Z-Scheme 2D/3D hierarchical MoS2?CoMoS4flower-shaped arrays with enhanced full spectrum light photoelectrocatalytic activity for H2O2/: p -aminophenol production and contaminant degradation

Article abstract of DOI:10.1039/d0ta07796h

Developing high-performance catalysts for converting naturally existing simple molecules/poisonous chemicals into value-added commodity chemicals with environmental and socioeconomic benefits is a great challenge. Herein, Z-scheme 2D/3D hierarchical MoS2?CoMoS4 flower-shaped arrays as dual-functional electrodes for photoelectrocatalytic (PEC) hydrogen peroxide (H2O2)/p-aminophenol (p-AP) production and lomefloxacin (LOM) degradation were fabricated via a strategy of merging 2D MoS2 nanosheets into the nano-leaves of 3D CoMoS4 micro-flowers. MoS2?CoMoS4 as a photocathode provides a green, economic and efficient route to achieve photoelectric-driven high productivity toward H2O2 (about 205 μM of H2O2 was produced under irradiation for 120 min) and p-AP (the corresponding p-AP yield was about 83% under illumination for 180 min) by using 5.0 mg of catalyst without any co-catalyst, while as a photoanode it also exhibits enhanced PEC performance for LOM oxidative degradation. The improved photoelectro-chemical redox activity is primarily attributed to the formation of a Z-scheme charge-transfer path, which can restrain the recombination of charges and lead to significantly enhanced redox ability of excited e- and h+. The unique 2D/3D hierarchical MoS2?CoMoS4 flower-shaped arrays can economically achieve maximal harvesting of solar energy and full-spectrum light absorption, and provide more active sites, thus synergistically enhancing the catalytic performance. This work is instructive for the design of efficient bifunctional photoelectrocatalysts for meeting demands for chemical resources and concerns about environmental remediation through constructing a Z-scheme heterostructure photoelectrocatalyst. This journal is

