AuCu Alloy Nanoparticle Embedded Cu Submicrocone Arrays for Selective Conversion of CO2 to Ethanol

Article abstract of DOI:10.1002/smll.201902229

The CO₂ reduction reaction (CO₂RR) driven by renewable electricity represents a promising strategy toward alleviating the energy shortage and environmental crisis facing humankind. Cu species, as one type of versatile electrocatalyst for the CO₂RR, attract tremendous research interest. However, for C₂ products, ethanol formation is commonly less favored over Cu electrocatalysts. Herein, AuCu alloy nanoparticle embedded Cu submicrocone arrays (AuCu/Cu-SCA) are constructed as an active, selective, and robust electrocatalyst for the CO₂RR. Enhanced selectivity for EtOH is gained, whose Faradaic efficiency (FE) reaches 29 ± 4%, while ethylene formation is relatively inhibited (16 ± 4%) in KHCO₃ aqueous solution. The ratio between partial current densities of EtOH and C₂H₄ (j_EtOH/j_C2H4) can be tuned in the range from 0.15 ± 0.27 to 1.81 ± 0.55 by varying the Au content of the electrocatalysts. The combined experimental and theoretical calculation results identify the importance of Au in modifying binding energies of key intermediates, such as CH₂CHO*, CH₃CHO*, and CH₃CH₂O*, which consequently modify the activity and selectivity (j_EtOH/j_C2H4) for the CO₂RR. Moreover, AuCu/Cu-SCA also shows high durability with both the current density and FE_EtOH being largely maintained for 24 h electrocatalysis.

Full text of DOI:10.1002/smll.201902229

FULL PAPER
Ethanol-Selectivity
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AuCu Alloy Nanoparticle Embedded Cu Submicrocone
Arrays for Selective Conversion of CO to Ethanol
2
Sibo Shen, Xianyun Peng, Lida Song, Yuan Qiu, Chao Li, Longchao Zhuo, Jia He,*
Junqiang Ren, Xijun Liu,* and Jun Luo
1
. Introduction
The CO reduction reaction (CO RR) driven by renewable electricity represents
2
2
a promising strategy toward alleviating the energy shortage and environmental
crisis facing humankind. Cu species, as one type of versatile electrocatalyst for
the CO RR, attract tremendous research interest. However, for C products,
ethanol formation is commonly less favored over Cu electrocatalysts. Herein,
AuCu alloy nanoparticle embedded Cu submicrocone arrays (AuCu/Cu-SCA)
are constructed as an active, selective, and robust electrocatalyst for the
The ever-increasing energy shortage and
environmental crisis facing mankind
have stimulated the rapid development of
energy conversion systems using renew-
2
2
able energies including solar, wind, geo-
[1–3]
thermal, and tidal, etc.
One promising
strategy for this purpose is the carbon
CO RR. Enhanced selectivity for EtOH is gained, whose Faradaic efficiency
dioxide reduction reaction (CO RR), which
2
2
can be driven by renewable electric ener-
gies to generate value-added chemicals
(
FE) reaches 29 ± 4%, while ethylene formation is relatively inhibited
(16 ± 4%) in KHCO aqueous solution. The ratio between partial current
3
and simultaneously consume the exces-
densities of EtOH and C H (jEtOH/j ) can be tuned in the range from
C H
2 4
0
[4–8]
2
4
sive CO in the atmosphere.
Compared
2
.15 ± 0.27 to 1.81 ± 0.55 by varying the Au content of the electrocatalysts.
with C products, e.g., carbon monoxide
1
The combined experimental and theoretical calculation results identify the
importance of Au in modifying binding energies of key intermediates, such
as CH CHO*, CH CHO*, and CH CH O*, which consequently modify the
(CO) and methane (CH ) from the CO RR,
4
2
C products, e.g., ethanol (EtOH) and eth-
2
[
9–11]
ylene (C H ) are more meritorious.
