Symmetry-Broken Au–Cu Heterostructures and their Tandem Catalysis Process in Electrochemical CO2 Reduction

Article abstract of DOI:10.1002/adfm.202101255

Symmetry-breaking synthesis of colloidal nanocrystals with desired structures and properties has aroused widespread interest in various fields, but the lack of robust synthetic protocols and the complex growth kinetics limit their practical applications. Herein, a general strategy is developed to synthesize the Au–Cu Janus nanocrystals (JNCs) through the site-selective growth of Cu nanodomains on Au nanocrystals, which is directed by the substantial lattice mismatch between them, with the assistance of judicious manipulation of the growth kinetics. This strategy can work on Au nanocrystals with different architectures for the achievement of diverse asymmetric Au–Cu hybrid nanostructures. Of particular note, the obtained Au nanobipyramids (Au NBPs)-based JNCs facilitate the conversion of CO₂ to C₂ hydrocarbon production during electrocatalysis, with the Faradaic efficiency and maximum partial current density being 4.1-fold and 6.4-fold higher than those of their monometallic Cu counterparts, respectively. The excellent electrocatalytic performances benefit from the special design of the Au–Cu Janus architectures and their tandem catalysis mechanism as well as the high-index facets on Au nanocrystals. This research provides a new approach to synthesize various hybrid Janus nanostructures, facilitating the study of structure-function relationship in the catalytic process and the rational design of efficient heterogeneous electrocatalysts.

Full text of DOI:10.1002/adfm.202101255

ReseaRch aRticle
www.afm-journal.de
Symmetry-Broken Au–Cu Heterostructures and their
Tandem Catalysis Process in Electrochemical CO2 Reduction
Henglei Jia, Yuanyuan Yang, Tsz Him Chow, Han Zhang, Xiyue Liu, Jianfang Wang,*
and Chun-yang Zhang*
of the greatest challenges for this conver-
Symmetry-breaking synthesis of colloidal nanocrystals with desired structures
and properties has aroused widespread interest in various fields, but the
lack of robust synthetic protocols and the complex growth kinetics limit their
practical applications. Herein, a general strategy is developed to synthesize
the Au–Cu Janus nanocrystals (JNCs) through the site-selective growth of Cu
nanodomains on Au nanocrystals, which is directed by the substantial lattice
mismatch between them, with the assistance of judicious manipulation of the
growth kinetics. This strategy can work on Au nanocrystals with different archi-
tectures for the achievement of diverse asymmetric Au–Cu hybrid nanostruc-
tures. Of particular note, the obtained Au nanobipyramids (Au NBPs)-based
JNCs facilitate the conversion of CO2 to C2 hydrocarbon production during elec-
trocatalysis, with the Faradaic efficiency and maximum partial current density
being 4.1-fold and 6.4-fold higher than those of their monometallic Cu coun-
terparts, respectively. The excellent electrocatalytic performances benefit from
the special design of the Au–Cu Janus architectures and their tandem catalysis
mechanism as well as the high-index facets on Au nanocrystals. This research
provides a new approach to synthesize various hybrid Janus nanostructures,
facilitating the study of structure-function relationship in the catalytic process
and the rational design of efficient heterogeneous electrocatalysts.
sion is to develop catalysts with the capa-
bility of reducing CO2 into more valuable
products. Among various metal electro-
catalysts, Cu has attracted great interest as
the catalyst for electrocatalytic CO2 reduc-
tion reaction (CO2RR) due to its unique
capability of converting CO2 into a wide
spectrum of useful products, such as C1
(CO, CH4, formate) and C2 (C2H4, C2H6)
products, but poor selectivity is a major
drawback.[3–6] From the fundamental per-
spective, poor selectivity originates from
the moderate binding energy of most
reaction intermediates.[7] In comparison
with C1 products, C2 products are more
appealing because of their higher energy
density and larger economic value. Con-
siderable efforts have been devoted to the
unraveling of various factors that impact
the C2 product activity and selectivity,[8–10]
including the manipulation of catalyst
morphology,[11–15] controlling of oxide
state,[16–20] engineering of crystal facet,[21,22]
and surface modification.[23,24] However, it
has remained a great challenge for monometallic Cu catalysts
to efficiently convert CO2 into C2 products.
1. Introduction
The electrochemical conversion of greenhouse gas CO2 into the
value-added fuels and feedstocks represents a green avenue to
address the energy demands and climate change issues.[1,2] One
Recent advances have brought Cu-based bimetallic catalysts
to the forefront for the improvement of C2 selectivity during
CO2RR. The associated variations in composition, electronic
structure, and spatial elemental distribution of bimetallic cat-
alysts can alter the intermediate binding energetics.[7,25–28] Au
nanocrystals have aroused extraordinary interest in the fields
of photocatalysis,[29,30] optics,[31] and biomedical technolo-
gies[32,33] due to their well-controlled morphologies and unique
plasmonic properties, but their applications in CO2RR are still
at their infancy. Au nanocrystals have recently shown great
promise as catalysts for efficient CO2 reduction to CO with
Prof. H. L. Jia, Y. Y. Yang, X. Y. Liu, Prof. C.-Y. Zhang
College of Chemistry
Chemical Engineering and Materials Science
Collaborative Innovation Center of Functionalized Probes for Chemical
Imaging in Universities of Shandong
Key Laboratory of Molecular and Nano Probes
Ministry of Education
Shandong Provincial Key Laboratory of Clean Production
of Fine Chemicals, Shandong Normal University
Jinan 250014, China
E-mail: cyzhang@sdnu.edu.cn
Dr. T. H. Chow, Dr. H. Zhang, Prof. J. F. Wang
Department of Physics
good selectivity.[34–37] Since the adsorbed CO is critical for C C

bond coupling and the subsequent formation of C2 products,[38]
the integration of Au nanocrystals with Cu catalysts is expected
to improve the C2 selectivity through a tandem catalysis mecha-
nism,[39–41] where CO2 is reduced to CO on the Au nanocrystal
and subsequently reduced on the neighboring Cu component.
However, what really matters for the tandem catalysis process is
the geometric arrangement of Au and Cu in the bimetallic cata-
lyst.[26,27,42] For example, the phase-separated bimetallic nano-
structures facilitate the C2 production compared with the alloy
type.[42] Inspired from the ancient two-faced Roman god Janus,
The Chinese University of Hong Kong
Shatin, Hong Kong SAR, China
E-mail: jfwang@phy.cuhk.edu.hk
The ORCID identification number(s) for the author(s) of this article
can be found under https://doi.org/10.1002/adfm.202101255.
DOI: 10.1002/adfm.202101255
Adv. Funct. Mater. 2021, 2101255
2101255 (1 of 11)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.afm-journal.de
the Janus nanostructures comprising two or more spatially sep-
arated components with dissimilar physical and chemical func-
tionalities have triggered extraordinary interests in various fields
due to their intricate properties and potential applications.[43]
Unlike the centrosymmetric core@shell nanostructures with
the exposure of the only outermost shell surface, asymmetric
Janus nanostructures possess two or more different surfaces
with at least one sharing heterointerface. These diverse sur-
faces in Janus structures can participate and play different roles
in the catalytic process, endowing them with desired catalytic
features and even synergistic effects. Because of their unique
architecture, the synthesis of Janus nanostructures is required
to employ unconventional synthesis approaches like symmetry-
breaking synthesis (e.g., surface-protection growth, kinetically
controlled manipulation, and seed-mediated growth).[44–48]
However, the lack of a universal synthetic strategy to obtain
the Au–Cu Janus nanocrystals (JNCs) strongly restricts their
further applications in CO2RR. Therefore, the development of
spatially separated Au–Cu JNC catalysts for the sustainable pro-
duction of C2 products is highly desirable.
