Ultrathin Bismuth Nanosheets as a Highly Efficient CO2 Reduction Electrocatalyst

Article abstract of DOI:10.1002/cssc.201702229

Electrochemical reduction of CO₂ to value-added products is an important and challenging reaction for sustainable energy study. Herein, bismuth nanosheets with thickness of around 10 nm were prepared through the electrochemical reduction of Bi³⁺. Ultrathin Bi nanosheets with numerous low-coordination sites can efficiently reduce CO₂ to formate in aqueous solution. Within the potential range of ?0.9 to ?1.2 V vs. reversible hydrogen electrode (RHE), the faradaic efficiency of formate is over 90 %, outperforming many Bi catalysts. At ?0.7 V, the Bi nanosheets exhibit much higher current for formate generation than that of bulk Bi, attributed to a high surface area and also modified intrinsic electronic properties brought about by the ultrathin structure. DFT calculations demonstrate that Bi nanosheets have much higher density of states at the Fermi level compared to bulk Bi, favoring improved CO₂ reduction on Bi nanosheets. At ?1.0 V, Bi nanosheets exhibit high selectivity for formate and excellent stability during 5 h of electrolysis.

Full text of DOI:10.1002/cssc.201702229

Accepted Article
Title: Ultrathin Bismuth nanosheets as highly efficient electrocatalyst
for CO2 reduction
Authors: Panpan Su, Wenbin Xu, Yanling Qiu, Taotao Zhang, Xianfeng
Li, and Huamin Zhang
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: ChemSusChem 10.1002/cssc.201702229
Link to VoR: http://dx.doi.org/10.1002/cssc.201702229
A Journal of
www.chemsuschem.org

10.1002/cssc.201702229
ChemSusChem
COMMUNICATION
Ultrathin Bismuth nanosheets as highly efficient electrocatalyst
for CO2 reduction
Panpan Su,[a] Wenbin Xu[a], Yanling Qiu[a], Taotao Zhang[a] [b], Xianfeng Li[a] [c]*, and Huamin Zhang[a] [c]*
95%,[8] while the high price of noble metal hinders their widely
Abstract: Electrochemical reducing CO2 to value-added products is
practical application.
an important and challenging reaction for sustainable energy study.
Bi catalyst possessing the features of low toxicity, cost-
In this study, bismuth nanosheets with thickness of ~10 nm were
effectiveness, as well as excellent stability, has attracted much
successfully prepared via electrochemical reduction of Bi3+. Ultrathin
attention for CO2 electrocatalytic reduction. In aqueous
Bi nanosheets with numerous low-coordination sites can efficiently
electrolyte, the main reduction product on Bi catalysts is formic
reduce CO2 to formate in aqueous solution. During the potential
range of - 0.9 V to - 1.2 V vs RHE, the faradaic efficiency of formate
is over 90%, which is one of the best reported Bi catalysts. At −0.7
V, the prepared Bi nanosheets exhibit much higher current for
formate generation than that of bulk Bi, which is due to not only high
surface area but also intrinsic electronic property change of ultrathin
structure. Further, DFT calculation demonstrates that Bi nanosheets
have the much higher electron state density around Fermi level than
bulk counterpart, which favors the improvement of CO2 reduction on
Bi nanosheets. At −1.0 V, Bi nanosheets exhibit high selectivity for
formate and excellent stability during 5 hrs electrolysis measurement.
The prepared Bi nanosheets with high activity and superior stability
show great potential toward CO2 reduction area.
acid. Similarly with other electrocatalysts, the CO2RR activity
intensely depends on the morphology of Bi.[9] Recently, Bi with
dendritic morphology prepared by electrodeposition method
under the assist of halide ions, shows very high current density
and formate selectivity for CO2 reduction.[10] Besides dendrite
morphology, nanosheet structure with numerous coordinately
unsaturated sites favors the stabilization of intermediate species
generated during reaction and exhibits great advantage in CO2
reduction area. For instance, Prof. Xie reported that Co3O4 with
ultrathin structure can effectively catalyze CO2 reduction and
exhibit much higher formate selectivity than bulk cases.[11] Sn
quantum sheet with lowered tin–tin coordination numbers
facilitate the electron transfer from CO2 to CO2− intermediate,
accompanying the decrease of overpotential for formate
generation.[12] Therefore, designing the ultrathin-structured Bi is
expected to promote the CO2 electrocatalytic reduction
performances.
