Hierarchical Co0.85Se-CdSe/MoSe2/CdSe Sandwich-Like Heterostructured Cages for Efficient Photocatalytic CO2 Reduction

Article abstract of DOI:10.1002/smll.202100412

Fabricating efficient photocatalysts with rapid charge carrier separation and high visible light harvesting is an advisable strategy to improve CO₂ reduction performance. Herein, hierarchical Co_0.85Se-CdSe/MoSe₂/CdSe cages with sandwich-like heterostructure are prepared to act as efficient photocatalysts for CO₂ reduction. In this study, the structure and composition of the final products can be regulated through the cation-exchange reaction in the presence of ascorbic acid. In the Co_0.85Se-CdSe/MoSe₂/CdSe cages, MoSe₂ nanosheets function as a bridge to integrate Co_0.85Se-CdSe and CdSe on both sides of the MoSe₂ nanosheet shell into a sandwich-like heterostructured catalyst system, which possesses multiple positive merits for photocatalysis, including accelerated transport and separation of photogenerated carriers, improved visible light utilization, and increased catalytic active sites. Thus, the optimized Co_0.85Se-CdSe/MoSe₂/CdSe cages exhibit remarkable visible-light photocatalytic performance and outstanding stability for CO₂ reduction with a high CO average yield of 15.04?μmol g^?1 h^?1 and 90.14% selectivity, which are much higher than those of other control samples including single-component catalysts and binary hybrid catalysts. This study provides a promising way for the design and fabrication of high-efficiency photocatalysts.

Full text of DOI:10.1002/smll.202100412

ReseaRch aRticle
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Hierarchical Co0.85Se-CdSe/MoSe2/CdSe Sandwich-Like
Heterostructured Cages for Efficient Photocatalytic CO2
Reduction
Lizhi Du, Yajie Chen,* Qi Wang, Yumeng Zhao, Longge Li, Xiu Liu, and Guohui Tian*
few catalytic sites.[5] Therefore, exploring
heterogeneous photocatalysts with excel-
lent performance and high stability has
drawn increasing research attention.
Fabricating efficient photocatalysts with rapid charge carrier separation and
high visible light harvesting is an advisable strategy to improve CO2 reduc-
tion performance. Herein, hierarchical Co0.85Se-CdSe/MoSe2/CdSe cages
with sandwich-like heterostructure are prepared to act as efficient photocata-
lysts for CO2 reduction. In this study, the structure and composition of the
final products can be regulated through the cation-exchange reaction in the
presence of ascorbic acid. In the Co0.85Se-CdSe/MoSe2/CdSe cages, MoSe2
nanosheets function as a bridge to integrate Co0.85Se-CdSe and CdSe on both
sides of the MoSe2 nanosheet shell into a sandwich-like heterostructured
catalyst system, which possesses multiple positive merits for photocatalysis,
including accelerated transport and separation of photogenerated carriers,
improved visible light utilization, and increased catalytic active sites. Thus,
the optimized Co0.85Se-CdSe/MoSe2/CdSe cages exhibit remarkable visible-
light photocatalytic performance and outstanding stability for CO2 reduction
with a high CO average yield of 15.04 µmol g−1 h−1 and 90.14% selectivity,
which are much higher than those of other control samples including single-
component catalysts and binary hybrid catalysts. This study provides a prom-
ising way for the design and fabrication of high-efficiency photocatalysts.
Some of metal selenides (e.g., CoSe,
CdSe, and ZnSe) are intriguing materials for
photocatalytic applications because of their
excellent optical properties, suitable band
gaps, and good electron mobility.[6] Never-
theless, the photocorrosion problem is an
inherent drawback of metal selenides.[7] It
is, therefore, vital to inhibit photocorrosion
via advanced surface engineering methods.
The addition of carbon coating has been
proved to be effective in inhibiting the pho-
tocorrosion.[8] Generally, single metal sele-
nide often results in rapid photogenerated
charge carrier recombination that limits
electron utilization. It is gratifying that the
construction of heterojunctions has been
widely adopted to facilitate the separation
of photogenerated charge and inhibit photo-
corrosion, thus enhancing photo (electro)
catalytic activity and stability.[9]
In recent years, the heterostructure composites composed
of different metal selenides have been often used to sensitize
wide bandgap semiconductor materials such as, ZnSe/CdSe
sensitized ZnO/CuxS core–shell nanowire array and ZnSe/
CdS/CdSe sensitized TiO2 photoelectrodes.[10] These hetero-
structured metal selenides function as an efficient absorber to
capture visible light and meanwhile improve the transportation
and separation of the photoinduced charge carriers. Thus, these
co-sensitization structures have exhibited greater efficiency
than the corresponding single metal selenide sensitized photo-
electrodes.[11] In our recent study, we have prepared prepared
NiSe-Ni0.85Se heterostructure nanoflake arrays on carbon paper
(CP).[12] The enhanced electric conductivity caused by the syn-
ergistic effects of NiSe and Ni0.85Se make NiSe-Ni0.85Se/CP
exhibit much higher overall water splitting performance than
the single Ni0.85Se/CP and NiSe/CP. Furthermore, the design
of the nanojunctions also influences the photo (electro) cata-
lytic performances.[13] Recent research demonstrates that multi-
junction nanomaterials have shown higher efficiency than the
corresponding single-junction nanomaterials.[14] The main
reason is that single-junction nanomaterials often result in
rapid charge–carrier recombination. Therefore, rational design
of metal selenide heterostructure hybrids with multi-junctions
is an effective way to improve the photocatalytic performance.
1. Introduction
With the rapid consumption of fossil resources, environmental
problems are becoming more and more serious.[1] The rapid
increase of atmospheric CO2 concentrations creates serious
greenhouse effect.[2] Among various technologies used for CO2
conversion, semiconductor photocatalysis has been regarded
as a promising technical solution to convert CO2 into valuable
chemicals because it can utilize clean solar energy in a sustain-
able manner.[3] In recent years, lots of semiconductors like TiO2,
CeO2, and CdS have been widely studied in the field of photoca-
talysis.[4] Nevertheless, the CO2 conversion efficiencies of semi-
conductor photocatalysts are relatively low due to poor charge
carrier separation, low visible light utilization, and relatively
L. Z. Du, Prof. Y. J. Chen, Q. Wang, Y. M. Zhao, L. G. Li,
X. Liu, Prof. G. H. Tian
Key Laboratory of Functional Inorganic Material Chemistry
Ministry of Education of the People’s Republic of China
Heilongjiang University
Harbin 150080, P. R. China
E-mail: chenyajie1970@163.com; tiangh@hlju.edu.cn
The ORCID identification number(s) for the author(s) of this article
can be found under https://doi.org/10.1002/smll.202100412.
DOI: 10.1002/smll.202100412
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Similar to MoS2, recently, MoSe2 has gained great atten-
tion for photocatalytic application due to its proper electronic
properties, high chemical stability, and good surface adsorption
ability.[15] In contrast with MoS2, MoSe2 has a higher electrical
conductivity, which contributes to the improvement of photo-
catalytic activity.[16] Moreover, constructing heterostructured
photocatalysts by coupling MoSe2 with other semiconductors is
considered to be an effective strategy to enhance photocatalytic
activity.[17] Inspired by these findings, it is expected to control-
lably construct MoSe2-based multi-junction metal selenide het-
erostructures for photocatalytic CO2 generation.
As it is well known, catalyst morphology greatly influences
the quantity of accessible active sites and incident light uti-
lization.[18] Therefore, it is critical to delicately design and
rationally fabricate heterojunction photocatalysts with suitable
architectures.[19] So far, numerous hollow structured photocata-
lysts have been rationally designed in solar energy conversion
applications owing to their advantages of reduced bulk-to-
surface transfer distance of charge carriers, abundant catalytic
active sites, and increased optical utilization ability.[20] Especially
for the hollow core/shell heterostructure in which semicon-
ductor nanosheets are grown on the hollow core substrate, the
merits mentioned above play a more positive role in improving
solar-to-fuels energy conversion.[21] Furthermore, the preferred
nanosheet-like nature of the semiconductor shell is advanta-
geous to load nanoparticles to construct hollow tandem het-
erojunction photocatalysts, which makes it possible for hybrid
catalysts to further boost the photocatalytic performance.[22]
Therefore, it might be expected to fabricate efficient photocata-
lysts with desired components and advanced structure.