Herein, we develop a facile and general approach for the
synthesis of Au–Cu JNCs through a seed-mediated growth
method by taking advantage of a relatively large lattice mis-
match (≈11.4%) between them[49] in combination with the
judicious manipulation of the surfactant concentration. The
penta-twinned Au nanobipyramids (Au NBPs) are used as
the seeds for the direct overgrowth of Cu nanodomains. Owing
to the large lattice mismatch, Cu selectively overgrows on the
side surface of the Au NBPs through controlling the growth
kinetics, leading to the formation of spatially separated Au–Cu
heterostructures. This site-selective overgrowth protocol can be
simply extended to various Au cores, from 0D, 1D, to 2D Au
nanocrystals, suggesting the generality of the proposed method.
To the best of our knowledge, our research demonstrates for the
first time the development of a general method for the prepara-
tion of Au–Cu Janus heterostructures. In addition, the tandem
catalysis process resulting from the unique spatially separated
architecture and the high-index facets of Au NBPs endows the
Au–Cu JNCs with much higher C2 activity and good selectivity,
with the Faradaic efficiency (FE) and the maximum partial cur-
rent density being 4.1-fold and 6.4-fold compared with those of
the monometallic Cu counterparts.
Scheme 1. a) Schematic illustration for the selective growth process of a
Au NBP–Cu hybrid nanostructure. b) Schematic showing the generality
of the site-selective growth strategy for Au nanocrystals with different
architectures.
mismatch (≈11.4%) between Au and Cu,[49] the growth of Cu on
the Au NBPs prefers to adopt the classic Volmer–Weber model
through a 3D island growth (Scheme 1a, the second step).[49,53]
Further deposition of Cu atoms will mainly take place at the
original Cu surface in order to minimize new interfacial free
energy resulting from the Au–Cu nanointerface (Scheme 1a,
the third step). Consequently, the Au NBP–Cu hybrid nano-
structures featured with Au and Cu nanodomains and a sharing
interface are obtained. Notably, the site-selective overgrowth
protocol can work on Au nanocrystals with different architec-
tures, leading to the formation of diverse asymmetric Au-Cu
hybrid nanostructures (Scheme 1b).
The penta-twinned Au NBPs are obtained through the seed-
mediated growth method in combination with a depletion
force-induced purification process.[54,55] The average length and
middle diameter are 103.4 2.9 and 34.6 1.9 nm, respectively
(Figure 1a). The representative low-magnification transmission
electron microscopy (TEM) image of the Au NBP–Cu JNCs is
shown in Figure 1b with the Cu nanodomains (47.3 2.9 nm)
on the side surface of the Au NBPs. To uncover such a hetero-
structure feature, high-angle annular dark-field scanning trans-
mission electron microscopy (HAADF-STEM) imaging and ele-
mental mapping were conducted (Figure 1c). The results clearly
reveal the presence of spatially separated Au and Cu nanodo-
mains with a sharp interface contacting with each other. After
the growth of Cu nanodomain, the plasmon resonance peak of
the Au NBPs red-shifts, accompanied by a broad peak, which
is caused by the overgrowth of Cu (Figure S2a, Supporting
Information). A remarkable increase in the extinction below
600 nm is observed for the Au NBP–Cu JNCs, suggesting the
presence of excess hexadecylamine (HDA)–Cu complex in the
solution.[56] The successful overgrowth of Cu on the Au NBPs
is confirmed by the color change from reddish-brown to yellow-
brown (Figure S2a, Supporting Information). Notably, the low-
magnification TEM image (Figure S3, Supporting Information)
2. Results and Discussion
Scheme 1a illustrates the site-selective growth process of a Cu
nanodomain on the side surface of a Au NBP to produce the Au
NBP–side Cu JNCs (Au NBP–Cu JNCs). Each Au NBP featuring
a fivefold rotational symmetry structure and consisting of two
base-stacked pentagonal pyramids[50] is utilized as the seed. The
crystalline structure of a Au NBP is depicted in Figure S1, Sup-
porting Information, with each NBP being encapsulated with
10 facets.[51,52] The side facets are stepped periodically along the
length direction to form the high-index {116} facets.[50,51] Cu
atoms are expected to initially nucleate on one high-index {116}
facet, because the Au atoms at the steps are generally coordi-
nately unsaturated and are more active for the nucleation of
Cu (Scheme 1a, the first step). Due to the considerable lattice
Adv. Funct. Mater. 2021, 2101255
2101255 (2 of 11)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.afm-journal.de
Figure 1. Au NBP–Cu JNCs. a,b) TEM images of the as-synthesized Au NBPs (a) and Au NBP–Cu JNCs (b). c) HAADF-STEM image (left) and the cor-
responding elemental maps of Au (middle) and Cu (right) of a representative Au NBP–Cu heterostructure. d) Aberration-corrected HRTEM images at
the Au–Cu interface of single Au NBP–Cu JNC. Four typical regions are marked by dashed white boxes (1–4) and the corresponding enlarged images
identify the facets of Au and Cu.
reveals a high yield (≈96%) of the Au NBP–Cu JNCs. To gain
a deep insight into the overgrowth behavior of the Cu nano-
domain on the Au NBPs, we took the aberration-corrected
high-resolution TEM (HRTEM) images of the Au–Cu interface
(Figure 1d). As expected, the Cu nanodomain is mainly grown
on the Au {111} facet, which confirms the proposed growth
mechanism. In addition, the lattice fringes of the Cu {111}
facets at the Au–Cu interface (Figure 1d 3) are slightly wider
than the theoretical value (2.088 Å) due to the misfit disloca-
tion at the interface as a result of a large lattice mismatch. The
lattice mismatch value calculated from the lattice fringes at
the Au–Cu interface is 11.0%, consistent with the reported value
of 11.4%.[49] Moreover, the lattice fringes turn gradually close
to the theoretical value when they are away from the interface,
indicating the release of lattice strain. Above all, the aberration-
corrected HRTEM results reveal the growth behavior of Cu
nanodomain on the Au NBP.
To examine the crystalline nature and chemical composi-
tion of the Au NBP–Cu JNCs, we measured X-ray diffraction
(XRD) and X-ray photoelectron spectra (XPS). The XRD spec-
trum (Figure S4, Supporting Information) shows only two
distinct sets of diffraction patterns, indicating the presence of
pure metallic Au and Cu phases, consistent with the observa-
tion from the high-resolution XPS spectra (Figure S5, Sup-
porting Information). The high-resolution Cu 2p XPS spectrum
exhibits two peaks, which can be assigned to the Cu 2p3/2
(932.9 eV) and Cu 2p1/2 (952.6 eV) peaks of pure metallic Cu,
respectively. The absence of any satellite peaks suggests that
the dominant form of Cu in the Au NBP–Cu JNCs is the pure
metallic Cu.[56] A wide O 1s peak centered at 531.3 eV originates
from either the chemisorbed water or the inevitable occurrence
of oxidation upon exposure to air.[25]
Notably, the synthetic protocol works for different pre-
grown Au nanocrystals from 0D to 2D, enabling the gen-
eration of diverse asymmetric Au–Cu nanostructures. Three
typical Au nanocrystals including 0D Au nanospheres (Au
NSs), 1D long Au nanorods (Au NRs), and 2D hexagonal Au
nanoplates (Au NPLs) were prepared as the seeds to direct
the growth of Cu domains (Figure 2a–c). The average diam-
eter of the Au NSs, the average length/diameter of the long
Au NRs, and the average lateral size of the Au NPLs (which
is the perpendicular distance between two parallel edges)
are 49.6 3.2, 709.5 38.3 / 25.8 2.4, and 153.2 5.1 nm,
respectively. The obtained asymmetric Au–Cu nanostructures
are displayed in Figure 2d–f. Obviously, the Au NS–Cu hybrid
nanostructures (Au NS–Cu JNCs) are composed of two segre-
gated nanodomains and a shared interface (Figure 2d). Two
segregated domains consisting of Au and Cu are verified by the
elemental mapping (Figure 2g). The presence of pure metallic
Au and Cu phases in the Au NS–Cu JNCs is further verified
by HRTEM and XRD (Figure S6, Supporting Information).
