Photocatalytic CO2 Conversion of M0.33WO3 Directly from the Air with High Selectivity: Insight into Full Spectrum-Induced Reaction Mechanism

Article abstract of DOI:10.1021/jacs.8b12928

Natural photosynthesis is a solar light-driven process utilized by plants to convert CO₂ and water into carbohydrate molecules. The goal of artificial photosynthesis is the reduction of CO₂ directly from air into high purity value-added products at atmospheric pressure. However, its realization, combined with deep mechanism investigation, is a huge challenge. Herein, we demonstrate that hexagonal tungsten bronze M_0.33WO₃ (M = K, Rb, Cs) series with {010} facets, prepared by a peculiar "water-controllable releasing" solvothermal method, showed excellent full spectrum (UV, visible, and NIR lights)-induced photocatalytic CO₂ reduction performance directly from the air at ambient pressure. Particularly, after 4 h near-infrared light irradiation, ca. 4.32% CO₂ in the air could be converted into CH₃OH with 98.35% selectivity for Rb_0.33WO₃. The experiments and theoretical calculations unveiled that the introduced alkali metal atom occupied the tunnel of hexagonal structure and donated more free electrons to reconstruct the electronic structure of M_0.33WO₃, which can enhance the polaron transition, modify the energy band structure, selectively adsorb CO₂ rather than O₂ from the air, decrease the activation energy of CO₂ reaction, and finally make the effective CO₂ reduction in the air a reality. This work may provide a new possibility for the practical application of artificial photosynthesis.

Full text of DOI:10.1021/jacs.8b12928

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Article
Photocatalytic CO2 conversion of M0.33WO3 directly from the air with
high selectivity: Insight into full spectrum induced reaction mechanism
Xiaoyong Wu, Yuan Li, Gaoke Zhang, Hong Chen, Jun Li,
Kai Wang, Yang Pan, Yan Zhao, Yongfu Sun, and Yi Xie
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.8b12928 • Publication Date (Web): 05 Mar 2019
Downloaded from http://pubs.acs.org on March 5, 2019
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Photocatalytic CO Conversion of M WO Directly from the Air
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with High Selectivity: Insight into Full Spectrum Induced Reaction
Mechanism
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†
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Xiaoyong Wu , Yuan Li , Gaoke Zhang , Hong Chen , Jun Li , Kai Wang , Yang Pan , Yan
2*
4*
4
Zhao , Yongfu Sun , Yi Xie
1
Hubei Key Laboratory of Mineral Resources Processing and Environment, School of Resources and Environmental
Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, China.
State Key Laboratory of Silicate Materials for Architectures, International School of Materials Science and
Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, China.
School of environmental science and engineering, Southern University of Science and Technology, 1088 Xueyuan
2
3
Road, Shenzhen 518055, China.
4 Hefei National Laboratory for Physical Sciences at Microscale, CAS Center for Excellence in Nanoscience,
University of Science and Technology of China, Hefei 230026, China.
5
†
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China.
Xiaoyong Wu and Yuan Li contributed equally to this work.
KEYWORDS: Artificial photosynthesis; Conversion of CO
2
from air; Full spectrum light response; M0.33WO
3
.
ABSTRACT: The natural photosynthesis is a solar light-driven process utilized by plants to convert CO
carbohydrate molecules. The goal of artificial photosynthesis is the reduction of CO directly from air into high purity of
value-added products at atmospheric pressure. However, its realization, combining with deeply mechanism investigation,
is a huge challenge. Herein, we demonstrate that hexagonal tungsten bronze M0.33WO (M=K, Rb, Cs) series with {010}
facets, prepared by a peculiar “water-controllable releasing” solvothermal method, showed excellent full spectrum (UV,
visible and NIR lights) induced photocatalytic CO reduction performance directly from the air at ambient pressure.
Particularly, after 4 h near infrared light irradiation, ca. 4.32 % CO in the air could be converted into CH OH with 98.35
selectivity for Rb0.33WO . The experiments and theoretical calculations unveiled that the introduced alkali metal atom
occupied the tunnel of hexagonal structure and donated more free electrons to reconstruct the electronic structure of
, which can enhance the polaron transition, modify the energy band structure, selectively adsorb CO rather
from the air, decrease the activation energy of CO reaction, and finally make the effective CO reduction in the
air a reality. This work may provide new possibility for the practical application of artificial photosynthesis.
2
and water into
2
3
2
2
3
%
3
M0.33WO
3
2
than O
2
2
2
effectively adsorbed and activated on the surface of most
INTRODUCTION
The dramatically boosting concentration of CO in the
2
atmosphere seriously destructs the natural carbon
balance, aggravates global warming and becomes a
worldwide challenge and urgent issue. Inspired by the
nature photosynthesis, photocatalytic reduction of CO
has been considered as one of the ideal solutions to
address this issue since it can not only reduce the CO
concentration environmental friendly but also enable to
12-14
photocatalysts,
and the anaerobic atmosphere is
requisite to prevent the adverse oxidation reaction from
15-17
happening.
In addition, the irradiation sources for
photocatalytic carbon dioxide reduction (PCR) are usually
1
,2
18,19
ultraviolet (UV) and visible lights;
while near infrared
2
(NIR) light is rarely utilized, which accounts for ca. 50 %
of natural solar light. Moreover, the corresponding CO2
conversion efficiency is extremely lower as compared to
2
20-22
those of UV and visible lights induced ones.
