Nickel Metal–Organic Framework Monolayers for Photoreduction of Diluted CO2: Metal-Node-Dependent Activity and Selectivity

Article abstract of DOI:10.1002/anie.201811545

Photocatalytic conversion of diluted CO₂ into solar fuel is highly appealing yet still in its infancy. Herein, we demonstrate the metal-node-dependent performance for photoreduction of diluted CO₂ by constructing Ni metal–organic framework (MOF) monolayers (Ni MOLs). In diluted CO₂ (10 %), Ni MOLs exhibit a highest apparent quantum yield of 1.96 % with a CO selectivity of 96.8 %, which not only exceeds reported systems in diluted CO₂ but also is superior to most catalysts in pure CO₂. Whereas isostructural Co MOLs is almost inactive in diluted CO₂, indicating the performance is dependent on the metal nodes. Experimental and theoretical investigations show that strong CO₂ binding affinity of Ni MOLs is the crucial factor, which stabilizes the Ni-CO₂ adducts and facilitates CO₂-to-CO conversion.

Full text of DOI:10.1002/anie.201811545

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Ni Metal-Organic Frameworks Monolayers for Photoreduction of
Diluted CO2: Metal Nodes-Dependent Activity and Selectivity
Authors: Bin Han, Xinwen Ou, Ziqi Deng, Yao Song, Chen Tian, Hong
Deng, Yi-Jun Xu, and Zhang Lin
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201811545
Angew. Chem. 10.1002/ange.201811545
Link to VoR: http://dx.doi.org/10.1002/anie.201811545
http://dx.doi.org/10.1002/ange.201811545

10.1002/anie.201811545
Angewandte Chemie International Edition
COMMUNICATION
Ni Metal-Organic Frameworks Monolayers for Photoreduction of
Diluted CO2: Metal Nodes-Dependent Activity and Selectivity
Bin Han+, Xinwen Ou+, Ziqi Deng, Yao Song, Chen Tian, Hong Deng, Yi-Jun Xu, Zhang Lin*
Abstract: Photocatalytic conversion of diluted CO2 into solar fuel is
highly appealing yet still in its infancy. Herein, we demonstrate the
metal nodes-dependent performance for photoreduction of diluted
CO2 by constructing Ni metal-organic frameworks monolayers (Ni
MOLs). In diluted CO2 (10%), Ni MOLs exhibits a highest apparent
quantum yield of 1.96% with a spectacular CO selectivity of 96.8%,
which not only exceeds reported systems in diluted CO2 but also is
superior to most catalysts in pure CO2. Whereas its isostructural Co
MOLs is almost inactive in diluted CO2, indicating the performance is
dependent on the metal nodes. Experimental and theoretical
investigations show that strong CO2 binding affinity of Ni MOLs is the
crucial factor, which is beneficial to stabilize the Ni-CO2 adducts and
facilitates CO2-to-CO conversion. The universality of the superiority of
Ni for CO2 photoreduction can be extended to other Ni MOFs,
providing an effective general strategy for the design of inorganic-
organic complexes for artificial photosynthesis.
step towards future practical implementation of CO2
photoreduction yet rarely reported.[8-9]
Metal-organic frameworks (MOFs), a class of inorganic-
organic hybrid materials composed of high-density metal nodes
and tailorable bridging organic ligands, are rapidly emerging as
promising catalysts for CO2 photoreduction.[10-11] Although MOFs
based catalysts for CO2 photoreduction have been widely
reported,[12-13] researches on photocatalytic conversion of diluted
CO2 over MOFs are still in its infancy. Kitagawa and co-workers
first reported the feasibility of converting diluted CO2 over MOFs
by integrating CO2 reducing catalyst into a CO2-adsorptive
MOFs.[14] However, this initial MOFs system suffers from low
durability and low selectivity of CO2 reduction. Very recently,
Zhang et al. have demonstrated that Co based MOFs bearing μ-
OH− ligands neighboring the open Co centers can efficient
catalyze low concentration of CO2 to CO by a post-processing of
MOFs in KOH solution.[15] Nevertheless, the insufficient stability
of most MOFs in aqueous alkali limits the application of this
method.[16] As such, facile and general design principle for
constructing MOFs catalysts for photoreduction of diluted CO2 is
essential but still lacking.