Inspired by the aforementioned considerations, herein, we
provide a rational approach to prepare hierarchical Co0.85Se-
CdSe/MoSe2/CdSe sandwich-like heterostructured cages.
Starting from ZIF-67 polyhedron precursors, Co0.85Se polyhe-
dron cages are produced via the selenylation process (Figure 1).
Afterward, Co0.85Se polyhedron cages acted as substrate to load
MoSe2 nanosheets and construct Co0.85Se/MoSe2 hollow double-
shell hybrid cages. In Co0.85Se/MoSe2 cages, MoSe2 nanosheets
act as photocatalyst, and meanwhile were used as substrate to
load CdSe nanoparticles formed via the cation-exchange reac-
tion between Co0.85Se and Cd2+ in the presence of ascorbic
acid. The addition of ascorbic acid is critical to accomplish the
conversion from Co0.85Se to CdSe via ion exchange and realize
the construction of Co0.85Se-CdSe/MoSe2/CdSe sandwich-like
tandem heterostructured cages. There is a synergistic effect
between Co0.85Se, CdSe, and MoSe2. MoSe2 nanosheets func-
tion as a bridge to link Co0.85Se-CdSe and CdSe on both sides
of the MoSe2 nanosheet shell into an integral tandem system.
Thus, the separation of photogenerated charge carriers in the
Co0.85Se-CdSe/MoSe2/CdSe sandwich-like tandem heterostruc-
ture can be effectively realized compared with that of the single
or binary components. The accumulated photogenerated elec-
trons on the surface of MoSe2 nanosheets are beneficial for
the multi-electron photocatalytic CO2 reduction. Moreover,
the novel hierarchical hollow sandwich-like cages significantly
enhance visible light utilization and increase catalytic active
sites. As expected, the optimized Co0.85Se-CdSe/MoSe2/CdSe
sandwich-like cages exhibit remarkably improved performance
for visible light CO2 photoreduction as compared with single
catalysts (Co0.85Se, CdSe, and MoSe2) and binary hybrid cata-
lysts (Co0.85Se/MoSe2, CdSe/MoSe2, and CdSe/MoSe2/CdSe).
2. Results and Discussion
2.1. Characterizations of Catalysts
The ZIF-67 crystals were successful prepared according to the
X-ray powder diffraction (XRD) characterization (Figure S1, Sup-
porting Information) and showed typical microporous charac-
ters (Figure S2, Supporting Information). The scanning electron
microscopy (SEM) and transmission electron microscopy (TEM)
characterizations verify the rhombic dodecahedral shape of the
prepared ZIF-67 crystals with a smooth surface and a particle
size of ≈2 0.3 µm (Figure 2a,b). After the selenylation reaction,
the produced product is confirmed to be Co0.85Se from the XRD
pattern in Figure 2c. The Co0.85Se well inherits the basic dodeca-
hedral shape of the original ZIF-67 (Figure 2d). The TEM image
(Figure 2e) unambiguously validates the interior hollow dodeca-
hedron cage-like structure. In the high-resolution TEM (HRTEM)
image (Figure 2f), the lattice distance of 0.265 nm is indexed
to the (101) plane of Co0.85Se.[23] The SEM and TEM images
(Figure 2g,h) of the Co0.85Se/MoSe2 cages confirm that MoSe2
nanosheets are uniformly covered on the Co0.85Se cages. The
HRTEM image (Figure 2i) of the outermost MoSe2 nanosheets
shows a clear lattice fringe of 0.634 nm, which corresponds
to the (002) plane of MoSe2. Meanwhile, the diffraction peaks
corresponding to (002) and (102) planes of MoSe2 (JCPDS no
29–0914) were also found in the XRD pattern of Co0.85Se/MoSe2
(Figure 2c). The results indicate the formation of the Co0.85Se/
MoSe2 hollow double-shell heterostructured cages.[24] The scan-
ning transmission electron microscopy (STEM) image and the
energy-dispersive X-ray spectroscopy (EDS) element mapping
images reveal the distribution of Co, Se, and Mo elements
Figure 1. Schematization of the synthesis of hierarchical Co0.85Se-CdSe/MoSe2/CdSe sandwich-like cages.
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Figure 2. a,b) SEM and TEM images of ZIF-67. c) XRD patterns of different samples. d,e,f) SEM, TEM, and HRTEM images of Co0.85Se. g,h,i) SEM,
TEM, and HRTEM images of Co0.85Se/MoSe2.
within the Co0.85Se/MoSe2 cages (Figure S3, Supporting Infor-
mation). Se element is located throughout the shell, while the
Co and Mo elements localize toward the inner and outer layers
of the shell, respectively, demonstrating the formation of double-
layer heterostructure cages. The results further demonstrate
the successful synthesis of strongly coupled Co0.85Se/MoSe2
heterostructured cages. Meanwhile, a small amount of carbon
derived from the ZIF-67 precursor can be found in the EDX
spectrum (Figure S4, Supporting Information). Moreover, to
optimize photocatalytic performance, the Co0.85Se/MoSe2 sam-
ples with different amounts of MoSe2 nanosheets were also
successfully prepared by changing the amounts of starting mate-
rials (verified by the XRD patterns and energy dispersive X-ray
(EDS) spectra (Figure S4, Supporting Information)). Moreover,
there were obvious surface morphology differences of Co0.85Se/
MoSe2 samples with different MoSe2 amounts (Figure S5, Sup-
porting Information). For comparison, pure MoSe2 was also pre-
pared and showed significant aggregation behavior (Figure S6,
Supporting Information). Therefore, Co0.85Se cages are valuable
for building hollow double-shell heterostructures with strong
interface interaction.
After the Cd2+ ions exchange reaction, Co0.85Se-CdSe/MoSe2/
CdSe sandwich-like cages were successfully produced, which
was confirmed from the XRD pattern (Figure S7, Supporting
Information). The obtained Co0.85Se-CdSe/MoSe2/CdSe cages
well maintained the overall morphology of Co0.85Se/MoSe2
cages (Figure 3a,b,d). Furthermore, some nanoparticles are
uniformly anchored on the surface of MoSe2 nanosheets
(Figure 3c–e). In the HRTEM image (Figure 3f), clear lattice
fringes of 0.378 and 0.634 nm correspond to the CdSe (100)
plane and MoSe2 (002) plane, respectively.[25] The EDS spec-
trum (Figure S8, Supporting Information) suggests the pres-
ence of Co, Cd, Se, and Mo in the hybrid cages together with
a minor amount of carbon. The STEM image (Figure 3g) and
element mappings of Co0.85Se-CdSe/MoSe2/CdSe sandwich-like
cages reveal the differentiated distribution of Co, Cd, Se, and
Mo elements throughout the cages. The EDS line-scan profile
(Figure 3h) across a single isolated cage suggests Se and Cd are
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Figure 3. a–c) FESEM, d,e) TEM, and f) HRTEM images of the Co0.85Se-CdSe/MoSe2/CdSe sandwich-like cages. g) STEM image and corresponding
elemental mappings for Co (yellow), Cd (purple), Mo (red), and Se (green) elements of an individual Co0.85Se-CdSe/MoSe2/CdSe cage. h) SEM image
and corresponding EDS elemental line profiles of Co0.85Se-CdSe/MoSe2/CdSe.
located throughout the shell, while the concentration of Co is
higher in the inner region of the shell. These results further
demonstrate that the cation exchange reaction initiates from
the inner shell region and leads to the formation of sandwich-
like heterostructures with Co0.85Se-CdSe and CdSe in the inner
and outer shell regions, respectively.
The schematic of the synthesis of hierarchical Co0.85Se-
CdSe/MoSe2/CdSe cages with sandwich-like heterostructure is
depicted in Figure 1. In the first step, Co0.85Se cages were pre-
pared by the selenylation of ZIF-67 under hydrothermal con-
ditions. During the hydrothermal process, Co2+ ions in ZIF-67
were released from ZIF-67 and reacted with the produced Se2−
ions to form a layer of Co0.85Se around the ZIF-67 polyhedrons.
