Atomically Dispersed Ruthenium Species Inside Metal–Organic Frameworks: Combining the High Activity of Atomic Sites and the Molecular Sieving Effect of MOFs

Article abstract of DOI:10.1002/anie.201814182

Incorporating atomically dispersed metal species into functionalized metal–organic frameworks (MOFs) can integrate their respective merits for catalysis. A cage-controlled encapsulation and reduction strategy is used to fabricate single Ru atoms and triatomic Ru₃ clusters anchored on ZIF-8 (Ru₁@ZIF-8, Ru₃@ZIF-8). The highly efficient and selective catalysis for semi-hydrogenation of alkyne is observed. The excellent activity derives from high atom-efficiency of atomically dispersed Ru active sites and hydrogen enrichment by the ZIF-8 shell. Meanwhile, ZIF-8 shell serves as a novel molecular sieve for olefins to achieve absolute regioselectivity of catalyzing terminal alkynes but not internal alkynes. Moreover, the size-dependent performance between Ru₃@ZIF-8 and Ru₁@ZIF-8 is detected in experiment and understood by quantum-chemical calculations, demonstrating a new and promising approach to optimize catalysts by controlling the number of atoms.

Full text of DOI:10.1002/anie.201814182

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
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Accepted Article
Title: Atomically dispersed Ru species inside MOFs combining high
activity of atomic sites and molecular sieving effect of MOFs
Authors: Yadong Li, Shufang Ji, Yuanjun Chen, Shu Zhao, Wenxing
Chen, Lijun Shi, Yu Wang, Juncai Dong, Zhi Li, Fuwei Li,
Chen Chen, Qing Peng, Jun Li, and Dingsheng Wang
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201814182
Angew. Chem. 10.1002/ange.201814182
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10.1002/anie.201814182
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Atomically dispersed Ru species inside MOFs combining high
activity of atomic sites and molecular sieving effect of MOFs
Shufang Ji, Yuanjun Chen, Shu Zhao, Wenxing Chen, Lijun Shi, Yu Wang, Juncai Dong, Zhi Li,Fuwei
Li, Chen Chen, Qing Peng, Jun Li, Dingsheng Wang, Yadong Li
Abstract: Incorporating atomically dispersed metal species into
functionalized metal-organic frameworks (MOFs) can integrate their
respective merits to have important applications in catalysis. Here we
report a cage-controlled encapsulation and reduction strategy to
fabricate single Ru atoms and triatomic Ru3 clusters anchored on ZIF-
8 (Ru1@ZIF-8, Ru3@ZIF-8). The highly efficient and selective
catalysis for semi-hydrogenation of alkyne is observed. The excellent
activity derives from high atom-efficiency of atomically dispersed Ru
active sites and hydrogen enrichment by ZIF-8 shell. Meanwhile, ZIF-
8 shell serves as a novel “molecular sieve” for olefins to achieve the
absolute regioselectivity of catalyzing terminal alkynes but not internal
alkynes. Moreover, the size-dependent performance between
Ru3@ZIF-8 and Ru1@ZIF-8 is detected in experiment and understood
MNPs/MOFs composites composites undergo
a
high-
temperature reduction to transform metal precursors into
nanoparticles, which is hard to control the dispersion property and
uniformity[6]. Such structural heterogeneity becomes a key
obstacle to improve catalytic selectivity because substrates may
adsorb on different structural surfaces and undergo different
reaction pathways, leading to generation of side products.