Considering that the metal nodes of MOFs provide high-
density catalytic sites, the reasonable design of metal nodes may
provide a common approach for photoreduction of diluted CO2.
Herein, by elaborately constructing Ni MOFs monolayers (Ni
MOLs) with abundant coordinatively unsaturated Ni sites, for the
first time, we demonstrate the metal nodes-dependent
performance for selective photoreduction of diluted CO2 with
recorded performance to date, providing general insights into the
rational design of efficient metal-organic complexes for diluted
CO2 photoreduction.
Photocatalytic conversion of CO2 into valuable carbon-based
fuels and chemical feedstocks provides a long-term solution to
simultaneously mitigate global climatic change and ameliorate
energy shortage.[1-2] However, efficient CO2 photoreduction with
high selectivity still remains a critical issue for the high
dissociation energy of the C=O bond (∼750 kJ/mol) and the
kinetically challenging multi-electron reaction process.[3-4]
Moreover, the CO2 concentration in the exhaust gases discharged
from heavy industries, such as fire power plants, is relatively low,
further restricting the practical implementation of CO2
photoreduction.[5-7] As such, unearthing highly efficient catalysts
to directly convert the low concentration of CO2 into desirable
reaction products meanwhile suppressing other competing
photocatalytic reactions, such as H2 evolution, is a mandatory
Ni MOLs has been prepared by a traditional ultrasonication
method,[17] followed by a large amount water-assisted freezing
process to prevent MOLs from aggregating together, as illustrated
in Figure 1a. The as-prepared sample shares identical crystalline
structure with the previously reported monoclinic Ni2(OH)2BDC
MOF (no. 985792, Cambridge Crystallographic Data Centre).[18]
The four diffraction peaks can be indexed to (200), (001), (201)
and (-201) crystallographic planes, respectively, as shown in
Figure 1b. According to the XRD results, Ni atoms are
coordinated by six O atoms forming O6 octahedra which are
further corner/edge connected with each other in the (200),
resulting in 2D metallic layers separated by BDC ligands, as
depicted in Figure 1c. The thickness of two coordination
structural layers is about 21.7 Å. The XPS spectra (Figure S1)
confirm that C, O, and Ni are the main elements and the valence
of Ni is divalent in the sample. Inductively coupled plasma optical
emission spectrometer (ICP-OES) reveals that Ni content is
35.5%, very close to the calculated value (37.3%) based on the
crystal structures. For comparison, bulk Ni MOFs has been
constructed, which displays the same XRD pattern with Ni MOLs,
as shown in Figure 1b.
[*]
B. Han+, X.W. Ou+, Z.Q. Deng, Y. Song, Ch. Tian, Prof. Dr. H.
Deng, Prof. Dr. Zh. Lin
School of Environment and Energy, Key Laboratory of Pollution
Control and Ecosystem Restoration in Industry Clusters (Ministry of
Education), South China University of Technology, Guangzhou (P.
R. China)
E-mail: zlin@scut.edu.cn
B. Han+, X.W. Ou+, Z.Q. Deng, Y. Song, Ch. Tian, Prof. Dr. H.
Deng, Prof. Dr. Zh. Lin
Guangdong Engineering and Technology Research Center for
Environmental Nanomaterials, South China University of
Technology, Guangzhou, 510006 (P. R. China)
Prof. Dr. Y-J. Xu
State Key Laboratory of Photocatalysis on Energy and
Environment, College of Chemistry, Fuzhou University, Fuzhou
350116 (P. R. China)
Prof. Dr. Y-J. Xu
College of Chemistry, New Campus, Fuzhou University, Fuzhou
350116 (P. R. China)
[+]
These authors contributed equally to this work.
Supporting information for this article is given via a link at the end
of the document.
This article is protected by copyright. All rights reserved.