As the reaction went on, the inner part of ZIF-67 polyhedrons
became vulnerable, and the outward diffusing Co2+ ions further
reacted with inward diffusing Se2− ions, leading to the forma-
tion of Co0.85Se polyhedron cages. In the second step, ultrathin
MoSe2 nanosheets were grown on the surface of Co0.85Se cages
to form Co0.85Se/MoSe2 heterostructured hollow double-shell
cages through a solvothermal reaction. In the third step, the
cation exchange reaction between Cd2+ ions and Co2+ ions hap-
pened. In this reaction system, ascorbic acid (Vc) acts as a mild
reducing agent. The presence of Vc can realize and promote
the incorporation of guest Cd2+ cations by breaking the Se Se

bonds similar to the cation exchange reaction between Cd2+
and Cu2−xS.[26] So Co0.85Se in the inner layer of Co0.85Se/MoSe2
double-shell cages can be in situ converted into CdSe. The
control experiments show that Co0.85Se cannot be converted
into CdSe in the absence of Vc according to XRD characteri-
zation (Figure S9, Supporting Information). The SEM, TEM,
and HRTEM images (Figure S10, Supporting Information)
confirmed that CdSe was successfully prepared and kept the
original morphology of Co0.85Se polyhedron cages. Meanwhile,
partial Cd2+ replacement of Co0.85Se was also realized according
to XRD (Figure S11, Supporting Information) and SEM charac-
terizations (Figure S12, Supporting Information). While MoSe2
keeps its initial phase structure, and cannot be replaced in the
presence of Vc (Figure S13, Supporting Information). Due to
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Figure 4. High-resolution XPS spectra of a) Se, b) Mo 3d, c) Cd 3d, and d) Co 2p of different samples.
the different elemental stoichiometric ratios in Co0.85Se and
CdSe, some Se2− ions released from Co0.85Se penetrate to the
outer surface of hybrid cages and react with Cd2+ ions on the
outermost of MoSe2 nanosheets to produce CdSe nanoparticles.
By controlling cation exchange reaction time, the compositions
of the products can be regulated effectively. When reaction time
is moderate, Co2+ ions were partially exchanged by Cd2+, and
hierarchical Co0.85Se-CdSe/MoSe2/CdSe sandwich-like hetero-
structured cages could be obtained (Figures S14 and S15, Sup-
porting Information). When reaction time is long enough (6 h),
Co2+ ions were entirely exchanged by Cd2+; the final product is
CdSe/MoSe2/CdSe (Figure S16, Supporting Information). The
SEM, TEM, and HRTEM images (Figure S17, Supporting Infor-
mation) elucidated that the morphology and structure of CdSe/
MoSe2/CdSe are similar to that of Co0.85Se-CdSe/MoSe2/CdSe
sandwich-like heterostructured cages.
The element valence states and heterointerface interactions
of the Co0.85Se-CdSe/MoSe2/CdSe cages were studied by X-ray
photoelectron spectroscopy (XPS). In Figure 4a, the Se 3d
spectra show two peaks at 54.2 and 55.1 eV, which are attributed
to Se 3d5/2 and Se 3d3/2, respectively, revealing the oxidation
state of Se2− (Figure 4a).[27] For pure MoSe2, the binding ener-
gies of Mo 3d5/2 and Mo 3d3/2 are located at 228.8 and 231.9 eV,
respectively, highlighting the existence of Mo4+ (Figure 4b).[28]
Whereas, the Mo 3d peaks of Co0.85Se-CdSe/MoSe2/CdSe shifted
toward higher binding energy positions (Figure 4b). The shift
of the binding energies of Cd 3d in Co0.85Se-CdSe/MoSe2/CdSe
to lower binding energies was found as compared to those in
CdSe (Figure 4c). In Co 2p XPS spectrum of Co0.85Se, the peaks
at 792.78 and 777.64 eV belong to the Co 2p1/2 and Co 2p3/2 of
Co3+, respectively. The two peaks located at 796.09 and 779.79 eV
belong to the Co 2p1/2 and Co 2p3/2 of Co2+, respectively.[29] Com-
pared with Co0.85Se, these peaks of Co0.85Se-CdSe/MoSe2/CdSe
shifted to the higher binding energy positions. The Co 2p XPS
spectrum of Co0.85Se shows two peaks at 785.9 and 802.5 eV,
which are assigned to the satellite peaks of Co 2p3/2 and Co 2p1/2
,
respectively (Figure 4d). These results suggest strong electronic
and chemical interactions among Co0.85Se, CdSe, and MoSe2 in
Co0.85Se-CdSe/MoSe2/CdSe cages.
In the UV–vis diffuse reflectance spectra (Figure 5a), a broad
optical absorption can be observed in the visible light region.
Compared to Co0.85Se, MoSe2, and Co0.85Se/MoSe2, the Co0.85Se-
CdSe/MoSe2/CdSe has an increased visible light absorption. But
its visible light absorption is lower than that of CdSe and CdSe/
MoSe2/CdSe. The band gap energies (calculated from the Tauc
plots) of Co0.85Se, CdSe, MoSe2, and Co0.85Se-CdSe/MoSe2/CdSe
are 1.66, 1.68, 1.65, and 1.67 eV, respectively (Figure 5b). Thus,
electron−hole pairs can be generated by exciting these samples
under visible light irradiation.
The results of N2 adsorption–desorption tests show that the
samples possess type IV isotherms, indicating the existence of
mesopores (Figure 5c; Figure S18, Supporting Information).
The surface area (61 m2 g−1) and pore volume (0.154 cm3 g−1) of
the Co0.85Se-CdSe/MoSe2/CdSe sandwich-like cages are larger
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Figure 5. a) UV–vis absorption spectra. b) The corresponding Tauc plots. c) N2 adsorption and desorption isotherms. d) CO2 adsorption isotherms
at 273.15 K.
than those of the other control samples (Table S1, Supporting
Information). Large surface area and abundant mesopores can
provide more active sites for CO2 photoreduction reaction. The
CO2 adsorption isotherms of different samples were shown in
Figure 5d. As expected, the Co0.85Se-CdSe/MoSe2/CdSe showed
significantly increased CO2 adsorption capacity than Co0.85Se,
MoSe2, and Co0.85Se/MoSe2. The higher affinity of Co0.85Se-
CdSe/MoSe2/CdSe toward CO2 gas can increase the chance of
proton capture by intermediates formed in the CO2 photore-
duction process and accelerate the whole photocatalytic reduc-
tion reaction rate of CO2 to CO and CH4.
photoinduced charges caused by the formed heterojunctions
in Co0.85Se/MoSe2 cages. Moreover, the loading amounts of
MoSe2 nanosheets on Co0.85Se cages also influence CO2 photo-
reduction performance of Co0.85Se/MoSe2 cages. The CO
evolution rate of Co0.85Se/MoSe2 cages first increases and
then decreases with increasing the loading amounts of MoSe2
nanosheets (Figure S19, Supporting Information). The increase
of MoSe2 nanosheets can enhance surface area. whereas
the excessive MoSe2 loading amount leads to the extension of the
diffusion length of photogenerated carriers and the existence
of separated MoSe2 nanosheets (Figure S5, Supporting Infor-
mation). So the Co0.85Se/MoSe2 cages with moderate loading
amounts of MoSe2 nanosheets exhibit optimal photocatalytic
CO2 reduction performance. Strikingly, the optimized hierar-
chical Co0.85Se-CdSe/MoSe2/CdSe sandwich-like heterostruc-
tured cages present the highest CO and CH4 yield rates of 15.04
and 0.41 µmol g−1 h−1, respectively, which are remarkably supe-
rior to those of Co0.85Se, MoSe2, CdSe, and Co0.85Se/MoSe2.
The selectivity of the main product CO is 90.17% (Table S2, Sup-
porting Information). Meanwhile, the photocatalytic activities
of Co0.85Se-CdSe/MoSe2/CdSe-0.5 with low Cd2+ replacement
degree, Co0.85Se-CdSe/MoSe2/CdSe-1.5 with high Cd2+ replace-
ment degree, and CdSe/MoSe2/CdSe are much inferior to
that of the optimized Co0.85Se-CdSe/MoSe2/CdSe (Figure S20,
Supporting Information). The enhanced CO2 reduction per-
formance of Co0.85Se-CdSe/MoSe2/CdSe originates from the
unique sandwich-like heterostructure and ternary composi-
tional features. The hollow cage-type polyhedron can not only
implement multiple reflections inside the cage to improve
visible light utilization, but also serve as a suitable substrate
2.2. Photocatalytic Activity Tests
The photocatalytic activities toward CO2 photoreduction of dif-
ferent catalysts were evaluated. In this photocatalysis system,
CO was produced as the major product, and meanwhile a
small amount of CH4 can also be detected. Figure 6a,b show
the evolution amounts of CO and CH4 from the CO2 photore-
duction during 4 h under visible-light irradiation, respectively.