As accelerated depletion of fossil fuels, accompanying
growingly global warming, the capture and reutilization of CO2
become more and more imperative.[1] Electrochemical CO2
reduction (CO2RR) as one of the most promising alternative to
produce useful fuel has attracted renewed attention, due to its
environmental operation condition and easily controlled
features.[2] However, electrochemical CO2 reduction reaction still
exist some challenges, such as high overpotential, low Faradaic
efficiency, because of the kinetically favored competition
reaction from hydrogen evolution reaction (HER) in aqueous
electrolyte, and poor product selectivity.[3] In order to improve
electrochemical CO2 reduction selectivity, a wide variety of novel
metallic electrodes (such as Au, Ag, Pd) have been extensively
explored for the CO2 electrochemical reduction.[4] Combing
experimental investigation and theoretical calculation verified
that the structures (including size, geometry, morphology) of
novel metal greatly affect the corresponding catalytic activity,
and low dimensional structures revealed robust vigor for CO2
reduction. For instance, Au nanowire, triangular silver
nanoplates and AgIn dentrite can effectively catalyze the
reduction of CO2 to CO due to the high ratio of edge to corner
sites and optimal exposed crystal facets.[5] Further, Oxide-
derived nanostructured metal with roughness surface can
selectively suppress proton reduction and improve CO2
Herein, layer structural Bi was fabricated via
electrochemical reduction of bismuth oxide sulfates and bismuth
sulfides grown on carbon paper (scheme 1). During reduction
process, Bi atoms transformed from Bi3+ in precursor with
dendrite morphology endure restructuring and lead to the
formation of nanosheet structure. It is interesting to find that the
nanosheet morphology of prepared Bi is independent on the
anions of precursor. Ultrathin Bi layer with thickness of ~10 nm
shows much higher selectivity for formate than bulk Bi. During
wide potential range, the faradaic efficiency for formate is over
90%. The excellent CO2 reduction activity of prepared Bi may
come from the low-coordinating number of Bi on ultrathin
structure, which favors the stabilization of intermediate species
for formate generation. Further, DFT calculation evidenced that
layer structure has high density of electron state than Bi bulk.
The present work provides a new avenue for the fabrication of
ultrathin layered structure.
reduction selectivity.[6] Until now, variously delicate structures of
noble metal have been designed for CO2RR,[4c,
and the
7]
selectivity for CO2 reduction in aqueous solution can come up to
[a]
Dr. P. Su, W. Xu, Y. Qiu,T. Zhang, Prof. Dr. X. Li, Prof. Dr. H. Zhang
Division of Energy Storage
Dalian Institute of Chemical Physics, Chinese Academy of Sciences
457 Zhongshan Road, Dalian, 116023, China.
E-mail: lixianfeng@dicp.ac.cn; zhanghm@dicp.ac.cn.
University of Chinese Academy of Sciences, Beijing 100039, China.
Prof. Dr. X. Li, Prof. Dr. H. Zhang
[b]
[c]
Collaborative Innovation Center of Chemistry for Energy Materials
(iChEM),
Dalian, 116023, China.
Supporting information for this article is given via a link at the end of
the document.
Scheme 1. Schematic illustration of synthesis procedure for Bi nanosheets via
electroreduction method.
This article is protected by copyright. All rights reserved.

10.1002/cssc.201702229
ChemSusChem
COMMUNICATION
vs RHE. The positive shift of 130 mV for onset potential on Bi
nanosheet compared with commercial bulk Bi particles means
that CO2 reduction occurs on the surface of Bi nanosheet
becomes much more energy-favorable than that of bulk Bi
catalyst.
The Bi2S3 was prepared by the reaction of bismuth nitrate
and thiourea in aqueous solution based on hydrothermal method.
