Enhanced catalytic activity of Au core Pd shell Pt cluster trimetallic nanorods for CO2 reduction

Article abstract of DOI:10.1039/c8ra10494h

Herein, Au core Pd shell Pt cluster nanorods (Au@Pd@Pt NRs) with enhanced catalytic activity were rationally designed for carbon dioxide (CO₂) reduction. The surface composition and Pd-Pt ratios significantly influenced the catalytic activity, and the optimized structure had only a half-monolayer equivalent of Pt (_Pt = 0.5) with 2 monolayers of Pd, which could enhance the catalytic activity for CO₂ reduction by 6 fold as compared to the Pt surface at -1.5 V vs. SCE. A further increase in the loading of Pt actually reduced the catalytic activity; this inferred that a synergistic effect existed among the three different nanostructure components. Furthermore, these Au NRs could be employed to improve the photoelectrocatalytic activity by 30% at -1.5 V due to the surface plasmon resonance. An in situ SERS investigation inferred that the Au@Pd@Pt NRs (_Pt = 0.5) were less likely to be poisoned by CO because of the Pd-Pt bimetal edge sites; due to this reason, the proposed structure exhibited highest catalytic activity. These results play an important role in the mechanistic studies of CO₂ reduction and offer a new way to design new materials for the conversion of CO₂ to liquid fuels.

Full text of DOI:10.1039/c8ra10494h

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PAPER
Enhanced catalytic activity of Au core Pd shell Pt
cluster trimetallic nanorods for CO2 reduction†
Cite this: RSC Adv., 2019, 9, 10168
*
Xiao-qing Liu,
Lan-qi He, Hao Yang, Jia-jun Huang, Xi-hong Lu,
Gao-Ren Li,
*
*
Ping-ping Fang
and Ye-xiang Tong
Herein, Au core Pd shell Pt cluster nanorods (Au@Pd@Pt NRs) with enhanced catalytic activity were
rationally designed for carbon dioxide (CO2) reduction. The surface composition and Pd–Pt ratios
significantly influenced the catalytic activity, and the optimized structure had only a half-monolayer
equivalent of Pt (qPt ¼ 0.5) with 2 monolayers of Pd, which could enhance the catalytic activity for CO2
reduction by 6 fold as compared to the Pt surface at ꢀ1.5 V vs. SCE. A further increase in the loading of
Pt actually reduced the catalytic activity; this inferred that a synergistic effect existed among the three
different nanostructure components. Furthermore, these Au NRs could be employed to improve the
photoelectrocatalytic activity by 30% at ꢀ1.5 V due to the surface plasmon resonance. An in situ SERS
investigation inferred that the Au@Pd@Pt NRs (qPt ¼ 0.5) were less likely to be poisoned by CO because
of the Pd–Pt bimetal edge sites; due to this reason, the proposed structure exhibited highest catalytic
activity. These results play an important role in the mechanistic studies of CO2 reduction and offer a new
way to design new materials for the conversion of CO2 to liquid fuels.
Received 22nd December 2018
Accepted 15th March 2019
DOI: 10.1039/c8ra10494h
rsc.li/rsc-advances
new catalysts with high efficiency that are less likely to be
poisoned by CO.11
Introduction
Indeed, novel heterogeneous nanocatalysts with optimized
characteristics are usually achieved by rationally tuning their
compositions and nanostructures. Several reviews have been
recently reported to address the signicance of these
designs.12,13 Interestingly, in recent years, in addition to
compositions,14 morphology adjustments,15 and structure
interface,16 surface plasmon resonance (SPR) has emerged as
another highly important factor and useful strategy to regulate
the activities of the nanocatalysts.17,18 For nanocatalysts con-
sisting of plasmonic metals (such as Au, Ag, and Cu), the
electric eld aroused by SPR can directly enhance the catalytic
activity. In addition, the light energy can be effectively coupled
with these nanocrystals because the hot-electrons induced by
illumination can function as carriers to convert the light
energy into chemical energy, and thus, enhancement in the
photocatalytic ability can be achieved.19 Compared with their
monometallic and bimetallic counterparts, trimetallic nano-
composites embedded within a plasmonic metal core exhibit
remarkable advantages as their catalytic characteristics are
better tailored. This is because their catalytic properties can be
divided into two parts: the photocatalytic activity resulting
from the SPR core and the electrocatalytic activity stemming
from the bimetal surface coating. As a consequence, by nely
tuning their nanoarchitectures, compositions, or particle
sizes, it is possible to obtain trimetallic nanocrystals with
optimal catalytic activity for various important chemical
reactions.
