Sustainable Synthesis of Bimetallic Single Atom Gold-Based Catalysts with Enhanced Durability in Acetylene Hydrochlorination

Article abstract of DOI:10.1002/smll.202004599

Gold single-atom catalysts (SACs) exhibit outstanding reactivity in acetylene hydrochlorination to vinyl chloride, but their practical applicability is compromised by current synthesis protocols, using aqua regia as chlorine-based dispersing agent, and their high susceptibility to sintering on non-functionalized carbon supports at >500 K and/or under reaction conditions. Herein, a sustainable synthesis route to carbon-supported gold nanostructures in bimetallic catalysts is developed by employing salts as alternative chlorine source, allowing for tailored gold dispersion, ultimately reaching atomic level when using H₂PtCl₆. To rationalize these observations, several synthesis parameters (i.e., pH, Cl-content) as well as the choice of metal chlorides are evaluated, hinting at the key role of platinum in promoting a chlorine-mediated dispersion mechanism. This can be further extrapolated to redisperse large gold agglomerates (>70?nm) on carbon carriers into isolated atoms, which has important implications for catalyst regeneration. Another key role of platinum single atoms is to inhibit the sintering of their spatially isolated gold-based analogs up to 800 K and during acetylene hydrochlorination, without compromising the intrinsic activity of Au(I)-Cl active sites. Accordingly, exploiting cooperativity effects of a second metal is a promising strategy towards practical applicability of gold SACs, opening up exciting opportunities for multifunctional single-atom catalysis.

Full text of DOI:10.1002/smll.202004599

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Sustainable Synthesis of Bimetallic Single Atom
Gold-Based Catalysts with Enhanced Durability in
Acetylene Hydrochlorination
Selina K. Kaiser, Adam H. Clark, Lucrezia Cartocci, Frank Krumeich,
and Javier Pérez-Ramírez*
clusters, and particularly single atoms
can unfold remarkable activity for diverse
reactions relevant to commodities manu-
facture, emissions control, and energy
Gold single-atom catalysts (SACs) exhibit outstanding reactivity in acety-
lene hydrochlorination to vinyl chloride, but their practical applicability is
compromised by current synthesis protocols, using aqua regia as chlorine-
based dispersing agent, and their high susceptibility to sintering on non-
functionalized carbon supports at >500 K and/or under reaction conditions.
Herein, a sustainable synthesis route to carbon-supported gold nanostruc-
tures in bimetallic catalysts is developed by employing salts as alternative
chlorine source, allowing for tailored gold dispersion, ultimately reaching
atomic level when using H PtCl . To rationalize these observations, several
synthesis parameters (i.e., pH, Cl-content) as well as the choice of metal
chlorides are evaluated, hinting at the key role of platinum in promoting a
chlorine-mediated dispersion mechanism. This can be further extrapolated to
redisperse large gold agglomerates (>70 nm) on carbon carriers into isolated
atoms, which has important implications for catalyst regeneration. Another
key role of platinum single atoms is to inhibit the sintering of their spatially
isolated gold-based analogs up to 800 K and during acetylene hydrochlo-
rination, without compromising the intrinsic activity of Au(I)-Cl active sites.
Accordingly, exploiting cooperativity effects of a second metal is a promising
strategy towards practical applicability of gold SACs, opening up exciting
opportunities for multifunctional single-atom catalysis.
[2]
conversion. A prominent example is
acetylene hydrochlorination, a key tech-
nology for the manufacture of vinyl chlo-
−1
ride monomer (VCM, 13 Mton y ), which
still runs over highly toxic and volatile
mercuric chloride-based catalysts, the use
[3]
of which will be banned in 2022. Gold
SACs stand out as the most active system
2
6
[
3b,4]
described to date for this reaction.
comparison, their nanoparticle-based ana-
logs are virtually inactive.
In
[1e,4a]
Besides this
nuclearity effect, also the coordination envi-
ronment of the Au single atoms, as defined
through interactions with atoms from the
host (i.e., C,O) or ligands (i.e., Cl) strongly
affects the catalytic response, with Au(I)–Cl
single atoms reaching the highest activity.
However, owing to the high mobility of
Au–Cl single atoms on non-functionalized
carbon supports, agglomeration into nano-
particles readily occurs under reaction con-
[1e,4a]
ditions, leading to catalyst deactivation.