The result of X-ray diffraction (XRD) demonstrates the formation
of Bi2S3 phase, which shows branch like morphology detected
by scanning electron spectroscopy (SEM) (Figure S1). After
calcination at 500oC in air atmosphere, Bi2S3 was transformed
into bismuth oxide sulfate [Bi28O32(SO4)10] phase and the
branchlike morphology was still remained in bismuth oxide
sulfate (Figure S2). The electrochemical reduction of bismuth
oxide sulfate were performed in CO2 saturated NaHCO3 (0.5 M)
aqueous solution at -1.0 V vs RHE for 2 h. At the same time, the
color of bismuth species on carbon paper changed from white to
dark brown, which indicates the component change during
electrochemical reduction process. The obtained Bi catalyst was
structurally characterized by XRD, and the XRD pattern is
assigned to rhombohedral metallic Bi phase, corresponding to
JCPDS card No. 85-1329 (Figure 1b). The morphology observed
by SEM and high resolution transmission electron spectroscopy
(HRTEM) shows that the synthesized Bi has ultrathin layer
structures with the thickness of ~ 10 nm (Figure 1a-1c and
Figure S3). The inset in Figure 1c shows that the lattice fringe
distance of 2.3 Å ascribes to the (110) interplanar spacing of the
rhombohedral Bi indicating the formation of Bi phase, which is
well matched with XRD result. It should be noted that bismuth
sulfides can also be transformed into layer-structured Bi via
electroreduction process (Figure S4).
The CO2 reduction products in the gas phase and liquid
phase were quantitatively analyzed during constant electrolysis
by online-gas chromatography (GC) and ion chromatography
(IC), respectively (details shown in experimental section).
Formate as liquid product was detected and corresponding
faradaic efficiencies at different potentials were shown in
Figure 2c. At -0.6V, faradaic efficiency of formate comes up to
~60%, which is much higher than that of bulk Bi (~10%),
dendrite-shaped Bi previously reported by our group and other
nanostructured Bi catalyst.[9, 13] During the potential range of -
0.9V ~ -1.2V vs RHE, the faradaic efficiencies (FEs) of formate
are over 90%, while the FEs on bulk Bi is below 80% during all
the measured potential range. For gas products, H2 and CO
were observed, and corresponding faradaic efficiencies were
displayed in Figure 2d. It is clear that side product H2
generated via proton reduction was greatly suppressed on
synthesized Bi nanosheet catalyst compared to that of bulk Bi,
especially at the low overpotential region. The amount of
generated CO on these two types of Bi catalyst is trace and
FEs were below 5%. Combing the low onset potential for
formate generation and high formate selectivity, Bi nanosheets
are more effective than bulk Bi toward electrochemical CO2
reduction. Moreover, the substrate of carbon paper was used
as working electrode for CO2 reduction, H2 as the main product
was detected and FEs was over 90% during all the applied
potential range (Figure S5). FEs of both CO and formate were
below 5%. So that, the high formate selectivity of Bi
nanosheets comes from Bi species not the substrate of carbon
paper. The origin of Bi nanosheets with high activity was likely
due to high amount of low coordinated sites on the surface of
Bi nanosheets, which enhances the adsorption of CO2
molecular and favors the stabilization of intermediate species.
a
b
2 μm
b
a
0
-5
0
-4
*
c
d
(110)
Bi
*
CO2
N2
CO2
N2
#
graphite
-10
-15
-20
-25
-30
#
-8
*
*
*
2nm
Bi nanosheets
*
*
*
*
*
*
*
#
*
*
*
*
*
*
*
*
*
*
-12
-16
100 d
*
bulk Bi
*
*
*
-1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0
Potential (V vs RHE)
0
*
*
-1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2
*
*
*
*
Potential (V vs RHE)
20
40
60
80
c
2 Theta (degree)
H2-Bi nanosheets
Bi nanosheets
bulk Bi
120
100
80
60
40
20
0
CO-Bi nanosheets
H2-bulk Bi
80
60
40
20
0
Figure 1. SEM image (a), HRTEM images with different magnifications (b-c) of
prepared Bi catalyst and XRD patterns of synthesized Bi grown on carbon
paper and commercial bulk Bi (d).