Lastly, it
3
-8
convert CO
application of artificial photosynthesis, there are still
some challenges to overcome. Many CO reduction
systems demand relatively complicated reaction
2
into renewable resources. For widespread
is difficult to control the selectivity of PCR, and the
products tend to be two or more of CO, HCOOH, HCHO,
23,24
2
3 4
CH OH and CH , etc.
Therefore, developing a photocatalyst, which can
effectively reduce CO directly from air into value-added
9
-11
conditions.
special CO
Generally, high concentration of CO
-capturing devices are required, because the
makes it very difficult to be
2
or
2
2
product of high selectivity under the irradiation of full
spectrum (UV, visible and NIR lights) at ambient
low concentration of CO
2
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Page 2 of 12
condition, without the addition of any other special
additive, sacrificial agent or CO -capturing device, and
corresponding CO reduction
are grand challenges but extremely
in Figure 1c. It is clear that the sample, which was simply
washed using distilled water for next PCR test, still
presented nice performance without obvious activity
decrement after 7 times PCR tests in the air (4 h full
spectrum light irradiation for each time). Besides,
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elucidating
mechanism,
promising.
the
2
25-28
3
performance of the sample Rb0.33WO in a prolonged run
Herein, we report a series of noble metal-free hexagonal
tungsten bronze, M0.33WO (M=K, Rb, Cs), as sole photo-
was displayed in the Figure S5, S6, indicating that the
water content on the surface of the sample obviously
affected the reaction performance. Moreover, the sample
3
catalyst to achieve the above-expected effectively PCR
directly from air at atmospheric pressure under the
irradiation of full spectrum (UV, visible and NIR lights).
Rb0.33WO
3
kept nice stability in the air without light
irradiation. The old sample Rb0.33WO , which stored in
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Typically, under the irradiation of NIR light, Rb0.33WO
and Cs0.33WO could present fascinating PCR performance
in air with production selectivity above 98 % towards
CH OH. Besides, the CO and temperature-
3
plastic vessel in the air atmosphere for more than 5
months, still displayed nice performance (Figure S7, S8).
More importantly, when PCR was conducted in the air
under the irradiation of NIR light (>800 nm), the samples
3
3
2
O
2
programmed desorption (TPD), X-ray absorption near-
edge spectroscopy (XANES) and calculation of energy loss
function, etc. were employed to study the M0.33WO series
3
for the mechanism explanation. We found that the
polaron transition induced short wavelength of NIR light
played the predominant role in the outstanding NIR light
Cs0.33WO
3
and Rb0.33WO
3
still exhibited outstanding
CH
.27 and 2.33 µmol h g (Figure 1d), respectively. Figure 1e
illustrate the variation of CO in the air and the main
products produced in PCR process referred to the sample
in above scenario. It is noticeable that the
displayed ca. 98.35 % PCR selectivity
OH production and ca. 4.32 % conversion
efficiency for CO after 4 h reaction (Table S4).
Furthermore, as show in Tables S5, S6, it can be found out
that the decrease of CO and the increase of gas products
3
OH production activity with the conversion rate of
-1
-1
1
2
Rb0.33WO
sample Rb0.33WO
3
3
induced PCR performance of the M0.33WO series. Last but
3
not least, the density functional theory (DFT) study of the
reaction paths for PCR revealed that the existence of
alkali metal atoms was remarkably beneficial for the high
for CH
3
2
2
efficiency of full spectrum induced CO reduction to
2
CH OH directly from the air.
3
in PCR are stoichiometric under full spectrum light
irradiation and NIR light irradiation, respectively.
RESULTS AND DISCUSSION
3
To confirm that the production of CH OH was really
originated from PCR of the sample instead of other
approaches, the PCR process was also conducted in pure
The M0.33WO
3
series were prepared by a peculiar
water-controllable releasing” solvothermal method using
tungsten hexacarbonyl and nitrate salts as raw materials
see Supporting Information for more details), assisted by
a H reduction. The PCR performance of the samples was
“
N
2
atmosphere and various CO
2
concentrations. Under N
showed no detectable
2
(
atmosphere, the sample Rb0.33WO
PCR activity (Figure 1f, S9). Meanwhile, the CO
3
2
12
2
and
evaluated in a customized sealed quartz glass vessel under
the irradiation of 300 W Xe lamp (350-2500 nm) with or
without light filter (Figure S1, S2, S3). Noteworthily, the
fresh air with standard atmospheric pressure was directly
used as carbon source. Figure 1a show the corresponding
PCR performance of the samples under the irradiation of
13
CO
OH stemmed from CO
S11). Fourier transform infrared (FTIR) spectrum of PCR
reaction of the sample Rb0.33WO also present the
obviously new signals for the functional groups of C-H
and O-H as compared to the fresh sample Rb0.33WO and
the no-light matched groups (Figure S12). Besides, when
the PCR activity of the sample Rb0.33WO was evaluated in
various CO concentrations, the sample presented
increasing CH OH production rate with rising CO
contents, so all that verified that the generating CH OH
was converted by CO . Particularly, as PCR was tested in
pure CO atmosphere, the CH OH production rate
achieved ca. 26.50 µmol h (Figure S9) under full
2
labeling experiment reveal that the produced
CH
3
2
photoreduction (Figure S10,
3
full spectrum light of Xe lamp. The commercial WO
exhibited no observable PCR activity, and trace
performances for heat-treated Rb0.33WO3.165 and W18
Table S1). While ca. 17.50, 15.10 and 7.70 µmol of CH OH
product were respectively detected for per gram of the
samples Cs0.33WO after 4 h PCR
that were much higher than the performance of sample
Au@TiO in the same scenario (Figure S4). In terms of full
spectrum light irradiation, the main PCR products of the
consisted of ca. 21.59 % of HCHO and
OH (Figure 1b), with trace amount of
. The total conversion rate for HCHO and
3
3
O
49
3
(
3
2
3
2
3 3 3
, Rb0.33WO and K0.33WO
3
2
2
3
2
-1
-1
g
-1
-1
spectrum light irradiation and ca. 15.48 µmol h g was
reached for the NIR light induced one, which is much
superior over most of the reported NIR light induced PCR
(Table S7). More interestingly, it was found that the
introduced water strongly influenced the process of PCR
sample Rb0.33WO
3
ca. 76.51 % of CH
CO and CH
CH OH achieved about 4.78 µmol h g (Table S1), and
the concentration of oxygen slightly increased as well
Table S2), but we did not detect the signal of hydrogen.