Catalytic reactions take place primarily on the surface of metal
nanoparticles, while inner atoms usually do not participate[7]. Thus,
metal nanoparticles suffer from low metal atom-utilization
efficiency and significant decline in the number of exposed active
sites compared with single atoms and clusters.
by quantum-chemical calculations, demonstrating
a new and
As a bridge between homogeneous and heterogeneous
catalysis, atomically dispersed catalysts integrate their
advantages of homogenized active sites and easy recovery,
which have delivered extraordinary activity in a variety of
reactions[8]. And the nature of uniform sites is expected to
enhance selectivity owing to similar spatial and electronic
interaction with substrates[9]. Moreover, well-defined structure and
coordination environment are conducive to identification of active
sites, which facilitates studies of structure-performance
relationship at atomic level[10]. Therefore, developing an effective
strategy to form uniform atomically dispersed active sites, and
simultaneously make them be incorporated into functionalized
MOFs is highly desirable, which can combine the merits of atomic
sites and MOFs to synergistically enhance catalytic performance.
promising approach to optimize catalysts by preciously controlling the
number of atoms.
Developing heterogeneous catalysts with high activity and
selectivity has become a focus in catalysis research[1]. Metal-
organic frameworks (MOFs) are known as a new class of porous
crystalline materials[2], whose high porosity facilitates accessibility
of active species and boosts efficiency by enriching gas
molecules[3]. In addition, the regularity of pore sizes render
molecular sieving function, which can enhance selectivity by
regulating the transport and diffusion of substrates[3b,4]
.
Incorporating metal nanoparticles (MNPs) into metal-organic
frameworks (MOFs) can inherit the above advantages of MOFs
and faciliate catalysis[5]. However, these MNPs/MOFs composites
are confronted with some shortages that limit their further
enhancement on catalytic performance. Most synthetic routes to
[*]
S. Ji[+], Y. Chen[+], Dr. W. Chen, Dr. Z Li, Prof. C. Chen, Prof. Q.
Peng, Prof. J. Li, Prof. D. Wang, Prof. Y. Li
Department of Chemistry, Tsinghua University, Beijing 100084
China
E-mail: wangdingsheng@mail.tsinghua.edu.cn
ydli@mail.tsinghua.edu.cn
Dr. S. Zhao[+]
Beijing Guyue New Materials Research Institute, Beijing University
of Technology, Beijing 100124, China
L. Shi, Prof. F. Li
State Key Laboratory for Oxo Synthesis and Selective Oxidation,
Suzhou Research Institute of LICP, Lanzhou Institute of Chemical
Physics (LICP), Chinese Academy of Sciences, Lanzhou 730000,
China
Figure 1. Schematic preparation process of (a,b) Ru3@ZIF-8 and (c,d)
Ru1@ZIF-8 catalyst.
Dr. Y. Wang
Shanghai Synchrotron Radiation Facilities, Shanghai Institute of
Applied Physics, Chinese Academy of Sciences, Shanghai 201204,
China
Herein, we construct single Ru atoms and triatomic Ru3
clusters confined in functionalized ZIF-8 via a cage-controlled
encapsulation and reduction strategy (Ru1@ZIF-8, Ru3@ZIF-8).
For semi-hydrogenation of phenylacetylene, Ru3@ZIF-8 exhibit
excellent activity with the turnover frequency (TOF) of 360 h-1,
absolute regioselectivity of catalyzing terminal alkynes (but not
internal alkynes) and outstanding chemoselectivity of 97% for
Dr. J. Dong
Beijing Synchrotron Radiation Facility, Institute of High Energy
Physics, Chinese Academy of Sciences, Beijing, China
[+] These authors contributed equally to this work.
Supporting information for this article is given via a link at the end of
the document.
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10.1002/anie.201814182
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styrene. The highly efficient and selective catalysis are ascribed
to atomically dispersed Ru sites and molecular sieving effect of
MOFs. Moreover, the size-dependent performance is evidently
detected, with Ru3@ZIF-8 exhibiting better activity and selectivity
than Ru1@ZIF-8. We further carried out density functional theory
(DFT) calculations to evaluate the difference of structural
properties and the reaction mechanism between Ru3@ZIF-8 and
Ru1@ZIF-8 to better understand drastically different properties.
(Figure S2), consistent with FTIR results (Figure S3 and S4).