CO-bulk Bi
To investigate the electrochemical activity of Bi catalysts, cyclic
voltammograms (CVs) of fabricated Bi nanosheets were
carried out in CO2 bubbled NaHCO3 solution (pH=7.2) and N2
bubbled NaH2PO4/Na2HPO4 solution (pH=7.2), respectively. As
shown in Figure 2a, the reduction current greatly increased in
CO2 atmosphere compared with that of N2 atmosphere, and
the onset potential for clear reduction current in CO2 bubbled
KHCO3 was -0.58V vs RHE. At the same condition, CVs for
commercial bulk Bi as the control sample were evaluated, and
the current density in the presence of CO2 was also enhanced
(Figure 2b), which indicated that both of synthesized Bi
nanosheet and bulk Bi exhibit effective catalytic activity for CO2
reduction. While the onset potential for bulk Bi is about -0.71 V
-0.6 -0.7 -0.8 -0.9 -1.0 -1.1 -1.2
Potential (V vs. RHE)
-0.6 -0.7 -0.8 -0.9 -1.0 -1.1 -1.2
Potential (V vs. RHE)
Figure 2. Cyclic voltammograms curves of ultrathin Bi nanosheets (a) and
commercial bulk Bi (b) in N2 bubbled NaH2PO4/Na2HPO4 solution (0.5M,
pH=7.2) and CO2 bubbled NaHCO3 (0.5M) aqueous solution with scanning
rate of 10 mVs-1, FEs for formate (c), CO and H2 (d) catalyzed by
synthesized Bi nanosheets and Bi bulk.
The partial current densities of formate on two types of Bi
This article is protected by copyright. All rights reserved.

10.1002/cssc.201702229
ChemSusChem
COMMUNICATION
catalysts were shown in Figure 3a, ultrathin Bi displays much
higher cathodic current for formate generation than Bi bulk. At
−0.7 V, formate partial current on Bi nanosheets reached 1.53
mA/cm2, which is 19 times higher than that of bulk Bi with 0.08
mA/cm2 (Figure 3a). The greatly enhanced CO2 reduction
activity of Bi nanosheets could be closely related with the
increased active sites exposed on the surface of catalysts. To
estimate the intrinsic activity of Bi catalysts on per active site,
the electrochemically surface area (ECSA) was determined via
the redox of surface active sites, and the area of redox peak
represents the amount of the active Bi species during
electrochemical process (Figure S6). ECSA of Bi nanosheets
shows 8.3 times higher than that of bulk Bi. It means that the
enhanced CO2 reduction activity of Bi nanosheets is not only
due to the increase of ECSA, but also intrinsic property change
of Bi with the morphology tuned from bulk to ultrathin layers. At
high overpotential (-1.0V vs RHE), the difference in formate
production rate on these two type of Bi catalysts decreases to
2 times, which is much less than the observed difference of
ECSA. The possible reason is that the Bi nanosheets are not
fully accessible by CO2 molecular due to the limit of mass
diffusion and low concentration of CO2 in aqueous solution, yet
accompanying the high CO2 consumption rate at high
overpotential. Therefore, the surface area effect on CO2
reduction rate was overestimated at high overpotential.
96 mVdec-1 and 155 mVdec-1, respectively, which are similar
with theoretical value of 118 mVdec-1, indicating that one
electron transferring to adsorbed CO2 and forming the *CO2
intermediate species is the rate-limiting step for CO2 reduction
catalyzed by two types of Bi catalysts.[14] The lower tafel slope
(96 mVdec-1) of Bi nanosheets than that of bulk Bi (155 mVdec-
1) clearly demonstrated the remarkable improvement for
formate generation on ultrathin Bi nanosheets than bulk Bi.
-
0.1 M
0.3 M
0.5 M
16
12
8
4
0
-0.6
-0.7
-0.8
-0.9
-1.0
-1.1
Potential (V vs RHE)
a
20
Figure 4. Formate partial current densities of Bi nanosheets in CO2 bubbled
NaHCO3 aqueous solution with different concentrations: 0.1 M (black line),
0.3 M (red line) and 0.5 M (blue line).
Bi nanosheets
Bi bulk
16
Further, the effect of electrolyte concentration for CO2
reduction on Bi nanosheets electrode was explored. When the
concentration of NaHCO3 was decreased from 0.5 M to 0.3 M
or 0.1 M, the main product of CO2 reduction was still formate.
Partial current density and FEs of formate were shown in
Figure 4 and Figure S7, respectively. As the decrease of
electrolyte concentration, both of the current density and FEs
of formate generation decrease. At -0.8V vs RHE, the partial
current density of formate decreases from 3.95 mA cm-2 to
1.92 mA cm-2 and 0.30 mA cm-2, corresponding FEs drops
from 88.7% to 59.8% and 20.6%, as the concentration of
12
8
4
0
-0.6
-0.8
-1.0
-1.2
Potential (V vs RHE)
NaHCO3 decreases from 0.5
M to 0.3 M and 0.1M,
respectively. The above results indicate high concentration of
NaHCO3 favors the reduction of CO2 to formate, which is
consistent with the literature result.[15]
b
1.2
1.0
0.8
0.6
0.4
Bi nanosheets
Bi bulk
12
bulk-p
nanosheets-p
bulk-d
10
nanosheets-d
8
155 mV dec-1
96 mV dec-1
6
4
2
0
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
Log [ formate current density (mA cm-2)]
Figure 3. Formate partial current densities (a) and tafel plots for formate
production (b) on synthesized Bi nanosheets and bulk Bi.
