was supported by the National Natural Science 17 J. J. Xie, R. X. Jin, A. Li, Y. P. Bi, Q. S. Ruan, Y. C. Deng, Y. J. Zhang,
S. Y. Yao, G. Sankar, D. Ma and J. W. Tang, Nat. Catal., 2018, 1, 889.
8 Y. W. Kwon, T. Y. Kim, G. H. Kwon, J. H. Yi and H. J. Lee, J. Am.
Chem. Soc., 2017, 139, 17694.
Foundation of China (91945301), the National Key R&D Program
of China (2017YFB0602202), the Program of Shanghai Academic/
1
Technology Research Leader (20XD1404000), the Key Research 19 H. Zhou, T. Y. Liu, X. Y. Zhao, Y. F. Zhao, H. W. Lv, S. Fang,
X. Q. Wang, F. Y. Zhou, Q. Xu, J. Xu, C. Xiong, Z. G. Xue, K. Wang,
W. C. Cheong, W. Xi, L. Gu, T. Yao, S. Q. Wei, X. Hong, J. Luo, Y. F. Li
Program of Frontier Sciences of the Chinese Academy of Sciences
(Grant No. QYZDB-SSW-SLH035), the ‘‘Transformational Technol-
and Y. E. Wu, Angew. Chem., Int. Ed., 2019, 58, 18388.
0 X. J. Cui, H. B. Li, Y. Wang, Y. L. Hu, L. Hua, H. Y. Li, X. W. Han,
Q. F. Liu, F. Yang, L. M. He, X. Q. Chen, Q. Y. Li, J. P. Xiao,
D. H. Deng and X. H. Bao, Chem, 2018, 4, 1902.
1 W. J. Zang, T. Yang, H. Y. Zou, S. B. Xi, H. Zhang, X. M. Liu,
Z. K. Kou, Y. H. Du, Y. P. Feng, L. Shen, L. L. Duan, J. Wang and
S. J. Pennycook, ACS Catal., 2019, 9, 10166.
2 H. Yan, Y. Lin, H. Wu, W. H. Zhang, Z. H. Sun, H. Cheng, W. Liu,
C. L. Wang, J. J. Li, X. H. Huang, T. Yao, J. L. Yang, S. Q. Wei and
J. L. Lu, Nat. Commun., 2017, 8, 1070.
ogies for Clean Energy and Demonstration’’ and Strategic Priority
Research Program of CAS (Grant No. XDA21020600) and the
Youth Innovation Promotion Association of CAS.
2
2
2
Conflicts of interest
There are no conflicts to declare.
2
2
2
2
2
2
3 Y. Yu, W. Yan, X. F. Wang, P. Li, W. Y. Gao, H. S. Zou, S. M. Wu and
K. J. Ding, Adv. Mater., 2018, 30, 1705060.
4 X. X. Jin, R. Y. Wang, L. X. Zhang, R. Si, M. Shen, M. Wang, J. J. Tian
and J. L. Shi, Angew. Chem., Int. Ed., 2020, 59, 6827.
5 F. Li, G. F. Han, H. J. Noh, S. J. Kim, Y. L. Lu, H. Y. Jeong, Z. P. Fu
and J. B. Baek, Energy Environ. Sci., 2018, 11, 2263.
6 P. T. Wang, M. Qiao, Q. Shao, Y. C. Pi, X. Zhu, Y. F. Li and
X. Q. Huang, Nat. Commun., 2018, 9, 4933.
7 T. Zhang, D. Zhang, X. H. Han, T. Dong, X. W. Guo, C. S. Song, R. Si,
W. Liu, Y. F. Liu and Z. K. Zhao, J. Am. Chem. Soc., 2018, 140, 16936.
8 X. X. Wang, D. A. Cullen, Y. T. Pan, S. Hwang, M. Wang, Z. Feng,
J. Wang, M. H. Engelhard, H. Zhang, Y. He, Y. Shao, D. Su,
K. L. More, J. S. Spendelow and G. Wu, Adv. Mater., 2018,
Notes and references
1
P. Tang, Q. J. Zhu, Z. X. Wu and D. Ma, Energy Environ. Sci., 2014,
, 2580.
7
2
E. V. Kondratenko, T. Peppel, D. Seeburg, V. A. Kondratenko,
N. Kalevaru, A. Martin and S. Wohlrab, Catal. Sci. Technol., 2017,
7, 366.
3
4
P. Schwach, X. L. Pan and X. H. Bao, Chem. Rev., 2017, 117, 8497.
L. S. Meng, Z. Y. Chen, Z. Y. Ma, S. He, Y. D. Hou, H. H. Li,
R. S. Yuan, X. H. Huang, X. X. Wang, X. C. Wang and J. L. Long,
Energy Environ. Sci., 2018, 11, 294.
5
6
A. Holmen, Catal. Today, 2009, 142, 2.
N. Agarwal, S. J. Freakley, R. U. McVicker, S. M. Althahban,
N. Dimitratos, Q. He, D. J. Morgan, R. L. Jenkins, D. J. Willock,
S. H. Taylor, C. J. Kiely and G. J. Hutchings, Science, 2017, 358, 223.
M. H. Ab Rahim, M. M. Forde, R. L. Jenkins, C. Hammond, Q. He,
N. Dimitratos, J. A. Lopez-Sanchez, A. F. Carley, S. H. Taylor,
30, 1706758.
2
9 S. X. Bai, F. F. Liu, B. L. Huang, F. Li, H. P. Lin, T. Wu, M. Z. Sun,
J. B. Wu, Q. Shao, Y. Xu and X. Q. Huang, Nat. Commun., 2020,
11, 954.
7
D. J. Willock, D. M. Murphy, C. J. Kiely and G. J. Hutchings, 30 H. Song, X. G. Meng, S. Y. Wang, W. Zhou, X. S. Wang, T. Kako and
Angew. Chem., Int. Ed., 2013, 52, 1280. J. H. Ye, J. Am. Chem. Soc., 2019, 141, 20507.
1
4680 | Chem. Commun., 2020, 56, 14677--14680
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