Analogously, the lattice fringes of the Cu {111} facets at the
Adv. Funct. Mater. 2021, 2101255
2101255 (3 of 11)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.afm-journal.de
Figure 2. Growth of Cu nanodomains on Au nanocrystals with different morphologies from 0D to 2D. a–c) TEM images of 0D Au NSs (a), 1D long
Au NRs (b), and 2D hexagonal Au NPLs (c). d–f) TEM images of the corresponding asymmetric Au–Cu nanostructures. g) HAADF-STEM image (left)
and the corresponding elemental maps of Au (middle) and Cu (right) of a representative Au NS–Cu heterostructure.
Au–Cu interface (2.119 Å, Figure S6b, Supporting Informa-
tion) are also slightly wider than the theoretical value (2.088 Å),
but they are smaller than those of the Au NBP–Cu JNCs
(2.126 Å, Figure 1d 3). This result suggests that the high-index
facets of Au NBPs can cause larger misfit dislocation than that
of the low-index facets on Au NSs. Notably, the number yield
of the Au NS–Cu JNCs is nearly 100% (Figure S7, Supporting
Information), suggesting the good universality of the proposed
synthesis strategy. In addition, Cu shell is selectively formed
on one end of the long Au NRs with a long tail exposure as a
result of the large lattice mismatch (Figure 2e). When the Au
NPLs are used as the seeds, Cu nanodomain deposition occurs
preferentially on one corner of the hexagonal plates (Figure 2f),
because the Au atoms at the corner sites are more undercoordi-
nated and consequently more active in the Cu deposition pro-
cess.[57] Our above results clearly demonstrate the development
of a universal approach for the preparation of Au–Cu JNCs.
We further performed a series of control experiments to
investigate the growth behavior. The surfactant concentra-
tion plays an important role in the site-selective growth of a
second material on Au nanocrystals.[29] We first investigated
the effect of cetyltrimethylammonium bromide (CTAB) con-
centration upon the overgrowth behavior of Cu (Figure S8,
Supporting Information). Appropriate low-concentration
CTAB (10–200 μm) is required to obtain a high yield of the Au
NBP–Cu JNCs (Figure S8a–c, Supporting Information), but
extremely low-concentration CTAB may induce the aggregation
of the Au NBPs. When the CTAB concentration is increased to
400 μm, long Cu NRs tend to grow at one end of the Au NBPs
(Figure S8d, Supporting Information). Further increase of
CTAB concentration (>500 μm) will induce the self-nucleation
of Cu nanoparticles (Figure S8e,f, Supporting Information).
The nonuniform distribution of the CTAB bilayer is essential to
the site-selective growth behavior. At a low CTAB concentration,
the CTAB bilayers at the edges of the Au NBPs are packed less
compactly than those on the side facets due to the larger cur-
vature (Figure S1, Supporting Information),[29] facilitating the
preferential nucleation of Cu at one edge and the subsequent
overgrowth of a Cu nanodomain for the covering of adjacent
facets. In addition, the high-energy sites at the edges favor pref-
erential Cu deposition. When the CTAB concentration is large
enough, all the surfaces of the Au NBPs are densely covered by
the surfactant molecules, which hinders the deposition of Cu
atoms. Notably, the HDA concentration plays an important role
(Figure S9, Supporting Information). HDA is an effective cap-
ping agent for Cu nanocrystals due to its amino group-induced
strong coordination effect toward Cu (II) ions.[58,59] Appropriate
low-concentration Cu (II) ions (≈5 mm) is indispensable for
the site-selective growth of Cu on the Au nanocrystals. Since
HDA can act as the capping agent for both Cu and Au,[60,61] the
adsorption of HDA on the surface of Au nanocrystals can occur
at high concentration (10 mm), which may reduce the nonuni-
form distribution of surfactant molecules and the number yield
of the Au NBP–Cu JNCs (Figure S9e, Supporting Information).
Adv. Funct. Mater. 2021, 2101255
2101255 (4 of 11)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.afm-journal.de
On the contrary, low-concentration HDA is inadequate for the
adsorption and stabilization of the formed Cu nanodomain on
the Au nanocrystal (Figure S9a, Supporting Information). Thus,
appropriate-concentration HDA facilitates its binding to the
Cu nanodomain and meanwhile does not disturb the distribu-
tion of surfactant CTAB on the surface of Au nanocrystals. In
addition, the length of the alkyl chain (Figure S10, Supporting
Information), the type of precursor (Figure S11, Supporting
Information), and the amount of precursor (CuCl2) (Figure S12,
Supporting Information) affect the morphology of the Au–Cu
hybrid nanostructure as well. In general, the site-selective
growth behavior of Cu on the Au NBPs is mainly determined
by the concentrations of surfactants and the choice of Cu
precursor.
product of Au NBP catalyst with a maximal FE of 27.8% at
-1.29 V (vs reversible hydrogen electrode (RHE)). Three types
of gas products including CO, CH4, and C2H4 are detected
in the presence of Cu NS catalyst (Figure 3b). The FE of CH4
increases linearly when the potential becomes more negative,
with CH4 becoming the dominant product when the potential
is more negative than -1.1 V. C2H4 is the main C2 product in
the presence of Cu NS catalyst, with an optimal FE of 11.3%
at -1.06 V. Similar results are obtained in the presence of the
catalyst mixture (Figure 3c). The FE values of C1 products (i.e.,
CO and CH4) increase slightly in the presence of the mixture of
Au NBPs and Cu NSs, but there is no significant change in the
C2H4 selectivity, suggesting the absence of a synergistic effect.
The core@shell nanostructures exhibit worse performance
than either the Cu NS or the catalyst mixture (Figure 3d) due to
the complete blocking of active sites of the Au NBPs. Notably,
the CO2 reduction can only take place on the surface of the
Cu shell in the core@shell nanostructures, similar to the Cu
NS catalyst, and the larger Cu nanocrystals favor the reduc-
tion of water to H2 rather than CO2RR.[66] Consequently, the
core@shell catalyst with a larger Cu shell (length/diameter
is 116.9 10.1 nm / 98.7 9.5 nm) exhibits higher selectivity
toward H2 evolution than the smaller Cu NS (36.2 2.6 nm)
and the catalyst mixture. Impressively, the two spatially sepa-
rated Au–Cu JNCs exhibit much higher C2 selectivity than the
other catalysts (Figure 3e,f). The optimal FE value of C2H4 is
22.8% for the Au NS–Cu JNCs and 41.5% for the Au NBP–Cu
JNCs. Notably, a new C2 product (i.e., C2H6) produced through
14e reduction[2,67] is obtained for both Au–Cu JNCs, with max-
imum FE being 5.1% for the Au NBP–Cu JNCs. In addition,
the main liquid products obtained by using these six catalysts
are all formate, with most of the FEs being smaller than 5%
(Figure S15, Supporting Information). Both the Au NS–Cu
JNCs and Au NBP–Cu JNCs exhibit better activities toward the
liquid product, with the formate FE being 2.1-fold and 2.4-fold
compared with that of the Cu NSs, respectively.
To trace the carbon source of the products, control experi-
ments were performed in an Ar-saturated 0.1 m KHCO3
aqueous solution with the Au NBP–Cu JNCs as the catalyst
(Figure S16, Supporting Information). H2 is the only product
at different potentials and the obtained FE values are all close
to 100%, suggesting that the carbon source of the products
is the reduction of CO2. To investigate the stability of the Au
NBP–Cu JNCs, TEM imaging and XRD were obtained after the
typical electrocatalytic process. No morphological and structural
changes are observed, indicating the excellent stability of the
hybrid nanostructures (Figure S17a,b, Supporting Information).