The corresponding generation rates of CO and CH4 are shown
in Figure 6c. The bare Co0.85Se, CdSe, and MoSe2 show a rela-
tively low CO evolution rate of 4.54, 7.04, and 5.54 µmol g−1 h−1,
respectively, owing to the insufficient photogenerated charge
separation. As expected, the Co0.85Se/MoSe2 heterostruc-
tured cages show moderately enhanced CO evolution rate
of 6.65 µmol g−1 h−1 compared with the corresponding indi-
viduals. This enhanced CO2 photoreduction performance
mainly comes from the accelerated separation and transfer of
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Figure 6. Time courses of a) CO and b) CH4 production from different photocatalysts. c,d) Cycling tests of different catalysts. e) Average CO and CH4
generation rates over different catalysts. f) The gas chromatography–mass spectrometry analysis over Co0.85Se-CdSe/MoSe2/CdSe during the 13CO2
photoreduction.
for vertical growth of cross-linked MoSe2 thin nanosheets,
on which CdSe nanoparticles can be uniformly loaded. The
ingenious hierarchical Co0.85Se-CdSe/MoSe2/CdSe hetero-
structure successfully prevents the self-aggregation of MoSe2
thin nanosheets and CdSe nanoparticles, resulting in high
surface area and abundant exposed active edge sites. Mean-
while the formed sandwich-like tandem heterojunction facili-
tates the separation/transfer and efficient utilization of the
photogenerated charge carriers. Furthermore, the higher
affinity of Co0.85Se-CdSe/MoSe2/CdSe toward CO2 can increase
the chance of proton capture by intermediates formed and
accelerate the whole reaction rate in the photocatalytic CO2
reduction process. Moreover, the Co0.85Se-CdSe/MoSe2/CdSe
exhibits higher CO2 reduction performance than the control
Co0.85Se-CdSe/MoSe2 and CdSe/MoSe2 samples, further
confirming the importance of sandwich-like tandem hetero-
structure (Figure S21, Supporting Information).
In addition, apparent quantum yields and solar-to-chemical
fuel conversion efficiencies of the prepared photocatalysts were
calculated (Table S2, Supporting Information). The apparent
quantum yield (0.390%) and overall conversion efficiency
(0.036%) of Co0.85Se-CdSe/MoSe2/CdSe are higher than those
of the other control samples. Moreover, O2 formation rates of
the different samples were also quantified during CO2 photore-
duction process according to the previous report (Table S3 Sup-
porting Information).[30] The average yields of O2 from different
samples approximate their theoretical O2 evolution yields based
on the redox reaction mechanism. The results indicate that the
photogenerated electrons and holes participate in the reduction
and oxidation reactions during the CO2 photorduction. Among
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them, the O2 evolution yield of Co0.85Se-CdSe/MoSe2/CdSe is
the highest (7.59 µmol g−1 h−1).
carbon source of CO, 13CO2 labeling experiments were carried
out using 13CO2 as the reactant. The mass spectrum signals
revealed that only 13CO (m/z = 29) was produced (Figure 6f).
Such observations strongly corroborated that the CO indeed
originated from the photocatalytic reduction of CO2 reactant.
To deeply understand the formed intermediates and the
mechanism of chemical activation of CO2 molecules in the
photocatalytic CO2 reduction process, In situ Fourier transform
infrared (FTIR) spectra (Figure S24, Supporting Information)
of CO2 adsorpted on different catalysts under gas–solid condi-
tion were analyzed. Without visible light irradiation, exposing
Co0.85Se-CdSe/MoSe2/CdSe cages in CO2 shows negligible
signal. When irradiating Co0.85Se-CdSe/MoSe2/CdSe cages with
visible light, some peaks (1265, 1048 1438, 1512, and 1631 cm−1)
belonging to carbonate species were found. Some important
Notably, the reusability tests showed that the catalytic activi-
ties of single Co0.85Se, MoSe2, and CdSe show only slight
decrease after four consecutive cycles. The relatively high sta-
bility can be attributed to the existence of small amount of
carbon in the cages. Carbon coating has been proved to be
effective in inhibiting photocorrosion of metal chalcogenides.[31]
Especially, the Co0.85Se-CdSe/MoSe2/CdSe shows outstanding
stability after a long time test. The SEM image and XRD pat-
tern of Co0.85Se-CdSe/MoSe2/CdSe after four testing cycles
also demonstrate the intact morphology and crystal structure
(Figure S22, Supporting Information). The results showed
that the formed sandwich-like tandem heterostructure further
inhibited their photocorrosion.[32] Owing to their intimate inter-
facial contact and matched band position, the photogenerated
electrons of CdSe can transfer quickly to MoSe2 nanosheets.
On the other hand, the holes transfer to the other side to oxi-
dize H2O to form O2, thus suppressing the backward reaction
and photocorrosion. Notably, the CO evolution rate over the
Co0.85Se-CdSe/MoSe2/CdSe can be compared to that of the
best photocatalysts previously reported without sacrificial rea-
gent and noble-metal co-catalysts under similar test conditions
(Table S4, Supporting Information).
−
intermediates such as CO2 species (at 1258 and 1700 cm−1)
were observed. Moreover, the amounts gradually increased with
extending visible light irradiation time. It reveals that the pho-
tocatalytic reduction over the catalyst undergoes a multi-step
process involving CO2 molecules adsorption, production of
intermediates, and final conversion of CO2 into CO.
Steady-state fluorescence photoluminescence (PL) spectra
were employed to investigate the interface charge transfer prop-
erty of catalysts. The PL spectra in Figure 7a reveals one wide
strong mission peak at 440 nm in all the samples produced by
the recombination of the photoinduced electron−hole pairs.
However, significant fluorescence quenching from Co0.85Se-
CdSe/MoSe2/CdSe sample can be observed, revealing its greatly
inhibited electron−hole recombination. Moreover, the time-
resolved photoluminescence (TRPL) spectra (Figure 7b) show
that the average fluorescence lifetime (Table S5, Supporting
To verify the origin of CO and CH4, several controlled experi-
ments were conducted. No CO and CH4 were detected without
photocatalyst or under dark (Figure S23, Supporting Informa-
tion). Meanwhile, CO and CH4 were still not detected under
Ar atmosphere. The results confirm that the coexistence of
photocatalyst, light irradiation, and CO2 atmosphere is the
necessary condition for CO2 photoreduction. To prove the true
Figure 7. a) Steady-state fluorescence spectra and b) TRPL decay spectra. c) Transient photocurrent spectra. d) EIS Nyquist plots of different samples.
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Information) of Co0.85Se-CdSe/MoSe2/CdSe is longer than that
of Co0.85Se, CdSe, MoSe2, and Co0.85Se/MoSe2, which indicates
the hierarchical sandwich-like heterostructure can greatly accel-
erate the charge separation and extend the lifetime of photo-
generated carriers, further demonstrating more photogenerated
electrons can participate in CO2 photoreduction reaction.
The improved migration and separation of photogenerated
charge carriers in Co0.85Se-CdSe/MoSe2/CdSe were further
investigated by photoelectrochemical characterization tech-
niques. Transient photocurrent of Co0.85Se-CdSe/MoSe2/CdSe
is 8 µA cm−2, which is higher than that of Co0.85Se (2 µA cm−2),
MoSe2 (3 µA cm−2), Co0.85Se/MoSe2 (6 µA cm−2), and
CdSe/MoSe2/CdSe (7 µA cm−2) under visible light irradiation
(Figure 7c). Impressively, the chronoamperometry response of
Co0.85Se-CdSe/MoSe2/CdSe remains relatively constant. It indi-
cates that the tight coupling among Co0.85Se, CdSe, and MoSe2
contributes to achieving rapid charge transfer kinetics and
excellent structural stability. Meanwhile, the improved charge
transport kinetics in Co0.85Se-CdSe/MoSe2/CdSe is also verified
by the results of the electrochemical impedance spectra (EIS).
Figure 7d shows the Nyquist plots of different samples. The
corresponding equivalent circuit was presented in the inset.