And energy-dispersive X-ray spectroscopy (EDS) analysis
confirm that Ru, C,
N and Zn elements were uniformly
distributed (Figure 2c and S8). To directly observe the dispersion
of Ru at atomic scale, aberration-corrected HAADF-STEM (AC
HAADF-STEM) was carried out. Due to the Z-contrast, brighter
dots (identified as Ru atoms) can be distinguished from ZIF-8
matrix[11]. A group of three brighter dots marked by yellow cycles
is in agreement with triangular Ru3 clusters (Figure 2d), while the
observation of two adjacent bright dots coincides with Ru3 clusters
that are not over against the projection direction for
several possible structures by DFT simulation (Figure 2e and
area 1 to area 6 in Figure 2d). From different areas in AC
HAADF-STEM images (Figure 2d and S9), statistical analysis of
Ru-Ru distance from more than 100 pairs of neighboring Ru
atoms were performed, revealing Ru-Ru distance at 2.2±0.3 Å,
consistent with Ru-Ru bond lengths of Ru3 clusters (Figure 2f).
For Ru1@ZIF-8, as observed by isolated brighter dots and the
intensity profiles (Figure 2h,i), isolated Ru atoms are uniformly
dispersed in Ru1@ZIF-8.
To achieve our design goal of atomically dispersed metal
species and MOFs composites, we used MOFs as hosts to in-situ
encapsulate and separate preselected precursors, followed by
thermal treatment for removing the ligands. The preparation
process is illustrated in Figure 1. The preselected precursor
Ru3(CO)12 was in situ encapsulated during the crystallization of
ZIF-8 (Ru3(CO)12@ZIF-8, Figure 1a and Figure S1a to S1e). The
synthesis of Ru(acac)3@ZIF-8 is the same as the above
procedure expect that Ru3(CO)12 is replaced by Ru(acac)3
(Figure 1c and S1f). The combination of measurements was
performed (Figure S2 to S7) to confirm that Ru3(CO)12 and
Ru(acac)3 were respectively encapsulated within ZIF-8. Then,
Ru3(CO)12@ZIF-8 and Ru(acac)3@ZIF-8 underwent thermal
reduction treatment to form Ru3 clusters and Ru1 single atoms
stabilized by the framework of ZIF-8 (Figure 1b,d).
To gain local structure of Ru3@ZIF-8 and Ru1@ZIF-8, X-ray
absorption near-edge structure (XANES) and extended X-ray
absorption fine structure (EXAFS) were performed. The energy
absorption threshold values of Ru3@ZIF-8 and Ru1@ZIF-8 are
between those of RuO2 and Ru foil (Figure 3a), suggesting Ru3
clusters and Ru1 single atoms carry partially positive charge. The
Fourier transform (FT) of EXAFS spectra are shown in Figure 3b.
For Ru1@ZIF-8, only one obvious Ru-C scattering peak around
~1.5Å is detected. And no scattering peaks from Ru-Ru
coordination is observed, revealing the sole presence of isolated
Ru atoms. Whereas, at the FT curve of Ru3@ZIF-8, besides a
strong peak at ~1.5 Å from Ru-C contribution, another higher shell
peak located at ~2.4 Å are detected, indicating the presence of
Ru-Ru contribution derived from Ru3 clusters.
Figure 2. (a) TEM, (b) enlarged TEM, (c) EDS maps, (d) AC HAADF-STEM
images of Ru3@ZIF-8, (e) Illustrations of Ru3 clusters from top and side view. (f)
Statistical Ru–Ru distance in the observed Ru3 clusters. (g) TEM and (h) AC
HAADF-STEM images of Ru1@ZIF-8. (i) Intensity file of Ru1@ZIF-8 in the cyan
dotted rectangle area of Figure 1h.