In addition, the Au NBP–Cu JNCs retain their catalytic activity
at -0.981 V for 10 h (Figure S17c, Supporting Information), sug-
gesting good electrocatalytic stability of the Au NBP–Cu JNCs.
Since C2 products possess higher energy densities with wider
applications than C1 compounds, their selectivity toward total
C2 products (C2H4 + C2H6) was further investigated (Figure 4).
The Au NBPs exhibit no activity toward the C2 products, while
the C2 FE values of the other catalysts display a volcano-shaped
dependence upon the potential (Figure 4a). The optimal FE
values of these catalysts are selected and plotted in Figure 4b
for comparison. The highest C2 product FEs of the Au NS–Cu
JNCs and Au NBP–Cu JNCs are 25.2 and 46.4%, which are
The Cu-based nanomaterials offer exciting opportunities
for producing high-value hydrocarbons from CO2RR.[2,62] The
well-defined spatially separated Au–Cu hybrid nanostructure
allows for the investigation of the structure-dependent catalytic
performances. Two types of Au–Cu JNCs (i.e., the Au NBP–Cu
JNCs and the Au NS–Cu JNCs) with high number yields were
selected as the catalysts. For comparison, Au NBPs (Figure 1a),
Cu nanospheres (Cu NSs) (Figure S13a, Supporting Informa-
tion), Au NBP@Cu core@shell nanostructures (Figure S13b,
Supporting Information), and the mixture of Au NBPs with Cu
NSs were prepared as the catalysts. It should be noted that the
residual surfactant molecules in these catalysts were not com-
pletely removed to stabilize the morphology, which may block
the active sites and reduce the activity of catalysts. In addition,
the remaining surfactants in these catalysts may influence the
CO2 absorption and subsequently alter the product selectivity.
A recent study demonstrated that surfactants in Au catalysts
can induce a decrease of mass activity but a negligible change
in product selectivity during CO2RR.[63] In order to investigate
the effect of morphology and to maintain the stability of cata-
lysts, the surfactant removal step was not carried out, because
the reaction environment and surfactant molecules used for the
preparation of Au–Cu JNCs are similar. In addition, the product
selectivity is both voltage- and facet-dependent.[64] XRD results
have confirmed that the crystalline nature of the Au NS–Cu
JNCs (Figure S6, Supporting Information) and the Au NBP–Cu
JNCs (Figure S4, Supporting Information) are all same under
the similar reaction conditions. For the study of structure-
dependent catalytic activity and selectivity, the possible facet
effect during CO2RR is not taken into account. The FE and the
current density were used to characterize the electrocatalytic
performance.[65] To accurately obtain the FE data, each electrode
allows quantitative 5 Coulombs of charges to pass through the
catalyst using chronoamperometry (Figure S14, Supporting
Information).[17] All electrochemical measurements were per-
formed in a CO2-saturated 0.1 m KHCO3 aqueous solution
with a gastight two-compartment cell, and the products were
detected with off-line gas chromatography in combination with
ion chromatography. The catalyst-modified flat glassy carbon
electrode was employed as the working electrode and was acti-
vated prior to each test.
Figure 3 shows the FE results of the major gas products
obtained by using six types of catalysts. H2 is the by-product
of CO2RR and is produced through the electrochemical reduc-
tion of water. As shown in Figure 3a, CO is the only CO2RR
Adv. Funct. Mater. 2021, 2101255
2101255 (5 of 11)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.afm-journal.de
Figure 3. Electrochemical CO2 reduction performances. The FEs of the major gaseous products obtained by using a) Au NBP, b) Cu NS, c) Au NBP +
Cu NS mixture, d) Au NBP@Cu core@shell, e) Au NS–Cu JNC, and f) Au NBP–Cu JNC catalysts, respectively.
2.2-fold and 4.1-fold compared with that of the Cu NS counter-
part, respectively, suggesting the synergistic effect of Au and Cu
in the hybrid nanostructure. The optimal C2 FE value of the Au
NBP–Cu JNCs is comparable or even superior to the reported
Cu-base bimetallic electrocatalysts (Table S1, Supporting Infor-
mation). In addition, the catalyst mixture exhibits a similar C2
performance as the Cu NSs, suggesting that the formation of
a directly contacted interface between Au and Cu is the deci-
sive factor for the improvement of C2 selectivity. The catalytic
activities were further investigated by measuring the current
densities at different potentials. As shown in Figure 4c, both
Au–Cu JNCs exhibit higher total activities than the Cu NS
counterparts. It should be noted that the total current density is
contributed by the reduction of water to H2 and the reduction
of CO2 to both C1 and C2 products. To pinpoint the proportion
of the C2 activity, we compared the partial current densities for
C2 production obtained by using different catalysts (Figure 4d).
Impressively, the Au NBP–Cu JNCs induce significant improve-
ment of C2 activity compared with the Cu NS counterparts, with
maximum partial current density on the Au NBP–Cu JNCs (at
-1.118 V) being 6.4-fold higher than that of the Cu NS sample
(at -1.06 V). A decrease peak in the partial current density of
the Au NBP–Cu JNCs (at -1.05 V) (Figure 4d) originates from
the decrease of both C2H4 and C2H6 FE values at this potential.
Therefore, the Au NBP–Cu heterostructure featured with the
spatially separated Au and Cu nanodomains and the unique Au
NBP structural property facilitates the conversion of CO2 to C2
products.

The C C coupling is crucial to the generation of the C2
products in CO2RR, and it is highly sensitive to the structure
and composition of catalyst. Cu is the unique metal cata-
lyst with the capability of producing high-value hydrocarbons
during CO2RR, but it suffers from poor selectivity due to its
moderate binding energies with most reaction intermediates.[2]
The low O and H affinities endow Au with a weak binding
energy for the CO intermediate, which makes CO become the
major product.[7] A tandem catalysis process is feasible as an
alternative mechanism for high C2 activity and selectivity of the
Au–Cu heterostructures.[39] In this tandem catalysis process,
CO is generated on the Au catalyst through the reduction of
CO2, and subsequently migrates to the active sites of nearby
Cu for further CO dimerization, which is the rate-determining
step in the C2 pathway. However, this tandem catalysis process
relies heavily on the spatial arrangement of Au and Cu compo-
nents in the nanostructure. In the catalyst mixture, the tandem
catalysis process is very weak due to the large distance between
them and the poor solubility of CO, resulting in the separate
catalysis by Au and Cu independently (Figure 5a). In the core@
shell nanostructure, the Au component is buried inside the Cu
shell, which hinders the access of Au to reactant CO2 molecules
Adv. Funct. Mater. 2021, 2101255
2101255 (6 of 11)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.afm-journal.de
Figure 4. Comparison of the electrochemical CO2 reduction performances. a) FEs of C2 products obtained by using different catalysts. b) Comparison
of optimal C2 FE value obtained by using different catalysts. c) Total current density and d) C2 product partial current density of different catalysts.
Figure 5. Proposed mechanism of the C2 production on a) the mixture of the Au NBP and the Cu NS, b) the Au@Cu core@shell nanostructure, and
c) the Au NBP–Cu JNC catalysts, respectively.
Adv. Funct. Mater. 2021, 2101255
2101255 (7 of 11)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.afm-journal.de
(Figure 5b). In this scenario, catalysis can only take place on
the surface of the Cu shell, and the Au core is actually not
functional toward tandem electrocatalysis. In contrast, the spa-
tially separated hybrid nanostructure and the intimate contact
of two domains in the Au–Cu JNCs enable the occurrence of
tandem catalysis process, which facilitates the generation of C2
production (Figure 5c). In the first step of the tandem catalysis
process, the catalytic activity for CO2 reduction to CO depends
on the energetic stabilization of COOH* intermediate by the
active sites on Au nanocrystals.[34] Excellent CO2 adsorption and
activation capability of Au nanocrystals facilitate the conversion
of CO2 to CO. As shown in Figure S1, Supporting Informa-
tion, Au NBPs are encapsulated with 10 high-index {116} facets.