Carbon dioxide (CO2) is a greenhouse gas released by both
natural and articial processes and causes a number of envi-
ronmental problems,1,2 which have driven extensive research
interest in CO2 reduction catalysis;3 in this regard, the electro-
chemical reduction of CO2 into useful fuels in an aqueous
solution has attracted signicant attention because it is envi-
ronmentally clean and the products obtained can be stored in
the form of chemical energy.4 The most commonly explored
electrocatalysts for CO2 reduction are transition metal
elements5 and their alloys6,7 such as bimetals8 or trimetals.9 This
is probably because these metals have vacant orbitals and active
d-electrons, which are believed to energetically facilitate the
adsorption and desorption bonding between the metal and the
CO2 forming products; however, the electrochemical CO2
reduction reaction suffers from poor efficiency due to the
requirement of a large over potential, CO poisoning and so on.10
The mechanism of this reaction is still not clearly understood,
and the intermediates and other reaction steps have also been
discussed controversially. Therefore, it is necessary to design
KLGHEI of Environment and Energy Chemistry, MOE of the Key Laboratory of
Bioinorganic and Synthetic Chemistry, The Key Lab of Low-Carbon Chemistry and
Energy Conservation of Guangdong Province, School of Chemistry, Sun Yat-Sen
University, Guangzhou 510275, China. E-mail: liuxiaoq5@mail.sysyu.edu.cn;
fangpp3@mail.sysu.edu.cn; chedhx@mail.sysu.edu.cn
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c8ra10494h
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Herein, we report Au core Pd shell Pt cluster nanorods
RSC Advances
(Au@Pd@Pt NRs) with enhanced electrocatalytic and photo-
catalytic activity for CO2 reduction. By subtly controlling the
atom monolayers of the Pt clusters, we obtained ideal Au core
Pd shell Pt cluster nanorods with optimized photo-
electrocatalytic ability for the reduction of CO2. As above-
mentioned, the enhancement in the photocatalytic activity
should be attributed to the SPR phenomenon resulting from the
plasmonic Au core. A synergistic effect between the Pd shell and
the Pt clusters was demonstrated by systematic investigation of
the inuence of the thickness of the Pt coverage on the elec-
troreduction of CO2. Furthermore, in situ surface enhanced
Raman spectrum (SERS) was obtained to study the mechanism
of CO2 reduction and investigate the active site.
Fig. 2 UV-Vis spectra of the 49 nm Au@Pd@Pt NRs with varied qPt
Results and discussion
from 0.1 to 5 layers.
The Au@Pd@Pt NRs were freshly prepared according to our
previously reported method with slight modications (see the
details in the Experimental section of the ESI†). Generally, the
thickness of Pd was maintained at 2 layers on the 49 nm Au
core, and the Pt coverage on Au@2Pd was varied from 0.1 to 5
layers (hereinaer denoted as qPt) by nely tuning the amount
of H2PtCl6 used during the reduction process. The as-prepared
nanocrystals were rst characterized by a transmission elec-
tron microscope (TEM) (Fig. S1 in ESI†). The Au@Pd@Pt NRs
show a quite uniform size distribution, and the Pt clusters can
only be clearly seen on the surface when they are sufficiently
thick, with a Pt coverage of 5 layers for instance (Fig. 1); similar
structures for the Au@Pd@Pt NRs have been reported in our
previous studies.20 To verify the existence of Pt, we obtained
the cyclic voltammograms of various Au@2Pd with different Pt
coverages in 0.5 M H2SO4. With an increase in the Pt coverage
thickness, the typical oxygen desorption peak shied to more
positive values; this demonstrated that the electrochemical
properties of these NRs switched from those of Pd to those of
Pt (Fig. S2 in ESI†). Elemental analysis by ICP-AES also
conrmed the effective coating of Pt on the Au@2Pd surface
(Table S1 in ESI†).