Figure 3. (a) XANES, (b) EXAFS, (c) WT of Ru1@ZIF-8, Ru3@ZIF-8, RuO2 and
Ru foil, respectively. Corresponding EXAFS R space fitting curve of (d)
Ru1@ZIF-8 and (e) Ru3@ZIF-8, respectively. Inset: Simulations models of
Ru1@ZIF-8 and Ru3@ZIF-8, respectively.
Transmission
electron
microscopy
(TEM)
images
demonstrate that Ru3@ZIF-8 and Ru1@ZIF-8 display a rhombic
dodecahedron morphology (Figures 2a, b and g). The XRD
patterns of Ru3@ZIF-8 and Ru1@ZIF-8 exhibit characteristic
peaks of ZIF-8, indicating the crystallinity of ZIF-8 is not destroyed
To further reinforce atomic structure of Ru3@ZIF-8 and
Ru1@ZIF-8, we carried out Wavelet transform (WT) analysis,
which can provide powerful resolution in both k and R spaces[12]
.
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Figure 3c shows that WT plot of Ru1@ZIF-8 displays only one
intensity maximum near ~ 4.0 Å-1 from Ru-C backscattering
contributions. Compared with Ru foil, no other maximum at
around 8.0 Å-1 is detected in the higher shell peak, suggesting that
the sole dispersion of single-atom Ru. For Ru3@ZIF-8, two
intensity maximum at ~ 4.0 Å-1 and ~8.0 Å-1 are observed for Ru
species. 4.0 Å–1 of intensity maximum is assigned to Ru-C path,
implying Ru-C contribution of the first nearest-neighbor
coordination shell. Whereas the other obvious intensity maximum
at near 8.0 Å-1 in the higher coordination shell can be attributed to
the presence of Ru-Ru scattering contribution. All the findings
demonstrate that Ru clusters are atomically dispersed in
Ru3@ZIF-8. Quantitative EXAFS curve fittings were performed to
extract the structural parameters in Table S1 and the fitting results
are summarized in Figure 3d, e and Figure S10 to S12. The
most stable structures of Ru1@ZIF-8 and Ru3@ZIF-8 samples are
further verified by first-principles calculations (insets of Figure 3d
and 3e, Table S2 and S3).
carbon-carbon triple bonds (C≡C) at the end of phenyl ethyne,
intramolecular C≡C of diphenylacetylene cannot contact
encapsulated Ru active species, resulting in absolute
regioselectivity (Figure 4c). To further confirm the regioselectivity
of catalyzing terminal unsaturated hydrocarbon but not internal
unsaturated hydrocarbon, other substrate molecules are chosen
and the catalytic results are summarized in Table S4. In addition,
the excellent styrene selectivity is 97% for Ru3@ZIF-8 and 91%
for Ru1@ZIF-8, implying a high chemoselectivity (Figure 4d). For
comparison, Ru nanoparticles encapsulated in ZIF-8 (marked Ru
NPs@ZIF-8) were prepared and fully characterized (Figure S14
and 15), which exhibits lower conversion (13%) and poorer
selectivity (82%). And few activity is observed for pure ZIF-8.
Furthermore, the TOF of Ru3@ZIF-8 achieves as high as 360 h-1,
which is 10 times and 13.8 times of Ru1@ZIF-8 (36 h-1) and Ru
NPs@ZIF-8 (26 h-1) (Figure 4e). The enhanced performance is
attributed to atomically dispersed Ru3 clusters and ZIF-8 shell as
well-confined nanoreactors for hydrogen enrichment. To assess
the recyclability of Ru3@ZIF-8, five consecutive runs were
performed. Similar conversion and selectivity are detected
compared with fresh catalyst, indicating excellent recyclability
(Figure 4f). Moreover, the spent catalyst were fully characterized,
which clearly reveals atomic dispersion of Ru and framework of
ZIF-8 are well preserved (Figure S16 and S17).