2
4
2
3
3
2
Especially, EtOH with high energy density
and ease of storage is a highly desirable
liquid fuel as a viable substitute for gaso-
line. Due to the high thermodynamic sta-
activity and selectivity (jEtOH/j
) for the CO RR. Moreover, AuCu/Cu-SCA
2
C H
2
4
also shows high durability with both the current density and FEEtOH being
largely maintained for 24 h electrocatalysis.
bility of CO molecules, it is indispensable
2
to design and employ superior electrocata-
[
4]
lysts to facilitate the CO RR. To date, copper (Cu) species with
2
Dr. S. B. Shen, X. Y. Peng, L. D. Song, Dr. Y. Qiu, Dr. C. Li, Dr. J. He,
Dr. X. J. Liu, Prof. J. Luo
Center for Electron Microscopy and Tianjin Key Lab of Advanced
Functional Porous Materials
Institute for New Energy Materials & Low-Carbon Technologies
School of Materials Science and Engineering
Tianjin University of Technology
cost-effective, environmentally suitable and reserve-rich prop-
[
8,12]
erties attract tremendous research interests.
Moreover, it
has been demonstrated that Cu was the only transition metal
with the ability to generate various multicarbon hydrocarbons
[
13]
and oxygenates. However, EtOH formation is commonly less
favored compared with C2H4 over the Cu electrocatalysts.
To date, vast efforts have been devoted to optimizing the
Tianjin 300384, China
E-mail: hejia@tjut.edu.cn; xjliu@tjut.edu.cn
Dr. S. B. Shen
electrocatalytic CO RR to EtOH, mainly through tailoring the
2
Hebei Key Laboratory of Active Components and Functions in Natural
Products (under planning)
College of Chemical Engineering
Hebei Normal University of Science and Technology
Qinhuangdao 066600, China
physical structures and surface compositions of the applied
[
3,10,11,14–16]
Cu-based electrocatalysts.
Based on these efforts,
one strategy is constructing steps, edges, or grain boundaries
on the electrocatalyst surface to expose under-coordinated Cu
Prof. L. C. Zhuo
atoms, which could act as the catalytically active sites for C
2
School of Materials Science and Engineering
Xi’an University of Technology
Xi’an 710048, China
[10,14,15]
products formation.
For example, oxide derived Cu films
with rough appearance could generate C H and EtOH of Fara-
2
4
[
10]
daic efficiency (FE) of 39% and 16%, respectively. The other
strategy is introducing a cocatalyst to catalyze additional CO
formation, which acts as a feedstock during the CO2RR; the
formed CO molecules from the cocatalyst sites would couple
Prof. J. Q. Ren
State Key Laboratory of Advanced Processing and Recycling
of Nonferrous Metals
Lanzhou University of Technology
Lanzhou 730050, China
with CH * intermediate (* indicates the adsorbed species) on
2
The ORCID identification number(s) for the author(s) of this article
can be found under https://doi.org/10.1002/smll.201902229.
[3,11,16]
Cu sites to promote EtOH production.
Excellent CO-
producing cocatalysts cover Au, Zn, and Ag, etc. For example,
compared with Cu nanoparticles (NPs), AuCu bimetallic NPs
DOI: 10.1002/smll.201902229
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2
. Results and Discussion
The synthetic procedure of AuCu alloy NPs embedded Cu sub-
microcone arrays (AuCu/Cu-SCA) is schematically described
in Figure 1. First, Cu-SCA was synthesized on cleaned copper
foil (CF) by an electrodeposition method (see the Experimental
Section in the Supporting Information for more details). During
the electrodeposition, Cu2 in the electrolyte was reduced to
metallic Cu at the Cu foil surface and deposited to form Cu-SCA
via the electrocrystallization process. Subsequently, AuCu
NPs were embedded on the surface of Cu-SCA via an in situ
+
Figure 1. Schematic illustration of the synthetic procedure of AuCu/
Cu-SCA.