-15
-10
-5
0
5
E-Ef (ev)
To get the kinetic insights for CO2 reduction to formate, the
tafel plots are fitted in the low-overpotential region and shown
in Figure 3b, the slope value for Bi nanosheets and bulk Bi are
Figure 5. Partial density of states for p band and d band of Bi nanosheets
and bulk Bi.
This article is protected by copyright. All rights reserved.

10.1002/cssc.201702229
ChemSusChem
COMMUNICATION
Damao, 36%) were used as received. Commercial bulk Bi was brought
from sigma aldrich. CO2 gas (99.9995%) was purchased from the Dalian
DATE gas company. Ultrapure water was obtained by a ELGA Lab Water
system. Carbon paper (T060, Toray) was treated via calcination-process
in muffle oven at 500 C for 6 h under air atmosphere to remove organic
impurities remaining on the surface of carbon paper.
In order to deeply understand the enhancement of intrinsic
catalytic activity of Bi nanosheets to bulk Bi, DFT was
performed to calculate the density of state (DOS) of Bi. Based
on the result of total and partial density of state (PDOS) of p
band and d band (Figure 5 and Figure S8), electron state for d
band is negligible, and p band nearly determines the total
electron state of Bi catalyst. Compared with bulk Bi, Bi
nanosheet shows a remarkably higher PDOS of p band
surrounding Fermi level, which usually participates the orbit
hybridization of catalyst with adsorbed reactant. High DOS
around Fermi level optimizes the affinity of the catalyst surface
to the intermediate species and facilitates CO2 reduction.[16] So
that the electron state of Bi nanosheet is much more active
than bulk case, and contributes to the high CO2 reduction
activity.
Finally the stability of Bi nanosheets was evaluated at -
1.0V vs RHE. As Figure 6 displaying, during operation
conditions for 5hrs, the change of the cathodic current and
faradaic efficiency for formate generation is negligible. After
CO2 reduction for 5hrs, crystal phase of synthesized Bi was
well remained evidenced by XRD result (Figure S9). The highly
effective activity together with robust stability make Bi
nanosheets as electrocatalyst unprecedented promising for
CO2 electrochemical reduction.
o
Preparation of Bi based electrodes
Briefly, Bi electrode was prepared via four steps and carbon paper
was used as substrate. Firstly, Bi crystals were introduced on the
substrate via chronoamperometry technique in a three electrodes system.
The treated carbon paper was used as working electrode, Pt wire and an
Hg2Cl2/Hg/saturated KCl electrode (SCE) were used as the counter
electrode and the reference electrode, respectively. 20 mM Bi(NO3)3
aqueous solution containing 0.6 M hydrochloric acid was used as
electrolyte. The electrochemical deposition experiment was carried out at
a constant potential of -0.35 V versus SCE for 200s. Then, carbon paper
deposited with Bi crystals was immersed into a 50 mL Teflon-lined
stainless-steel autoclave containing 40mL Bi(NO3)3 (0.49g) and thiourea
(0.2g) aqueous solution. The autoclave was heated at 180 °C for 20 h
and then cooled down naturally. The carbon paper was taken out from
the autoclave, sequentially rinsed with ultra-pure water and dried at 80 oC
for overnight. Thirdly, the carbon paper grown with black bismuth sulfide
was calcinated at 500 oC for 2hs in air atmosphere, to transform bismuth
sulfide to bismuth oxide sulfate. Finally, the above bismuth oxide sulfate
based-electrode was electrochemically reduced in CO2 bubbled NaHCO3
(0.5M) aqueous reduction at -1.0 V (vs. RHE) for 2hs to get metallic Bi
electrode.