Furthermore, the generation of different products of the
under full spectrum irradiation and in
3
4
-1
-1
3
but no significant effect by H
irradiation, CO could directly react with water on the
surface of Rb0.33WO , rather than the common reduction
process that water firstly was decomposed to H and then
CO reacted with H (Figure S13). More intriguing, the
catalyst Rb0.33WO can be used continuously in a flowing
2
, implying that under light
(
2
sample Rb0.33WO
3
3
the pure CO2 atmosphere are approximately
stoichiometric (Table S3). The PCR stability of the sample
Rb0.33WO conducted in the air atmosphere was revealed
3
2
2
2
3
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air and still demonstrated nice performance (Figure S3
and Table S8).
(Figure S15, S16). Thus, the {010} and {001} facets were
both considered as the candidates for CO adsorption.
The density functional theory (DFT) calculations
confirmed that the CO is much easier to be adsorbed on
the {010} facets with much lower adsorption energy of -
1.00 eV than that on the {001} facets with the adsorption
energy of -0.38 eV (Table S11), and even the bond angle in
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Characterization of physical and chemical properties of
the samples is one of the best ways to shed light on the
2
superior PCR performance of M0.33WO
comparisons. It is well acknowledged that the crystal
structure, the adsorption of CO and O adsorption on the
3
series over other
2
2
2
CO has changed after adsorption on the {010} facets
surface of catalyst, and the light absorption capability as
well as activation energy are four key factors for high
(Figure 3a, 3b). This advantage for {010} facets was partly
due to that the {010} facets exposing cut open hexagonal
tunnel and then much more alkali metal ions were
exposed on surface to decrease adsorption energy, as
29-32
efficiency of PCR activity in air atmosphere.
following discussion will be elaborated from above four
points. In this work, the M0.33WO series were prepared by
above-mentioned “water-controllable releasing”
Thus, the
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compared to that of {001} facets exposing. Besides, CO
adsorption capacities of Rb0.33WO 49 are also
different (Figure 3c) that the Rb0.33WO has much higher
CO adsorption capacity than The CO
temperature programmed desorption (TPD) analysis
2
3
and W18O
solvothermal method, in which the acetic acid and
ethanol mixed solutions were used as reaction solvent.
With rising heating temperature, the acetic acid and
ethanol will gradually react to release water and then
control the hydrolysis of tungsten hexacarbonyl;
meanwhile, the ethanol could be used as reduction agent
3
2
W
18
O
49
.
2
confirms that the Rb0.33WO
predominant desorption peaks around 100 and 300 C,
respectively (Figure 3d), which were probably owing to
3
sample exhibited two
o
5
+
to produce reduced W . In this case, the particle size,
morphology, light harvesting and alkali metal introducing
2
the desorption of CO from various W sites on different
exposed facets, while only weak desorption peak around
3
for tungsten bronze M0.33WO series could be nicely
o
2
00 and 300 C was observed for prepared W18
O
49
.
optimized. The XRD patterns and corresponding
structure information of the as-prepared samples were
shown in Figure 2a, 2b, S14 and Table S9. Commercial
Furthermore, with increasing alkali metal ionic radius for
K to Cs, the corresponding intensities for these two peaks
increased (Figure S17), which were well indexed to the
WO
3
and W18
O
49 were assigned to orthorhombic and
were
variation tendency of the calculated CO
energies (Table S11). Therefore, the alkali metal ion
introducing on the surface of M0.33WO series with {010}
facets exposing is in favor of CO adsorption over other
samples. Besides, the adsorption of O over the samples
should be considered for PCR performance since O from
air has competitive effect for CO adsorption on the
sample surface and is detrimental for CO reduction
owing to its oxidation property. The sample Rb0.33WO
represented very poor adsorption ability for O , but the
sample W18 49 showed strong one for O (Figure 3e).
Therefore, M0.33WO series with {010} facets exposing has
interesting adsorption selectivity for CO over O in the
air, making PCR of M0.33WO directly in the air possible.
2
adsorption
monoclinic systems, respectively, while all M0.33WO
3
well indexed to a peculiar hexagonal system. In this
unique hexagonal tungsten bronze crystal (Figure 2b), the
corner-sharing WO octahedron built up the tungsten-
6
3
2
2
oxygen framework to form uniformly dispersed trigonal
and hexagonal tunnels, and then large amounts of alkali
metal ions could be regularly introduced in the hexagonal
2
2
5+
2
tunnel. In this condition, great numbers of reduced W
3
would be produced in this unique M0.33WO
3
crystal
33
2
structure to keep charge balance. It is well known that
unsaturated transition metal and alkali metal introduced
in semiconductors are beneficial to light absorption and
O
2
3
adsorption as well as activation.34-36 So from the
2
2
CO
viewpoint of structure, the employed M0.33WO
2
3
3
series are
promising candidates for PCR and the detailed effect of
unsaturated transition metal and introduced alkali metal
on PCR performance will be elucidated later.