700 nm. The shorter peak at 530 nm was caused by transverse
SPR absorption, whereas the longer peak at 700 nm corre-
sponded to longitudinal SPR absorption. The two absorption
peaks experienced a slight blue-shi and gradually damped
with an increase in the Pt coverage from 0.1 to 5 layers. These
spectral behaviours reasonably inferred that the total optical
properties of the core–shell–cluster nanostructures changed
from core dominant to shell cluster dominant.21
The catalytic performance of different nanocatalysts for CO2
reduction was then investigated by linear sweep voltammetry
(LSV) in 0.1 M KHCO3 saturated with CO2 gas. We found that
the introduction of Pt on the Au@Pd surface led to an improved
catalytic performance for CO2 electroreduction, and the trime-
tallic nanocatalyst exhibited higher catalytic activity as
compared to Au@Pt nanoparticles. It is thus highly probable
that a synergistic effect exists in the trimetallic nanocomposites
(Fig. S3 in the ESI†).
To verify this viewpoint, LSV was further employed to reveal
the inuence of qPt on the catalytic activity of the 49 nm
Au@Pd@Pt NRs toward CO2 electroreduction. As shown in
Fig. 3a, with a xed Au NR core and a Pd-shell thickness of about
2 monolayers, the catalytic activity of the core–shell–cluster NRs
for CO2 reduction was remarkably dependent on qPt. The
highest catalytic activity was achieved when qPt was at about 0.5,
which was about 6-fold at ꢀ1.5 V vs. saturated calomel electrode
(SCE) than that obtained at the qPt of 0.1 or 5 (Fig. 3b). A further
increase in the loading of Pt actually decreased the catalytic
activity; this conrmed that a synergistic effect existed among
the three different nanostructure components. Cai et al. also
found that the Pd–Pt bimetal surface exhibited higher catalytic
activity towards CO2 reduction than its monometallic counter-
part. However, they did not optimize the Pd and Pt composi-
tion.22 They also proved that the Pd–Pt bimetal could
signicantly reduce the production of H2 and enhance CO2
reduction.23 The 49 nm Au@Pd@Pt NRs exhibited maximum
catalytic activity when qPt was 0.5; this implied that the ratio of
their Pt-cluster to Pd shell was optimal for the electroreduction
of CO2. This core–shell–cluster nanostructure is completely
The optical properties of Au@Pd@Pt NRs were then inves-
tigated by UV-Vis spectroscopy (Fig. 2). As observed, all
Au@Pd@Pt NRs had two absorption peaks at ca. 530 nm and ca.
Fig. 1 TEM images of (a) the 49 nm Au NRs and (b) Au@Pd@Pt NRs (qPt
¼ 5).
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Fig. 3 Influence of qPt on the LSV curves of (a) 49 nm Au@Pd@Pt NRs
measured in 0.1 M KHCO3 (pH ¼ 6.8). Scan rate: 50 mV sꢀ1; current
density of (b) 49 nm Au@Pd@Pt NRs at ꢀ1.5 V (vs. SCE) with different
qPt.