Furthermore, the use of corrosive aqua
regia as chlorine-based dispersing agents in typical synthesis
Heterogeneous catalysis by gold is a prime example on the
impact of the metal nanostructure on reactivity, a concept that
has gained tremendous attention in recent years, particularly in
context to single-atom catalysts (SACs), referring to spatially iso-
lated atoms or ions stabilized on a solid carrier. While gold in
its bulk form is catalytically inert, supported gold nanoparticles,
[
2b,3b,4a]
protocols,
represents another obstacle in the develop-
ment of practically applicable Au SACs. To overcome these hur-
dles, several strategies have been developed to i) replace aqua
regia, through the use of sulfur-containing ligands in aqueous
[1]
[
5]
[4b]
solution or non-polar organic solvents, and ii) increase the
catalyst stability through host functionalization (e.g., N-doped
[
4a,6]
carbons, mechanically milled carbon–CeO2 mixtures),
or
S. K. Kaiser, L. Cartocci, Dr. F. Krumeich, Prof. J. Pérez-Ramírez
Institute for Chemical and Bioengineering
Department of Chemistry and Applied Biosciences
ETH Zurich
[7]
addition of promoters or second metals. Particularly the latter
approach has been widely studied in view of potential bimetallic
synergies, stabilizing Au in high oxidation states and balancing
HCl and C H adsorption. In particular, non-noble metals (e.g.,
Vladimir-Prelog-Weg 1, Zürich 8093, Switzerland
E-mail: jpr@chem.ethz.ch
2
2
[7]
[8]
Cu, Ni, Co, Ba, La) and precious metals (e.g., Pt, Pd, Ir, Rh)
Dr. A. H. Clark
Paul Scherrer Institut
Villigen PSI 5232, Switzerland
have been shown to promote and lower the performance of Au-
based catalysts in acetylene hydrochlorination, respectively. How-
ever, possible correlations to the metal nanostructures were not
undertaken at the time, as the structure of the active Au site had
not yet been identified. At this time, the metal nanostructure is
widely accepted as the key descriptor, determining performance
The ORCID identification number(s) for the author(s) of this article
can be found under https://doi.org/10.1002/smll.202004599.
DOI: 10.1002/smll.202004599
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in acetylene hydrochlorination, as has further been demon-
[9]
[10]
strated for ruthenium and platinum. Contrary to gold, plat-
inum single atoms exhibits high thermal and chemical stability
on carbon hosts and may be prepared via simple incipient wet-
ness impregnation from aqueous solution. In this regard, mul-
timetallic single-atom catalysis may lead to potential synergies.
Pioneering work in this direction revealed encouraging catalytic
performances in electrocatalytic (i.e., carbon-supported Pt-Ru
[11]
SAC, denoted as Pt–Ru/C) and organic transformations (i.e.,
Rh–Ru/CeO2[ and Ir–La/C ), opening up one of the most
12]
[13]
[1f ]
recent and intriguing frontiers of the field. In this contribu-
tion, we explore potential synergies between gold and platinum
as optimally nanostructured bimetallic SACs, with the aim to
enable a greener synthesis (i.e., replacement of aqua regia) and
improved stability in acetylene hydrochlorination.
By extrapolating the previously developed synthetic approach
to derive carbon-supported Pt SACs (Pt/C) from aqueous solu-
[
10]
tion (nominal metal loading 0.5 weight percent, wt%)
to
Au/C, large agglomerates form with an average particle size
exceeding 70 nm (Figure 1a). The origin of this severe agglom-
eration during the synthesis has been ascribed to the reduc-
tive properties of the carbon host and the reduced stability of
[
4b,14]
the gold chloride precursor (HAuCl ) in polar solutions.