To study full spectrum and NIR lights induced PCR
performance, the light absorption capability of
photocatalyst is a crucial factor. Figure 4a exhibit the
diffuse reflectance spectroscopy (DRS) of the samples. All
the samples displayed excellent intrinsic light absorption
in the UV range. Moreover, with the increment of alkali
metal ionic radius, the absorption edges of the samples
were shifted to the long wavelength (Figure S18),
indicating the narrowed band gap. More importantly,
Due to the small and similar specific surface area of the
samples (Table S10), the exposed facets should be key
37
point for gas adsorption. Figure 2c, 2d, 2e, 2f present the
transmission electron microscopy (TEM), elementary
mapping,
microscopy (HRTEM) images and selected area electron
diffraction (SAED) pattern of the sample Rb0.33WO . The
high-resolution
transmission
electron
3
M0.33WO series and W18O49 presented interesting and
3
very strong light absorption from 500 to 2200 nm, and the
corresponding color images of particles were provided in
Figure S19, while no detectable corresponding absorption
for the sample Rb0.33WO3.165 and weak intensity for
sample exhibited flower liked shape, consisted of
nanorods, and the Rb, W and O atoms were uniformly
dispersed in the particles. In addition, the two closest
spots in SAED pattern were respectively attributed to the
planes of (300) and (102), indicating the main exposed
commercial WO
3
. Therefore, M0.33WO
3
series could
present excellent PCR performance under full spectrum
light irradiation. On the other hand, the NIR light
absorption shape of the samples was not symmetric,
which is probably due to more reasons rather than sole
facets in Rb0.33WO
exposed facets on tips of nanorod should be {001} facets.
The other series of M0.33WO particles also displayed
nanorod shape with dominant exposed {010} facets
3
was {010} facets and the minor
3
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one. Some works explained that the intriguing NIR light
absorption for WO3-x or W18 49 should be owing to the
existence of oxygen vacancies. However, in this work, no
hard evidences were observed for the existence of oxygen
atoms were nicely ionized and then provided huge
amounts of free electrons to the crystal. Therefore,
polaron transition and LSPR effect were reasonably
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O
20
accounts for the strong NIR light absorption of M0.33WO
series.
3
3
vacancies in the M0.33WO sample by means of electron
paramagnetic resonance (ESR) tests (Figure S20) and
thermogravimetric analysis as well as poor adsorption
To investigate the effect of polaron transition and LSPR
induced NIR light absorption on the PCR performance in
detail, the PCR activity of the samples as a function of
irradiation wavelengths of NIR lights and reaction
temperatures were studied (Figure S25, S26). As we all
know, the harvesting of long wavelength of NIR light
from LSPR leads to photothermal effect (Figure S27, S28).
5
+
ability for O
2
. In addition, the reduced W in M0.33WO
3
+
could be compensated by induced M ions instead of
oxygen vacancies, so the oxygen vacancies were not
3
necessary for forming M0.33WO crystal and the NIR light
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0
absorption of M0.33WO samples was probably not
3
induced by oxygen vacancies. The true mechanisms of
NIR light absorption were further investigated by some
When PCR of the sample Rb0.33WO
3
was respectively
o
performed at 60 and 150 C, no product was detected
without irradiation, and no big difference was observed
under full spectrum and NIR lights irradiation,
respectively. But much less activity was presented as PCR
optical
measurement
technologies.
Firstly,
the
photoluminescence (PL) spectra of the samples were
recorded in Figure S21. It is interesting that with the
excitation wavelengths of 550 and 580 nm, the samples
displayed two emission peaks at 825 and 870 nm,
respectively. Since the PL spectra is a nice and indirect
way to reflect the light harvesting mechanism of
semiconductor, the strong NIR light harvesting of
reaction temperature of the sample Rb0.33WO
3
was fixed at
o
1
0
C, which should be owing to that at lower
temperature, most of water in reaction vessel kept the
liquid states rather than vapor, then no enough H
2
O
vapor to contact with photocatalyst to conduct PCR.
Obviously, the relatively high temperature did not have
significant impact on the PCR performance. Besides,
under the irradiation of NIR light with the wavelength
above 800 nm and full spectrum light, the sample
M
0.33WO
3
series should be owing to two different
mechanisms. Therefore, the dielectric functions and
energy loss function of the sample Rb0.33WO were
3
calculated (Figure 4b, 4c). It is apparent in Figure 4b that
a strong peak was appeared at ca. 3.8 eV in ɛ2, which is
assigned to the intrinsic transition from the valence to
Rb0.33WO
3
presented prominent PCR performance;
however, under the irradiation of light above 900 nm, no
distinct activity was observed (Figure S25), and the
detailed reason was described in the supporting
information. Thus, it can be learned that the NIR light
38
conduction band. Notably, a relatively weak peak with
asymmetrical profile at around 1.5 eV was observed in
both ɛ1 and ɛ2, which should be ascribed to the polaron
6
absorption with the WO octahedron as the host polarons
3
induced PCR performance of M0.33WO series was mainly
induced by free electrons in crystal.38-40 Derived from the
dielectric functions results, the energy loss function of the
contributed by polaron transition induced by the short
wavelength of NIR light rather than LSPR induced
photothermal transition. And the corresponding band
3
sample Rb0.33WO presented two distinct peaks around 1.4
and 2.0 eV(Figure 4c), which should be attributed to the
localized surface plasmon resonance (LSPR) and
3
structure of Rb0.33WO was shown in Figure S29, S30.