The fitting parameters are listed in Table S6, Supporting Infor-
mation. The two resistances, Rct and Rs, are the charge transfer
resistance and series resistance, respectively. The capacitor
Cct refers to the capacitance at the surface. The formation of
sandwich-like heterostructured cage architecture resulted in
a remarkable decrease in Rct of Co0.85Se-CdSe/MoSe2/CdSe
compared with the other counterparts, thus promoting the
accelerated transfer and separation of charge carriers. In addi-
tion, Mott–Schottky tests were carried out to study the charge
transfer behavior of different samples (Figure S25, Supporting
Information). These Mott–Schottky curves showed positive
slopes, indicating these materials are n-type semiconductors.
The calculated carrier densities were listed in Table S7, Sup-
porting Information. Obviously, the Co0.85Se-CdSe/MoSe2/CdSe
shows the highest carrier densities (12.51 × 1019), which makes
a vital contribution to improving photocatalytic CO2 reduction
reactions.
Hence, the excellent performance for photocatalytic CO2
reduction of Co0.85Se-CdSe/MoSe2/CdSe can be attributed to its
hierarchical hollow sandwich-like heterostructured cage archi-
tecture, which serves as an integrated photocatalysis system
and plays multiple roles in the photocatalytic process. First,
the hierarchical hollow cage-type polyhedron can improve vis-
ible light utilization by multiple internal reflections of incident
light inside the cage and possess abundant exposed active sites
due to the high surface area and porous structure. Second, the
higher affinity of Co0.85Se-CdSe/MoSe2/CdSe toward CO2 can
increase the chance of proton capture by intermediates and
accelerate the whole reaction rate in the photocatalytic CO2
reduction process. Moreover, the formed sandwich-structured
tandem heterojunction facilitates the separation/transfer and
efficient utilization of the photogenerated charge carriers.
The tandem band alignments (Figure 8d) of Co0.85Se, CdSe,
and MoSe2 in Co0.85Se-CdSe/MoSe2/CdSe cages are determined
according to the reported method.[33] The Mott–Schottky plots
(Figure 8a–c) are applied to determine flat band potentials of the
different samples, which are close to the Fermi energy levels.
Together with XPS valence band (VB) spectra (Figure S26,
Supporting Information), the distances between the Fermi
energy level and VB are determined (Table S8, Supporting
Information). Thus, the valence band edge positions (EVB) of
different samples were obtained (Table S8, Supporting Informa-
tion). The band gaps (Eg) were calculated from the Tauc plots of
the UV–vis absorption spectra (Figure 5a,b). According to the
equation (Eg = EVB−ECB), the corresponding conduction band
edge positions (ECB) of the different samples were also deter-
mined (Table S8, Supporting Information). These band poten-
tials can drive CO2 photoreduction reaction (Figure 8d). Under
visible light irradiation, Co0.85Se, CdSe, and MoSe2 are excited
to produce electrons (e−) and holes (h+). Because the conduc-
tion band (CB) potentials of Co0.85Se and CdSe are more posi-
tive than that of MoSe2 (−0.71 V vs NHE), the photogenerated
electrons in the CB of Co0.85Se and CdSe can rapidly transfer
to the CB of MoSe2. In Co0.85Se-CdSe/MoSe2/CdSe tandem
heterojunction, MoSe2 nanosheets function as a bridge to link
Co0.85Se-CdSe and CdSe on both sides of the MoSe2 nanosheet
shell into an integral tandem system. Thus, the separation of
photogenerated charge carriers in Co0.85Se-CdSe/MoSe2/CdSe
sandwich-like tandem heterostructure can be realized. The
photogenerated electrons accumulated on the surface of MoSe2
nanosheets are beneficial for the multi-electron photocatalytic
CO2 reduction (Figure 8e). Meanwhile, the photogenerated
holes oxidate H2O to produce O2.
For Co0.85Se-CdSe/MoSe2/CdSe hybrid, its band alignment
was also determined using the previous report.[34] The valence
band energy (Ev) was determined to be 5.35 eV (21.22 − 19.88 +
4.01 = 5.35 eV) by ultraviolet photoeletron spectroscopy (UPS)
(Figure S27, Supporting Information), thus confirming the
suitable valence band position for O2 evolution. The band gap
energy (Eg) was calculated from the Tauc plot of the UV–vis
absorption spectrum (Figure 5a,b). Thus the conduction band
energy (Ec) of Co0.85Se-CdSe/MoSe2/CdSe was calculated to be
according to the formula: Ec = Ev − Eg. The band alignment
was listed in Figure S27b, Supporting Information. Obviously,
Co0.85Se-CdSe/MoSe2/CdSe meets the thermodynamic require-
ment for the photocatalytic CO2 reduction to CO and CH4.
The band alignment of Co0.85Se-CdSe/MoSe2/CdSe was also
checked using electrochemical method (Figure S28, Supporting
Information).[33a] The two results are close to each other. This
shows that the band alignment of Co0.85Se-CdSe/MoSe2/CdSe
can meet the thermodynamic requirement for the photocata-
lytic CO2 reduction to CO and CH4. Thus, the CO2 photoreduc-
tion can occur over Co0.85Se-CdSe/MoSe2/CdSe sandwich-like
tandem heterostructure cages.
3. Conclusion
In summary, the hierarchical Co0.85Se-CdSe/MoSe2/CdSe cages
with sandwich-structured tandem heterojunction were syn-
thesized to perform visible light photocatalytic CO2 reduction
reaction. The proposed synthetic strategy can realize rational
structure and composition control of the final hybrid products
with the assistance of ascorbic acid. The prepared hybrid cages
possess unique structure and component features including
sandwich-structured multi-interfacial contacts, accelerated
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Figure 8. Mott–Schottky plots of a) Co0.85Se, b) CdSe, and c) MoSe2. d) Band structure alignment of Co0.85Se, CdSe, and MoSe2. e) Schematics of the
Co0.85Se-CdSe/MoSe2/CdSe cages with sandwich-structured tandem heterojunctions for CO2 photoreduction.
charge separation and transfer, accelerated transportation of
CO2 molecules, enhanced visible light-harvesting, and abundant
4. Experimental Section
Preparation of Catalysts: ZIF-67 polyhedrons were synthesized
active sites for the CO2 reduction reaction. Consequently, the
optimized hierarchical Co0.85Se-CdSe/MoSe2/CdSe sandwich-
structured tandem heterojunction cages exhibit a high CO evo-
lution rate of 15.04 µmol g−1 h−1 and 90.17% selectivity, which is
remarkably superior to that of individual components and binary
heterojunction cages. This work suggests that rational architec-
ture design and compositional control of hybrid catalysts might
be expected to improve solar-to-fuel conversion efficiency.
according to
a g of
typical synthetic method.[35] First, 0.9850
2-methylimidazole and 0.8730 g of Co(NO3)2·6H2O were added to
the mixed alcoholic solution (10 mL ethanol and 10 mL methanol)
under magnetic stirring, respectively. After that, the alcoholic solution
containing 2-methylimidazole was quickly poured into the alcoholic
solution containing Co(NO3)2·6H2O, followed by stirring for 10 s. The
resulting mixture was then aged for 20 h under normal temperature.
Finally, the obtained purple precipitate was centrifuged and washed with
absolute ethanol and then dried at 60 °C overnight.
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Synthesis of Co0.85Se Dodecahedral Cages: 17.8 mg of NaBH4 and
8.8 mg of Se powder were added to ethanol (4 mL) to form a mixed
solution. Then, 6 mL of ethanol solution containing 22 mg ZiF-67 was
added into the above mixed-solution. The resulting mixture was put
into a 40 mL Teflon-lined autoclave and heated at 200 °C for 2 h. The
obtained material was rinsed with absolute ethanol and then dried at
60 °C overnight.
Synthesis of Hierarchical Co0.85Se/MoSe2 Core/Shell Heterostructured
Cages: Typically, 8 mg of Se powder and 15.6 mg of NaBH4 were added to
ethanol (4 mL) to form a mixed-solution. Then, 2 mL of Na2MoO4·2H2O
solution (0.05 mm) was added to the above mixed-solution, followed by
stirring for 20 min. After that, 10 mL ethanol solution containing certain
amounts of the Co0.85Se cages (15, 22, and 34 mg) was added into the
above mixed-solution and stirred for 30 min. The resulting mixture was
put into a 40 mL Teflon-lined autoclave and heated at 200 °C for 10 h.