4
We demonstrate here that this limitation can be fully over-
come through the stoichiometric addition of chloroplatinic
acid (H PtCl ), yielding highly dispersed Au–Pt/C catalysts
2
6
from aqueous solution, as visualized by scanning transmission
electron microscopy (STEM) and corroborated by the absence
of Au reflections in the X-ray diffraction (XRD) spectrum
(Figures S1, S2, Supporting Information). To gain further
insight into the nature of the individual metal sites in Au–Pt/C,
X-ray absorption spectroscopy (XAS) was employed (for details
on the experimental and fitting procedure, see Supporting
Information). Comparison of the white-line intensity at around
1
1 925 eV in the normalized Au L -edge X-ray absorption near
3
edge spectrum (XANES), indicated a generally lower degree of
highly charged and/or chlorinated metal species, compared to
benchmark Au-SA/C prepared from aqua regia (Figure 1b). Fit-
ting of the extended X-ray absorption fine structure (EXAFS),
using Au–C/O, Au–Cl and Au–Au/Pt contributions on the Au
L edge and Pt–C/O, Pt–Cl and Pt–Pt/Au on the Pt L edge,
3
3
revealed a decrease in the Au–Cl contribution in the order of
Au–SA/C >Au–Pt/C > Au–NP/C (Figure 1c; Figure S3, Table S1,
Supporting Information, coordination number, CN = 2.7 ± 0.3,
Figure 1. a) Schematic representation of the synthetic routes to carbon-
supported Au-, Pt-, and Au–Pt single-atom catalysts. Color code: C, grey; Cl,
green; Au, gold; Pt, purple. The STEM images of the mono and bimetallic
catalysts visualize the remarkable redispersing effect of platinum chloride,
transforming large Au agglomerates into small clusters and single atoms
in aqueous solution. b,c) Au L3 edge XANES and EXAFS spectra.
≈
0.9, and 0.4 ± 0.1, respectively). Similar to the Au single
atoms, also the Pt sites are surrounded by Cl neighboring
atoms (Figure S4, Table S2, Supporting Information, CN = 2.6),
suggesting that Cl ions are not removed during the synthesis
[
4,12]
of the catalyst, in line with previous literature reports
and
corroborated by the surface and bulk chlorine contents derived
from X-ray photoelectron spectroscopy (XPS) and elemental
analysis, respectively (Table S3, Supporting Information).
Besides metal-chloride contributions, the EXAFS fitting results
for Au–Pt/C suggest further, the presence of metal–metal inter-
actions (Table S1, Figure S3, Supporting Information). How-
ever, owing to an overlap between the Au L and Pt L edges,
these results exhibit a high degree of uncertainty and can only
suffice as a general guideline. Additionally, due to the virtually
undistinguishable Au and Pt scattering paths, it is beyond the
scope of this technique to indicate whether the metallic contri-
butions are of mono or bimetallic nature (i.e., AuPt or AuAu
bonds). Particularly the presence of low-nuclearity clusters (i.e.,
dimers, trimers) seems to be a viable possibility, as the latter
are virtually indistinguishable by STEM and would not be vis-
ible by XRD analysis. Similarly, also STEM electron energy
loss spectroscopy (EELS) cannot be employed to gain additional
insights into the interaction and/or proximity between the Au
and Pt sites, as this technique is only applicable to systems in
which the atoms of interest are stationary (i.e., highly stabilized
[
15]
3
3
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acetylene hydrochlorination was employed as a means to indi-
rectly assess the degree of Au dispersion, taking advantage of
the well-known high structure-sensitivity of this reaction (Tbed
=
4
73 K, HCl:C H = 1.1:1, gas hourly pace velocity based on acety-
2
2
−
1
lene GHSV(C H ) = 1500 h ). At low activation temperatures
2
2
of 473 K, both Au–Pt/C and Au–SA/C exhibit comparably high
initial catalytic activity, as is well in line with the presence of
Au single atoms in these samples. However, following thermal
activation >600 K, the initial catalytic activity of Au–SA/C
sharply drops, while the performance of Au–Pt/C remains high
up to activation temperatures of 900 K. Following these encour-
aging results, we assessed the stability of Au–Pt/C in acetylene
hydrochlorination in comparison to Au–SA/C, within 50 h tests
−
1
(
GHSV(C H ) = 560 h , Figure 2c). Although both systems
2 2
gradually deactivate, Au–Pt/C exhibits a ≈2-fold improved sta-
bility, which relates well to the significantly reduced sintering of
Au under reaction conditions, as evident from STEM and XRD
analysis of the used catalysts (Figure 2d; S6, Supporting Infor-
mation). Notably, the surface area decreased gradually for both
catalysts with prolonged reaction time, indicating coking as
additional cause of catalyst deactivation (Table S5, Supporting
Information). While these results confirm the stabilizing effect
of Pt on Au nanostructures, also under reaction conditions of
acetylene hydrochlorination, evaluation of the reaction kinetics
of Au–SA/C and Au–Pt/C showed only marginal differences
(Figure S7, Supporting Information).