It is worth noting that Ru3@ZIF-8 and Ru1@ZIF-8 exhibit
different catalytic performance for the selective hydrogenation of
phenylacetylene, with Ru3@ZIF-8 possessing higher activity and
selectivity. This observed result provides a successful paradigm
for demonstrating size-dependent effect between single-atom and
multi-atom catalysts. To further investigate this size-dependent
effect, we selected acetylene (the simplest alkynes molecule) as
a model substrate. The molecular size of acetylene (2.5 Å) is
smaller than the pore aperture size of ZIF-8 (3.4 Å)[13], acetylene
can enrich in and diffuse through the pore apertures of ZIF-8
without obstacle. Figure 5a shows that activity of Ru3@ZIF-8
(603.6 molC2H2 molnoble metal -1 h-1) is higher than that of Ru1@ZIF-8
Figure 4. Studies of catalytic properties for Ru3@ZIF-8 and Ru1@ZIF-8
catalysts. (a) Nitrogen-sorption isotherms, (b) conversion, (c) molecular sieving
size-selectivity sketch of phenylacetylene and diphenylacetylene, (d) selectivity
and (e) TOFs for hydrogenation of phenylacetylene over Ru3@ZIF-8, Ru1@ZIF-
8 and references. (f) Catalytic performance of Ru3@ZIF-8 for several recycles
of repeated reactions.
-1
(12.5 molC2H2 molnoble metal h-1). And Ru3@ZIF-8 exhibits better
ethylene selectivity of ~84% than Ru1@ZIF-8 (Figure 5b).
To better understand drastically different properties between
Ru3@ZIF-8 and Ru1@ZIF-8, DFT calculations were performed.
The energy profiles containing the entropic effects from gas phase
acetylene and hydrogen to gas phase ethane on Ru1@ZIF-8 and
Ru3@ZIF-8 are shown in Figure 5c. The computational details
are in the Supporting Information (Table S5-S7 and Figure S18-
23). On Ru3@ZIF-8, the first hydrogenation step is found to have
the lowest activation barrier (TS1, 0.39 eV) in the whole pathway
and exothermic by 0.47 eV. The next two steps have higher
barriers of 0.93 eV (TS2) and 0.85 eV (TS3), and the reactions
are exothermic by 0.40 eV and 0.04 eV, respectively. Desorption
energy of C2H4 at 500 K is 0.57 eV, smaller than its further
hydrogenation barrier (0.85 eV). More importantly, the transition-
state energy of C2H4 hydrogenation (TS3) is above the energy of
gas-phase ethylene (Figure 5c), which suggests that the ethylene
prefers desorption to further hydrogenation in the following
process.
From the N2 adsorption and desorption isotherms (Figure 4a),
the N2 sharp uptake indicates a standard type I isotherm, implying
the existence of microporosity for Ru3@ ZIF-8 and Ru1@ZIF-8.
Figure S13 demonstrates the incorporation of Ru3 clusters and
Ru1 single atoms does not alter the pore-size distribution of ZIF-
8.
Integrating unique properties of atomically dispersed species
and versatile functionalities of MOFs, Ru3@ZIF-8 and Ru1@ZIF-
8 composites have great potential applications in catalysis.
Hydrogenation of phenylacetylene and diphenylacetylene were
thus chosen as model reactions. As shown in Figure 4b,
Ru3@ZIF-8 and Ru1@ZIF-8 both exhibit significant conversion of
phenylacetylene (47% for Ru3@ZIF-8 and 18% for Ru1@ZIF-8).