As control sample, commercial bulk Bi sample was grinded into
particles with a mortar. Bulk Bi based electrode was casted as the
following procedure. 1 g bulk Bi catalysts and 300μL Nafion (5 wt.%, Du
Pont, Corp.) were mixed with 3 mL ethanol and dispersed into uniform
ink by ultrasonic. The obtained ink was spray-coated onto carbon paper
(4 cm2), and then dried by air, to yield a catalyst layer with a loading
weight of 0.25 g cm-2.
100
-5
-10
Materials characterization
Powder X-ray diffraction (XRD) were measured on
a Rigaku
D/Max2500PC diffractometer with Cu Kα radiation (λ=1.5418 Å)
operating at 40 kV and 40 mA over the 2θ range of 5o-90o with a scan
speed of 5o/min. Scanning electron microscopy (SEM) was recorded on
JEOL JSM-6360 operating at an acceleration voltage of 20 kV. High
resolution transmission electron microscopy (HRTEM) was collected on a
JEOL JEM-2000EX (120 kV) microscope.
50
-15
-20
0
50
100 150 200 250 300
Time (min)
Electrochemical measurements for CO2 reduction.
Electrochemical measurements were performed on a Princeton
Applied Research VersaSTAT 3 potentiostat (EG&G Instrument) in a
two-compartment electrochemical cell (separated by nafion membrane)
with three electrodes system. Pt wire and an Hg2Cl2/Hg/saturated KCl
electrode (SCE) were used as the counter electrode and the reference
electrode, respectively. The above prepared Bi catalyst-based electrode
was used as working electrode. CO2 saturated NaHCO3 (0.5 M) aqueous
solution was used as electrolyte, and the electrolyte in cathodic part of
reaction cell was bubbled by CO2 gas and stirred at the rate of 500 rpm
during CO2 electrolysis process. The generated gas products were on-
line analyzed by a gas chromatograph (GC, Shimadzu GC-2014). The
hydrogen and CO were quantified by a thermal conductivity detector
(TCD) and flame ionization detector (FID), respectively. Standard line
was determined by using CO and H2 samples with different
concentrations. The liquid product was quantified by ion chromatography
(ICS-1100, Dionex Corporation). FEs was calculated as the following
formula:
Figure 6. Cathodic current and faradaic efficiencies for formate generation
on prepared Bi nanosheets in CO2 bubbled 0.5 M NaHCO3 solution at the
potential of -1.0V vs RHE for 5h.
In conclusion, Bi nanosheet structure was successfully
fabricated to effectively reduce CO2 to formate in aqueous
solution. Compared to bulk Bi, Bi nanosheets show much
higher cathodic current of formate generation on per active
site, which contribute to numerous of low-coordinated Bi atoms
on the surface of nanosheet structure and high electron state
around Fermi level verified by DFT calculation. Further Bi
nanosheets exhibit high selectivity and excellent stability during
5hrs electrolysis measurement at -1.0V vs RHE. This work
provides new insight for the synthetic protocol of nanosheet
structures, and experimentally and theoretically demonstrate
the advantage of nanostructured Bi in electrocatalysis area.
C ×V ×n
FEs =
× 100%
I ×t /F
C: the concentration of product, unit: molar/L;
V: the volume of reduction product, unit: L;
푛: the number of electron transferred for product generation, which is 2
for formate, CO and H2;
Experimental Section
I: reaction current, unit: A;
t: reaction time, unit: s；
퐹: Faradaic constant, 96485 C mol-1;
Chemicals
Bi(NO3)3 •5H2O (Sinopharm, 99%), thiourea (Tianjin Damao, 99.0%),
NaHCO3 (sigma-Aldrich, 99.7%) and HCl aqueous solution (Tianjin
This article is protected by copyright. All rights reserved.

10.1002/cssc.201702229
ChemSusChem
COMMUNICATION
The calculation of electrochemical surface area (ECSA)
Liu, H. Tao, L. Zeng, Q. Liu, Z. Xu, Q. Liu, J.-L. Luo, J. Am. Chem. Soc.
2017, 139, 2160-2163.
The cyclic voltammetry of ultrathin Bi nanosheets and bulk Bi
electrode was measured in 50mM KOH aqueous solution with scanning
rate of 10mV s-1. During the cathodic scanning period, the reduction peak
appears and this peak corresponds to the reduction of the oxide
monolayer formed during the anodic scan period (Figure S5). ECSA was
estimated based on the area of reduction peak.