Figure 2. a) Evolution of the Au particle size, derived from STEM anal-
ysis in the absence or presence of Pt atoms as a function of the thermal
activation temperature and corresponding acetylene hydrochlorination
activity, expressed as the yield of VCM. b) STEM image of Au–Pt/C after
thermal activation at 873 K, showing predominantly isolated atoms with
occasional Au agglomerates (see inset). c,d) Comparison of the stability
of Au–SA/C and Au–Pt/C in acetylene hydrochlorination, accompanied
This result, in combination with the comparable initial
activity of the two catalysts per mole of gold, hints at the pre-
dominating role of Au(I)–Cl single atoms as the active site in
the bimetallic catalyst, rather than Pt(II)–Cl single atoms, which
generally exhibit only half the activity of their Au-based counter-
by the respective deactivation constants (k ), and XRD spectra of both
D
[
12]
parts (Figure S2b, Supporting Information). These assump-
tions further imply that platinum does not majorly modify the
structure of the active Au site and the two metals are too far
apart to enable the spillover of reactants (i.e., >5 Å, in neigh-
boring cavities). However, as the agglomeration rate of gold is
markedly reduced in the presence of platinum single atoms, we
further hypothesize that the latter effectively block the move-
ment of gold in neighboring sites (immediate or close), which
is a rather statistical process, while energetic alternations due
to proximity are less likely. To further investigate the remark-
able stabilization potential of Pt on Au single atoms and assess
whether also other metals may be employed in place of Pt, an
array of Au-bimetallic catalysts was prepared, using alkali and
earth alkaline metal-, non-noble, and precious metal chlorides
(Figure S2, Supporting Information). Combination of XRD
analysis and evaluation in acetylene hydrochlorination identifies
a positive correlation between a reduced Au particle size and
the catalytic activity for all bimetallic catalysts, reinforcing Au
dispersion as the determining descriptor for initial activity. In
particular, combinations with Cu, Rh, Ir, Pd, Zn, and Ni, show
enhanced activity compared to Au–NP/C, whereas all other
metals exhibit similar or lower (Au–Fe/C) performance. Com-
parable conversion levels to Au–SA/C were achieved with Au–
Cu/C and Au–Rh/C, which is well in line with the high degree
of Au dispersion (i.e., presence of single atoms and small nano-
particles with an average particle size of 1.2–1.4 nm, Figure 3)
in these samples. In the case of Au–Ir/C and Au–Ni/C also
larger Au agglomerates were identified, (average particle size
catalysts after 50 h time-on-stream (tos). Diffraction patterns of metallic
Au and graphitic carbon are highlighted with vertical lines, respectively.
on the support) under the electron beam.[16] This is not the
case for Au–Cl single atoms on carbon, which are very mobile
and readily agglomerate upon prolonged exposure to an elec-
tron beam.[ In this regard, also XPS analysis is limited by the
high susceptibility of Au–Cl single atoms to undergo photore-
duction to metallic Au species upon exposure to the incident
X-ray beam during acquisition (Figure S5, Table S4, Supporting
4a]
[
3b,4a]
Information), in line with previous literature reports.
Hence, deeper insights into the interaction and/or proximity
between the metal sites remain unsolved since this represents
the frontier of what state-of-the art characterization techniques
can achieve today.[ Thus, it can only be concluded that the
degree of Au dispersion is significantly improved in Au–Pt/C
compared to benchmark Au–NP/C.
1f ]
To probe whether this dispersing effect of H PtCl can be
2
6
further exploited to improve the thermal stability of Au atoms
on carbon, the benchmark Au/C SAC prepared from aqua regia
(denoted as Au–SA/C) and Au–Pt/C were thermally activated at
varying temperatures up to 1073 K (N atmosphere, 12 h) and
2
analyzed by STEM. While in the case of Au–SA/C, severe par-
ticle agglomeration occurs at temperatures >500 K, exceeding
an average particle size of 16 nm at 600 K, the bimetallic coun-
terpart is significantly stabilized, maintaining high dispersion
up to 800 K and following afterwards a much slower sin-
tering rate (Figure 2a,b). To further corroborate these results,
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Figure 3. a) Acetylene hydrochlorination performance of selected bimetallic Au-based catalysts as a function of the gold particle size, derived from
STEM analysis and EXAFS fitting (Au–Au coordination number). b)Impact of the choice of Pt precursor on the degree of Au dispersion and yield of
VCM. c) Correlation between catalytic performance and the redox potential of the second metal, the Cl:Au ratio as calculated from the respective
stoichiometry in the metal chlorides, and acidity of the selected metal precursor, as derived from 25 samples (Figure S9, Supporting Information).