Negligible activity of Ru3@ZIF-8 and Ru1@ZIF-8 are detected in
catalyzing hydrogenation of diphenylacetylene. The obviously
different conversion for alkynes demonstrated the selective
catalysis is successfully achieved by molecular sieving effect of
ZIF-8 shell. Owing to the steric effect of restriction, compared with
On Ru1@ZIF-8, heterolysis of H2 has a low barrier of 0.23 eV,
and exothermic by 0.66 eV (Figure S23). After dissociation, one
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of the hydrogen adsorbed on Ru atom and the other one bonds
to the carbon atom in ZIF-8. The hydrogenation of C2H2 to C2H3
is most kinetically feasible among the whole hydrogenation
processes, with a barrier of 0.23 eV (TS1). Then, H migrates from
ZIF-8 to the single Ru site with a high barrier of 1.35 eV (TS-H1),
and strongly endothermic by 0.88 eV. The next step (C2H3 + H →
C2H4) has a barrier of 1.11 eV (TS2), and highly exothermic by
0.70 eV. The further hydrogenation of C2H4 to C2H5 has barrier of
1.01 eV (TS3), which is lower than the desorption energy of C2H4
(1.33 eV) and much lower than the energy of gas-phase ethylene
at 500 K (Figure 5c). Thus, C2H4 will be further hydrogenated to
undesirable ethane rather than desorbed directly. For the whole
hydrogenation pathway, the effective barrier on Ru1@ZIF-8 is
much higher than that on Ru3@ZIF-8 (2.17 vs. 1.43 eV), indicating
that the Ru3@ZIF-8 catalyst is more active for the semi-
hydrogenation of acetylene than Ru1@ZIF-8. A high selective
catalyst should have a low desorption energy and a high
hydrogenation barrier of ethylene. So the difference (E) between
the hydrogenation barrier and the desorption energy of C2H4 is
calculated to estimate the selectivity (Table S8)[14]. We find that
Ru3@ZIF-8 has higher E (0.28 eV) than Ru1@ZIF-8 (-0.32 eV),
suggesting the Ru3@ZIF-8 is more selective to semi-
hydrogenation of acetylene.
alkynes; and (4) outstanding chemoselectivity of semi-
hydrogenation with hydrogenating alkynes to alkenes is achieved
by intrinsic nature of atomically dispersed Ru species. Moreover,
the size-dependent performance between Ru3@ZIF-8 and
Ru1@ZIF-8 is observed in experiment and understood by DFT
studies, which provides a concrete paradigm to reveal that
tunable catalytic performance can be achieved by precious
control on the number of atoms. These findings present a
promising inkling to design and optimize catalysts by combining
high performance of atomic sites and molecular sieving effect of
MOFs. The new catalysts based on Ru1 and Ru3 cluster reveal
the promise of utilizing well-defined, controllable single-atom and
single-cluster active centers in catalytic design for complicated
chemical reactions.[15]
Acknowledgements
This work was supported by China Ministry of Science and
Technology under Contract of 2016YFA (0202801), the National
Natural Science Foundation of China (21521091, 21390393,
U1463202, 21471089, 21671117, 91645203, 21590792) and the
Beijing Natural Science Foundation (2184097). We thank
Shanghai Light Source for use of the instruments. The
calculations were performed using supercomputers at Tsinghua
National Laboratory for Information Science and Technology and
the Supercomputer Center of the Computer Network Information
Center at the Chinese Academy of Sciences.
Keywords: single atom • cluster • MOFs • composites • catalyst
[1] a) E. Gross, G. A. Somorjai, Top. Catal. 2013, 56, 1049-1058; b) R. Noyori,
Nat. Chem. 2009, 1, 5-6; c) K. Na, K. M. Choi, O. M. Yaghi, G. A. Somorjai,
Nano. Lett. 2014, 14, 5979-5983; d) G. Chen, C. Xu, X. Huang, J. Ye, L.
Gu, G. Li, Z. Tang, B. Wu, H. Yang, Z. Zhao, Z. Zhou, G. Fu, N. Zheng,
Nat. Mater. 2016, 15, 564-569.
[2] a) H. Furukawa, K. E. Cordova, M. O'Keeffe, O. M. Yaghi, Science 2013, 341,
1230444; b) A. J. Howarth, Y. Liu, P. Li, Z. Li, T. C. Wang, J. T. Hupp, O.