Fig. 4 Influence of the illumination time on the LSV curves of (a)
49 nm Au@Pd@Pt NRs and (b) Pd@Pt nanocubes in 0.1 M KHCO3 (pH ¼
6.8) qPt ¼ 0.5; scan rate: 50 mV sꢀ1
.
was absent in this nanomaterial. By comparing the LSV curves
obtained with and without 20 min light illumination, we found
that light irradiation did not impact the electrocatalytic process
of CO2 on these Pd@Pt nanocubes (Fig. 4b). Therefore, the
enhancement of the photocatalytic activity of the Au@Pd@Pt
nanocrystals should be ascribed to the SPR effect from the Au
core, as expected.
Finally, the CO2 reduction mechanism on the 49 nm
Au@Pd@Pt NRs was studied by in situ SERS. CO is an inevitable
intermediate in the CO2 electroreduction to produce hydrocar-
bons or alcohols.24 Therefore, herein, we mainly studied the
SERS signal of CO and investigated how CO affected the cata-
lytic activity in our system.
different from other bimetallic and trimetallic alloy/composite
nanostructures because the proportions of the core, shell and
cluster can be subtly tuned independently to utilize the syner-
gistic effect for maximum enhancement.
We then investigated the impact of light exposure duration
on the photocatalytic activity. As presented in Fig. 4a, the
catalytic activity of Au@Pd@Pt NRs gradually increased with an
increase in the illumination time in the rst 20 min and then
remained constant. The surface temperature of the nano-
catalysts with Au cores could reach higher than 95 ꢁC by
constant light irradiation over 20 min, accelerating the chem-
ical reaction rate by heating, as demonstrated in our previous
study.18 Indeed, 20 min light irradiation resulted in ca. 30%
enhancement in the catalytic activity at ꢀ1.5 V vs. SCE. This
improvement in the catalytic performance might be caused by
the photoelectronic and photothermal effect induced by the
SPR of the Au core.
When the Pt coverage became thicker, the SPR of the 49 nm
Au@Pd@Pt NRs was greatly blocked due to the decreased
surface area of the Au core exposed to the illumination, and it
thus weakened the enhancement of the photocatalytic activity
(Fig. S4 in ESI†). Moreover, to verify that the SPR effect played
a vital role in the improvement of the catalytic performance,
control experiments were conducted on Pd nanocubes coated
by Pt clusters. Note that no SPR effect could be detected since Au
The Raman shi between 2020 and 2090 cmꢀ1 corre-
sponded to the on-top adsorption of CO on Pt,25 whereas the
Raman shi between 1900 and 2000 cmꢀ1 was assigned to the
bridge adsorption of CO.26 We observed that the on-top
adsorption of CO gradually increased with a decrease in the
applied potential and nally disappeared at ꢀ1.0 V. No
bridge adsorption of CO was detected in the potential region
studied herein (Fig. 5). It has been reported that CO has high
adsorption energy on separate Pt atoms; this causes easy
poisoning of the separate Pt atoms; on the other hand, due to
the low adsorption energy at the Pd–Pt edge sites, these sites
are not easily poisoned by CO.27 We thus believe that CO2 is
reduced to CO on the Pt atoms only and not on the Pd or Pd–
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Fig. 5 In situ Raman spectra of Au@2Pd@0.5Pt NRs in 0.1 M KHCO3
(pH ¼ 6.8) at different potentials (vs. SCE).
Pt bridge atoms. Namely, the Pd–Pt edge sites that were not
easily poisoned by CO were the active sites for CO2 reduction,
whereas the separated Pt atoms were easily poisoned by CO.
Therefore, the increase in the Pd–Pt edge site density could
greatly increase the catalytic activity. When qPt was about 0.5,
the Pd–Pt edge site density was maximum, and therefore, the
electrocatalytic activity became highest with qPt at about 0.5,
as shown in Fig. 3; moreover, when the potential decreased to
ꢀ1.0 V, the CO peak disappeared, and the peak intensity
Fig. 6 Product analysis of CO2RR on Au@2Pd (a) and Au@2Pd@0.5Pt
(b) by NMR.
been seldom reported, and the interesting results reported in
this study indicate that the trimetallic nanostructure is
favourable to the electrocatalytic transformation of CO2 to
alcohols due to the synergistic effect of the trimetallic
nanocrystals.
representing the C–H stretching (at 2800–2970 cmꢀ1
)
increased immediately;28 this suggested that CO was further
reduced to the hydrocarbon products aer ꢀ1.0 V.