d) STEM images of selected Au-bimetallic catalysts with average gold particle size distributions, obtained from >100 particles. e,f) Au L edge XANES
3
and EXAFS spectra of selected bimetallic Au-based catalysts in reference to Au–SA/C, Au–Pt/C and Au–NP/C.
2
5 and 33 nm), co-existing with isolated atoms, small clusters
data and the STEM results, XANES analysis (i.e., comparison
of the white-line intensities at 11 925 eV) and EXAFS fitting
and nanoparticles. Notably, no nanoparticles of the respective
second metals were observable in all samples, suggesting the
presence of low-nuclearity clusters and/or single atoms. To gain
further insights into the nature of the metal sites, their local
coordination environment, and possible interactions between
different entities, XAS analysis was performed. Inspection of
the Au L edge and respective other metal edges indicated the
absence of a direct AuM bond in all samples. Hence, the fit-
ting models were constructed, using Au–C/O, Au–Cl and Au–
at the Au L edge suggest the following order of increasing
3
Au–Cl content (decreasing Au–Au contribution): Au–Fe/C
< Au–NP/C < Au–Ni/C < Au–Rh/C < Au–Cu/C < Au–Ir/C
(Figure 3e,f; Figure S3, Table S1, Supporting Information).
Detailed fitting of the respective other metal edges indicates
no metal–metal interaction (with the exception of Ni), corrobo-
rating the presence of isolated atoms as predominating species
(Figure S4, Table S2, Supporting Information). Mostly chlo-
rine-containing atoms were formed, with the notable excep-
tion of Cu and Ni, exhibiting only O/C-neighbors, hinting at
3
Au contributions on the Au L edge and M–C/O, M–Cl and
M–M on the M edges. In good agreement with the catalytic
3
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the presence of hydrated species. Stability assessment in acety-
lene hydrochlorination within 12 h tests, revealed an increasing
deactivation rate in the order of Au–Pt/C < Au–Ni/C ≈ Au–
Cu/C < Au–SA/C < Au–Rh/C ≈ Au–Ir/C (Figure 2c; Figure S8,
Supporting Information). Accordingly, due to exhibiting supe-
rior initial activity and stability compared to benchmark Au–
SA/C at equal loading, Au–Pt/C and Au–Cu/C were identified
as the most attractive systems.
explorations and developments of characterization tools to
deepen our understanding on the complex interactions of mul-
timetallic SACs.
Supporting Information
Supporting Information is available from the Wiley Online Library or
from the author.
Besides the central role of the second metal, also the Au:M
molar ratio, the acidity of the MClx precursor solution and
the availability of chlorine ligands were studied as potential
factors, influencing the overall degree of Au dispersion and Acknowledgements
thus performance in acetylene hydrochlorination (Figure 3b;
This work was supported by ETH research grant ETH-40 17-1. The authors
Figures S6, S9, Supporting Information). Evaluation of these
parameters for the whole platform of 25 bimetallic catalysts
indicated high catalytic activity, if three factors were fulfilled:
i) a high redox potential of the second metal, ii) high acidity of
the metal precursor solution, and iii) a large excess of chlorine
ligands during the impregnation step, as estimated from the
respective Cl:Au stoichiometry in the metal chloride precursor
salts (Figure 3c, see the Experimental Section in Supporting
thank Simon Büchele for conducting XPS analyses and Ivan Surin for
assistance with catalyst preparation and testing. The Scientific Center for
Optical and Electron Microscopy at the ETH Zurich, ScopeM, and the
SuperXAS beamline at PSI, are thanked for access to their facilities. The
service for Microelemental Analysis at ETH Zurich is acknowledged for
chlorine analyses.