K. Farha, Nat. Rev. Mater. 2016, 1, 15018.
Figure 5. Size-dependent effect of uniform controlled ruthenium species for
hydrogenation reaction. (a) Reaction activity and (b) ethylene selectivity in
selective hydrogenation of acetylene on Ru1@ZIF-8, Ru3@ZIF-8 and ZIF-8.
(c) Step-by-step hydrogenation mechanism of acetylene to ethane on the
Ru1@ZIF-8 and Ru3@ZIF-8. Structures of transition states of C2H2
hydrogenation on Ru3@ZIF-8 (blue line) and Ru1@ZIF-8 (yellow line) (Ru:
orange, C: gray, H: white).
[3] a) G. Li, H. Kobayashi, J. M. Taylor, R. Ikeda, Y. Kubota, K. Kato, M. Takata,
T. Yamamoto, S. Toh, S. Matsumura, H. Kitagawa, Nat. Mater. 2014, 13,
802-806; b) M. Zhao, K. Yuan, Y. Wang, G. Li, J. Guo, L. Gu, W. Hu, H.
Zhao, Z. Tang, Nature 2016, 539, 76-80.
[4] a) G. Lu, S. Li, Z. Guo, O. K. Farha, B. G. Hauser, X. Qi, Y. Wang, X. Wang,
S. Han, X. Liu, J. S. DuChene, H. Zhang, Q. Zhang, X. Chen, J. Ma, S.
C. Loo, W. D. Wei, Y. Yang, J. T. Hupp, F. Huo, Nat. Chem. 2012, 4, 310-
316; b) Z. Li, R. Yu, J. Huang, Y. Shi, D. Zhang, X. Zhong, D. Wang, Y.
Wu, Y. Li, Nat. Commun. 2015, 6, 8248.
In summary, we develop an effective strategy to construct
ideal composites by combining the advantages of atomically
dispersed Ru species and functionalized MOF, which
synergistically facilitate catalysis. In this work, Ru3@ZIF-8 and
Ru1@ZIF-8 demonstrate the following advantages: (1) The spatial
separation of Ru single atom and triatomic Ru3 cluster is
precontrolled by cages of ZIF-8 to prevent active species from
migration and agglomeration for excellent stability and
recyclability; (2) atomic dispersion of active Ru species with
maximum atom efficiency and H2 enrichment by porous structure
of ZIF-8 is beneficial for enhanced activity; (3) molecular sieve
effect of MOF enables selection of substrates to exhibit absolute
regioselectivity of catalyzing terminal alkynes but not internal
[5] a) L. Chen, R. Luque, Y. Li, Chem. Soc. Rev. 2017, 46, 4614-4630; b) Q.
Yang, Q. Xu, H. L. Jiang, Chem. Soc. Rev. 2017, 46, 4774-4808.
[6] a) Z. Guo, C. Xiao, R. V. Maligal-Ganesh, L. Zhou, T. W. Goh, X. Li, D.
Tesfagaber, A. Thiel, W. Huang, ACS Catal. 2014, 4, 1340-1348.; b) Q.
L. Zhu, J. Li, Q. Xu, J. Am. Chem. Soc. 2013, 135, 10210-10213.
[7] a) N. Ta, J. Liu, S. Chenna, P. A. Crozier, Y. Li, A. Chen, W. Shen, J. Am.
Chem. Soc. 2012, 134, 20585-20588; b) J. H. K. Pfisterer, Y. Liang, O.
Schneider, A. S. Bandarenka, Nature 2017, 549, 74.
[8] a) B. Qiao, A. Wang, X. Yang, L. F. Allard, Z. Jiang, Y. Cui, J. Liu, J. Li, T.
Zhang, Nat. Chem. 2011, 3, 634-641; b) M. Hu, J. Zhang, W. Zhu, Z.
Chen, X. Gao, X. Du, J. Wan, K. Zhou, C. Chen, Y. Li, Nano Res. 2018,
11, 905-912.; c) H. Yang, C. Wang, F. Hu, Y. Zhang, H. Lu, Q. Wang, Sci.