[6]
[7]
a) Y. Chen, C. W. Li, M. W. Kanan, J. Am. Chem. Soc. 2012, 134,
19969-19972; b) C. W. Li, M. W. Kanan, J. Am. Chem. Soc. 2012, 134,
7231-7234; c) Y. Chen, M. W. Kanan, J. Am. Chem. Soc. 2012, 134,
1986-1989.
a) C. Shan, E. T. Martin, D. G. Peters, J. M. Zaleski, Chem. Mater.
2017, 29, 6030-6043; b) 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, B. R. Cuenya, Nat. Commun. 2016, 7, 12123; c) S. 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, 47-50; d) J. Choi, M. J. Kim,
S. H. Ahn, I. Choi, J. H. Jang, Y. S. Ham, J. J. Kim, S.-K. Kim, Chem.
Eng. J. 2016, 299, 37-44; e) Z. Chang, S. Huo, W. Zhang, J. Fang, H.
Wang, J. Phys. Chem. C 2017, 121, 11368-11379; f) H. Lee, S.-K. Kim,
S. H. Ahn, J. Ind. Eng. Chem. 2017, 54, 218-225; g) E. Hwang, H. Park,
H. Kim, S. H. Ahn, S.-K. Kim, Bull. Korean Chem. Soc. 2017, 38, 607-
613; h) Y. S. Ham, S. Choe, M. J. Kim, T. Lim, S.-K. Kim, J. J. Kim,
Appl. Catal. B-Environ. 2017, 208, 35-43; i) W. Luc, C. Collins, S. Wang,
H. Xin, K. He, Y. Kang, F. Jiao, J. Am. Chem. Soc. 2017, 139, 1885-
1893.
Computational details
In order to interpret the higher electrochemical CO2 reduction activity
observed over layer slab structure compared with bulk slab, the total
density of states (TDOS) and the local density of states (LDOS) have
been calculated, based on Density Functional Theory (DFT). All the
electronic structure calculations were performed using the gradient
corrected
Perdew-Burke-Ernzerh
(GGA-PBE)[17]
functional
as
implemented in the VASP code.[18] The electron-ion interactions were
described by the projector augmented wave (PAW)[19] method with a
kinetic energy cutoff of 400 eV. We used a 3x3x6 slab size to simulate
the 1.5nm thick layer slab with a vacuum in the direction perpendicular to
the surface of 15 Å. The 8x8x8 K-points and 11x11x1 K-points have been
employed for bulk structure and layer structure respectively with 0.1 eV
smearing of the fermi-level, and the force convergence was set to be
smaller than 0.02 eV/Å. Meanwhile, the spin polarization effect and
dipole corrections for (100) surface were taken into account.
[8]
[9]
X. Feng, K. Jiang, S. Fan, M. W. Kanan, J. Am. Chem. Soc. 2015, 137,
4606-4609.
a) S. Kim, W. J. Dong, S. Gim, W. Sohn, J. Y. Park, C.J. Yoo, H. W.
Jang, J -L Lee, Nano Energy 2017, 39, 44–52; b) W. Lv, J. Bei, R.
Zhang, W. Wang, F. Kong, L. Wang, W. Wang, ACS Omega 2017, 2,
2561−2567.
Acknowledgements
This work was financially supported by National Natural Science
Foundation of China (Grant No. 21577141).
[10] a) H. Zhong, Y. Qiu, T. Zhang, X. Li, H. Zhang, X. Chen, J. Mater.
Chem. A 2016, 4, 13746-13753.
[11] a) S. Gao, X. Jiao, Z. Sun, W. Zhang, Y. Sun, C. Wang, Q. Hu, X. Zu, F.
Yang, S. Yang, L. Liang, J. Wu, Y. Xie, Angew. Chem. 2016, 128, 708-
712; Angew. Chem. Int. Ed. 2016, 55, 698-702; b) S. Gao, Y. Lin, X.
Jiao, Y. Sun, Q. Luo, W. Zhang, D. Li, J. Yang, Y. Xie, Nature 2016,
529, 68-71.
Keywords: CO2 reduction • electrocatalysis • nanosheets • non-
precious metal • bismuth
[1]
[2]
a) V. Scott, S. Gilfillan, N. Markusson, H. Chalmers, R. S. Haszeldine,
Nat. Clim. Change 2013, 3, 105-111.
[12] F. Lei, W. Liu, Y. Sun, J. Xu, K. Liu, L. Liang, T. Yao, B. Pan, S. Wei, Y.