Information for details). Under these optimal conditions, large Conflict of Interest
Au agglomerates (i.e., >70 nm in Au–NP/C) can be redispersed
The authors declare no conflict of interest.
on carbon into isolated atoms (or low-nuclearity clusters)
through the simple addition of H PtCl in aqueous solution
2
6
(
Figure S10, Supporting Information). These observations
Keywords
hint at the key role of Pt in promoting a chlorine-mediated
oxidation of reduced Au sites, leading to high Au dispersion
and possibly further improving Au stabilization in chlorine-
containing atmosphere. In line with this hypothesis, the sur-
face chlorine content of Au–Pt/C, as derived by XPS analysis,
increases from 0.18 to 0.86 wt% within 12 h time-on-stream
in acetylene hydrochlorination, which is enhanced compared
to Au–Cu/C (0.18 to 0.43 wt%) and contrasts the decrease
observed for Au–SA/C (1.10 to 0.74 wt%, Table S3, Supporting
Information).
In summary, we developed a sustainable and potentially scal-
able route for the synthesis of carbon-supported gold nanostruc-
tures in bimetallic catalysts, employing small amounts of metal
salts in aqueous solution as alternative chlorine source to corro-
sive aqua regia, widely used in previous protocols. Thereby, the
choice of metal chloride determines the degree of gold disper-
sion, ultimately reaching atomic level when using H PtCl . The
acetylene hydrochlorination, bimetallic catalysts, gold, platinum, single-
atom catalysis
Received: July 29, 2020
Revised: October 27, 2020
Published online: January 12, 2021
[
1] a) A. Wang, J. Li, T. Zhang, Nat. Rev. Chem. 2018, 2, 65;
b) M. Pagliaro, Single-Atom Catalysis – A Forthcoming Revolu-
tion in Chemistry, Elsevier, St. Louis, MO 2019; c) X. Li, Y. Huang,
B. Liu, Chem 2019, 5, 2733; d) X. Li, H. Rong, J. Zhang, D. Wang,
Y. Li, Nano Res. 2020, 13, 1842; e) G. Malta, S. A. Kondrat,
S. J. Freakley, C. J. Davies, S. Dawson, X. Liu, L. Lu, K. Dymkowski,
F. Fernandez-Alonso, S. Mukhopadhyay, E. K. Gibson, P. P. Wells,
S. F. Parker, C. J. Kiely, G. J. Hutchings, ACS Catal. 2018, 8, 8493;
f) S. K. Kaiser, Z. Chen, D. F. Akl, S. Mitchell, J. Pérez-Ramírez,
Chem. Rev. 2020, https://doi.org/10.1021/acs.chemrev.0c00576.
2
6
possible origin of this remarkable dispersion effect of platinum
and similarly for other metals such as copper), was ascribed
(
[
2] a) R. Ciriminna, E. Falletta, C. Della Pina, J. H. Teles, M. Pagliaro,
Angew. Chem., Int. Ed. 2016, 55, 14210; b) C. W. Corti, R. J. Holliday,
D. T. Thompson, Appl. Catal. A 2005, 291, 253; c) S. Ding,
M. J. Hülsey, J. Pérez-Ramírez, N. Yan, Joule 2019, 3, 2897; d) Q. Fu,
H. Saltsburg, M. Flytzani-Stephanopoulos, Science 2003, 301, 935;
e) G. J. Hutchings, Catal. Today 2005, 100, 55.
to the key role in promoting a chlorine-mediated dispersion
mechanism, which can be further exploited to redisperse large
gold agglomerates (>70 nm) on carbon carriers into isolated
atoms, a phenomenon of practical relevance for catalyst regen-
eration strategies. We further show for the first time, that in the
presence of platinum single atoms, the stability of their gold-
based analogs can be increased against sintering up to 800 K,
which translates into a two-fold improved lifetime in acetylene
hydrochlorination, without compromising on the high catalytic
activity of Au(I)–Cl active sites. This observation indicates that
the two metals are likely spatially isolated and Pt single atoms
effectively block the gold diffusion paths. In this regard, the
herein uncovered cooperativity effects have important implica-
tions for the frontier of single-atom catalysis and call for further
[
3] a) R. Lin, A. P. Amrute, J. Pérez-Ramírez, Chem. Rev. 2017, 117,
182; b) G. Malta, S. A. Kondrat, S. J. Freakley, C. J. Davies, L. Lu,
4
S. Dawson, A. Thetford, E. K. Gibson, D. J. Morgan, W. Jones,
P. P. Wells, P. Johnston, C. R. Catlow, C. J. Kiely, G. J. Hutchings,
Science 2017, 355, 1399; c) United Nations Environment Programme,
Minamata Convention on Mercury, www.mercuryconvention.org/,
(accessed: July 2020).