The obtained materials were rinsed with absolute ethanol and then dried
at 60 °C overnight. The obtained samples were denoted as 0.5-Co0.85Se/
MoSe2, Co0.85Se/MoSe2 and 2-Co0.85Se/MoSe2, respectively.
Photocatalytic Tests for CO2 Reduction: The CO2 photoreduction
experiments were carried out in a gas-solid reactor (80 mL, PLS-SXE300,
Perfectlight, China). A 300 W Xe lamp with a 400 nm bandpass filter
was used as the visible light source. Before the tests, the photocatalyst
powder (30 mg) was placed on a glass sheet (2.5 cm × 2.5 cm) support
in the reactor, and geometric surface area of catalyst was 1 cm2. The
high-purity CO2 was bubbled into the reactor to reach ambient pressure
through deionized water. After equilibration for 30 min, the reactor was
sealed and exposed to the visible light. A circulation water system was
applied to maintain reaction temperature at ≈293 K. After every 1 h of
reaction, 1 mL reactant gas was taken and quantified with GC7900 gas
chromatograph. 13CO2 gas was used to detect carbon source on the
quadrupole-type mass spectrometer (OmniStar 300). 13CO2 gas (Beijing
Gaisi Chemical Gases Company) was applied to detect carbon source on
the GC-MS analyzer (Agilent 6890N/5973N).
Supporting Information
Supporting Information is available from the Wiley Online Library or
from the author.
For comparison, the nanosheet-assembled MoSe2 particles were
also prepared under the same reaction conditions without introducing
Co0.85Se cages.
Synthesis of Hierarchical Co0.85Se-CdSe/MoSe2/CdSe and CdSe/MoSe2/
CdSe Sandwich-Like Heterostructured Cages: The conversion of Co0.85Se/
MoSe2 cages to Co0.85Se-CdSe/MoSe2/CdSe and CdSe/MoSe2/CdSe
cages was realized through a cation exchange reaction in the presence
of ascorbic acid. Typically, 0.4 mmol CdCl2 and 20 mg ascorbic acid
were dissolved into 20 mL methanol solution under stirring. Then, the
Co0.85Se/MoSe2 cages were added to the above solution. The resulting
mixture was put into a 40 mL Teflon-lined autoclave and heated at 160 °C
for 1, 3, 4, and 6 h, respectively. The obtained materials were rinsed
with absolute ethanol and then dried at 60 °C overnight. The products
were designated as Co0.85Se-CdSe/MoSe2/CdSe-0.5, Co0.85Se-CdSe/
MoSe2/CdSe, Co0.85Se-CdSe/MoSe2/CdSe-2, and CdSe/MoSe2/CdSe,
respectively. Pure CdSe cages were synthesized under the same cation
exchange reaction conditions using Co0.85Se to replace Co0.85Se/MoSe2
as the starting material.
Acknowledgements
The authors acknowledge support from the National Natural Science
Foundation of China (No. 51772079, 22072037) and the Natural Science
Foundation of Heilongjiang Province of China (LH2020B018).
Conflict of Interest
The authors declare no conflict of interest.
Synthesis of Hierarchical Co0.85Se-CdSe/MoSe2 and CdSe/MoSe2
Cages: Co0.85Se-CdSe/MoSe2 and CdSe/MoSe2 cages with core/
shell heterostructure were prepared using two steps. In the first step,
Co0.85Se-CdSe and CdSe cages were prepared via the cation exchange
reaction between Co0.85Se and Cd2+ similar to the cation exchange
reaction conditions of Co0.85Se-CdSe/MoSe2/CdSe. In the second step,
MoSe2 nanosheets were grown on the surface of the Co0.85Se-CdSe and
Data Availability Statement
Research data are not shared.
CdSe cages to obtain Co0.85Se-CdSe/MoSe2 and CdSe/MoSe2 cages Keywords
through the hydrothermal process similar to the synthesis of Co0.85Se/
MoSe2, respectively.
cation-exchange
photoreduction, sandwich-like heterostructure
reaction,
Co0.85Se-CdSe/MoSe2/CdSe,
CO2
Sample Characterization: X-ray diffraction (XRD) patterns were
obtained from a diffractometer (SmartLab, 9 KW, CuKa radiation). The
morphology and structures were observed on Sigma 500 scanning
electron microscopy (SEM) and JEM-F200 transmission electron
microscopy (TEM). X-ray photoelectron spectroscopy (XPS) was
implemented on a AXIS-ULTRA DLD-600W instrument using a Al
Ka X-ray source. The surface area and CO2 adsorption curves were
determined on an autosorb iQ instrument (Quantachrome). UV–vis
diffuse reflectance spectra (DRS) were acquired on a Lambda 950 UV–vis
spectrophotometer (Perkin-Elmer). The photoluminescence spectra
(PL) were obtained on a FLS920P Edinburgh Instrument. In situ Fourier-
transform infrared (FTIR) tests were carried out using an infrared
spectrometer (Nicolet IS-50) with an in situ Harrick IR cell.
Received: January 22, 2021
Revised: April 12, 2021
Published online: June 23, 2021
[1] a) Q. Wang, J. Z. Luo, Z. Y. Zhong, A. Borgna, Energy Environ. Sci.
2011, 4, 42; b) Y. Wang, Z. Zhang, L. Zhang, Z. Luo, J. Shen, H. Lin,
J. Long, J. C. S. Wu, X. Fu, X. Wang, C. Li, J. Am. Chem. Soc. 2018,
140, 14595; c) S. Sorcar, S. Yoriya, H. Lee, C. A. Grimes, S. P. Feng,
Mater. Today Chem. 2020, 16, 100264; d) X. Q. Wu, J. X. He,
M. Zhang, Z. Liu, S. Zhang, Y. Zhao, T. Li, F. Zhang, Z. Peng,
N. Y. Cheng, J. Y. Zhang, X. J. Wen, Y. W. Xie, H. Tian, L. Gao, L. Bi,
Y. Du, H. L. Zhang, J. Cheng, X. G. An, Y. Lei, H. H. Shen, J. T. Gan,
X. T. Zu, S. Li, L. Qiao, Nano Energy 2020, 67, 104247.
[2] a) P. Li, Y. Zhou, H. Li, Q. Xu, X. Meng, X. Wang, M. Xiao, Z. Zou,
Chem. Commun. 2015, 51, 1743; b) W. H. Zhang, A. R. Mohamed,
W. J. Ong, Angew. Chem., Int. Ed. 2020, 59, 1914925; c) W. J. Ong,
L. K.Putri, A. R. Mohamed, Chem. Eur. J. 2020, 26, 9710.
Photoelectrochemical
Measurements:
Photocurrent
response
and Mott–Schottky measurements were carried out on a BAS100B
electrochemical work station. Platinum wire and saturated calomel
electrode (SCE) were used as the counter electrode and reference
electrode, respectively. The electrolyte was 0.1 m Na2SO4 solution, and
illumination source was a 300 W Xe lamp with a 400 nm bandpass
filter. Electrochemical impedance spectra (EIS) were acquired from an
electrochemical workstation (Zahner Elektrik). The cyclic voltammetric
(CV) experiments of the samples were carried out in MeCN.
2100412 (11 of 13)
© 2021 Wiley-VCH GmbH
Small 2021, 17, 2100412

www.advancedsciencenews.com
www.small-journal.com
[3] a) M. Zhou, S. Wang, P. Yang, C. Huang, X. Wang, ACS Catal.
2018, 8, 4928; b) Y. Q. He, H. Rao, K. P. Song, J. X. Li, Y. Yu, Y. Lou,
C. G. Li, Y. Han, Z. Shi, S. H. Feng, Adv. Funct. Mater. 2019, 29,
1905153; c) M. Y. Sun, B. H. Zhao, F. P. Chen, C. B. Liu, S. Y. Lu,
Y. F. Yu, B. Zhang, Chem. Eng. J. 2021, 408, 127280; d) F. Raziq,
M. Humayun, A. Ali, T. Wang, A. Khan, Q. Y. Fu, W. Luo, H. P. Zeng,
Z. P. Zheng, B. Khan, H. H. Shen, X. T. Zu, S. Li, L. Qiao, Appl.
Catal. B 2018, 237, 1082.