These high-index facets with abundant atomic steps can serve
as the active sites for CO2 adsorption and hydrogenation to gen-
erate COOH* intermediate. The Gibbs free energy required to
form the COOH* intermediate on the high-index facets of Au
NBPs is significantly lower than that on the low-index facets
of Au NSs.[68] As a result, Au NBPs exhibit higher CO produc-
tion activity (Figure 3a) than Au NSs (Figure S18, Supporting
Information). In the second step, the atomic steps on Au NBPs
can maximize the interfacial coupling with the supported Cu
domains and optimize the binding of key intermediates in
the C2 pathway, boosting the generation of C2 products.[7,69]
Therefore, the Au NBP–Cu hybrid nanostructures can become
superior electrocatalysts for the tandem catalysis process. Scat-
tered atoms or clusters can work as active species for CO2RR as
well. Figures 1c and 2g indicate the possible presence of some
scattered Cu atoms or clusters on Au nanocrystals, which are
formed in the nucleation and growth steps. Previous researches
demonstrated that small Cu nanoparticles (<5 nm) or Cu clus-
ters may promote the reduction of water at the expense of the
CO2RR.[5,70] On the other hand, single-atom Cu catalyst favors
the conversion of CO2 to C1 product,[71,72] while the C2 product
of Cu nanodomains after the growth on Au nanocrystals will
modify the binding strength of intermediates according to the
d-band model, which depresses the hydrogen evolution but pro-
motes the CO and C2 product generation.[75] Specifically, Au has
a higher electron affinity (2.309 eV) than Cu (1.228 eV), facili-
tating the electron transfer from Cu to Au in this hybrid nano-
structure[76] and resulting in a more positive binding energy of
the Cu nanodomain than the bulk Cu counterparts (Figure S5b,
Supporting Information). Electron-depleted Cu can increase
the CO adsorption energy and consequently improve the CO
dimerization yield, boosting the generation of C2 products.[77]
Above all, the synergistic effect of Au and Cu endows the Au
NBP–Cu JNCs with high activity and good selectivity toward C2
production.
3. Conclusions
In summary, a facile and general wet-chemistry method is
developed for the synthesis of spatially separated Au NBP–Cu
hybrid nanostructures on the basis of a large lattice mismatch
between them. The concentrations of CTAB and HDA play
crucial roles in the overgrowth of Cu nanodomains on the Au
NBPs and determine the morphology of the Au–Cu nanostruc-
tures. The proposed synthesis method can be simply extended
to other Au nanocrystals from 0D to 2D, enabling the produc-
tion of diverse asymmetric Au–Cu nanostructures. In addition,
the spatial-separation design of the Au–Cu heterostructure
possesses distinct advantages over the Cu NSs in the activity
and selectivity of C2 production. The optimal FE value and
maximum partial current density of the Au NBP–Cu JNCs are
4.1-fold and 6.4-fold compared with those of Cu counterparts.
This can be ascribed to the tandem catalysis process promoted
by the hybrid nanostructure and the high-index facets on the
Au NBPs. This research provides an alternative strategy for
the synthesis of spatially separated hybrid nanoblocks for effi-
cient electrochemical reactions, and it opens a new avenue for
pursuing high-efficiency catalysis through the manipulation of
reaction pathways in CO2RR.
is hardly generated due to the lack of sufficient neighboring Cu
[42]

atom ensembles that are critical for C C coupling. Thus,
these possible scattered Cu atoms or clusters on Au nanocrys-
tals make an almost negligible contribution to the C2 product
generation. In addition, the high C2 product selectivity of the
Au NBP–Cu JNC catalyst may be attributed to the suppression
of hydrogen evolution. Up to now, several mechanisms have
been proposed to explain the suppression of hydrogen evolu-
tion, including strain effect,[73] CO poisoning,[74] and electronic
effect.[75] Strain-induced formation of surface alloy can improve
the multicarbon product selectivity.[73] However, the strain effect
has a negligible effect on the C2 product selectivity because it is
absent from the alloyed interfaces in the Au–Cu JNC structures
(Figure 1d 3) and the Au atoms can hardly migrate to the whole
surface of Cu domains for the alloying process. The worse per-
formance of the core@shell nanostructures suggests that the
strain effect does not play an important role in CO2RR. In addi-
tion, the suppression of hydrogen evolution can be achieved by
CO poisoning when the surface of Cu catalysts is covered by
the adsorbed CO intermediates.[74] If CO poisoning occurs, the
generation of CO will be depressed. Conversely, the relatively
high CO FE values (Figure 3) of the Au–Cu JNC catalysts sug-
gest that the CO poisoning is unlikely the underlying effect. A
possible mechanism for the suppression of hydrogen evolution
is the electronic effect.[75] The change of electronic structure
4. Experimental Section
Chemicals: HDA (98%), copper(II) chloride (CuCl2, 99.999%),
l-ascorbic acid (AA) (≥99%), sodium borohydride (NaBH4, 99%),
silver nitrate (AgNO3, ≥99.0%), sodium citrate tribasic dihydrate
(TSC, ≥99%), copper(II) fluoride (CuF2, 98%), copper(II) bromide
(CuBr2, 99%), copper(I) iodide (CuI, 98%), copper(II) acetate
monohydrate (Cu(AC)2, ≥98%), dodecylamine (DDA, 98%), potassium
bicarbonate (KHCO3, 99.7%), potassium chloride (KCl, 99.0–100.5%),
and Nafion 117 solution (≈5%) were purchased from Sigma-Aldrich.
Tetrachloroauric(III) acid trihydrate (HAuCl4 3H2O), hydrochloric acid
(HCl, ≈36.0–38.0 w%), ammonia solution (NH3 H2O, ≈25.0–28.0
wt%), hydrogen peroxide aqueous solution (H2O2, ≥30.0 wt%), sodium
hydroxide (NaOH, ≥96.0%), and isopropanol (≥99.7%) were obtained
from Sinopharm Chemical Reagent. Hexadecyltrimethylammonium
chloride (CTAC, 97%), and potassium iodide (KI ≥99.0%) were
obtained from Aladdin Reagent. CTAB (>98%) was purchased from
Alfa Aesar. Octadecylamine (ODA, 90%) was obtained from Macklin.
Carbon dioxide (CO2, 99.999%), nitrogen (N2, 99.999%), hydrogen
(H2, 99.999%), argon (Ar, 99.999%), and helium (He, 99.999%) were
Adv. Funct. Mater. 2021, 2101255
2101255 (8 of 11)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.afm-journal.de
5A column and CO was detected with a thermal conductivity detector
(TCD). H2 was detected using the TCD by passing through a packed
MoleSieve 5A column with N2 as the carrier gas. The liquid products
(1 mL) were measured using either GC (Agilent Technologies 7890B)
or an ion chromatograph (Thermo Fisher Scientific Aquion). Formate
was detected using the ion chromatograph, while the other major liquid
products were analyzed using the FID of GC by passing through a
DB-WAX capillary column with N2 as the carrier gas.
Characterization: TEM imaging was obtained by an HT7700 electron
microscope operated at 100 kV. HRTEM, HAADF-STEM imaging, and
elemental mapping were obtained by an FEI Tecnai F20 microscopy
equipped with an Oxford energy-dispersive X-ray analysis system.
used as received. Deionized water with a resistivity of 18.2 MΩ cm was
used in all experiments.
