Highly Selective Hydrogenation of CO2to Ethanol via Designed Bifunctional Ir1-In2O3Single-Atom Catalyst

Article abstract of DOI:10.1021/jacs.0c08607

Recently, CO2 hydrogenation for the controlled growth of the carbon chain to produce high-value C2 or C2+ products has attracted great interest, where achieving high selectivity for a specific product remains a challenge, especially for ethanol. Herein, we have designed a bifunctional Ir1-In2O3 single-atom catalyst, integrating two active catalytic centers by anchoring the monatomic Ir onto the In2O3 carrier. This Ir1-In2O3 single-atom catalyst is efficient for the hydrogenation of CO2 in liquid, yielding a high selectivity for ethanol (>99%) with an excellent initial turnover frequency (481 h-1). Characterization shows that the isolated Ir atom couples with the adjacent oxygen vacancy forming a Lewis acid-base pair, which activates the CO2 and forms the intermediate species of carbonyl (CO*) adsorbed on the Ir atom. Coupling this CO? with the methoxide adsorbed on the In2O3 forms a C-C bond. The strategy of this effective bifunctional single-atom catalyst by synergistically utilizing the distinct catalytic roles of the single-atom site and the substrates provides a new avenue in catalyst design for complex catalysis.

Full text of DOI:10.1021/jacs.0c08607

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Highly Selective Hydrogenation of CO2 to Ethanol via Designed
Bifunctional Ir1−In2O3 Single-Atom Catalyst
Xue Ye, Chongya Yang, Xiaoli Pan, Junguo Ma,* Yaru Zhang, Yujing Ren, Xiaoyan Liu, Lin Li,
and Yanqiang Huang*
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ABSTRACT: Recently, CO2 hydrogenation for the controlled growth of the carbon chain to produce high-value C2 or C2+ products
has attracted great interest, where achieving high selectivity for a specific product remains a challenge, especially for ethanol. Herein,
we have designed a bifunctional Ir1−In2O3 single-atom catalyst, integrating two active catalytic centers by anchoring the monatomic
Ir onto the In2O3 carrier. This Ir1−In2O3 single-atom catalyst is efficient for the hydrogenation of CO2 in liquid, yielding a high
selectivity for ethanol (>99%) with an excellent initial turnover frequency (481 h−1). Characterization shows that the isolated Ir
atom couples with the adjacent oxygen vacancy forming a Lewis acid−base pair, which activates the CO2 and forms the intermediate
species of carbonyl (CO*) adsorbed on the Ir atom. Coupling this CO* with the methoxide adsorbed on the In2O3 forms a C−C
bond. The strategy of this effective bifunctional single-atom catalyst by synergistically utilizing the distinct catalytic roles of the
single-atom site and the substrates provides a new avenue in catalyst design for complex catalysis.
t is paramount to reduce the dependence on fossil energy
and to control CO2 emissions by developing renewable
Here, we designed a bifunctional SAC based on the synergy
of atomic Ir with In2O3 for converting of CO2 to ethanol.
In2O3 is an effective catalyst for hydrogenation of CO2 to
produce methanol,21 while the Ir-based mononuclear complex
can catalyze methanol carbonylation.22,23 We achieved
excellent ethanol selectivity of 99.7% with the highest initial
turnover frequency (TOF) of 481 h−1, outperforming the
precious metal catalysts. Theoretical calculation and infrared
spectra revealed that a Lewis acid−base pair was formed
between the monatomic Ir and the adjacent oxygen vacancy
(Ov) on In2O3 forming two distinct catalytic centers, which
reduces CO2 to active intermediates and then facilitates the
C−C coupling to form ethanol.