[4] a) J. Jin, J. Yu, D. Guo, C. Cui, W. Ho, Small 2015, 11, 5262;
b) N. Serpone, A. V. Emeline, J. Phys. Chem. Lett. 2012, 3, 673;
c) M. Fang, G. Dong, R. Wei, J. C. Ho, Adv. Energy Mater. 2017, 7,
1700559.
[5] a) W. G. Tu, Y. Zhou, Z. Zou, Adv. Mater. 2014, 26, 4607; b) T. Wang,
L. Shi, J. Tang, V. Malgras, S. Asahina, G. G. Liu, H. B. Zhang,
X. G. Meng, K. Chang, J. P. He, O. Terasaki, Y. Yamauchi, J. H. Ye,
Nanoscale 2016, 8, 6712; c) A. Kumar, P. Raizada, V. K. Thakur,
V. Saini, A. A. P. Khan, N. Singh, P. Singh, Chem. Eng. Sci. 2021,
230, 116219; d) J. L. Liang, Z. F. Jiang, P. K. Wong, C. S. Lee, Sol. RRL
2021, 5, 2000478.
[6] a) X. H. Sun, H. Du, ACS Sustainable Chem. Eng. 2019, 7, 16320;
b) Z. C. Lian, M. Sakamoto, Y. Kobayashi, N. Tamai, J. Ma,
T. Sakurai, S. Seki, T. Nakagawa, M. W. Lai, M. Haruta, H. Kurata,
T. Teranishi, J. Phys. Chem. Lett. 2018, 9, 2212; c) F. Raziq, A. Hayat,
M. Humayun, S. K. B. Mane, M. B. Faheem, A. Ali, Y. Zhao,
S. B. Han, C. Cai, W. Li, D. C. Qi, J. B. Yi, X. J. Yu, M. B. H. Breese,
F. Hassan, F. Ali, A. Mavlonov, K. Dhanabalan, X. Xiang, X. T. Zu,
S. Li, L. Qiao, Appl. Catal. B 2020, 270, 118867.
B. Cheng, M. Jaroniec, J. Mater. Chem. A 2014, 2, 3407; c) J. Wang,
S. Lin, N. Tian, T. Ma, Y. H. Zhang, H. W. Huang, Adv. Funct. Mater.
2020, 4, 2008008.
[16] a) S. Yang, C. L. Shao, R. Tao, X. W. Li, C. H. Han, H. Y. Liu, X. H. Li,
Y. C. Liu, ACS Sustainable Chem. Eng. 2018, 6, 14314; b) J. Zhang,
P. H. Tian, T.Tang, G. Z. H. , X. Chen, J. H. Zeng, B. Cui, Z. Kong,
H. B. Wang, J. H. Xi, Z. G. Ji, Int. J. Hydrogen Energy 2020, 45, 6519.
[17] a) S. Yang, C. L. Shao, X. J. Zhou, X. H. Li, R. Tao, X. W. Li, S. Liu,
Y. C. Liu, ACS Appl. Nano Mater. 2020, 3, 2278; b) Y. P. Liu, Y. H. Li,
Y. Lin, S. Y. Yang, Q. Zhang, F. Peng, Chem. Eng. J. 2020, 383,
123133.
[18] a) S. Wang, B. Y. Guan, X. Wang, X. W. D. Lou, J. Am. Chem.
Soc. 2018, 140, 15145; b) Y. Jiang, H. Y. Chen, J. Y. Li, J. F. Liao,
H. H. Zhang, X. D. Wang, D. B. Kuang, Adv. Funct. Mater. 2020, 30,
2004293; c) Y. Zhao, R. Li, L. C. Mu, C. Li, Cryst. Growth Des. 2017,
17, 2923; d) C. Zeng, Q. Zeng, C. Dai, Y. Hu, Dalton Trans. 2020, 49,
9213; e) Y. Zhao, C. Huang, Y. He, X. Wu, R. Ge, X. Zu, L. Qiao, J.
Power Sources 2020, 456, 228023.
[19] a) X. X. Chang, T. Wang, P. Zhang, J. J. Zhang, A. Li, J. L. Gong, J.
Am. Chem. Soc. 2015, 137, 8356; b) J. X. Lv, Z. M. Zhang, J. Wang,
X. L. Lu, W. Zhang, T. B. Lu, ACS Appl. Mater. Interfaces 2019, 11,
2655; c) C. Eley, T. Li, F. L. Liao, S. M. Fairclough, J. M. Smith,
G. Smith, S. C. E. Tsang, Angew. Chem., Int. Ed. 2014, 53, 7838;
d) A. Li, X. X. Chang, Z. Q. Huang, C. C. Li, Y. J. Wei, L. Zhang,
T. Wang, J. L. Gong, Angew.Chem., Int. Ed. 2016, 55, 13734.
[20] a) P. Zhang, S. B. Wang, B. Y. Guan, X. W. Lou, Energy Environ.
Sci. 2019, 12, 164; b) L. Wang, J. W. Wan, Y. S. Zhao, N. L. Yang,
D. Wang, J. Am. Chem. Soc. 2019, 141, 2238; c) N. N. Vu,
S. Kaliaguine, T. O. Do, ChemSusChem 2020, 13, 3967. d) J. Yu,
J. Low, W. Xiao, P. Zhou, M. Jaroniec, J. Am. Chem. Soc. 2014,
136, 8839.
[7] a) B. H. Chong, W. Zhu, Y. Liu, L. Guan, G. Z. Chen, J. Mater.
Chem. A 2016, 4, 1336; b) R. Shi, Y. H. Cao, Y. J. Bao, Y. F. Zhao,
G. I. N. Waterhouse, Z. Y. Fang, L. Z.Wu, C. H. Tung, Y. D. Yin,
T. R. Zhang, Adv. Mater. 2017, 29, 1700803.
[8] a) H. Hu, J. T. Zhang, B. Y. Guan, X. W. Lou, Angew. Chem. 2016,
128, 9666; b) L. Zhang, H. Cheng, R. Zong, Y. Zhu, J. Phys. Chem. C
2009, 113, 2368.
[9] a) C. Eley, T. Li, F. L. Liao, S. M. Fairclough, J. M. Smith, G. Smith,
S. C. E. Tsang, Angew. Chem., Int. Ed. 2014, 53, 7838; b) H. Z. Wang,
H. P. Rong, D. Wang, X. Y. Li, E. H. Zhang, X. D. Wan, B. Bai, M. Xu,
J. J. Liu, J. Liu, W. X. Chen, J. T. Zhang, Small. 2020, 16, 2000426;
c) C. H. Kuo, T. E. Hua, M. H. Huang, J. Am. Chem. Soc. 2009,
131, 17871; d) Y. Zhao, M. Zhao, X. Ding, Z. Liu, H. Tian, H. Shen,
L. Qiao, Chem. Eng. J. 2019, 373, 1132.
[21] a) Z. C. Kong, J. F. Liao, Y. J. Dong, Y. F. Xu, H. Y. Chen, D. B. Kuang,
C. Y. Su, ACS Energy Lett. 2018, 3, 2656; b) M. Guo, T. Zhao,
Z. Xing, Y. Qiu, K. Pan, Z. Z. Li, S. L. Yang, W. Zhou, ACS Appl.
Mater. Interfaces 2020, 12, 40328; c) J. Ran, M. Jaroniec, S. Z. Qiao,
Adv. Mater. 2018, 30, 1704649; d) B. Jin, N. Zuo, Z. Y. Hu, W. Cui,
R. Wang, G. V. Tendeloo, X. Zhou, T. Zhai, Adv. Funct. Mater. 2020,
30, 2006166.
[22] a) B. Sun, W. Zhou, H. Li, L. Ren, P. Qiao, W. Li, H. G. Fu, Adv. Mater.
2018, 30, 1804282; b) M. D. Sharma, C. Mahala, M. Basu, J. Colloid
Interface Sci. 2019, 534, 131; c) B. Khan, F. Raziq, M. B. Faheem,
M. U. Farooq, S. Hussain, F. Ali, A. Ullah, A. Mavlonov, Y. Zhao,
Z. R. Liu. H. Tian, H. H. Shen, X. T. Zu, S. Li, H. Y. Xiao, X. Xiang,
L. Qiao, J. Hazard. Mater. 2020, 381, 120972.
[10] a) W. X. Ouyang, Y. X. Yu, W. D. Zhang, Phys. Chem. Chem. Phys.