Finally, to shed light on the mechanism of whole
process of artificial photosynthesis for various samples,
3
8,40
polarons,
respectively. No such above phenomena
(Figure S22).
were observed for bulk WO
3
3 3
two different models, hexagonal WO and M0.33WO with
It is well recognized that the polaron transition and
LSPR are intimately related to the reduced W5+ and free
electrons for W related system. Because the polaron
transition is caused by the hopping of small polarons
{
010} exposed facets, were respectively established to
clarify the effect of alkali metal on the PCR process in the
air. The corresponding calculated stepwise Gibbs free
energy diagrams for CO reduction into CH OH and
2 3
relevant optimized structures were demonstrated in
Figure 5, and all presented intermediate states had been
optimized after considering various possibilities pathways
5
+
6+
from W to nearby W positions or transferring from
localized levels, which is formed by localized free
electrons, to conduction band, and the LSPR is originated
from large amounts of free electrons accumulated on the
with the lowest energies. To begin with, one CO
molecule was adsorbed into the nearby of W sites, and
then one H O molecule were adsorbed on the surface
2
3
8,41
conduction band.
W 4f XPS spectra (Figure 4d, and the
other elements of XPS spectra were supplemented in
Figure s23) and X-ray absorption near edge structure
2
with minimized energies. Interestingly, after structure
configuration optimization, we found that one hydrogen
(
XANES) spectra (Figure 4e, S24) explicitly exhibited that
5
+
great amounts of reduced W were really existed in the
series. It can also be seen from Figure 4f that, as
compared to WO , the Fermi level of M0.33WO series was
of H
to form COOH*(Step 2), which was well consistent with
the results obtained above that only O was observed in
2 2
O was automatically connected to the oxygen of CO
M
0.33WO
3
3
3
2
shifted to the conduction band, indicating the semi-
metallic states of these the samples, and many free
electrons were existed in crystal. In addition, alkali metal
atoms all contributed to the over-all density of states
GC for PCR reaction but no H2 was detected. Combined
with the FTIR spectra and in situ FTIR spectra (Figure S31,
S32), the above interesting phenomenon indicated that W
sites were possibly not only active for CO
2
adsorption and
O was
(
DOS) in upper conduction band, implying that these
activation but also for H O. After that, one more H
2
2
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transition was mainly contributed to the high NIR light
adsorbed on the surface (Step 3). Subsequently, COOH*
was further reacted to produce the sable intermediate
C(OH) *. The following two steps were the hydrogenation
of C(OH) * to form HC(OH) *, H COH*, respectively.
However, from HC(OH) * to H COH*, the hexagonal
WO exhibited increased energy of -2.10 eV while much
favorable energy of -7.25 eV for hexagonal Rb0.33WO
Finally, the intermediate H COH* was changed into the
OH* . Notably, in the whole possible
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
induced PCR performance. Finally, the DFT calculations
found that the alkali metal in hexagonal tungsten bronze
2
2
2
2
crystal was greatly in favor of CO
2
conversion into
2
2
CH OH. Our work may pave a new way for the PCR
3
3
directly from the air to high selectivity of value-added
product.
3
;
2
1
1
ASSOCIATED CONTENT
desirable CH
3
reaction steps, all showed negative energies, indicating
they were favorable reaction channels. More importantly,
from the free energies of all the samples as presented in
Table S12, it could be found that the existence of alkali
Supporting
Information.
Detailed
experimental
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
procedures, characterization, theoretical calculation and
additional figures and tables. This material is available free of
charge via the Internet at http://pubs.acs.org.
metal in crystal was greatly favorable for CO
into CH OH, and this effect was enhanced with the
increment of alkali metal ionic radius. Besides, the
possible reaction processes of CO reduction into HCHO
was also provided in Figure
2
reduction
AUTHOR INFORMATION
Corresponding Author
3
2
*
E-mail: gkzhang@whut.edu.cn; Yan2000@whut.edu.cn;
over the sample Rb0.33WO
S33.
3
yfsun@ustc.edu.cn.
Thus, from the viewpoint of reaction process (Table S12),
the sample Cs0.33WO should present the best PCR
ACKNOWLEDGMENT
3
This work was supported by the National Natural Science
Foundation of China (NSFC No.51472194, No. 21777045 and
No.51602237), the Fundamental Research Funds for the
Central Universities (WUT:2017 IVA 039 and 2017 IVB 015)
and the National Basic Research Program of China (973
Program No.2013CB632402). Use of the Stanford Synchrotron
Radiation Lightsource, SLAC National Accelerator
Laboratory, is supported by the U.S. Department of Energy,
Office of Science, Office of Basic Energy Sciences under
Contract No. DE-AC02-76SF00515. We thank Dr. Liang Liang
for SVUV-PIMS characterization.
performance over other the samples. Nevertheless, as for
photocatalytic activity, in addition to reaction energies,
2
the light absorption, CO adsorption capability, density
and separation ability of charge carries, etc. could also
4
2
affect the performance of PCR as well. Figure 4a show
that the sample Rb0.33WO exhibited the highest light
absorption from 200 to 900 nm. Meanwhile, the sample
has stronger instantaneous photo-current than
the sample Cs0.33WO under NIR light irradiation (Figure
S34), much superior over other the samples, but better
CO adsorption capability for the sample Cs0.33WO than
other ones. Under full spectrum light of Xe lamp
irradiation, the sample Cs0.33WO presented the best PCR
performance in the air, indicating CO adsorption
capability and reaction energies of CO reduction played
3
Rb0.33WO
3
3
2
3
REFERENCES
(
1) Hoffert, M. I.; Caldeira, Benford, K. G.; Criswell, D. R.;
Green, C.; Herzog, H.; Jain, A. K.; Kheshgi, H. S.; Lackner,
K. S.; Lewis, J. S. Advanced technology paths to global
climate stability: energy for a greenhouse planet. Science
3
2
2
dominant role in the superior PCR performance of the
samples. However, under the irradiation of NIR light, the
2
002, 298, 981-987.