10.1002/anie.201811545
Angewandte Chemie International Edition
COMMUNICATION
(abbreviated as Ru, bpy = 2’2-bipyridine) as photosensitizer and
triethanolamine (TEOA) as electron donor. CO and H2 are
detected as the main products, consistent with the results of
previously reported systems.[19-20] In pure CO2, ultrathin Ni MOLs
exhibits a considerable CO production rate of 12.5 μmol/h with a
H2 generation rate of 0.28 μmol/h during the 2-h reaction period,
obtaining a high CO selectivity of 97.8%, as displayed in Figure
3a. The CO production rate is about 24 times higher than that of
the blank system. Of note, Ni MOLs displays a superior apparent
quantum yield (A.Q.Y.) of ca. 2.2% at 420 nm, outperforming
reported photocatalytic systems under comparable conditions, as
displayed in Table S1. Isostructural bulk Ni MOFs exhibits
declined CO production rate of 7.23 μmol/h with a similar
selectivity of 96.1%, indicating that the selectivity of Ni MOFs is
irrelevant to the morphology. More importantly, in diluted CO2
(10% CO2, typical CO2 concentration of exhaust gas from fire
power plants[21]), Ni MOLs still exhibits a highest A.Q.Y. of 1.96%
with spectacular CO selectivity of 96.8%, which not only exceeds
reported systems in diluted CO2 (Table S2), but also is superior
to most catalysts in pure CO2. Cycling experiments and XRD
patterns of the fresh and used samples (Figure S3) confirm the
stability of Ni MOLs in the reaction system. The above results
provide a kind of efficient catalysts towards CO2 photoreduction
in low CO2 concentration, which is of great significance for future
practical implementation of photostimulated CO2 conversion due
to the avoidance of concentrating CO2.[7] The control experiment
in ultrapure Ar shows that only a small amount of H2 is generated
without any evolution of CO, as displayed in column 4 of Figure
3a, clearly indicating that the CO product indeed originates from
the splitting of CO2 molecules. Experiments carried out in the
absence of Ru or visible light irradiation or TEOA lead to the
formation of a trace amount of CO and H2, as revealed in column
5-7 of Figure 3a, indicating that the reaction is driven by the
harvested light photons of Ru, and the sacrificial agent is of great
significance.[22]
Figure 1. a) The schematic illustration for the preparation of Ni MOLs, b) X-ray
diffraction patterns and c) the atomic arrangements of resultant MOFs.
As shown in Figure 2a-b, the SEM image and TEM image
clearly demonstrate that the resultant Ni MOLs is entirely
composed of uniform ultrathin nanosheets. AFM image and
corresponding topographies reveal the ultrathin structure of
resultant Ni MOLs with an average thickness of ca. 1.0 nm, as
depicted in Figure 2c, close to the thickness of the single
coordination structural layer (ca. 1.1 nm, Figure 1b). Therefore,
the above characterizations jointly suggest the successful
preparation of Ni MOLs. On the other hand, SEM image and TEM
image of isostructural bulk Ni MOFs exhibit obvious accumulation
of the nanosheets (Figure S2). Benefiting from the termination of
the bonding between metal nodes and ligands, MOLs would be
expected to create abundant coordinatively unsaturated metal
sites on the exposed surfaces, thereby providing ideal models to
investigate the importance of metal sites.
To investigate the significant role of metal nodes in
photocatalytic CO2-to-CO, Co with only one d-orbital electron less
than Ni counterpart has been investigated to construct its
isostructural Co MOLs counterpart for comparative study (Figure
S4). Co MOLs shows silimiliar morphology and identical average
thickness with Ni MOLs, as revealed in Figure S5. In pure CO2,
Co MOLs sample shows a moderate CO production rate of 4.61
μmol/h and a CO selectivity of 66.3%, as shown in Figure 3b.