Xie, Nat. commun. 2016, 7, 12697.
a) R. J. Lim, M. Xie, M. A. Sk, J.-M. Lee, A. Fisher, X. Wang, K. H. Lim,
Catal. Today 2014, 233, 169-180; b) C. Costentin, M. Robert, J.-M.
Saveant, Chem. Soc. Rev. 2013, 42, 2423-2436; c) J. Qiao, Y. Liu, F.
Hong, J. Zhang, Chem. Soc. Rev. 2014, 43, 631-675; d) X.-M. Hu, M. H.
Ronne, S. U. Pedersen, T. Skrydstrup, K. Daasbjerg, Angew. Chem.
2017, 129, 6568-6572; Angew. Chem. Int. Ed. 2017, 56, 6468-6472.
a) D. T. Whipple, P. J. A. Kenis, J. Phys. Chem. Lett. 2010, 1, 3451-
3458; b) Y.-J. Zhang, V. Sethuraman, R. Michalsky, A. A. Peterson,
ACS Catal. 2014, 4, 3742-3748; c) J. T. Feaster, C. Shi, E. R. Cave, T.
T. Hatsukade, D. N. Abram, K. P. Kuhl, C. Hahn, J. K. Norskov, T. F.
Jaramillo, ACS Catal. 2017, 7, 4822-4827.
[13] J. Bei, R. Zhang, Z. Chen, W. Lv, W. Wang, Int. J. Electrochem. Sci.
2017, 12, 2365 – 2375.
[14] Y.-C. Hsieh, S. D. Senanayake, Y. Zhang, W. Xu, D. E. Polyansky,
ACS Catal. 2015, 5, 5349-5356.
[15] J. Wu, F.G. Risalvato, F.-S. Ke, P.J. Pellechia, X.-D. Zhou, J.
Electrochem. Soc. 2012, 159, F353-F359; b) F. Koleli, T. Atilan, N.
Palamut, A.M. Gizir, R. Aydin, C.H. Hamann, J. Appl. Electrochem.,
2003, 33, 447-450.
[3]
[4]
[16] K. Sun, L. Wu, W. Qin, J. Zhou, Y. Hu, Z. Jiang, B. Shen, Z. Wang, J.
Mater. Chem. A 2016, 4, 12616-12623.
a) D. Gao, H. Zhou, J. Wang, S. Miao, F. Yang, G. Wang, J. Wang, X.
Bao, J. Am. Chem. Soc. 2015, 137, 4288-4291; b) H. Mistry, R. Reske,
Z. Zeng, Z.-J. Zhao, J. Greeley, P. Strasser, B. R. Cuenya, J. Am.
Chem. Soc. 2014, 136, 16473-16476; c) Q. Lu, J. Rosen, Y. Zhou, G. S.
Hutchings, Y. C. Kimmel, J. G. Chen, F. Jiao, Nat. Commun. 2014, 5,
3242.
[17] J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett. 1996, 77, 3865-
3868.
[18] a) G. Kresse, J. Furthmuller, Phys. Rev. B 1996, 54, 11169-11186; b) G.
Kresse, J. Hafner, Phys. Rev. B 1994, 49, 14251-14269.
[19] J. J. Mortensen, L. B. Hansen, K. W. Jacobsen, Phys. Rev. B 2005, 71,
035109.
[5]
a) W. Zhu, Y.-J. Zhang, H. Zhang, H. Lv, Q. Li, R. Michalsky, A. A.
Peterson, S. Sun, J. Am. Chem. Soc. 2014, 136, 16132-16135; b) S.
This article is protected by copyright. All rights reserved.

10.1002/cssc.201702229
ChemSusChem
COMMUNICATION
COMMUNICATION
Panpan Su, Wenbin Xu, Yanling Qiu,
Taotao Zhang, Xianfeng Li*, and
Huamin Zhang*
Page No. – Page No.
Ultrathin Bismuth nanosheets as
highly efficient electrocatalyst for
CO2 reduction
Bismuth nanosheets with thickness of ~ 10nm were successfully fabricated
via electrochemical reduction of Bi3+. As CO2 reduction electrocatalyst,
ultrathin Bi nanosheets exhibit high selectivity for formate generation
contributed to the high electron state density around Fermi level verified by
DFT calculation.
This article is protected by copyright. All rights reserved.