could generate more EtOH (FE of 1.6%) than C H (FE of
2
4
3]
0
.6%).[
reduction method using HAuCl as the Au source. It is worth
4
+
Inspired by these pioneering works, we attempted to com-
bine the above two strategies to enhance the selectivity of
noting that although Au3 could be reduced to metallic Au by
0
3+
Cu-SCA through the replacement reaction (3Cu + 2Au
→
+
0
Cu-based electrocatalysts toward EtOH formation in C prod-
3Cu2 + 2Au ), NaBH was necessary to be added into the solu-
2
4
3+
2+
ucts. Herein, we developed a facile route to synthesize AuCu
alloy NPs embedded Cu submicrocone arrays via a combination
of electrodeposition and in situ chemical reduction. When
tion as a reducing agent to reduce Au and Cu in the vicinity
of Cu submicrocones into metallic ones to form AuCu alloy NPs.
X-ray diffraction (XRD) patterns of AuCu/Cu-SCA and
Cu-SCA are shown in Figure 2a. Only Cu diffraction peaks of
(111), (200), and (220) facets are present for the two samples,
indicating the content of Au in AuCu/Cu-SCA is very few and
below the detection limit. Notably, compared with Cu-SCA,
the diffraction peaks of (111), (200), and (220) facets of AuCu/
Cu-SCA shift to lower diffraction angles of ≈0.06°, respectively
(Figure 2b), which is ascribed to the substitution of Cu atoms
by Au atoms with bigger diameter in AuCu/Cu-SCA and lattice
expansion occurs, indicating that AuCu solid solution alloy is
evaluated as electrocatalyst for the CO RR, high selectivity for
2
EtOH formation with an FE of 29 ± 4% is achieved, while C H4
2
formation is relative inhibited (16 ± 4%) in KHCO aqueous
3
solution. It should be noted that the jEtOH/j
could be tuned
C H
2
4
in the range from 0.15 ± 0.27 to 1.81 ± 0.55 by varying the Au
content of the electrocatalysts. Moreover, the as-obtained elec-
trocatalyst displayed good stability during the 24 h electrolysis.
The mechanistic study indicated that the introduction of Au
contributed to the improved selectivity for EtOH product.
Figure 2. a) XRD patterns; b) Enlarged view of the XRD patterns in the regions of the diffraction peaks of (111), (200), and (220) facet. XPS spectra:
c) Cu 2p and d) Au 4f.
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Figure 3. Morphological characterization: a,b) Scanning electron microscopy (SEM) images of Cu-SCA; c) SEM image of AuCu/Cu-SCA; d) TEM image
of AuCu/Cu-SCA; e–g) HRTEM image of AuCu/Cu-SCA and the corresponding EDS elemental mapping.
formed.[17,18] The composition information of the as-prepared
AuCu/Cu-SCA and Cu-SCA was performed. As shown in
Figure 2c, the Cu 2p spectrum of AuCu/Cu-SCA is similar with
that of Cu-SCA, indicating the surface of both samples con-
AuCu/Cu-SCA (Figure 3c); their transmission electron micro-
scopy (TEM) image in Figure 3d shows that these AuCu alloy
NPs are assembled into a kind of loose structure. The high-
resolution transmission electron microscopy (HRTEM) image
and energy dispersive spectroscopy (EDS) elemental mapping
demonstrate the uniform distribution of Au and Cu elements
on the 1 nm scale (Figure 3e–g).
2
+
0
tain Cu species (953.8 and 935.3 eV) and Cu species and/or
+
[19,20]
Cu species (952.3 and 932.4 eV).
The oxidized Cu species
[
8,21]
appear as a result of exposure to the ambient atmosphere.
However, the Au 4f spectra of AuCu/Cu-SCA and Cu-SCA are
totally different (Figure 2d). The peaks at 88.0 and 84.3 eV of
AuCu/Cu-SCA correspond to Au species.