Obviously, both the performance of Ni MOLs in pure CO2 and
diluted CO2 are significantly higher than that of Co MOLs in pure
CO2. However, the CO evolution rate of Co MOLs dramatically
declines to 0.44 μmol/h with a selectivity of 9.6% in diluted CO2,
as demonstrated in Figure 3b. In brief, Co MOLs is almost
inactive in low concentration of CO2. Therefore, ruling out the
influences of morphology, organic ligands and structure on MOFs’
catalytic performance, the metal nodes-dependent performance
for CO2 photoreduction has been clearly observed, especially in
low concentration of CO2.
Figure 2. a) SEM image, b) TEM image, c) AFM image and corresponding
topographies of as-prepared Ni MOLs, respectively.
Photocatalytic CO2 reduction reactions have been conducted in a
visible-light-driven catalytic system with [Ru(bpy)3]Cl2·6H2O
This article is protected by copyright. All rights reserved.

10.1002/anie.201811545
Angewandte Chemie International Edition
COMMUNICATION
the H2O adsorption energy of the Co MOLs (-64.78 kJ/mol) is
slightly stronger than that of Ni MOLs (-62.47 kJ/mol). It is
generally accepted that stronger CO2 adsorption energy facilitates
the stabilization of initial metal-CO2 adducts and thus promotes
the CO2 reduction.[15] Whereas weaker H2O adsorption energy is
capable of suppressing the undesired metal-H2O adducts and
thereby reduces H2 byproduct. As such, the much stronger CO2
adsorption energy and weaker H2O adsorption energy are
expected to jointly elevate the activity and selectivity for CO
production of Ni MOLs.
Photocatalytic CO2-to-CO conversion generally refers to a
carboxyl intermediate (COOH*) via CO2* + H+ + e− → COOH*.[25-
26]
To deeply investigate the CO2 photoreduction process on
MOLs, the overall potential energy involving reduction of CO2* to
CO* via COOH* on Ni MOLs and Co MOLs are further calculated
by the DFT calculations. As displayed in Figure 3d, the results
disclose that the potential energy barrier corresponding to the
reduction of CO2* to COOH* is 30.5 kJ/mol for Co MOLs and 62.2
kJ/mol for Ni MOLs. Both the energy barriers are sufficiently small,
indicating that the reaction can proceed at room temperature. The
generated COOH* can be then reduced to CO* adducts by a
proton-electron transfer reduction process (COOH* + H+ + e− →
CO* + H2O) and CO is finally generated from the dissociation of
weakly bonded CO* adduct (CO* → CO).[27] The activation energy
barrier for COOH* formation suggested by the DFT calculations
over Co MOLs is slightly smaller than that of Ni MOLs, indicating
that Co MOLs is kinetically more favorable for the formation of
COOH* than its Ni MOLs counterpart, which is contrary to the
order of the CO production rate and selectivity. Therefore, the PL
measurements and DFT calculations explicitly elucidate that the
initial adsorption of CO2 molecules on MOLs should be the critical
step in this reaction system, rather than the electron transfer and
CO2 activation steps, verifying the previous speculation that the
selectivity of CO2 photoreduction reaction is directly linked to the
binding affinity to CO2.[28]
To confirm the widespread applicability of the superiority of Ni
species in facilitating CO2 photoreduction, another kind of
isostructural Ni (Co) MOFs with 2,5-thiophenedicarboxylic (TDA)
as organic linkers have been constructed for comparative study[29]
as shown in Figure S9a. In pure CO2 (Figure S9b), Ni TDA MOFs
exhibits a CO production rate of 6.7 μmol/h and CO selectivity of
94.7%, which are about 2 and 1.6 times of those of Co MOFs
under identical reaction conditions, respectively. Of note, Ni TDA
MOFs only reduces its CO production rate by 12% when CO2
partial pressure is dropped to 0.1 atm. However, about 90% of CO
production rate of Co TDA MOFs is lost in low CO2 concentration.
The results indicate that the superiority of Ni species on CO2
photoreduction, especially in diluted CO2, can be extended to
other MOFs, providing fundamental guidance for the design of
efficient inorganic-organic complexes for artificial photosynthesis
and other applications.