The Ir1−In2O3 SAC was synthesized through a modified
wet-chemical method. In2O3 was partially reduced with
hydrogen to generate Ov before Ir impregnation.21 Ov served
as the anchoring site for single atoms and trapped IrCl62− with
great affinity(Figure 1a).24 The Ir loading in the Ir1−In2O3
SAC was characterized by inductively coupled plasma optical
emission spectrometry (ICP-OES, Table S1). High angle dark-
field scanning transmission electron microscope images
confirmed the isolated single-atom structure of Ir (HAADF-
STEM, Figures 1b and S1), where no nanoparticles were
observed (Figure S2). Furthermore, the extended X-ray
absorption fine structure (EXAFS) of the Ir LIII-edge of the
k2 χ(k) data showed the Ir−O coordination number to be 4.8
I
energies.1,2 One of the most attractive strategies is to close the
carbon cycle by producing “liquid sunlight” by transforming
CO2 into liquid fuel.3 Thus, much attention is paid to the
hydrogenation of CO2 into safe and transportable liquid
hydrocarbons, including alcohols and gasoline.4,5 Among them,
ethanol is one of the most desirable products due to its
impressive energy density and existing engine technology.6
However, the direct synthesis of ethanol from CO2 is still
challenging due to the high energy barrier of C−C coupling.7,8
The synthesis of ethanol from CO2 has been realized using
Rh-, Fe-, or Co-based catalysts via an indirect Fischer−
Tropsch synthesis (FTS). Although C−C coupling can be
greatly promoted in FTS, the degree of C−C coupling is
difficult to control. The produced alcohols follow the
Anderson−Schulz−Flory (ASF) distribution with a typical
ethanol fraction of ∼35%.9−12
In an effort to improve ethanol selectivity, recent research
has focused on the design and modification of novel catalysts
for CO2 hydrogenation. Regulating active sites was the most
effective method to govern the carbon chain growth with
controlled alcohol distribution. For example, by modifying Cu-
or Co-based catalysts with ordered and isolated active sites, the
ethanol selectivity was improved.13−17 For this catalyst, the
separation of the catalytic site was essential for attaining
control over the carbon chain growth. Here, we propose a new
catalyst design strategy based on a single-atom catalyst (SAC)
with uniformly distributed atomic active sites18 to maximize
the ethanol selectivity. More importantly, SAC also serves as a
bridge between homogeneous and heterogeneous catalysis.
Our previous research suggests that the catalytic process that
normally occurs with the homogeneous catalyst can be well
realized using supported SACs.19,20
Received: August 11, 2020
https://dx.doi.org/10.1021/jacs.0c08607
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© XXXX American Chemical Society
A

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Figure 2. (a) Selectivity of ROHs (methanol and ethanol) and
achieved the yield of ethanol and (b) comparisons of the TOFIr values
over different Ir loadings on In2O3 during CO2 hydrogenation at 200
°C for 5 h. ROH yields and ethanol selectivity over Ir1−In2O3: effect
of temperature (c) and reaction time (d) in 3.0 mL of H2O, initial
pressure 6.0 MPa (H2 /CO2 = 5:1), catalyst 20 mg.
supports claimed that the selection of components (Ir−In2O3)
in the polar solvent was crucial (Tables S4 and S5).
The excellent catalytic performance of Ir1−In2O3 SAC was
closely related to its structure. Electrostatic potentials of In2O3
and Ir1−In2O3 were calculated to investigate the catalytic
mechanism (Figure 3a and b). The presence of monatomic Ir
Figure 1. (a) Schematic illustration of the fabrication procedures of
Ir1−In2O3. (b) HAADF-STEM image of Ir1−In2O3. Inset scale bar, 5
nm. (c) Ir LIII-edge EXAFS spectra in r-space with different Ir
loadings (without phase correction). (d) Wavelet transform of the k2-
weighted EXAFS spectrum of the Ir1−In2O3. (e) The fitted XPS
spectra of Ir 4f with diverse Ir loadings.