The electrocatalytic CO RR performances were evaluated
2
in a typical three-electrode H-type cell in CO -saturated
2
0
[22]
0.5 m KHCO3 aqueous solution. To examine the CO RR
2
Top-down surface morphology characterizations of Cu-SCA
and AuCu/Cu-SCA are shown in Figure 3. Cu-SCA consists
of radially dispersed Cu submicrocones with the full width
at half maximum of 576 ± 110 nm (Figure 3a); these submi-
crocones have several ridges around their axis on their sur-
face (Figure 3b), contributing to the formation of the rough
surface. As shown in Figure S1a (Supporting Information),
AuCu/Cu-SCA is also composed of radially dispersed Cu
submicrocones with similar low-magnification surface mor-
phology of Cu-SCA. However, their high-magnification sur-
face morphologies are different. Specifically, vast AuCu alloy
NPs are embedded on the surface of the submicrocones of
catalytic activity, linear sweep voltammetry (LSV) was first
−
1
conducted at a sweep rate of 10 mV s . For comparison, Au
NPs anchored on copper foil (Au NPs/CF) was synthesized. As
shown in Figure 4a, the AuCu/Cu-SCA exhibits a high current
−
2
density of −4.9 mA cm at −0.8 VRHE, which is 2.3, 3.1, and
18.1 times higher than that of Cu-SCA, Au NPs/CF, and CF,
respectively, indicating AuCu/Cu-SCA catalyst has high activity
toward CO RR. Furthermore, the electrochemical active sur-
2
face area (ECSA) of the sample was measured according to
[
23,24]
the obtained double layer capacitance (Cdl).
Figure S2 (Supporting Information), the high electrochemical
As shown in
−2
double layer capacitance (C ) of AuCu/Cu-SCA (2.06 mF cm )
dl
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Figure 4. CO RR performance: a) LSV curves measured in CO -saturated 0.5 m KHCO aqueous solution; b) FEs of EtOH and C H at various applied
2
2
3
2
4
potentials; c) Chronoamperometry curve over AuCu/Cu-SCA at −1.0 VRHE and the corresponding FE of EtOH; d) Tafel plots.
−
2
is higher than those of Cu-SCA (1.76 mF cm ) and Au NPs/CF
(
atoms in AuCu alloy NPs would play an analogous cocatalyst
effect as the Zn atoms aforementioned. It is noteworthy that Au
and Cu within the AuCu alloy NPs distribute uniformly on the
1 nm scale (Figure 3f,g), which is believed beneficial to the syn-
ergistic effect of Cu and Au sites. Furthermore, it is interesting
−
2
0.66 mF cm ), implying that AuCu/Cu-SCA also has higher
ECSA and more exposed active sites, which is beneficial to
[25]
enhance the CO RR activity.
2
The CO RR products were quantified using on-line gas
chromatography and a H nuclear magnetic resonance (NMR)
2
1
to find that there are no C products detected over Au NPs/CF
2
spectrometer. As Figure S3 (Supporting Information) depicts,
(Figure S3, Supporting Information), indicating that surface
composition is not the only factor for the enhanced selectivity for
EtOH over AuCu/Cu-SCA. As shown in Figure S1d (Supporting
Information), Au NPs/CF has a relatively flat surface, however,
AuCu/Cu-SCA has a unique hierarchical structure consisting
of Cu submicrocones with vast AuCu alloy NPs embedded on
their surface. AuCu alloy NPs assemblies are supposed to pro-
vide massive under-coordinated Cu and Au atoms as the cata-
at a typical applied potential of −0.8 VRHE, C H in C prod-
2
4
2
ucts is favored over Cu-SCA with an FE of 22 ± 8% and a
small amount of EtOH (6 ± 2%). By contrast, EtOH is the pre-
dominant product over AuCu/Cu-SCA with an FE of 20 ± 5%.
Notably, FE of the total C products over Cu-SCA and AuCu/
2
Cu-SCA are ≈(28–30%), suggesting that the embedded AuCu
alloy NPs on Cu-SCA could effectively promote the yield of
EtOH, meanwhile, inhibit C H formation.
lytic active sites for the CO RR, thus promoting the coverage
2
4
2
[10,27,28]
The enhanced selectivity for EtOH in C2 products over
AuCu/Cu-SCA might result partially from the introduced AuCu
alloy NPs, in which Au atoms could work as a cocatalyst for the
of C intermediates and then yielding C products.