[
4] a) S. K. Kaiser, R. Lin, S. Mitchell, E. Fako, F. Krumeich, R. Hauert,
O. V. Safonova, V. A. Kondratenko, E. V. Kondratenko, S. M. Collins,
P. A. Midgley, N. Lopez, J. Pérez-Ramírez, Chem. Sci. 2019, 10, 359;
Small 2021, 17, 2004599
2004599 (5 of 6)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.small-journal.com
b) X. Sun, S. R. Dawson, T. E. Parmentier, G. Malta, T. E. Davies,
Q. He, L. Lu, D. J. Morgan, N. Carthey, P. Johnston, S. A. Kondrat,
S. J. Freakley, C. J. Kiely, G. J. Hutchings, Nat. Chem. 2020, 12, 560;
c) Z. Chen, Y. Chen, S. Chao, X. Dong, W. Chen, J. Luo, C. Liu,
D. Wang, C. Chen, W. Li, J. Li, Y. Li, ACS Catal. 2020, 10, 1865.
[11] L. Zhang, R. T. Si, H. S. Liu, N. Chen, Q. Wang, K. Adair, Z. Q. Wang,
J. T. Chen, Z. X. Song, J. J. Li, M. N. Banis, R. Y. Li, T. K. Sham,
M. Gu, L. M. Liu, G. A. Botton, X. L. Sun, Nat. Commun. 2019, 10,
4936.
[12] B. B. Sarma, J. Kim, J. Amsler, G. Agostini, C. Weidenthaler,
N. Pfander, R. Arenal, P. Concepcion, P. Plessow, F. Studt, G. Prieto,
Angew. Chem., Int. Ed. 2020, 59, 5806.
[
[
5] P. Johnston, N. Carthey, G. J. Hutchings, J. Am. Chem. Soc. 2015,
37, 14548.
1
6] L. Ye, X. Duan, S. Wu, T. S. Wu, Y. Zhao, A. W. Robertson,
H. L. Chou, J. Zheng, T. Ayvali, S. Day, C. Tang, Y. L. Soo, Y. Yuan,
S. C. E. Tsang, Nat. Commun. 2019, 10, 914.
[13] S. Feng, X. Song, Z. Ren, Y. Ding, Ind. Eng. Chem. Res. 2019, 58,
4755.
[14] M. J. Richardson, J. H. Johnston, T. Borrmann, Eur. J. Inorg.Chem.
2006, 2006, 2618.
[
7] M. Zhu, Q. Wang, K. Chen, Y. Wang, C. Huang, H. Dai, F. Yu,
L. Kang, B. Dai, ACS Catal. 2015, 5, 5306.
8] M. Conte, A. Carley, G. Attard, A. Herzing, C. Kiely, G. Hutchings,
J. Catal. 2008, 257, 190.
9] S. K. Kaiser, R. Lin, F. Krumeich, O. V. Safonova, J. Pérez-Ramírez,
Angew. Chem., Int. Ed. 2019, 58, 12297.
10] S. K. Kaiser, E. Fako, G. Manzocchi, F. Krumeich, R. Hauert,
[15] E. Vorobyeva, E. Fako, Z. Chen, S. M. Collins, D. Johnstone,
P. A. Midgley, R. Hauert, O. V. Safonova, G. Vile, N. López,
S. Mitchell, J. Pérez-Ramírez, Angew. Chem., Int. Ed. 2019, 58,
8724.
[16] a) R. F. Egerton, M. Watanabe, Ultramicroscopy 2018, 193, 111;
b) K. Suenaga, M. Tence, C. Mory, C. Colliex, H. Kato, T. Okazaki,
H. Shinohara, K. Hirahara, S. Bandow, S. Iijima, Science 2000, 290,
2280.
[
[
[
A. H. Clark, O. V. Safonova, N. López, J. Pérez-Ramírez, Nat. Catal.
2
020, 3, 376.
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