(Table S2) without Ir−Ir contribution25 (Figure 1c). The
wavelet transformed plot of Ir1−In2O3 (Figure 1d) demon-
strates the existence of Ir single atoms. X-ray photoelectron
spectroscopy (XPS) (Figure 1e) revealed the binding energies
(BE) of 65.2 and 62.1 eV for Ir f5/2 and f 7/2, corresponding to
the higher oxidation state of Irδ+.26
The Ir1−In2O3 SAC was then used for CO2 hydrogenation
reactions in aqueous solution. Both gaseous and liquid
products were analyzed after the reaction, where only
methanol and ethanol were detected. Where pure In2O3 only
produced methanol, the Ir1−In2O3 SAC preferentially yielded
ethanol with a selectivity of 99.7% and a TOFIr value up to 481
h−1 (Figures 2a and b). This TOF was comparable with the
best literature results reported under similar conditions (Table
S3). Since the catalytic kinetics are dependent on the reaction
temperature, the dependency of ethanol production on time
and temperature was also investigated. As the temperature
increased from 180 to 240 °C, the yields of both ethanol and
methanol increased monotonically (Figure 2c). However, the
methanol yield increased at a higher rate, such that the
selectivity of ethanol decreased to 92.2% at 240 °C. Hence, a
lower temperature is more favorable to ethanol production. As
for reaction time, we found that the initial ethanol yield was
relatively low (0.016 mmol g−1 h−1) but increased to 0.99
mmol g−1 h−1 after 5 h (Figure 2d). Meanwhile, the methanol
yield remained constant at 0.012 mmol g−1 h−1, resulting in an
increase of ethanol selectivity from 51.6% to 99.7%. The results
suggested that the ethanol selectivity depended on the relative
production of methanol, which in turn indicated indirectly that
methanol could be an important intermediate for ethanol
synthesis. The research of different solvents, metals, and
Figure 3. Electrostatic potential figures of In2O3 (a) and Ir1−In2O3
catalyst surface (b). Free energy diagram for CO2 dissociation over
the In2O3 and Ir1−In2O3 catalyst (c).
created a negative potential, while the oxygen vacancy (Ov)
remained positively charged on the defective In2O3 basal
surface. As such, a local Lewis acid−base pair was formed
between the monatomic Ir and the adjacent Ov. DFT
calculations demonstrated that CO2 was more favorably
adsorbed onto Ir1−In2O3 than onto In2O3 (Figure 3c).
Chemisorbed CO2 formed CO2* (asterisk (*) represents the
surface-adsorbed species), where the C atom was directly
bound to the Ir atom and one of the O atoms was bound to the
adjacent Ov. This indicated a synergistic effect toward CO2
activation. The distinct adsorption geometry presented by the
Ir1−In2O3 catalyst enabled a decrease in the energy barrier for
CO2* dissociation to CO* from 0.77 eV on pure In2O3 to 0.48
eV. The resulting Irδ+−CO* intermediate was thought to play
a critical role in ethanol production.27
The CO2 transformation was also verified by the in situ
diffuse reflectance infrared Fourier transform spectroscopy
(DRIFTS, Figures 4a,b and S3). A key intermediate of CO
(2076 cm−1) appeared on Ir1−In2O3 after exposing CO2 at 200
B
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Figure 4. DRIFTS spectra of pure In2O3 (a) and Ir1−In2O3 catalyst (b) after exposure to CO2 at 200 °C. In situ FTIR spectra (c) of CO2
hydrogenation with Ir1−In2O3 catalyst bubbled in aqueous solution. Ir−In2O3 samples with different Ir loadings (d) after exposure to CO2 at 200
°C.
°C, confirmed the Irδ+−CO* formation.28−30 The peak
intensities attributed to carbonate (1309, 1365, and 1496
cm−1) and bicarbonate (1450 and 1630 cm−1) moieties31,32
were notably higher on Ir1−In2O3 than those on pure In2O3,
implying that the effect of the Lewis acid−base pair on CO2
activation was promoted. The adsorption of CO* was deemed
strong since no significant reduction of CO peak intensity in
Ar flush experiments (Figure S4). Meanwhile, the formation of
another important intermediate CH3O* (2856, 2960, and
2994 cm−1)33,34 was observed during hydrogenation with in
situ Fourier transform infrared spectroscopy (FTIR, Figure
4c). These peaks have rarely been observed using pure In2O3
based methanol catalysts, suggesting that the Ir single atoms
also help to stabilize the methoxide on the Ov of Ir1−In2O3.