(
2) Tee, S. Y.; Win, K. Y.; Teo, W. S.; Liu, L. D. S.; Teng, C. P.;
Han, M. Y. Recent progress in energy-driven water
splitting. Adv. Sci. 2017, 4, 1600337.
sample Rb0.33WO
in the air over the sample Cs0.33WO
3
showed the superior PCR performance
, and no distinct
3
activity was observed for other the samples. In this
scenario, light absorption made the main contribution to
the excellent PCR property of M0.33WO series.
3
(3) Inoue, T.; Fujishima, A.; Konishi, S.; Honda, K.
Photoelectrocatalytic reduction of carbon dioxide in
aqueous suspensions of semiconductor powders. Nature
1
979, 277, 637-638.
(
4) Kim, D.; Sakimoto, K. K.; Hong, D. C.; Yang, P. D.
Artificial photosynthesis for sustainable fuel and
chemical production. Angew. Chem. Int. Ed. 2015, 54,
3259-3266.
CONCLUSIONS
In summary, a series of hexagonal M0.33WO nanorods
3
with {010} exposed facets exhibited excellent PCR
performance directly in the air with atmospheric pressure
under the irradiation of full spectrum and NIR lights,
(5) Marshall, J. Solar energy: Springtime for the artificial leaf.
Nature 2014, 510, 22-24.
6) Creel, E. B.; McCloskey, B. D. Scalable CO -to-oxygenate
2
production. Nature Catal. 2018, 1, 6-7.
7) Pan, Y. X.; You, Y.; Xin, S.; Li, Y. T.; Fu, G. T.; Cui, Z. M.;
Men, Y. L.; Cao, F. F.; Yu, H. S.; Goodenough, J. B.
(
(
respectively, much superior over W18
O49, commercial
WO and Au@TiO . The experiments and theoretical
3
2
calculations confirmed that the exposed {010} facets with
large amounts of disclosed alkali metal and reduced W
Photocatalytic CO
oxide nanobelts. J. Am. Chem. Soc.2017, 139, 4123-4129.
(8) Li, H. J.; Gao, Y. Y.; Zhou, Y.; Fan, F. T.; Han, Q. T.; Xu, Q.
F.; Wang, X. Y.; Xiao, M.; Li, C.; Zou, Z. G. Construction
and nanoscale detection of interfacial charge transfer of
2
reduction by carbon-coated indium-
atoms on the surface for M0.33WO
for CO adsorption, and detrimental on O
provided possibility for conversion of CO
3
series were beneficial
2
2
adsorption. It
directly from
2
the air. Meanwhile, we found that the strong NIR light
absorption ability of dark blue M0.33WO series was
originated from polaron transition and LSPR, and polaron
elegant Z-scheme WO
Lett. 2016, 16, 5547-5552.
3 2 3
/Au/In S nanowire arrays. Nano
3
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 6 of 12
(
(
9) Sun, Z. Y.; Talreja, N.; Tao, H. C.; Texter, J.; Muhler, M.;
reversible electron acceptor in a TiO
for CO photoreduction. J. Am. Chem. Soc. 2017, 139, 1226.
(26) Shown, I.; Samireddi, S.; Chang, Y. C.; Putikam, R.;
Chang, P. H.; Sabbah, A.; Fu, F. Y.; Chen, W. F.; Wu, C.;
Yu, T. Y.; Chung, P. W.; Lin, M. C.; Chen, L. C.; Chen, K.
2
–Re catalyst system
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
Strunk, J.; Chen, J. F. Catalysis of carbon dioxide photo-
reduction on nanosheets: fundamentals and challenges.
Angew. Chem. Int. Ed.2018, 57, 7610-7627.
2
10) Wang, L. X.; Wang, L.; Zhang, J.; Liu, X. L.; Wang, H.;
Zhang, W.; Yang, Q.; Ma, J. Y.; Dong, X.; Yoo, S. J.; Kim, J.
G.; Meng, X. J.; Xiao, F. S. Selective hydrogenation of
CO2 to ethanol over cobalt catalysts. Angew. Chem. Int.
Ed. 2018, 57, 6104-6108.
2
H. Carbon-doped SnS nanostructure as a high-efficiency
solar fuel catalyst under visible light. Nat. Comm. 2018, 9,
169.
(27) Chen, X. X.; Li, Y. P.; Pan, X. Y.; Cortie, D.; Huang, X. T.;
Yi, Z. G. Photocatalytic oxidation of methane over silver
decorated zinc oxide nanocatalysts. Nat. Comm. 2016, 7,
12273.
(11) Li, H. L.; Wang, L. B.; Dai, Y. Z.; Pu, Z.; Lao, T.Z.; Chen,
H.; Wang, Y. W.; Zheng, M. L.; Zhu, X. S.; Zhang, J. F. W.