We further analysed the products of CO2 reduction by the
Au@Pd@Pt NRs using nuclear magnetic resonance (NMR). To
be specic, chronoamperometry was rst conducted under
a constant potential at ꢀ0.6 V for 2 h, and the content of the
electrolyte solution was then tested by NMR. Interestingly, we
found that the trimetallic Au@Pd@Pt NRs were prone to
converting CO2 into liquid products including methanol and
ethanol (Fig. 6); this was in accordance with our Raman results
(C–H stretching at 2800–2970 cmꢀ1). Moreover, a larger
amount of the liquid products was detected using
Au@2Pd@0.5Pt NRs as compared to that obtained using
Au@2Pd NRs under the same experimental conditions.
Furthermore, the reduction velocity for the Au@2Pd@0.5Pt
NRs is three times that for the Au@2Pd NRs. There was also
some ethanol among the products. Indeed, the transformation
of CO2 to alcohols, especially ethanol, by noble metals has
Fig. 7 Atomic view of four different sites for adsorption/reaction: (A)
a Pt cluster on-top site, (B) an isolated Pd hollow site, (C) a one Pt atom
and two Pd-atom mixed hollow site, and (D) a two Pd-atom between
two Pt clusters mixed hollow site.
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In our previous study, we found 4 possible reactive sites
(Fig. 7) on the Pd–Pt bimetal surface on the Au core by DFT
calculation.27 Indeed, the A, B and C sites could adsorb CO
strongly, whereas the CO adsorption on the D site was quite
weak.29 Therefore, the D site could not be poisoned by CO,
whereas the A, B and C sites could be easily poisoned by CO.
From the specic Raman shi of CO2 reduction by the
Au@Pd@Pt NRs in our experiments (Fig. 5), we only observed an
on-top adsorption of CO on the Au@Pd@Pt NPs; this suggested
that only the A site was easily poisoned by CO during CO2
reduction, whereas the B, C and D sites were possible active sites
for CO2 reduction on the Au@Pd@Pt NR surface. According to
the literature, CO2 was not easily reduced to CO on the separate
Pd sites.30 As a result, the B and C Pd–Pt bridge sites were the
possible active centres for CO2 reduction. The B and C sites
reached their maximum density when the Pt coverage was about
0.5, which caused the highest catalytic activity. Wang et al. found
that the Pd–Pt edges/ridges in the catalyst exhibited optimal
catalytic activity.31 The catalytic performance was thus closely
related to the number of Pd–Pt edge sites; this indicated that the
ratio of Pd to Pt greatly inuenced the CO2 reduction activity.
Preparation of the working electrode
The FTO glass substrates were thoroughly cleaned with ethanol
and acetone, washed with water, and then used to afford the
nanocatalysts. A certain amount of the trimetallic nanocatalyst
solution that ensured coverage of about a monolayer of the NPs
on the 20 mm ꢂ 10 mm FTO pieces (20% loss occurred during
centrifugation) was centrifuged three times, dropped onto the
FTO substrate and dried to act as the working electrode. The
electrochemical active surface area (ECSA) of the working elec-
trode was calculated according to the hydrogen adsorption/
desorption peaks and conrmed by the oxygen adsorption/
desorption peaks for the Au@Pd@Pt NRs in 0.5 M H2SO4
(Fig. S2 in ESI†).33 The measured currents were normalized by
the ECSA values to evaluate the catalytic performance of
different nanocatalysts.
Electrochemical measurements and spectroelectrochemical
studies
Electrochemical measurements were performed using the CHI
760E electrochemical workstation (CH Instruments, China).