Combined with the 13CH3OH isotope experiment (Figure S5),
we concluded that the stable intermediates of Irδ+−CO* and
CH3O*−Ov were the pivotal species for C−C coupling.35 The
proposed reaction path is shown in Scheme S1.
The excellent catalytic performance of the Ir1−In2O3 SAC
was the colocalization of atomically dispersed Ir and Ov in the
carrier phase. The importance of the atomic dispersion of Ir
was examined by preparing Ir−In2O3 catalysts with increased
Ir loading and then testing them under identical conditions.
The ethanol selectivity was suppressed significantly from 85.3%
to 5.7%, as the Ir content increased from 0.2 wt % to 1.0 wt %
(Figure 2a). The TOF also decreased accordingly (Figure 2b).
TEM and scanning electron microscopy energy-dispersive
X-ray spectroscopy (SEM-EDS) images revealed the growth of
Ir from small clusters (0.5 wt %, Figures S6−S8) to aggregated
nanoparticles of 1−2 nm in size (1.0 wt %, Figure S9). The
above structural features were also supported by X-ray
diffraction (XRD) patterns (Figure S10). The Ir LIII edge
EXAFS spectra revealed the presence of Ir−Ir metallic bond
with increasing intensity as the Ir loading augmented (Figures
1c and S11a; and Table S2). XPS spectra (Ir 4f, Figure 1e)
showed that the peak intensities associated with metallic Ir0
enhanced with increasing Ir loading,36 accompanied by the
redshift in In 3d BE (Figure S11b and Table S6). The soft X-
ray absorption spectra (XAS) showed a decrease in peak
intensity at the In M-edge and O K-edge as the Ir loading
augmented (Figure S12).37 Therefore, the increase of Ir also
caused a reduction of In2O3. The excessive reduction of In2O3
at higher Ir contents was also confirmed in the temperature-
programmed reduction (H2-TPR, Figure S13 and Table S7).
With the increase of Ir0, the In2O3 reduction peak shifted from
242 (In2O3) to 170 °C (1.0 wt % Ir−In2O3). The reduced
In2O3 became less active21,38 toward the formation of
methoxide with decreased ethanol selectivity. Besides, Ir1−
In2O3 showed a gradual decrease of TOF to a value of 186 h−1
after the fourth catalytic cycle (Table S8), also due to the
reduction of In2O3 (Figure S14).
CO2 activation was also affected by the increase in non-
monoatomic Ir loading. CO2 DRIFTS showed that the amount
of adsorbed CO2 species significantly decreased as the Ir
content increased (Figures 4d and S15). The formation of Ir0−
CO was evidenced with a peak at a lower wavenumber of 2040
cm−1 compared to Irδ+−CO.30 Hence, the C−O bond strength
was weaker on Ir0 than on Irδ+ due to more electron transfer
from Ir0 to CO 2π antibonding orbital,39 while the Ir0−C bond
became stronger. This meant that the alkylation activity was
C
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Communication
lowered while the cleavage of the C−O bond became easier.
The larger size of Ir0 particles could also enrich the surface H
concentration, resulting in a direct reduction of C1 species
forming methanol, while the C−C coupling activity decreased.
Our results confirmed that the over-reduction of In2O3 would
alter the coordination of critical intermediate components.
Hence, the SAC design of the monatomic Ir on In2O3 was
optimized for the selective hydrogenation of CO2 to ethanol.