We
1
2
deduce that a certain population of under-coordinated atoms on
Cu-based electrocatalysts should be requisite for C products
2
CO RR. Ren et al. proposed a two-site catalytic mechanism to
rationalize the synergy of Cu atoms and Zn atoms (cocatalyst)
formation. Based on the above analysis, the enhanced selectivity
for EtOH over AuCu/Cu-SCA was ascribed to two factors: Au
atoms in the introduced AuCu alloy NPs as the cocatalyst and
the unique hierarchical structure of Cu submicrocones offering
massive under-coordinated atoms.
2
in ZnCu bimetallic electrocatalysts to enhance the CO RR to
2
EtOH.[ Due to the binding strength of CO* intermediate on
11]
[26]
Zn sites is weaker than that of Cu sites, the produced CO
molecules on Zn sites could desorb and insert into the bonds
between Cu sites and CH * to form COCH *, further producing
To analyze the selectivity toward C product with different
2
applied potentials, the FEs (Figure S4, Supporting Information)
and partial current densities (Figure S5, Supporting Informa-
tion) for all gas and liquid products over the AuCu/Cu-SCA and
Cu-SCA catalysts show the same change trend as a function of
2
2
EtOH. It was reported that both Au and Zn belong to the group
4]
2
metals with high selectivity for CO.[ Moreover, excellent CO
selectivity of the introduced Au atoms in this work was verified
by the fact that FE of CO increased from 10 ± 5% over Cu-SCA
to 35 ± 12% over AuCu/Cu-SCA. We thus speculate that the Au
the applied potential. In detail, it can be found that the CO RR
2
carbonaceous products on the AuCu/Cu-SCA and Cu-SCA
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catalysts are EtOH, C H , HCOOH, and CO. Besides, H is
also detected due to the competing of hydrogen evolution and
reduces CO to alcohols. The dominant morphological features
of the Au/Cu catalyst prepared by a physical vapor deposition
method can be described as Au NPs on top of a polycrystalline
Cu foil. In this work, compared to Cu-SCA, the XRD diffrac-
tion peaks of (111), (200), and (220) facets of AuCu/Cu-SCA
shift to lower diffraction angles (Figure 2b), which is ascribed
to the formation of AuCu solid solution alloy and the con-
tent of Au in AuCu/Cu-SCA is very few. Thus, we speculate
that such tandem mechanism is difficult to take place on our
system.
2
4
2
CO reduction reaction. As the potential decreases from −0.5 to
2
−
1.4 V versus RHE, AuCu/Cu-SCA displays the maximum FE
of EtOH (29 ± 4%) with FE of C H of 16 ± 4% at −1.0 V
2
4
RHE
(Figure 4b), in which the responding partial current densities
of EtOH and C H (Figure S5, Supporting Information) were
2
4
−2
−2
−
5.59 ± 0.77 mA cm and −3.09 ± 0.83 mA cm , respec-
tively. Moreover, the selectivity of EtOH versus C H (defined
2
4
as jEtOH/j
) is 1.81 ± 0.55, which is higher than that over
C H
2
4
Cu-SCA (0.15 ± 0.22). For comparison, AuCu/Cu-SCA with dif-
ferent Au contents was synthesized by adjusting the addition
To further understand the reaction mechanism of the
CO RR over AuCu/Cu-SCA and Cu-SCA, we conducted den-
2
amount of HAuCl solution (Figure S1b,c and Table S1, Sup-
sity functional theory (DFT) calculations. Previous studies
showed that the exposed (100) facets on Cu electrocatalyst
4
porting Information). Obviously, the jEtOH/j
could be tuned
C H
2
4
[
41]
from 0.15 ± 0.27 to 1.81 ± 0.55 by tailoring the Au loading con-
tents from 0 to 22.42 at% (Figure S6, Supporting Information).