The CO2 reduction reaction was studied in a three-electrode
photoelectrochemical cell with a Pt wire and a SCE as the
counter and the reference electrodes, respectively. The catalytic
activity of CO2 reduction was investigated by linear sweep vol-
tammetry (LSV), and 0.1 M KHCO3 (pH ¼ 6.8) was used as the
electrolyte solution. The investigation of the light inuence was
achieved using a xenon lamp as the light source (LCS-100,
ORIEL, Newport). The intensity of the incident light was
always maintained at 100 mW cmꢀ2 during the photo-
electrochemical test. Raman spectra were obtained using a laser
micro-Raman spectrometer (Renishaw in Via) with an excitation
wavelength at 632.8 nm from a He–Ne laser, and in situ EC-SERS
measurements were performed in the photoelectrochemical
cell.
Experimental
Chemicals and materials
Water puried with a Milli-Q system (resistivity of 18.2 MU cm
ꢁ
at 25 C) was used throughout the study. PdCl2 (99%), HAuCl4
(99%) and H2PtCl6 (99%) were purchased from Alfa Aesar.
Unless stated, all the other chemicals were of analytical grade
and obtained from Shanghai Reagent Co. of Chinese Medicine.
The F-doped tin oxide (FTO) glass was bought from the NSG
Group. FTO glass slides (20 mm ꢂ 10 mm ꢂ 0.22 mm) were
selected for working electrode fabrication to afford the low
electrical resistance of 14 ohm and high transparency ($90%).
Characterization
Synthesis of the Au@Pd@Pt NRs
TEM images were acquired using Tecnai T12 (FEI, The Neth-
erlands) with an operation voltage of 120 kV, and the UV-Vis
absorption spectra were obtained by the Shimadzu UV-2450
Spectrophotometer.
The Au NRs were synthesized according to a procedure reported
in the literature18,32 with slight modication, whereas the Pd
and Pt coverage layers were coated above the Au core based on
our previous study.27 Briey, to coat a Pd shell of about 2
monolayers on the Au NRs, 1 ml of 1 mM H2PdCl4 and 0.5 ml of
10 mM ascorbic acid were mixed with the Au core solution and
Conclusions
stirring was continued at 30 ꢁC for 30 min. To coat Au@Pd with We designed Au core Pd shell Pt cluster NRs with enhanced
Pt clusters of different thicknesses, various volumes of 10 mM catalytic activity and photocatalytic activity for CO2 reduction.
ascorbic acid and 1 mM H2PtCl6 were subsequently added to the The improvement in the catalytic activity was obtained by
as-prepared solution at 80 ꢁC, and stirring was continued for tuning the Pt coverage on Pd, and the highest catalytic activity
30 min. However, we added 25% additional H2PtCl6 to the was achieved when qPt was about 0.5. In situ SERS further
solution during each synthesis to ensure the corresponding Pt conrmed that CO2 was reduced to CO only on the Pt top sites
coverage according to the literature.27 The nanocrystal solution and not on the Pd–Pt edge sites. Therefore, the Pd–Pt edge sites
was centrifuged and washed 3 times with water before use (see were the electroactive centres of the Au@Pd@Pt NRs for the
the synthetic details in the ESI†).
transformation of CO2 to liquid products. These Pd–Pt edge
It was necessary to mention that Pt grew on Pd as a set of sites reached highest density when qPt was about 0.5, leading to
clusters and not as consecutive monolayers; however, we used optimal catalytic activity. Moreover, owing to the SPR from the
monolayer-equivalents as a convenient way to describe the Au core, the catalytic activity could be further enhanced by 30%
amount of Pt added to the Au@Pd nanocomposite.
with light illumination. In summary, the Au core Pd shell Pt
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cluster NR structure not only takes advantage of the Pd–Pt 13 M. B. Gawande, A. Goswami, T. Asefa, H. Guo, A. V. Biradar,
bimetal surface to improve the electrocatalytic ability, but also
utilizes the Au core with SPR to improve the photocatalytic
D.-L. Peng, R. Zboril and R. S. Varma, Chem. Soc. Rev., 2015,
44, 7540–7590.