2015, 17, 14827; b) L. Yang, C. Mccue, Q. F. Zhang, E. Uchaker,
Y. H. Mai, G. Z. Cao, Nanoscale 2015, 7, 3173.
[11] a) X. Sheng, T. Xu, X. Feng, Adv. Mater. 2019, 31, 1805132;
b) L. P. Zhang, P. Cui, H. B. Yang, J. Z. Chen, F. X. Xiao, Y. Y. Guo,
Y. Liu, W. Zhang, F. W. Huo, B. Liu, Adv. Sci. 2016, 3, 1500243;
c) H. H. Yang, W. G. Fan, A. Vaneski, A. S. Susha, W. Y. Teoh,
A. L. Rogach, Adv. Funct. Mater. 2012, 22, 2821.
[12] a) Y. J. Chen, Z. Ren, H. Fu, X. Zhang, G. H. Tian, H. G. Fu,
Small 2018, 14, 1800763; b) W. S. Feng, W. B. Pang, Y. Xu, A. Guo,
X. H. Gao, X. Q. Qiu, W. Chen, ChemElectroChem 2020, 7, 31.
[13] a) J. Z. Y. Tan, F. Xia, M. M. Maroto-Valer, ChemSusChem 2019,
12, 5246; b) L. Zheng, F. Teng, X. Y. Ye, H. J. Zheng, X. S. Fang,
Adv. Energy Mater. 2020, 10, 1902355; c) M. Wang, P. Ju, J. J. Li,
Y. Zhao, X. X. Han, Z. M. Hao, ACS Sustainable Chem. Eng. 2017,
5, 7878; d) P. Prabhu, V. Jose, J. M. Lee, Adv. Funct. Mater. 2020,
30, 1910768.
[23] a) F. Gong, H. Wang, X. Xu, G. Zhou, Z. S. Wang, J. Am. Chem. Soc.
2012, 134, 10953; b) S. Naskar, F. Lübkemann, S. Hamid, A. Freytag,
A. Wolf, J. Koch, I. Ivanova, H. Pfnür, D. Dorfs, D. W. Bahnemann,
N. C. Bigall, Adv. Funct. Mater. 2017, 27, 1604685.
[24] a) M. L. Yuan, S. Dipazir, M. Wang, Y. Sun, D. L. Gao, Y. L. Bai,
M. Zhang, P. Lu, H. Y. He, X. Y. Zhu, S. W. Li, Z. J. Liu, Z. P. Luo,
G. J. Zhang, J. Mater. Chem. A 2019, 7, 3317; b) C. Yu, Z. Cao,
S. Chen, S. Wang, H. Zhong, Appl. Surf. Sci. 2020, 509, 145364.
[25] a) R. Qin, J. G. Hou, C. X. Xu, H. X. Yang, Q. X. Zhou, Z. Z. Chen,
H. Liu, Nano Res. 2020, 13, 2950; b) Y. Wang, J. X. Zhao, Z. Chen,
F. Zhang, W. Guo, H. M. Lin, F. Y. Qu, Appl. Catal. B 2019, 244, 76;
c) J. W. Huang, B. Jin, H. Q. Liu, X. J. Li, Q. C. Zhang, S. J. Chu,
R. F. Peng, S. Chu, J. Mater. Chem. A 2018, 6, 11424.
[26] Y. Xie, G. Bertoni, A. Riedinger, A. Sathya, M. Prato, S. Marras,
R. Y. Tu, T. Pellegrino, L. Manna, Chem. Mater. 2015, 27, 7531.
[27] Y. X. Wu, M. Q. Xu, X. Chen, S. L. Yang, H. S. Wu, J. Pan, X. Xiong,
Nanoscale 2016, 8, 440.
[28] a) C. Dai, E. P. Qing, Y. Li, Z. X. Zhou, C. Yang, X. K. Tian,
Y. X. Wang, Nanoscale 2015, 7, 19971; b) T. Yin, L. Long, X. Tang,
M. Qiu, W. Liang, R. Cao, Q. Zhang, D. Wang, H. Zhang, Adv. Sci.
2020, 7, 2001431.
[14] a) T. T. Yao, X. An, H. X. Han, J. Q. Chen, C. Li, Adv. Energy Mater.
2018, 8, 1800210; b) K. Liu, Z. Zhang, N. Lu, B. Dong, ACS Sustain-
able Chem. Eng. 2018, 6, 1934; c) V. D. Poimanov, A. N. Kuchko,
V. V. Kruglyak, Phys. Rev. Appl. 2018, 98, 104418; d) L. J. Yang, Y. Hu,
L. Zhang, Chem. Eng. J. 2019, 378, 122092.
[15] a) S. Kumar, A. Kumar, V. N. Rao, A. Kumar, M. V. Shankar,
V. Krishnan, ACS Appl. Energy Mater. 2019, 2, 5622; b) J.Yu, J. J. ,
Small 2021, 17, 2100412
2100412 (12 of 13)
© 2021 Wiley-VCH GmbH

www.advancedsciencenews.com
www.small-journal.com
[29] a) P. Zhou, Q. H. Zhang, Z. K. Xu, Q. Y. Shang, Guo, S. J. S , Adv.
Mater. 2020, 32, 1904249; b) X. Zhang, H. Liang, H. Li, Y. Xia,
D. Zhao, Angew. Chem., Int. Ed. 2019, 59, 1913600.
[30] G. H. Yin, X. Y. Huang, T. Y. Chen, W. Zhao, Q. Y. Bi, J. Xu, Y. F. Han,
F. Q. Huang, ACS Catal. 2018, 8, 1009.
[31] a) X. Deng, L. L. Yang, H. L. Huang, Y. Y. Yang, S. Q. Feng, M. Zeng,
Q. Li, D. S. Xu, Small 2019, 15, 1902287; b) X. J. Hu, X. J. Liu,
K. Chen, G. Wang, H. Wang, J. Mater. Chem. A 2019, 7, 11016.
[32] a) V. N. Rao, S. Pitchaimuthu, P. Ravi, M. Sathish, H. Han,
S. M. Venkatakrishnan, ChemCatChem 2020, 12, 3139; b) Z. Zhang,
M. Choi, M. Baek, K. Yong, Adv. Mater. Interfaces 2016, 3, 1500737;
c) C. Eley, T. Li, F. L. Liao, S. M. Fairclough, J. M. Smith, G. Smith,
S. C. E. Tsang, Angew. Chem., Int. Ed. 2014, 53, 7838.
A. Mavlonov, T. Ali, F. Hassan, X. Xiang, X. T. Zu, H. H. Shen,
S. Li, L. Qiao, Appl. Catal. B 2020, 270, 118870; b) M. Gao, J. Feng,
Z. Q. Zhang, M. Z. Gu, J. X. Wang, W. J. Zeng, Y. Z. Lv, Y. Ren,
T. Wei, Z. J. Fan, ACS Appl. Nano Mater. 2018, 1, 6733; c) L.Qiao,
S. Z. , H. Y. Xiao, D. J. Singh, K. H. L. Zhang, Z. J. Liu, X. T. Zu, S. Li,
J. Mater. Chem. C 2018, 6, 1239; d) L. Qiao, H. Y. Xiao, H. M. Meyer,
J. N. Sun, C. M. Rouleau, A. A. Puretzky, D. B. Geohegan,
I. N. Ivanov, M. Yoon, W. J. Weber, M. D. Biegalski, J. Mater. Chem.
C 2013, 1, 4628.
[34] J. Liu, L. Yang, N. Liu, Y. Han, X. Zhang, H. Huang, Y. Lifshitz,
S. T. Lee, J. Zhong, Z. Kang, Science 2015, 46, 970.
[35] a) Y. M. Jo, T. H. Kim, C. S. Lee, K. Lim, C. W. Na, F. A. Hady,
A. A. Wazzan, J. H. Lee, ACS Appl. Mater. Interfaces 2018, 10, 8860;
b) A. Call, M. Cibian, K. Yamamoto, T. Nakazono, K. Yamauchi,
K. Sakai, K , ACS Catal. 2019, 9, 4867.
[33] a) F. Raziq, J. He, J. Gan, M. Humayun, M. B. Faheem, A. Iqbal,
A. Hayat, S. Fazal, J. B. Yi, Y. Zhao, K. Dhanabalan, X. Q. Wu,
2100412 (13 of 13)
© 2021 Wiley-VCH GmbH
Small 2021, 17, 2100412