In conclusion, an Ir1−In2O3 single-atom catalyst for CO2
hydrogenation to ethanol was presented. Thanks to the
bifunctional nature of the Ir1−In2O3, composed of partially
reduced In2O3 and a Lewis acid−base pair between the single-
atom Ir and adjacent oxygen vacancy (Ov), it not only
promotes the adsorption and activation CO2 into CO* but
also provides great opportunities for C−C coupling between
CH3O*−Ov and Irδ+−CO*. As a result, CO2 was hydro-
genated into ethanol with a selectivity up to 99.7% at an initial
TOF up to 481 h−1. Our study presents a new, green, and
promising catalyst for the conversion of CO2 into a versatile
energy source; introduces the rational design of bifunctional
single-atom catalysts for simplifying complex reaction
processes, and expands the applications of single-atom
catalysts.
University of Chinese Academy of Science, Beijing 100049,
China
Yujing Ren − CAS Key Laboratory of Science and Technology
on Applied Catalysis, Dalian Institute of Chemical Physics,
Chinese Academy of Sciences, Dalian 116023, China;
University of Chinese Academy of Science, Beijing 100049,
China
Xiaoyan Liu − CAS Key Laboratory of Science and Technology
on Applied Catalysis, Dalian Institute of Chemical Physics,
Chinese Academy of Sciences, Dalian 116023, China;
orcid.org/0000-0003-2694-2306
Lin Li − CAS Key Laboratory of Science and Technology on
Applied Catalysis, Dalian Institute of Chemical Physics, Chinese
Academy of Sciences, Dalian 116023, China; orcid.org/
0000-0002-3036-0934
Complete contact information is available at:
https://pubs.acs.org/10.1021/jacs.0c08607
Author Contributions
All authors have given approval to the final version of the
manuscript.
Notes
The authors declare no competing financial interest.
ASSOCIATED CONTENT
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ACKNOWLEDGMENTS
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* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/jacs.0c08607.
This work was supported by the National Key R&D Program
of China (2016YFB0600902), the Strategic Priority Research
Program of the Chinese Academy of Sciences
(XDB36030200), the National Natural Science Foundation
of China (21925803, U19A2015), Dalian National Laboratory
for Clean Energy (DNL180401).
Experimental procedures, details on the synthesis of Ir/
In2O3 catalysts, and additional characterizations of the
Ir/In2O3 catalysts (PDF)
REFERENCES
■
AUTHOR INFORMATION
(1) Aresta, M.; Dibenedetto, A.; Angelini, A. Catalysis for the
valorization of exhaust carbon: from CO2 to chemicals, materials, and
fuels. technological use of CO2. Chem. Rev. 2014, 114 (3), 1709−
1742.
(2) Li, C. W.; Ciston, J.; Kanan, M. W. Electroreduction of carbon
monoxide to liquid fuel on oxide-derived nanocrystalline copper.
Nature 2014, 508 (7497), 504−507.
(3) Shih, C. F.; Zhang, T.; Li, J.; Bai, C. Powering the Future with
Liquid Sunshine. Joule 2018, 2 (10), 1925−1949.
■
Corresponding Authors
Junguo Ma − CAS Key Laboratory of Science and Technology on
Applied Catalysis, Dalian Institute of Chemical Physics, Chinese
Academy of Sciences, Dalian 116023, China;
Email: majunguo@outlook.com.
Yanqiang Huang − CAS Key Laboratory of Science and
Technology on Applied Catalysis, Dalian Institute of Chemical
Physics, Chinese Academy of Sciences, Dalian 116023, China;
Dalian National Laboratory for Clean Energy, Dalian 116023,
Liaoning, China; orcid.org/0000-0002-7556-317X;
Email: yqhuang@dicp.ac.cn.
(4) Liu, Q.; Yang, X.; Li, L.; Miao, S.; Li, Y.; Li, Y.; Wang, X.; Huang,
Y.; Zhang, T. Direct catalytic hydrogenation of CO2 to formate over a
Schiff-base-mediated gold nanocatalyst. Nat. Commun. 2017, 8, 1407.