Compared with the Cu-based electrocatalysts reported in the
literature (Table S2, Supporting Information), AuCu/Cu-SCA
were responsible for the production of C products. Thus,
2
Cu and Cu Au were selected as the prototypes and their pro-
3
jected densities of states (PDOS) of (100) facet were investi-
gated and shown in Figure 5a. It can be seen that PDOS of
pure Cu surface possesses a peak near Fermi level. On the
exhibits a high selectivity for EtOH in C products.
2
To test the operational stability of the catalysts, we car-
surface of Cu Au, the peak of the d-band of Cu shifts close
3
ried out CO RR reduction over an extended period of time.
to Fermi energy. This is mainly because that lattice of Cu Au
2
3
The AuCu/Cu-SCA exhibits relatively stable current density
and FEs toward EtOH, with relatively low decrease following
alloy is stretched by the addition of Au atoms. However, the
center of the d-band of the entire Cu Au alloy moves far away
3
2
4 h of continuous CO RR (Figure 4c). By contrast, the sta-
from Fermi level relative to the pure Cu surface. We can pre-
liminarily conclude that the activating ability of Cu surface
2
bility performance of the AuCu/Cu-SCA catalyst in KHCO3
aqueous solution also shows a high competitive advan-
tage as compared to the reported Cu-based electrocatalysts
for the intermediate, such as CH CHO*, is stronger than
2
that of Cu Au, leading to the increase of CO bond length as
3
(
Table S2, Supporting Information). Moreover, the AuCu/
depicted in Figure 5b. The longer bond length indicates that
CO is easier to break, which means that the formation of
C H is more favorable. In contrast, the shorter CO bond
Cu-SCA also kept its original morphology after the stability
test (Figure S7, Supporting Information). Additionally, the
Nyquist plots (Figure S8, Supporting Information) for the
AuCu/Cu-SCA catalysts before and after stability test are sim-
ilar, which are composed of one semicircle and a straight line
at the high-frequency and low-frequency region, respectively.
This also demonstrated that the AuCu/Cu-SCA catalyst had
excellent stability, agreeing with the characterization results
of the morphology of AuCu/Cu-SCA. This robustness stability
could be ascribed to its negligible selectivity toward methane,
2
4
length manifests that it is advantageous to produce EtOH
instead.
In order to further evaluate the catalytic selectivity of Cu-SCA
and AuCu/Cu-SCA, we calculated the Gibbs free energy profiles
of CO2 reduction to EtOH and C H4 over Cu and Cu Au
2
3
surfaces. The possible pathway was adopted as the same as
[
42]
previous literature. Since the process before the formation of
+
–
CH CHO* was the same, only (H + e ) transfers after hydro-
2
which was reported to be related to the formation of graphitic
genation of CH CHO* were considered. For Cu (Figure 5c and
2
carbon poisons.[
29,30]
To shed light on the kinetic mechanism
Table S3, Supporting Information), the generation of C H and
2
4
of the CO RR to EtOH over the AuCu/Cu-SCA catalyst, a plot
O* species from adsorbed CH CHO* is endothermic (0.34 eV).
2
2
of the log of the partial current density versus the potential for
EtOH production (Tafel plot) was obtained by stepped-poten-
The hydrogenation of CH CH O* is the potential-limiting step
3
2
due to the maximum ∆G values (0.38 eV) among all elementary
[
31]
tial electrolysis.
shows a Tafel slope of 137 mV dec , a value consistent with
As shown in Figure 4d. AuCu/Cu-SCA
steps for production of EtOH. Therefore, production of C H
2
4
−
1
is more favorable on the Cu surface. For Cu Au (Figure 5d
3
⦁
−
the mechanistic hypothesis that the formation of CO2 inter-
and Table S4, Supporting Information), the formation of C H
2
4
−
mediate from the initial e transfer is the possible rate-deter-
becomes difficult because ∆G from CH CHO* to O* and C H
2
2
4
mining step.[
32,33]
In contrast, Cu-SCA exhibits a higher Tafel
is as high as 0.86 eV. However, it is worth noting that all ele-
−
1
slope of 342 mV dec , indicating that its reaction kinetics
is significantly weaker than that of AuCu/Cu-SCA, which is
mentary steps from CH CHO* to EtOH is exothermic. From
2
the above analysis, we can deduce that it is easier to form EtOH
⦁
–
likely due to the better stabilization of CO intermediate by
over Cu Au electrocatalyst.