Figure 3. a) CO2 photoreduction performance under various reaction conditions,
b) comparison of CO2 photoreduction performance over Ni MOLs and Co MOLs
in pure CO2 and diluted CO2 (10%), c) comparison of the CO2 and H2O
adsorption energies of Ni MOLs and Co MOLs, d) potential energy diagram
describing the COOH* intermediate from CO2 reduction to CO over Ni MOLs
and Co MOLs under visible light irradiation.
To probe the origin of metal nodes-dependent performance for
CO2 photoreduction and provide fundamental guidance for the
design of next-generation efficient MOFs for CO2 photoreduction
and other applications, the whole reaction process has been
studied systematically. Firstly, the separation and transfer
process of photogenerated charge carriers in the CO2 reduction
system has been investigated by in-situ photoluminescence (PL)
measurements. As shown in Figure S6, the MOLs contained
systems show obviously declined PL intensities than the blank
system. Generally, the PL emission results from the
recombination of free charge carriers.[23] Therefore, lower PL
intensities of MOLs contained systems indicate that MOLs
catalysts are favorable for boosting the separation and transfer of
photogenerated charge carriers in the CO2 reduction system.
However, Co MOLs shows lower PL intensity than Ni MOLs,
contrary to the trend of photocatalytic performance. Therefore,
charge separation may not the main reason for the boosted CO
production rate and selectivity over Ni MOLs.
Then, DFT calculations have then been employed to
investigate the adsorption energies of CO2 and H2O onto the Ni
MOLs and Co MOLs, respectively. As shown in Figure S7, the
adsorbed CO2 exhibits a bent configuration like that of (CO2)−
anion, indicating that the activation of CO2 molecules can be
realized on the MOLs surface[24] (denoted as CO2*, where “*”
represents the corresponding active adsorption site on the
surface). On the other hand, the Ni-C bond (1.897 Å) on Ni MOLs
is obviously shorter than the Co-C bond (1.924 Å), suggesting a
stronger binding interaction between CO2 and Ni species. The
adsorption energy of CO2 on Ni MOLs is -200.11 kJ/mol, which is
much stronger than that of the Co MOLs (-140.32 kJ/mol), as
shown in Figure 3c, implying much stronger adsorption affinity of
Ni MOLs towards CO2. Such a sharp difference in adsorption
behavior of CO2 over Ni MOLs and Co MOLs has also been
proved by experimental measurements (Figure S8). However,
On the basis of the above results, a tentative reaction
mechanism for CO2 photoreduction over Ni MOLs has been
proposed, as schematically illustrated in Scheme 1. On visible
light irradiation, the photosensitizer [Ru(bpy)3]2+ (Ru) is excited to
produce [Ru(bpy)3]2+*, which is then reductively quenched by the
TEOA sacrificial electron donor, giving rise to the reduced species
This article is protected by copyright. All rights reserved.

10.1002/anie.201811545
Angewandte Chemie International Edition
COMMUNICATION
of [Ru(bpy)3]+. Subsequently, the [Ru(bpy)3]+ could transfer an
electron to Ni MOLs catalyst, which provides abundant
coordinatively unsaturated Ni sites on the surface for the
adsorption of CO2 molecules. The initial adsorption of CO2
molecules onto Ni MOLs is the critical step during the whole
reaction process. Strong CO2 adsorption affinity of Ni MOLs
endows it great potential for CO2 uptake and benefits the
stabilization of the initial Ni-CO2 adducts, thereby facilitating CO2-
to-CO conversion. Meanwhile, weak H2O adsorption affinity of Ni
MOLs inhibits the proton transfer and reduces the formation of H2
byproduct. Therefore, Ni MOLs displays higher activity and
selectivity for CO2 photoreduction in both pure CO2 and diluted
CO2.
Acknowledgments
The support from the National Natural Science Foundation of
China (Grant No. 21836002, 21777046 and 21477129), the
Fundamental Research Funds for the Central Universities (No.
2017PY009 and 2017BQ054), the Guangdong Innovative and
Entrepreneurial Research Team Program (No. 2016ZT06N569),
and Guangzhou Science and Technology Project (No.
201803030002) is gratefully acknowledged.