(5) Yang, P. P.; Zhang, X. L.; Gao, F. Y.; Zheng, Y. R.; Niu, Z. Z.;
Yu, X.; Liu, R.; Wu, Z. Z.; Qin, S.; Chi, L. P.; Duan, Y.; Ma, T.; Zheng,
X. S.; Zhu, J. F.; Wang, H. J.; Gao, M. R.; Yu, S. H. Protecting Copper
Oxidation State via Intermediate Confinement for Selective CO2
Electroreduction to C2+ Fuels. J. Am. Chem. Soc. 2020, 142 (13),
6400−6408.
Authors
Xue Ye − CAS Key Laboratory of Science and Technology on
Applied Catalysis, Dalian Institute of Chemical Physics, Chinese
Academy of Sciences, Dalian 116023, China; University of
Chinese Academy of Science, Beijing 100049, China
Chongya Yang − CAS Key Laboratory of Science and
Technology on Applied Catalysis, Dalian Institute of Chemical
Physics, Chinese Academy of Sciences, Dalian 116023, China;
University of Chinese Academy of Science, Beijing 100049,
China
Xiaoli Pan − CAS Key Laboratory of Science and Technology on
Applied Catalysis, Dalian Institute of Chemical Physics, Chinese
Academy of Sciences, Dalian 116023, China
Yaru Zhang − CAS Key Laboratory of Science and Technology
on Applied Catalysis, Dalian Institute of Chemical Physics,
Chinese Academy of Sciences, Dalian 116023, China;
(6) Goldemberg, J. Ethanol for a sustainable energy future. Science
2007, 315 (5813), 808−810.
(7) Montoya, J. H.; Peterson, A. A.; Nørskov, J. K. Insights into C−
C Coupling in CO2 Electroreduction on Copper Electrodes.
ChemCatChem 2013, 5 (3), 737−742.
(8) Luk, H. T.; Mondelli, C.; Ferre, D. C.; Stewart, J. A.; Perez-
Ramirez, J. Status and prospects in higher alcohols synthesis from
syngas. Chem. Soc. Rev. 2017, 46 (5), 1358−1426.
(9) Gogate, M. R.; Davis, R. J. Comparative study of CO and CO2
hydrogenation over supported Rh−Fe catalysts. Catal. Commun.
2010, 11 (10), 901−906.
(10) Gnanamani, M. K.; Jacobs, G.; Keogh, R. A.; Shafer, W. D.;
Sparks, D. E.; Hopps, S. D.; Thomas, G. A.; Davis, B. H. Fischer−
Tropsch synthesis: Effect of pretreatment conditions of cobalt on
D
https://dx.doi.org/10.1021/jacs.0c08607
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
pubs.acs.org/JACS
Communication
activity and selectivity for hydrogenation of carbon dioxide. Appl.
Catal., A 2015, 499, 39−46.
(27) He, M.; Sun, Y.; Han, B. Green carbon science: scientific basis
for integrating carbon resource processing, utilization, and recycling.
Angew. Chem., Int. Ed. 2013, 52 (37), 9620−9633.
(11) Kishida, M.; Yamada, K.; Nagata, H.; Wakabayashi, K. CO2
Hydrogenation for C2+ Alcohols Synthesis over Silica-Supported Ir-
Mo Catalysts. Chem. Lett. 1994, 23, 555−556.
́
(28) Gelin, P.; Auroux, A.; Taarit, Y. B.; Gravelle, P. C. Infrared and
calorimetric studies of the adsorption of carbon monoxide on zeolite-
supported iridium catalysts. Appl. Catal. 1989, 46 (2), 227−240.
(29) Solymosi, F.; Novak, E.; Molnar, A. Infrared spectroscopic
study on CO-induced structural changes of iridium on an alumina
support. J. Phys. Chem. 1990, 94 (18), 7250−7255.
(12) Tatsumi, T.; Muramats, A.; Tominaga, H. O. Alcohol synthesis
from CO2/H2 on silica-supported molybdenum catalysts.″. Chem.
Lett. 1985, 14, 593−594.
(13) Bai, S.; Shao, Q.; Wang, P.; Dai, Q.; Wang, X.; Huang, X.