Growth of the Au NBPs: The starting Au NBPs were prepared using
a seed-mediated growth method in combination with a depletion force-
induced purification process.[54,55] Specifically, the seed solution was
made by injecting a freshly prepared, ice-cold NaBH4 solution (10 mm,
125 μL) into an aqueous solution containing HAuCl4 (10 mm, 125 μL),
TSC (10 mm, 250 μL), and deionized water (9.625 mL) under vigorous
stirring. The resultant seed solution was kept at room temperature
for at least 2 h prior to use. The growth solution was prepared by the
sequential addition of HAuCl4 (10 mm, 2 mL), AgNO3 (10 mm, 400 μL),
HCl (1 m, 800 μL), and AA (0.1 m, 320 μL) into CTAB aqueous solution
(0.1 m, 40 mL). The seed solution (200 μL) was then injected into
the growth solution, followed by gentle inversion mixing for 10 s. The
resultant solution was kept undisturbed overnight at room temperature.
The obtained Au NBPs were further purified using a depletion force-
induced purification process.[55]
Growth of the Au NBP–Cu Janus Nanostructures: Typically, the obtained
Au NBP solution (5 mL) was centrifuged at 7500 rpm for 10 min, followed
by washing with deionized water (5 mL) to remove the excess surfactant.
The precipitate was redispersed in a CTAB solution (0.5 mm, 0.5 mL)
to get a final CTAB concentration of 100 μm. For the overgrowth of Cu
nanodomains on the Au NBPs, HDA (12 mg) was added in boiling water
(8.575 mL) in a 25-mL three-necked round-bottom flask and refluxed
in an oil bath at 100 °C under magnetic stirring. After the complete
dissolution of HDA, CuCl2 solution (0.1 m, 100 μL) was added and the
mixture was kept stirring for more than 10 min to form the Cu(II)–HDA
complexes. To initiate the overgrowth, the Au NBP solution (optical
density at the longitudinal dipole plasmon wavelength = 15, 500 μL) was
added, followed by the injection of AA solution (0.2 m, 825 μL). The total
volume of the solution was adjusted to 10 mL by adding deionized water
and the final concentrations of CTAB and HDA were 100 μm and 5 mm,
respectively. The resultant solution was further refluxed at 100 °C for 1 h
to produce the Au NBP–Cu JNCs, followed by cooling down to room
temperature naturally.
The aberration-corrected HRTEM imaging was performed on
a
Titan Themis G3 ETEM (Thermo Scientific Company) at 300 kV. The
extinction spectra were obtained by a Hitachi U-3900 ultraviolet/
visible/NIR spectrophotometer. XRD patterns were obtained by a Smart
Lab Se diffractometer equipped with Cu Kα radiation. XPS spectra
were obtained by a Thermo Scientific ESCALAB 250Xi spectrometer.
Inductively coupled plasma optical emission spectra (ICP-OES) were
obtained by a PerkinElmer Optima 7300 DV system.
Supporting Information
Supporting Information is available from the Wiley Online Library or
from the author.
Acknowledgements
H.L.J. and Y.Y.Y. contributed equally to this work. This work was
supported by the National Natural Science Foundation of China (Grant
No. 21735003), the Research Grants Council of Hong Kong (GRF,
14305819), the Natural Science Foundation of Shandong Province (No.
ZR2020MB040), and the Award for Team Leader Program of Taishan
Scholars of Shandong Province, China.
Growth of the Other Au Nanocrystals and Au–Cu Nanostructures: The
synthesis details were described in the Supporting Information.
Electrochemical Measurements: The working electrodes were prepared
by drop-casting the catalyst (26 μg) onto a glassy carbon plate in an
area of 1 cm2 (1 cm × 0.5 cm × 2). Before the electrochemical tests, the
as-prepared electrodes were stored in a vacuum oven to evaporate the
solvent and to prevent the oxidation of catalysts.
Conflict of Interest
The electrochemical measurements were conducted in a customized
gastight two-compartment cell, that was composed of an anodic
chamber and a cathodic chamber, separated by a Nafion 117 membrane.
Each chamber was loaded with CO2-saturated 0.1 m KHCO3 aqueous
solution (20 mL, pH = 6.8) as the electrolyte. A potentiostat (CHI
660E) equipped with a typical three-electrode system was employed
for the CO2RR experiments. The counter and reference electrode were
a graphite rod and an Ag/AgCl (filled with saturated KCl solution)
electrode, respectively. All potentials were recorded with the Ag/AgCl
electrode and converted to the RHE scale according to E (vs RHE) = E
(vs Ag/AgCl) + 0.197 V + 0.0591 × pH. The potentials (vs RHE) were
further manually corrected to compensate for 85% Ohmic loss.[17,46]
In order to calculate the FE, quantitative 5 Coulombs of charges were
allowed to pass through the catalyst using chronoamperometry. Prior
to each test, the working electrode was activated by passing through
2 Coulombs of charges.
Product Analysis: All gaseous products were quantitatively detected
by an off-line gas chromatograph (GC, Agilent Technologies 7890B).
The gas sample (2 mL) was taken using a syringe (2.5 mL, PTFE, Luer
Lock valve, Agilent Technologies) from the headspace of the electrolytic
cell and injected into the GC. Either He (99.999%) or N2 (99.999%)
was employed as the carrier gas. When He was used as the carrier gas,
the gas sample was split into two aliquots for detection. One aliquot
was routed through an HP-PLOT Al2O3/KCl capillary column and then
quantitatively analyzed all major hydrocarbons using a flame ionization
detector (FID), while the other was passed through a packed MoleSieve
The authors declare no conflict of interest.
Data Availability Statement
Research data are not shared.
Keywords
gold nanobipyramids, lattice mismatch, site-selective growth, symmetry-
breaking synthesis, tandem catalysis
Received: February 5, 2021
Revised: March 24, 2021
Published online:
[1] P. D. Luna, C. Hahn, D. Higgins, S. A. Jaffer, T. F. Jaramillo,
E. H. Sargent, Science 2019, 364, eaav3506.
[2] S. Nitopi, E. Bertheussen, S. B. Scott, X. Y. Liu, A. K. Engstfeld,
S. Horch, B. Seger, I. E. L. Stephens, K. Chan, C. Hahn,
J. K. Nørskov, T. F. Jaramillo, I. Chorkendorff, Chem. Rev. 2019, 119,
7610.
Adv. Funct. Mater. 2021, 2101255
2101255 (9 of 11)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.afm-journal.de
[3] C.-T. Dinh, T. Burdyny, M. G. Kibria, A. Seifitokaldani,
C. M. Gabardo, F. P. García de Arquer, A. Kiani, J. P. Edwards,
P. D. Luna, O. S. Bushuyev, C. Q. Zou, R. Quintero-Bermudez,
Y. J. Pang, D. Sinton, E. H. Sargent, Science 2018, 360, 783.
[4] D. Wakerley, S. Lamaison, F. Ozanam, N. Menguy, D. Mercier,
P. Marcus, M. Fontecave, V. Mougel, Nat. Mater. 2019, 18, 1222.
[5] R. Reske, H. Mistry, F. Behafarid, B. R. Cuenya, P. Strasser, J. Am.
Chem. Soc. 2014, 136, 6978.
[6] S. Popović, M. Smiljanić, P. Jovanovič, J. Vavra, R. Buonsanti,
N. Hodnik, Angew. Chem., Int. Ed. 2020, 59, 14736.
[7] A. Vasileff, C. C. Xu, Y. Jiao, Y. Zheng, S.-Z. Qiao, Chem 2018, 4,
1809.
[8] D. F. Gao, R. M. Arán-Ais, H. S. Jeon, B. R. Cuenya, Nat. Catal.
2019, 2, 198.
[9] Y. Zheng, A. Vasileff, X. L. Zhou, Y. Jiao, M. Jaroniec, S.-Z. Qiao, J.