China Mater. 2017, 60, 1-8; d) X. Qiu, J. Chen, X. Zou, R. Fang, L. Chen,
This article is protected by copyright. All rights reserved.

10.1002/anie.201814182
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COMMUNICATION
Z. Chen, K. Shen, Y. Li, Chem. Sci. 2018, (DOI: 10.1039/C8SC03549K).
[9] a) L. Wang, W. Zhang, S. Wang, Z. Gao, Z. Luo, X. Wang, R. Zeng, A. Li, H.
Li, M. Wang, X. Zheng, J. Zhu, W. Zhang, C. Ma, R. Si, J. Zeng, Nat.
Commun. 2016, 7, 14036; b) X. Guo, G. Fang, G. Li, H. Ma, H. Fan, L.
Yu, C. Ma, X. Wu, D. Deng, M. Wei, D. Tan, R. Si, S. Zhang, J. Li, L. Sun,
Z. Tang, X. Pan, X. Bao, Science 2014, 344, 616-619.
5, 843-847.
[12] H. Funke, A. C. Scheinost, M. Chukalina, Phys. Rev. B 2005, 71, 094110.
[13] D. Fairen-Jimenez, S. A. Moggach, M. T. Wharmby, P. A. Wright, S. Parsons,
T. Duren, J. Am. Chem. Soc. 2011, 133, 8900-8902.
[14] B. Yang, R. Burch, C. Hardacre, G. Headdock, Hu, P. ACS Cat. 2012, 2,
1027-1032.
[10] a) Y. Chen, S. Ji, Y. Wang, J. Dong, W. Chen, Z. Li, R. Shen, L. Zheng, Z.
Zhuang, D. Wang, Y. Li, Angew. Chem. Int. Ed. 2017, 56, 6937-6941; b)
S. Yang, J. Kim, Y. J. Tak, A. Soon, H. Lee, Angew. Chem. In.t Ed. 2016,
55, 2058-2062; c) Y. Chen, S. Ji, C. Chen, Q. Peng, D. Wang, Y. Li,
Joule 2018, 2, 1242-1264.
[15] a) S. Zhang, L. Nguyen, J.-X. Liang, J. Shan , J. Liu, A. I. Frenkel, A. Patlolla,
W. Huang, J. Li, F. Tao, Nat. Commun. 2015, 6, 7938; b) X.-L. Ma, J.-C.
Liu, H. Xiao, J. Li, J. Am. Chem. Soc. 2018, 140, 46-49; c) J.-C. Liu, X.-
L. Ma, Y. Li, Y.-G. Wang, H. Xiao, J. Li, Nat. Commun. 2018, 9, 1610.
[11] V. Ortalan, A. Uzun, B. C. Gates, N. D. Browning, Nat. Nanotechnol. 2010,
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10.1002/anie.201814182
Angewandte Chemie International Edition
COMMUNICATION
COMMUNICATION
Shufang Ji, Yuanjun Chen, Shu Zhao,
Wenxing Chen, Lijun Shi, Yu Wang,
Juncai Dong, Zhi Li,Fuwei Li, Chen
Chen, Qing Peng, Jun Li, Dingsheng
Wang*, Yadong Li*
Page No. – Page No.
Single Ru atoms and triatomic Ru3 clusters confined in functionalized ZIF-8 as
composites catalysts integrate the advantages of atomically dispersed Ru species
and microporous MOF structure, which synergistically facilitate highly efficient and
selective catalysis for semi-hydrogenation of alkyne and exhibit the molecular sieve
effect. The experiments and theoretical calculations further reveal the size-
dependent performance between Ru3@ZIF-8 and Ru1@ZIF-8 catalysts.
Atomically dispersed Ru species inside
MOFs combining high activity of atomic
sites and molecular sieving effect of
MOFs
This article is protected by copyright. All rights reserved.