Highly Active and Selective Hydrogenation of CO2 to Ethanol by
Ordered Pd-Cu Nanoparticles. J. Am. Chem. Soc. 2017, 139 (20),
6827−6830.
(14) Wang, L.; Wang, L.; Zhang, J.; Liu, X.; Wang, H.; Zhang, W.;
Yang, Q.; Ma, J.; Dong, X.; Yoo, S. J.; Kim, J. G.; Meng, X.; Xiao, F.
Selective hydrogenation of CO2 to ethanol over cobalt catalysts.
Angew. Chem., Int. Ed. 2018, 57 (21), 6104−6108.
(15) An, B.; Li, Z.; Song, Y.; Zhang, J.; Zeng, L.; Wang, C.; Lin, W.
Cooperative copper centres in a metal−organic framework for
selective conversion of CO2 to ethanol. Nat. Catal. 2019, 2 (8),
709−717.
(16) Zhang, S.; Liu, X.; Shao, Z.; Wang, H.; Sun, Y. Direct CO2
hydrogenation to ethanol over supported Co2C catalysts: Studies on
support effects and mechanism. J. Catal. 2020, 382, 86−96.
(17) Wang, L.; He, S.; Wang, L.; Lei, Y.; Meng, X.; Xiao, F.-S.
Cobalt−Nickel Catalysts for Selective Hydrogenation of Carbon
Dioxide into Ethanol. ACS Catal. 2019, 9 (12), 11335−11340.
(18) Pan, Y.; Lin, R.; Chen, Y.; Liu, S.; Zhu, W.; Cao, X.; Chen, W.;
Wu, K.; Cheong, W. C.; Wang, Y.; Zheng, L.; Luo, J.; Lin, Y.; Liu, Y.;
Liu, C.; Li, J.; Lu, Q.; Chen, X.; Wang, D.; Peng, Q.; Chen, C.; Li, Y.
Design of Single-Atom Co-N5 Catalytic Site: A Robust Electrocatalyst
for CO2 Reduction with Nearly 100% CO Selectivity and Remarkable
Stability. J. Am. Chem. Soc. 2018, 140 (12), 4218−4221.
(19) Su, X.; Yang, X.-F.; Huang, Y.; Liu, B.; Zhang, T. Single-Atom
Catalysis toward Efficient CO2 Conversion to CO and Formate
Products. Acc. Chem. Res. 2019, 52 (3), 656−664.
(20) Shao, X.; Yang, X.; Xu, J.; Liu, S.; Miao, S.; Liu, X.; Su, X.;
Duan, H.; Huang, Y.; Zhang, T. Iridium Single-Atom Catalyst
Performing a Quasi-homogeneous Hydrogenation Transformation of
CO2 to Formate. Chem. 2019, 5 (3), 693−705.
(21) Martin, O.; Martin, A. J.; Mondelli, C.; Mitchell, S.; Segawa, T.
F.; Hauert, R.; Drouilly, C.; Curulla-Ferre, D.; Perez-Ramirez, J.
Indium Oxide as a Superior Catalyst for Methanol Synthesis by CO2
Hydrogenation. Angew. Chem. 2016, 128 (21), 6369−6373.
(22) Gonsalvi, L.; Adams, H.; Sunley, G. J.; Ditzel, E.; Haynes, A.
Steric and electronic effects on the reactivity of Rh and Ir complexes
containing P-S, P-P, and P-O ligands. Implications for the effects of
chelate ligands in catalysis. J. Am. Chem. Soc. 2002, 124 (45), 13597−
13612.
(30) Hadjiivanov, K. I.; Vayssilov, G. N. Characterization of Oxide
Surfaces and Zeolites by Carbon Monoxide as an IR Probe Molecule.
Adv. Catal. 2003, 34 (17), 307−511.
(31) Ye, J.; Liu, C.; Ge, Q. DFT Study of CO2 Adsorption and
Hydrogenation on the In2O3 Surface. J. Phys. Chem. C 2012, 116 (14),
7817−7825.