Am. Chem. Soc. 2019, 141, 7646.
[10] L. Zhang, Z.-J. Zhao, J. L. Gong, Angew. Chem., Int. Ed. 2017, 56,
11326.
[27] J. J. Fu, W. L. Zhu, Y. Chen, Z. Y. Yin, Y. Y. Li, J. Liu, H. Y. Zhang,
J.-J. Zhu, S. H. Sun, Angew. Chem., Int. Ed. 2019, 58, 14100.
[28] Y. J. Han, Z. T. Wang, X. T. Han, W. S. Fang, Y. S. Zhou, K. Lei,
B. You, H. S. Park, B. Y. Xia, ACS Sustainable Chem. Eng. 2021, 9,
2609.
[29] H. L. Jia, A. X. Du, H. Zhang, J. H. Yang, R. B. Jiang, J. F. Wang,
C.-Y. Zhang, J. Am. Chem. Soc. 2019, 141, 5083.
[30] S. Mubeen, J. Lee, N. Singh, S. Krämer, G. D. Stucky, M. Moskovits,
Nat. Nanotechnol. 2013, 8, 247.
[31] M. W. Knight, H. Sobhani, P. Nordlander, N. J. Halas, Science 2011,
332, 702.
[32] E. C. Dreaden, A. M. Alkilany, X. H. Huang, C. J. Murphy, M. A. El-
Sayed, Chem. Soc. Rev. 2012, 41, 2740.
[33] R. Zhu, J. Li, L. S. Lin, J. B. Song, H. H. Yang, Adv. Funct. Mater.
2020, 31, 2005709.
[34] W. L. Zhu, R. Michalsky, Ö. Metin, H. F. Lv, S. J. Guo, C. J. Wright,
X. L. Sun, A. A. Peterson, S. H. Sun, J. Am. Chem. Soc. 2013, 135,
16833.
[11] Y. F. Li, F. Cui, M. B. Ross, D. Kim, Y. C. Sun, P. D. Yang, Nano Lett.
2017, 17, 1312.
[35] R. G. Mariano, K. McKelvey, H. S. White, M. W. Kanan, Science 2017,
358, 1187.
[12] A. Loiudice, P. Lobaccaro, E. A. Kamali, T. Thao, B. H. Huang,
J. W. Ager, R. Buonsanti, Angew. Chem., Int. Ed. 2016, 55,
5789.
[13] P. Grosse, D. F. Gao, F. Scholten, I. Sinev, H. Mistry, B. R. Cuenya,
Angew. Chem., Int. Ed. 2018, 57, 6192.
[36] S. Zhao, R. X. Jin, R. C. Jin, ACS Energy Lett. 2018, 3, 452.
[37] J. H. Lee, S. Kattel, Z. H. Xie, B. M. Tackett, J. J. Wang, C.-J. Liu,
J. G. G. Chen, Adv. Funct. Mater. 2018, 28, 1804762.
[38] Y. Y. Birdja, E. Pérez-Gallent, M. C. Figueiredo, A. J. Göttle, F. Calle-
Vallejo, M. T. M. Koper, Nat. Energy 2019, 4, 732.
[14] B. X. Zhang, J. L. Zhang, M. L. Hua, Q. Wan, Z. Z. Su, X. N. Tan,
L. F. Liu, F. Y. Zhang, G. Chen, D. X. Tan, X. Y. Cheng, B. X. Han,
L. R. Zheng, G. Mo, J. Am. Chem. Soc. 2020, 142, 13606.
[15] N.-T. Suen, Z.-R. Kong, C.-S. Hsu, H.-C. Chen, C.-W. Tung, Y.-R. Lu,
C.-L. Dong, C.-C. Shen, J.-C. Chung, H. M. Chen, ACS Catal. 2019,
9, 5217.
[16] P. D. Luna, R. Quintero-Bermudez, C.-T. Dinh, M. B. Ross,
O. S. Bushuyev, P. Todorović, T. Regier, S. O. Kelley, P. D. Yang,
E. H. Sargent, Nat. Catal. 2018, 1, 103.
[17] W. Zhang, C. Q. Huang, Q. Xiao, L. Yu, L. Shuai, P. F. An, J. Zhang,
M. Qiu, Z. F. Ren, Y. Yu, J. Am. Chem. Soc. 2020, 142, 11417.
[18] D. Ren, Y. L. Deng, A. D. Handoko, C. S. Chen, S. Malkhandi,
B. S. Yeo, ACS Catal. 2015, 5, 2814.
[19] Q. Lei, H. Zhu, K. P. Song, N. N. Wei, L. M. Liu, D. L. Zhang, J. Yin,
X. L. Dong, K. X. Yao, N. Wang, X. H. Li, B. Davaasuren, J. J. Wang,
Y. Han, J. Am. Chem. Soc. 2020, 142, 4213.
[20] P.-P. Yang, X.-L. Zhang, F.-Y. Gao, Y.-R. Zheng, Z.-Z. Niu, X. X. Yu,
R. Liu, Z.-Z. Wu, S. Qin, L.-P. Chi, Y. Duan, T. Ma, X.-S. Zheng,
J.-F. Zhu, H.-J. Wang, M.-R. Gao, S.-H. Yu, J. Am. Chem. Soc. 2020,
142, 6400.
[21] C. Hahn, T. Hatsukade, Y.-G. Kim, A. Vailionis, J. H. Baricuatro,
D. C. Higgins, S. A. Nitopi, M. P. Soriaga, T. F. Jaramillo, Proc. Natl.
Acad. Sci. U. S. A. 2017, 114, 5918.
[39] C. G. Morales-Guio, E. R. Cave, S. A. Nitopi, J. T. Feaster, L. Wang,
K. P. Kuhl, A. Jackson, N. C. Johnson, D. N. Abram, T. Hatsukade,
C. Hahn, T. F. Jaramillo, Nat. Catal. 2018, 1, 764.
[40] X. L. Wang, J. F. de Araújo, W. Ju, A. Bagger, H. Schmies, S. Kühl,
J. Rossmeisl, P. Strasser, Nat. Nanotechnol. 2019, 14, 1063.
[41] X. Zhao, L. J. Du, B. You, Y. J. Sun, Catal. Sci. Technol. 2020, 10, 2711.
[42] S. C. Ma, M. Sadakiyo, M. Heima, R. Luo, R. T. Haasch, J. I. Gold,
M. Yamauchi, P. J. A. Kenis, J. Am. Chem. Soc. 2017, 139, 47.
[43] X. C. Pang, C. S. Wan, M. Y. Wang, Z. Q. Lin, Angew. Chem., Int. Ed.
2014, 53, 5524.
[44] Z. Q. Huang, J. L. Gong, Z. H. Nie, Acc. Chem. Res. 2019, 52, 1125.
[45] Y. G. Sun, Natl. Sci. Rev. 2015, 2, 329.
[46] J. F. Huang, M. Mensi, E. Oveisi, V. Mantella, R. Buonsanti, J. Am.
Chem. Soc. 2019, 141, 2490.
[47] S. G. Kwon, G. Krylova, P. J. Phillips, R. F. Klie, S. Chattopadhyay,
T. Shibata, E. E. Bunel, Y. Z. Liu, V. B. Prakapenka, B. Lee,
E. V. Shevchenko, Nat. Mater. 2015, 14, 215.
[48] J. C. Wang, X. L. Wu, W. Ma, C. L. Xu, Adv. Funct. Mater. 2020, 30,
2000670.
[49] J. Liu, J. T. Zhang, Chem. Rev. 2020, 120, 2123.
[50] T. H. Chow, N. N. Li, X. P. Bai, X. L. Zhuo, L. Shao, J. F. Wang, Acc.
Chem. Res. 2019, 52, 2136.