H.; Si, C.; Ma, R.; Zeng, J. Synergetic interaction between
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
neighbouring
hydrogenation. Nat. Nanotech. 2018, 13, 411-417.
platinum
monomers
in
CO
2
(28) Diercks, C. S.; Liu, Y. Z.; Cordova, K. E.; Yaghi, O. M. The
2
role of reticular chemistry in the design of CO reduction
catalysts. Nat. Mater. 2018, 17, 301-307.
(
12) Gao, G. P.; Jiao, Y.; Waclawik, E. R.; Du, A. J. Single atom
(Pd/Pt) supported on graphitic carbon nitride as an
efficient photocatalyst for visible-light reduction of
carbon dioxide. J. Am. Chem. Soc. 2016, 138, 6292-6297.
13) Katte, S.; Ramírez, P. J.; Chen, J. G.; Rodriguez, J. A.; Liu,
(29) Liu, C.; Colon, B. C.; Ziesack, M.; Silver, P. A.; Nocera, D.
G. Water splitting–biosynthetic system with CO
2
reduction efficiencies exceeding photosynthesis. Science
2016, 352, 1210.
(
(
(
P. Active sites for CO
2
hydrogenation to methanol on
(30) Choi, K. M.; Kim, D.; Rungtaweevoranit, B.; Trickett, C.
A.; Barmanbek, J. T. D.; Alshammari, A. S.; Yang, P. D.;
Yaghi, O. M. Plasmon-enhanced photocatalytic CO2
conversion within Metal-Organic Frameworks under
visible light. J. Am. Chem. Soc. 2016, 139, 356-362.
(31) Schreier, M.; Curvat, L.; Giordano, F.; Steier, L.; Abate,
A.; Zakeeruddin, S.; Luo, J.; Mayer, M. T.; Gratzel, M.
Cu/ZnO catalysts. Science 2017, 355, 1296-1299.
14) Rao, H.; Schmidt, L. C.; Bonin, J.; Robert, M. Visible-
light-driven methane formation from CO
2
with a
molecular iron catalyst. Nature 2017, 548, 74-77.
15) Kajiwara, T.; Fujii, M.; Tsujimoto, M.; Kobayashi, K.;
Higuchi, M.; Tanaka, K.; Kitagawa, S. Photochemical
reduction of low concentrations of CO
2
in a porous
Efficient photosynthesis of carbon monoxide from CO
2
using perovskite photovoltaics. Nat. Commun. 2015, 6,
7326.
coordination polymer with a ruthenium(II)–CO complex.
Angew. Chem. Int. Ed. 2016, 55, 2697-2700.
(
(
16) Chen, Y.; Ji, G. P.; Guo, S. E.; Yu, B.; Zhao, Y. F.; Wu, Y. Y.;
Zhang, H. Y.; Liu, Z. H.; Han, B. X.; Liu, Z. M. Visible-
(32) Kuehnel, M. F.; Orchard, K. L.; Dalle, K. E.; Reisner, E.
2
Selective photocatalytic CO reduction in water through
light-driven conversion of CO
ionic liquid and a conjugated polymer. Green Chem. 2017,
9, 5777-5781.
2
from air to CO using an
anchoring of molecular Ni catalyst on CdS
a
nanocrystals. J. Am. Chem. Soc. 2017, 139, 7217.
1
(33) Sun, W. M.; Yeung, M. T.; Lech, A. T.; Lin, C. W.; Lee, C.;
Li, T. Q.; Duan, X. F.; Zhou, J.; Kaner, R. B. High surface
17) Guan, Y. B.; Xia, M.; Marchetti, A.; Wang, X. H.; Cao, W.
C.; Guan, H. X.; Kong, X. Q. Photocatalytic reduction of
CO2 from simulated flue gas with colored anatase. Catal.
2018, 8, 78.
area tunnels in hexagonal WO
4838.
3
. Nano Lett. 2015, 15, 4834-
(34) Lu, Z. Y.; Chen, G. X.; Siahrostami, S.; Chen, Z. H.; Liu, K.;
Xie, J.; Liao, L.; Wu, T.; Lin, D. C.; Liu, Y. Y.; Jaramillo, T.
F.; Nørskov, J. K.; Cui, Y. High-efficiency oxygen
reduction to hydrogen peroxide catalysed by oxidized
carbon materials. Nat. Catal. 2018, 1, 156-162.
(35) Wang, L.; Ghoussoub, M.; Wang, H.; Shao, Y.; Sun, W.;
Tountas, A. A.; Wood, T. E.; Li, H.; Loh, J. Y. Y.; Dong, Y.
C.; Xia, M. K.; Li, Y.; Wang, S. H.; Jia, J.; Qiu, C. Y.; Qian,
C. X.; Kherani, N. P.; He, L.; Zhang, X. H.; Ozin, G. A.
Photocatalytic hydrogenation of carbon dioxide with
high selectivity to methanol at atmospheric pressure.
Joule 2018, 2, 1369-1381.
(36) Ye, M. H.; Wang, X.; Liu, E. Z.; Ye, J. H.; Wang, D. F.
Boosting the photocatalytic activity of P25 for carbon
dioxide reduction by using a surface-alkalinized titanium
carbide MXene as cocatalyst. Chemsuschem. 2018, 11,
1606-1611.
2
(18) Gallagher, J. CO reduction: Boron in its element. Nat.
Energy 2017, 2, 17081.
(
(
(
19) Zhang, X.; Li, X. Q.; Zhang, D.; Su, N. Q.; Yang, W. T.;
Everitt, H. O.; Liu, J. Product selectivity in plasmonic
photocatalysis for carbon dioxide hydrogenation. Nat.