(32) Wang, Y.; Zhao, J.; Li, Y.; Wang, C. Selective photocatalytic
CO2 reduction to CH4 over Pt/In2O3: Significant role of hydrogen
adatom. Appl. Catal., B 2018, 226, 544−553.
(33) Fisher, I. A.; Bell, A. T. In-SituInfrared Study of Methanol
Synthesis from H2/CO2 over Cu/SiO2 and Cu/ZrO2/SiO2. J. Catal.
1997, 172 (1), 222−237.
(34) Yang, C.; Mu, R.; Wang, G.; Song, J.; Tian, H.; Zhao, Z.-J.;
Gong, J. Hydroxyl-mediated ethanol selectivity of CO2 hydrogenation.
Chem. Sci. 2019, 10 (11), 3161−3167.
(35) He, Z.; Qian, Q.; Ma, J.; Meng, Q.; Zhou, H.; Song, J.; Liu, Z.;
Han, B. Water-Enhanced Synthesis of Higher Alcohols from CO2
Hydrogenation over a Pt/Co3O4 Catalyst under Milder Conditions.
Angew. Chem., Int. Ed. 2016, 55 (2), 737−741.
(36) Chen, R.; Korotcov, A.; Huang, Y.; Tsai, D. One-dimensional
conductive IrO2 nanocrystals. Nanotechnology 2006, 17 (9), R67−
R87.
(37) Wu, J.; Xue, Y.; Yan, X.; Yan, W.; Cheng, Q.; Xie, Y. Co3O4
nanocrystals on single-walled carbon nanotubes as a highly efficient
oxygen-evolving catalyst. Nano Res. 2012, 5 (8), 521−530.
(38) García-Trenco, A.; Regoutz, A.; White, E. R.; Payne, D. J.;
Shaffer, M. S. P.; Williams, C. K. PdIn intermetallic nanoparticles for
the Hydrogenation of CO2 to Methanol. Appl. Catal., B 2018, 220, 9−
18.
(39) Blyholder, G.; Allen, M. C. Infrared spectra and molecular
orbital model for carbon monoxide adsorbed on metals. J. Am. Chem.
Soc. 1969, 91 (12), 3158−3162.
(23) Haynes, A.; Maitlis, P. M.; Morris, G. E.; Sunley, G. J.; Adams,
H.; Badger, P. W.; Bowers, C. M.; Cook, D. B.; Elliott, P. I. P.;
Ghaffar, T.; Green, H.; Griffin, T. R.; Payne, M.; Pearson, J. M.;
Taylor, M. J.; Vickers, P. W.; Watt, R. J. Promotion of iridium-
catalyzed methanol carbonylation: Mechanistic studies of the cativa
process. J. Am. Chem. Soc. 2004, 126 (9), 2847−2861.
(24) Liu, G.; Robertson, A. W.; Li, M. M.; Kuo, W. C. H.; Darby, M.
T.; Muhieddine, M. H.; Lin, Y. C.; Suenaga, K.; Stamatakis, M.;
Warner, J. H.; Tsang, S. C. E. MoS2 monolayer catalyst doped with
isolated Co atoms for the hydrodeoxygenation reaction. Nat. Chem.
2017, 9 (8), 810−816.
(25) Lin, J.; Wang, A.; Qiao, B.; Liu, X.; Yang, X.; Wang, X.; Liang,
J.; Li, J.; Liu, J.; Zhang, T. Remarkable performance of Ir1/FeO(x)
single-atom catalyst in water gas shift reaction. J. Am. Chem. Soc. 2013,
135 (41), 15314−15317.
(26) Geiger, S.; Kasian, O.; Ledendecker, M.; Pizzutilo, E.; Mingers,
A. M.; Fu, W. T.; Diaz-Morales, O.; Li, Z.; Oellers, T.; Fruchter, L.;
Ludwig, A.; Mayrhofer, K. J. J.; Koper, M. T. M.; Cherevko, S. The
stability number as a metric for electrocatalyst stability benchmarking.
Nat. Catal. 2018, 1 (7), 508−515.
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