[51] M. Z. Liu, P. Guyot-Sionnest, J. Phys. Chem.
B 2005, 109,
[22] Z. N. Wang, G. Yang, Z. R. Zhang, M. S. Jin, Y. D. Yin, ACS Nano
2016, 10, 4559.
22192.
[52] X. S. Kou, S. Z. Zhang, C.-K. Tsung, M. H. Yeung, Q. H. Shi,
G. D. Stucky, L. D. Sun, J. F. Wang, C. H. Yan, J. Phys. Chem. B 2006,
110, 16377.
[53] Z. N. Wang, Z. Z. Chen, H. Zhang, Z. R. Zhang, H. J. Wu, M. S. Jin,
C. Wu, D. R. Yang, Y. D. Yin, ACS Nano 2015, 9, 3307.
[54] X. S. Kou, W. H. Ni, C.-K. Tsung, K. Chan, H.-Q. Lin, G. D. Stucky,
J. F. Wang, Small 2007, 3, 2103.
[23] F. W. Li, A. Thevenon, A. Rosas-Hernández, Z. Y. Wang,
Y. L. Li, C. M. Gabardo, A. Ozden, C. T. Dinh, J. Li, Y. H. Wang,
J. P. Edwards, Y. Xu, C. McCallum, L. Z. Tao, Z.-Q. Liang, M. C. Luo,
X. Wang, H. H. Li, C. P. O’ Brien, C.-S. Tan, D.-H. Nam, R. Quintero-
Bermudez, T.-T. Zhuang, Y. G. C. Li, Z. J. Han, R. D. Britt, D. Sinton,
T. Agapie, J. C. Peters, E. H. Sargent, Nature 2020, 577, 509.
[24] Z. Weng, X. Zhang, Y. S. Wu, S. J. Huo, J. B. Jiang, W. Liu, G. J. He,
Y. Y. Liang, H. L. Wang, Angew. Chem., Int. Ed. 2017, 56, 13135.
[25] Y. Chen, Z. X. Fan, J. Wang, C. Y. Ling, W. X. Niu, Z. Q. Huang,
G. G. Liu, B. Chen, Z. C. Lai, X. Z. Liu, B. Li, Y. Zong, L. Gu,
J. L. Wang, X. Wang, H. Zhang, J. Am. Chem. Soc. 2020, 142,
12760.
[55] Q. Li, X. L. Zhuo, S. Li, Q. F. Ruan, Q.-H. Xu, J. F. Wang, Adv. Opt.
Mater. 2015, 3, 801.
[56] C.-F. Hsia, M. Madasu, M. H. Huang, Chem. Mater. 2016, 28, 3073.
[57] F. Qin, T. Zhao, R. B. Jiang, N. N. Jiang, Q. F. Ruan, J. F. Wang,
L.-D. Sun, C.-H. Yan, H.-Q. Lin, Adv. Opt. Mater. 2016, 4, 76.
[58] M. S. Jin, G. N. He, H. Zhang, J. Zeng, Z. X. Xie, Y. N. Xia, Angew.
Chem., Int. Ed. 2011, 50, 10560.
[26] D. Kim, C. L. Xie, N. Becknell, Y. Yu, M. Karamad, K. Chan,
E. J. Crumlin, J. K. Nørskov, P. D. Yang, J. Am. Chem. Soc. 2017, 139,
8329.
[59] M. S. Jin, H. Zhang, J. G. Wang, X. L. Zhong, N. Lu, Z. Y. Li,
Z. X. Xie, M. J. Kim, Y. N. Xia, ACS Nano 2012, 6, 2566.
Adv. Funct. Mater. 2021, 2101255
2101255 (10 of 11)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.afm-journal.de
[60] R. He, Y.-C. Wang, X. Y. Wang, Z. T. Wang, G. Liu, W. Zhou,
L. P. Wen, Q. X. Li, X. P. Wang, X. Y. Chen, J. Zeng, J. G. Hou, Nat.
Commun. 2014, 5, 4327.
[61] V. Kumar, V. Patil, A. Apte, N. Harale, P. Patil, S. Kulkarni, Langmuir
2015, 31, 13247.
[69] H.-E. Lee, K. D. Yang, S. M. Yoon, H.-Y. Ahn, Y. Y. Lee, H. Chang,
D. H. Jeong, Y.-S. Lee, M. Y. Kim, K. T. Nam, ACS Nano 2015, 9, 8384.
[70] J. F. Huang, N. Hörmann, E. Oveisi, A. Loiudice, G. L. De Gregorio,
O. Andreussi, N. Marzari, R. Buonsanti, Nat. Commun. 2018, 9,
3117.
[62] M. B. Ross, P. D. Luna, Y. F. Li, C.-T. Dinh, D. Kim, P. D. Yang,
E. H. Sargent, Nat. Catal. 2019, 2, 648.
[71] C. C. Xu, A. Vasileff, Y. Zheng, S.-Z. Qiao, Adv. Mater. Interfaces
2020, 8, 2001904.
[63] P. Godbold, G. Johnson, A. D. Obi, R. Brown, S. Hwang,
R. J. Gilliard Jr., S. Zhang, J. Am. Chem. Soc. 2021, 143, 2644.
[64] C. Y. Zhu, Z. B. Zhang, L. X. Zhong, C.-S. Hsu, X. Z. Xu,
Y. Z. Li, S. W. Zhao, S. H. Chen, J. Y. Yu, S. L. Chen, M. Wu,
P. Gao, S. Z. Li, H. M. Chen, K. H. Liu, L. M. Zhang, Chem 2021, 7,
406.
[72] Y. M. Cai, J. J. Fu, Y. Zhou, Y.-C. Chang, Q. H. Min, J.-J. Zhu,
Y. H. Lin, W. L. Zhu, Nat. Commun. 2021, 12, 586.
[73] E. L. Clark, C. Hahn, T. F. Jaramillo, A. T. Bell, J. Am. Chem. Soc.
2017, 139, 15848.
[74] Y.-J. Zhang, V. Sethuraman, R. Michalsky, A. A. Peterson, ACS Catal.
2014, 4, 3742.
[65] E. L. Clark, J. Resasco, A. Landers, J. Lin, L.-T. Chung, A. Walton,
C. Hahn, T. F. Jaramillo, A. T. Bell, ACS Catal. 2018, 8, 6560.
[66] P. lyengar, J. F. Huang, G. L. De Dregorio, C. Gadiyar, R. Buonsanti,
Chem. Commun. 2019, 55, 8796.
[75] D. Kim, J. Resasco, Y. Yu, A. M. Asiri, P. D. Yang, Nat. Commun.
2014, 5, 4948.
[76] M. Tsuji, D. Yamaguchi, M. Matsunaga, M. J. Alam, Cryst. Growth
Des. 2010, 10, 5129.
[67] K. D. Yang, W. R. Ko, J. H. Lee, S. J. Kim, H. Lee, M. H. Lee,
K. T. Nam, Angew. Chem., Int. Ed. 2017, 56, 796.
[68] C. Xiao, B.-A. Lu, P. Xue, N. Tian, Z.-Y. Zhou, X. Lin, W.-F. Lin,
S.-G. Sun, Joule 2020, 4, 2562.
[77] Y. S. Zhou, F. L. Che, M. Liu, C. Q. Zou, Z. Q. Liang, P. D. Luna,
H. F. Yuan, J. Li, Z. Q. Wang, H. P. Xie, H. M. Li, P. N. Chen,
E. Bladt, R. Quintero-Bermudez, T.-K. Sham, S. Bals, J. Hofkens,
D. Sinton, G. Chen, E. H. Sargent, Nat. Chem. 2018, 10, 974.
Adv. Funct. Mater. 2021, 2101255
2101255 (11 of 11)
© 2021 Wiley-VCH GmbH