Comm. 2017, 8, 14542.
20) Liang, L.; Li, X. D.; Sun, Y. F.; Tan, Y. L.; Jiao, X. C.; Ju, H.
X.; Qi, Z. M.; Zhu, J. F.; Xie, Y. Infrared light-driven CO
overall splitting at room temperature. Joule 2018, 2, 1004-
016.
2
1
21) Wang, X. N.; Wang, F. L.; Sang, Y. H.; Liu, H. Full-
spectrum solar-light-activated photocatalysts for light-
chemical energy conversion. Adv. Energy Mater. 2017, 7,
1
700473.
(22) Kong, X. Y.; Tan, W. L.; Ng, B. J.; Chai, S. P.; Mohamed,
A. R. Harnessing Vis-NIR broad spectrum for
photocatalytic CO2 reduction over carbon quantum
(37) Chen, X. Y.; Zhou, Y.; Liu, Q.; Li, Z. D.; Liu, J. G.; Zou, Z.
dots-decorated ultrathin Bi
017, 10, 1720-1731.
2
WO
6
nanosheets. Nano Res.
G. Ultrathin, single-crystal WO
dimensional oriented attachment toward enhanced
photocatalystic reduction of CO into hydrocarbon fuels
3
nanosheets by two-
2
(
23) Chen, Y.; Jia, G.; Hu, Y. F.; Fan, G. Z.; Tsang, Y. H.; Li, Z.
2
S.; Zou, Z. G. Two-dimensional nanomaterials for
photocatalytic CO reduction to solar fuels. Sustainable
2
Energy Fuels 2017, 1, 1875-1898.
under visible light. ACS Appl. Mater. Interfaces 2012, 4,
3372-3377.
(38) Adachi, K.; T Asahi, T. Activation of plasmons and
polarons in solar control cesium tungsten bronze and
reduced tungsten oxide nanoparticles. J. Mater. Res. 2012,
27, 965-970.
(39) Salje, E.; Guttler, B. Anderson transition and
intermediate polaron formation in WO3-x Transport
(
(
24) Lingampalli, S. R.; Ayyub, M. M.; Rao, C. N. R. Recent
progress in the photocatalytic reduction of carbon
dioxide. ACS Omega 2017, 2, 2740-2748.
25) Abdellah, M.; El-Zohry, A. M.; Antila, L. J.; Windle, C. D.;
Reisner, E.; Hammarström, L. Time-resolved IR
spectroscopy reveals a mechanism with TiO
2
as a
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properties and optical absorption. Philos. Mag. B 1984,
1
2
3
4
5
6
7
8
9
50, 607-620.
40) Deneuville,
(
A.;
Gerard,
P.
J.
Influence
of
substoichiometry, hydrogen content and crystallinity on
the optical and electrical properties of H WO thin films.
x y
J. Electron. Mater. 1978, 7, 559.
(
41) Niklasson, G. A.; Klasson, J.; Olsson, E. Polaron
absorption in tungsten oxide nanoparticle aggregates.
Electrochim. Acta 2001, 46, 1967-1971.
(42) Li, J.; Wu, X. Y.; Pan, W. F.; Zhang, G. K.; Chen, H.
Vacancy-rich monolayer BiO2−x as a highly efficient UV,
Visible, and Near-Infrared responsive photocatalyst.
Angew. Chem. Int. Ed. 2018, 57, 491-495.
1
1
1
1
1
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9
0
Figure 1. PCR performances of the M0.33WO
49 as well as WO under full spectrum light irradiation; (b) the variation contents of CO
photocatalytic process over the sample Rb0.33WO
the sample Rb0.33WO under full spectrum light irradiation for 4 h each time; (d) CO
samples under NIR light irradiation; (e) the variation contents of CO and product during photocatalytic process over
the sample Rb0.33WO under NIR light irradiation; and (f) CO reduction activities of the sample Rb0.33WO with
respect to divergence atmosphere and CO
3
samples. (a) CO
2
reduction activities of M0.33WO
3
series, Rb0.33WO3.165 and
and products during
W
18
O
3
2
3
under full spectrum light irradiation; (c) photocatalytic stability of
reduction activities of the
3
2
2
3
2
3
2
concentrations under NIR light irradiation.
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Figure 2. (a) XRD patterns of samples, (b) crystal structure, (c) TEM, (d) element mapping, (e) HRTEM image and (f)
SAED pattern of the sample Rb0.33WO .
3
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Figure 3. The optimized structure of CO
, respectively. (c) CO adsorption isotherms; (d) CO
3 49
without O ; and (e) O TPD spectra of the samples Rb0.33WO and W18O .
2
adsorbed on the surface of {001} (a) and {010} (b) facets for the sample
Rb0.33WO
3
2
2
TPD spectra of the samples conducted in simulated air
2
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Figure 4. Optical properties and mechanism. (a), DRS spectra of the samples. (b), Calculated dielectric functions of
3
the sample Rb0.33WO . (c), Energy loss function derived from b. (d), W 4f XPS spectra of the samples. (e), Magnified W
L
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-edge XANES spectra of the samples. (f), TDOS spectra of the samples.
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Journal of the American Chemical Society
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2 3 3
Figure 5. PCR mechanism. Free energy diagrams for reduction of CO to CH OH over the sample Rb0.33WO and
comparison hexagonal WO
steps from 1-7.
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based on DFT calculation as well as corresponding structure models for every reaction
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Journal of the American Chemical Society
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Table of Contents
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