Keywords: MOFs • monolayers • CO2 photoreduction • low
concertation • selectivity
[1]
[2]
[3]
[4]
S. J. Davis, K. Caldeira, H. D. Matthews, Science 2010, 329, 1330.
H. Rao, L. C. Schmidt, J. Bonin, M. Robert, Nature 2017, 548, 74.
J. Ran, M. Jaroniec, S.-Z. Qiao, Adv. Mater. 2018, 30, 1704649.
M. Ou, W. Tu, S. Yin, W. Xing, S. Wu, H. Wang, S. Wan, Q. Zhong, R.
Xu, Angew. Chem. Int. Ed. 2018, 57,13570.
[5] T. Nakajima, Y. Tamaki, K. Ueno, E. Kato, T. Nishikawa, K. Ohkubo, Y.
Yamazaki, T. Morimoto, O. Ishitani, J. Am. Chem. Soc. 2016, 138, 13818.
[6] D.-C. Liu, H.-J. Wang, J.-W. Wang, D.-C. Zhong, L. Jiang, T.-B. Lu,
Chem. Commun. 2018, 54, 11308.
[7] X. Zhang, F. Han, B. Shi, S. Farsinezhad, P. Dechaine Greg, K. Shankar,
Angew. Chem. Int. Ed. 2012, 51, 12732.
[8] J. L. White, M. F. Baruch, J. E. Pander Iii, Y. Hu, I. C. Fortmeyer, J. E.
Park, T. Zhang, K. Liao, J. Gu, Y. Yan, T. W. Shaw, E. Abelev, A. B. Bocarsly,
Chem. Rev. 2015, 115, 12888.
[9]
C. Dong, C. Lian, S. Hu, Z. Deng, J. Gong, M. Li, H. Liu, M. Xing, J.
Zhang, Nat. Commun. 2018, 9, 1252.
[10] R. Li, W. Zhang, K. Zhou, Adv. Mater. 2018, 1705512.
[11] A. Dhakshinamoorthy, A. M. Asiri, H. García, Angew. Chem. Int. Ed.
2016, 55, 5414.
[12] S. Wang, W. Yao, J. Lin, Z. Ding, X. Wang, Angew. Chem. Int. Ed. 2014,
53, 1034.
Scheme 1. Proposed mechanism for the photocatalytic conversion of CO2 to
CO over Ni MOLs under visible light irradiation with [Ru(bpy)3]2+ as the
photosensitizer and triethanolamine (TEOA) as electron donor.
[13] K. Niu, Y. Xu, H. Wang, R. Ye, H. L. Xin, F. Lin, C. Tian, Y. Lum, K. C.
Bustillo, M. M. Doeff, M. T. M. Koper, J. Ager, R. Xu, H. Zheng, Sci. Adv. 2017,
3, e170092.
[14] T. Kajiwara, M. Fujii, M. Tsujimoto, K. Kobayashi, M. Higuchi, K. Tanaka,
S. Kitagawa, Angew. Chem. Int. Ed. 2016, 55, 2697.
In summary, the universal metal nodes-dependent
performance for photoreduction of diluted CO2 has been
demonstrated by deliberately constructing Ni MOLs. In pure CO2,
Ni MOLs exhibits spectacular CO selectivity of 97.8% with a
highest apparent quantum yield of ca. 2.2% at 420 nm among
analogous systems. In a simulated flue-gas (10% CO2), Ni MOLs
exhibits a highest apparent quantum yield of 1.96% with
spectacular CO selectivity of 96.8%, which not only exceeds
reported systems in dilute CO2 but also is superior to most
catalysts in pure CO2. Whereas Co MOLs is almost inactive in low
concentration of CO2, obviously indicates the metal nodes-
dependent performance for CO2 photoreduction, especially in
diluted CO2. Experimental and calculation characterizations
elucidate that the initial adsorption of CO2 molecules is the critical
step in the whole reaction process. The general applicability of the
superiority of Ni species has been further confirmed by comparing
with Co metal in other MOFs. This work demonstrates metal
nodes-dependent performance for photoreduction of diluted CO2,
providing intriguing possibilities to develop many other metal-
organic complexes for solar energy conversion and other
applications.