2
3
the AuCu alloy NPs.[
34–36]
In order to confirm the enhanced activity toward EtOH on
AuCu alloy surface, another recently reported mechanism was
also investigated on the theoretical front. Ager et al. found a
new mechanism involving water molecules in a concerted
reaction with the *CCH intermediate to form *CHCHOH,
subsequently leading to EtOH through experimental and theo-
The comprehensive mechanism of CO or CO electroreduc-
2
tion to C species might vary directly with the exposed facets,
2
[
37–42]
solvents, and other factors.
In the previously reported
work,[ the authors suggest that the trends in alcohol produc-
40]
tion originate from CO following a tandem catalysis mecha-
2
[
37]
nism, where Au NPs reduces CO to CO near the Cu surface,
retical studies. Thus, we calculated the corresponding rate-
determining step (from *CCH to *CHCHOH) as a tentative
2
driving by a high CO coverage, and the Cu surface further
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Figure 5. DFT calculations: a) PDOS of d-band for Cu (100) and Cu Au (100) catalysts. b) Schematic illustration of key intermediate CH CHO* to
3
2
yield C H and EtOH over Cu (100) and Cu Au (100) surfaces. Free energy diagrams for C H and EtOH formation over c) Cu (100) and d) Cu Au
2
4
3
2
4
3
(100), respectively.
exploration in Figure S9 (Supporting Information). The Supporting Information
results demonstrated that the energy barrier on Cu Au (100)
3
Supporting Information is available from the Wiley Online Library or
from the author.
was significantly lower than that on pure Cu (100) surface,
preliminarily indicating the increased EtOH activity for
AuCu alloy. Our theoretical calculation results provide some
mechanical explanations for the cocatalyst effect of Au atoms
in the introduced AuCu alloy NPs, which are consistent with
our experimental evidence that AuCu/Cu-SCA could exert an
Acknowledgements
S.B.S. and X.Y.P. contributed equally to this work. This work is financially
supported by National Key R&D Program of China (2017YFA0700104),
National Natural Science Foundation of China (21601136, 21603161,
enhanced CO RR catalytic selectivity for EtOH than Cu-SCA,
2
meanwhile, inhibit C H formation.
2
4
2
1501132, 51802221, and 51761165012), National Program for
Thousand Young Talents of China, Tianjin Municipal Education
Commission, Tianjin Municipal Science and Technology Commission
(
15JCYBJC52600), and Fundamental Research Funds of Tianjin
3
. Conclusion
University of Technology. The authors also acknowledge National
Supercomputing Center in Shenzhen for providing the computational
resources and materials studio (Version 7.0, Dmol3).
In summary, we have synthesized AuCu alloy nanoparticles
embedded Cu submicrocone arrays for CO RR by a two-step
2
route. The catalyst displayed an enhanced FE for EtOH produc-
tion in comparison with the generation of C H . Meanwhile,
the current density and selectivity for EtOH formation kept
stable for more than 24 h with negligible degradation. More
importantly, the Au content of the catalyst has an impact on the
2
4
Conflict of Interest
The authors declare no conflict of interest.
variation of the jEtOH/j
. DFT calculations further unravel
C H
2
4
the origin of the improved selectivity for EtOH electrosynthesis Keywords
due to the cocatalyst effect of Au atoms from the introduced
AuCu alloy nanoparticles, showing the importance of com-
positional and structural engineering of electrocatalysts with
AuCu alloys, CO reduction, Cu submicrocone arrays, ethanol
2
Received: May 2, 2019
Revised: July 2, 2019
Published online:
potential applications for renewable electricity-to-C chemicals
2
conversion.
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