activity. This study sheds light on the CO2 reduction mecha- 14 H. Sheng, M. H. Oh, W. T. Osowiecki, W. Kim, A. P. Alivisatos
nism on the trimetallic nanocrystals and offers an innovative and H. Frei, J. Am. Chem. Soc., 2018, 140, 4363–4371.
idea to design a series of new catalysts with better catalytic 15 S. Liu, H. Tao, L. Zeng, Q. Liu, Z. Xu, Q. Liu and J. L. Luo, J.
properties to convert CO2 to liquid fuels such as methanol and
ethanol.
Am. Chem. Soc., 2017, 139, 2160–2163.
16 D. Gao, Y. Zhang, Z. Zhou, F. Cai, X. Zhao, W. Huang, Y. Li,
J. Zhu, P. Liu, F. Yang, G. Wang and X. Bao, J. Am. Chem. Soc.,
2017, 139, 5652–5655.
17 C. Wang, X. G. Nie, Y. Shi, Y. Zhou, J. J. Xu, X. H. Xia and
H. Y. Chen, ACS Nano, 2017, 11, 5897–5905.
Conflicts of interest
There are no conicts to declare.
18 H. Yang, Z. H. Wang, Y. Y. Zheng, L. Q. He, C. Zhan, X. H. Lu,
Z. Q. Tian, P. P. Fang and Y. X. Tong, J. Am. Chem. Soc., 2016,
138, 16204–16207.
19 L. Zhang, M. Can, S. W. Ragsdale and F. A. Armstrong, ACS
Catal., 2018, 8, 2789–2795.
20 H. Yang, L.-Q. He, Z.-H. Wang, Y.-Y. Zheng, X. Lu, G.-R. Li,
P.-P. Fang, J. Chen and Y. Tong, Electrochim. Acta, 2016,
209, 591–598.
21 X. Liu, J. Iocozzia, Y. Wang, X. Cui, Y. Chen, S. Zhao, Z. Li and
Z. Lin, Energy Environ. Sci., 2017, 10, 402–434.
22 F. Cai, D. Gao, R. Si, Y. Ye, T. He, S. Miao, G. Wang and
X. Bao, Electrochem. Commun., 2017, 76, 1–5.
23 F. Cai, D. Gao, H. Zhou, G. Wang, T. He, H. Gong, S. Miao,
F. Yang, J. Wang and X. Bao, Chem. Sci., 2017, 8, 2569–2573.
24 T.-T. Zhuang, Z.-Q. Liang, A. Seitokaldani, Y. Li, P. De Luna,
T. Burdyny, F. Che, F. Meng, Y. Min, R. Quintero-Bermudez,
C. T. Dinh, Y. Pang, M. Zhong, B. Zhang, J. Li, P.-N. Chen,
X.-L. Zheng, H. Liang, W.-N. Ge, B.-J. Ye, D. Sinton,
S.-H. Yu and E. H. Sargent, Nature Catalysis, 2018, 1, 421–
428.
Acknowledgements
This work was supported by the National Key Research and
Development Program of China (2016YFA0202604), the Natural
Science Foundation of China (21405182, 21802173 and
21773315), the Science and Technology Plan Project of Guang-
dong Province (2015B010118002), the Guangdong Province
Universities and Colleges Pearl River Scholar Funded Scheme
(2017), the Natural Science Foundation of Guangdong Province
(No. 2018A030310301), the Pearl River S&T Nova Program of
Guangzhou (201710010019), the Fundamental Research Funds
for the Central Universities (17lgjc36) and the Guangdong
Provincial Key Platform and Major Scientic Research Projects
for Colleges and Universities (2015KCXTD029).