[15] Y. Wang, N.-Y. Huang, J.-Q. Shen, P.-Q. Liao, X.-M. Chen, J.-P. Zhang,
J. Am. Chem. Soc. 2018, 140, 38.
[16] X.-F. Lu, P.-Q. Liao, J.-W. Wang, J.-X. Wu, X.-W. Chen, C.-T. He, J.-P.
Zhang, G.-R. Li, X.-M. Chen, J. Am. Chem. Soc. 2016, 138, 8336.
[17] S. Zhao, Y. Wang, J. Dong, C.-T. He, H. Yin, P. An, K. Zhao, X. Zhang,
C. Gao, L. Zhang, J. Lv, J. Wang, J. Zhang, A. M. Khattak, N. A. Khan, Z. Wei,
J. Zhang, S. Liu, H. Zhao, Z. Tang, Nature Energy 2016, 1, 16184.
[18] A. Mesbah, P. Rabu, R. Sibille, S. Lebègue, T. Mazet, B. Malaman, M.
François, Inorg. Chem. 2014, 53, 872.
[19] K. Zhao, S. Zhao, C. Gao, J. Qi, H. Yin, D. Wei, F. Mideksa Megasia, X.
Wang, Y. Gao, Z. Tang, R. Yu, Small 2018, 14, 1800762.
[20] S. Wang, Y. Hou, X. Wang, ACS Appl. Mater. Inter. 2015, 7, 4327.
[21] G. V. Last, M. T. Schmick, Environ. Earth. Sci. 2015, 74, 1189.
[22] S. Wang, B. Guan, X. W. D. Lou, Energy Environ. Sci. 2018, 11, 306.
[23] B. Han, S. Liu, N. Zhang, Y.-J. Xu, Z.-R. Tang, Appl. Catal., B 2017, 202,
298.
[24] X. Lin, Y. Gao, M. Jiang, Y. Zhang, Y. Hou, W. Dai, S. Wang, Z. Ding,
Appl. Catal., B 2018, 224, 1009.
[25] X. Li, W. Bi, M. Chen, Y. Sun, H. Ju, W. Yan, J. Zhu, X. Wu, W. Chu, C.
Wu, Y. Xie, J. Am. Chem. Soc. 2017, 139, 14889.
[26] W. Bi, X. Li, R. You, M. Chen, R. Yuan, W. Huang, X. Wu, W. Chu, C.
Wu, Y. Xie, Adv. Mater. 2018, 30, 1706617.
[27] C. Zhang, S. Yang, J. Wu, M. Liu, S. Yazdi, M. Ren, J. Sha, J. Zhong, K.
Nie, S. Jalilov Almaz, Z. Li, H. Li, I. Yakobson Boris, Q. Wu, E. Ringe, H. Xu, M.
Ajayan Pulickel, M. Tour James, Adv. Energy Mater. 2018, 8, 1703487.
[28] C. S. Diercks, Y. Liu, K. E. Cordova, O. M. Yaghi, Nat. Mater. 2018, 17,
301.
[29] Y. Ning, X. Lou, C. Li, X. Hu, B. Hu, Chem. Eur. J. 2017, 23, 15984.
This article is protected by copyright. All rights reserved.

10.1002/anie.201811545
Angewandte Chemie International Edition
COMMUNICATION
COMMUNICATION
B. Han+, X.w. Ou+, Z.q. Deng, Ch. Tian,
H. Deng, Y.-J.Xu, Zh. Lin *
Page No. – Page No.
Ni Metal-Organic Frameworks
Monolayers for Photoreduction of
Diluted CO2: Metal Nodes-Dependent
Activity and Selectivity
Photocatalytic conversion of diluted CO2 with high efficiency and selectivity can be achieved on Ni MOFs monolayers. The initial
adsorption of CO2 molecules is the critical step, providing an effective general strategy for the rational design of inorganic-organic
complexes for artificial photosynthesis.
This article is protected by copyright. All rights reserved.