Notes and references
1 J. Ran, M. Jaroniec and S.-Z. Qiao, Adv. Mater., 2018, 30,
1704649.
2 L. Zhang, Z.-J. Zhao, T. Wang and J. Gong, Chem. Soc. Rev.,
2018, 5423–5443.
25 K. G. Schmitt and A. A. Gewirth, J. Phys. Chem. C, 2014, 118,
17567–17576.
3 H. Mistry, A. S. Varela, C. S. Bonifacio, I. Zegkinoglou,
I. Sinev, Y. W. Choi, K. Kisslinger, E. A. Stach, J. C. Yang,
P. Strasser and B. R. Cuenya, Nat. Commun., 2016, 7, 12123.
26 N. Todoroki, H. Osano, T. Maeyama, H. Yoshida and
T. Wadayama, Appl. Surf. Sci., 2009, 256, 943–947.
27 P.-P. Fang, S. Duan, X.-D. Lin, J. R. Anema, J.-F. Li, O. Buriez,
Y. Ding, F.-R. Fan, D.-Y. Wu, B. Ren, Z. L. Wang, C. Amatore
and Z.-Q. Tian, Chem. Sci., 2011, 2, 531–539.
28 Y. Guo, O. Yaffe, D. W. Paley, A. N. Beecher, T. D. Hull,
G. Szpak, J. S. Owen, L. E. Brus and M. A. Pimenta, Phys.
Rev. Mater., 2017, 1, 042401.
´
4 A. Garcıa-Trenco, E. R. White, A. Regoutz, D. J. Payne,
M. S. P. Shaffer and C. K. Williams, ACS Catal., 2017, 7,
1186–1196.
5 C. W. Li and M. W. Kanan, J. Am. Chem. Soc., 2012, 134, 7231–
7234.
6 W. Luc, C. Collins, S. Wang, H. Xin, K. He, Y. Kang and
F. Jiao, J. Am. Chem. Soc., 2017, 139, 1885–1893.
7 B. Kumar, J. P. Brian, V. Atla, S. Kumari, K. A. Bertram,
R. T. White and J. M. Spurgeon, ACS Catal., 2016, 4739–4745.
8 G. Gao, Y. Jiao, E. R. Waclawik and A. Du, J. Am. Chem. Soc.,
2016, 138, 6292–6297.
9 P. Frontera, A. Macario, A. Malara, S. Santangelo, C. Triolo,
F. Crea and P. Antonucci, Catalysts, 2018, 8, 435.
10 M.-J. Cheng, E. L. Clark, H. H. Pham, A. T. Bell and M. Head-
Gordon, ACS Catal., 2016, 6, 7769–7777.
29 S. Duan, Y. F. Ji, P. P. Fang, Y. X. Chen, X. Xu, Y. Luo and
Z. Q. Tian, Phys. Chem. Chem. Phys., 2013, 15, 4625–4633.
30 R.-H. Guo, C.-F. Liu, T.-C. Wei and C.-C. Hu, Electrochem.
Commun., 2017, 80, 24–28.
31 X. Wang, M. Vara, M. Luo, H. Huang, A. Ruditskiy, J. Park,
S. Bao, J. Liu, J. Howe, M. Chi, Z. Xie and Y. Xia, J. Am.
Chem. Soc., 2015, 137, 15036–15042.
32 H. Yang, L. Q. He, Y. W. Hu, X. Lu, G. R. Li, B. Liu, B. Ren,
Y. Tong and P. P. Fang, Angew. Chem., Int. Ed., 2015, 54,
11462–11466.
33 J. C. Matsubu, V. N. Yang and P. Christopher, J. Am. Chem.
Soc., 2015, 137, 3076–3084.
11 R. Ahmad and A. K. Singh, J. Mater. Chem. A, 2018, 6, 21120–
21130.
12 K. D. Gilroy, A. Ruditskiy, H. C. Peng, D. Qin and Y. N. Xia,
Chem. Rev., 2016, 116, 10414–10472.
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