Full text of DOI:10.1039/d0ta07796h

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Materials Chemistry A
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Z-Scheme 2D/3D hierarchical MoS @CoMoS4
2
flower-shaped arrays with enhanced full spectrum
Cite this: DOI: 10.1039/d0ta07796h
light photoelectrocatalytic activity for H O /p-
2
2
aminophenol production and contaminant
degradation†
Ao Zhang, Lijun Yang and Lei Zhang
*
Developing high-performance catalysts for converting naturally existing simple molecules/poisonous chemicals
into value-added commodity chemicals with environmental and socioeconomic benefits is a great challenge.
Herein, Z-scheme 2D/3D hierarchical MoS
2
@CoMoS
4
flower-shaped arrays as dual-functional electrodes for
photoelectrocatalytic (PEC) hydrogen peroxide (H
2
O )/p-aminophenol (p-AP) production and lomefloxacin
2
(
LOM) degradation were fabricated via a strategy of merging 2D MoS
CoMoS micro-flowers. MoS @CoMoS as a photocathode provides a green, economic and efficient route to
achieve photoelectric-driven high productivity toward H (about 205 mM of H was produced under
2
nanosheets into the nano-leaves of 3D
4
2
4
2
O
2
2 2
O
irradiation for 120 min) and p-AP (the corresponding p-AP yield was about 83% under illumination for 180
min) by using 5.0 mg of catalyst without any co-catalyst, while as a photoanode it also exhibits enhanced PEC
performance for LOM oxidative degradation. The improved photoelectro-chemical redox activity is primarily
attributed to the formation of a Z-scheme charge-transfer path, which can restrain the recombination of
ꢀ
+
charges and lead to significantly enhanced redox ability of excited e and h . The unique 2D/3D hierarchical
MoS @CoMoS flower-shaped arrays can economically achieve maximal harvesting of solar energy and full-
2
4
Received 8th August 2020
Accepted 18th November 2020
spectrum light absorption, and provide more active sites, thus synergistically enhancing the catalytic
performance. This work is instructive for the design of efficient bifunctional photoelectrocatalysts for meeting
demands for chemical resources and concerns about environmental remediation through constructing a Z-
scheme heterostructure photoelectrocatalyst.
DOI: 10.1039/d0ta07796h
rsc.li/materials-a
3
water solubility. H
2
O
2
as a kind of cleaning oxidant is not only
Introduction
a substitute for hydrogen in single-cell battery power generation
With the unscientic use of non-renewable energy sources and but also has low cost and minimal environmental impact,
6
the development it has sparked in industry and agricultural particularly since its only by-product is water. Therefore, the
production, the global energy crisis and environmental deteri- green production of H
2
O
2
has attracted more and more atten-
oration have become increasingly serious, which are also the tion, because traditional methods for producing H
2 2
O
, such as
main challenges facing mankind at present. As one of the the anthraquinone method, are limited by their high costs and
cleanest, richest and greenest sources of energy, solar energy is toxic by-products involved in multi-step chemical reactions.
of great signicance to alleviate the increasingly serious energy Thus, there is an urgent need to nd a high-performance, cost-
1
,2
3
crisis in modern industry. In particular, generating H
2
O
2
, H
2
effective and renewable green method to produce H
There are usually two possible synthesis routes for H O ,
2 2
2 2
O .
4
5
and O
2
,
removing organic/inorganic contaminants, and
sunlight-driven catalytic reactions can be carried out efficiently, both the oxygen reduction reaction (ORR) at the cathode and
which is an ideal way to realize green chemistry, and resolve the the water oxidation reaction (WOR) at the anode. However, the
energy and environmental problems. Compared with H and WOR itself has been extremely challenging up to now due to the
2
O , H O can be more safely stored and transported due to its uphill thermodynamics (1.76 V) together with sluggish kinetics
2
2 2
and the generation of by-product O
2
with kinetic advantages
(
1.23 V). Therefore, the production of H O
2 2
through ORR under
College of Chemistry, Liaoning University, 66 Chongshan Middle Road, Shenyang,
Liaoning, 110036, People's Republic of China. E-mail: zhanglei63@126.com; Fax:
7,8
acidic conditions has been extensively studied.
At present, some researchers use noble metals and their
+
†
1
86 24 62202380; Tel: +86 24 62207809
9
10
11
alloys (for example Pd–Hg, Pt–Hg and Pd–Au ), or corre-
sponding hybrids (Pt/TiN, Pt/CuS
Electronic supplementary information (ESI) available. See DOI:
0.1039/d0ta07796h
12
13
x
) as electrocatalysts for the
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high-selectivity synthesis of H
Paper
2
O
2
in the electrocatalysis eld greatly improved PEC activity for HER due to the fact that unsatu-
31,32
but they suffer from high cost, which makes them unsuitable in rated sites and surface defects can expose more active sites.
commercial applications. There is still a lack of an efficient Therefore, embedding crystalline MoS2 in amorphous CoMoS4
cheap catalyst to selectively reduce O to H O , especially in might achieve maximal harvesting of solar energy and full-
2
2 2
14
acidic environments.
production of H via ORR is also restricted owing to its high CoMoS
energy consumption. common elements Mo and S, which inspired us to fabricate a 3D
Photocatalytic “green” technology has attracted growing hierarchical MoS @CoMoS Z-scheme heterojunction catalyst to
Furthermore, the electrocatalytic spectrum light absorption. It is worth noting that both MoS
2
and
2
O
2
4
had a matched band gap for PEC applications, as well as
2
4
research as an alternative method of solar energy storage and give it a multifunctional purpose for the production of H
2 2
O /p-AP
capture, and has displayed potential applications in green and the degradation of pollutants.
15
synthesis and oxidative degradation. The advantages of photo-
Hence, in this study a novel 3D hierarchical ower-shaped
catalysis for ORR and WOR to H O are low energy consumption, MoS @CoMoS Z-scheme hybrid was successfully prepared by
2
2
2
4
cleanliness and safety. At present, the search for a catalyst for the a simple solvothermal synthetic method. It should be noted that
photocatalytic production of H is mainly concentrated on the 3D hierarchical structure was constructed by integrating 2D
various modied g-C materials. Some researchers reported that nanosheets and 3D micro-owers, which combined the merits of
various modied g-C photocatalysts, such as silver-decorated both materials. The fabricated Z-scheme 3D MoS @CoMoS
ultrathin g-C nanosheets, mellitic triimide-doped g-C
biphenyl diimide doped g-C N , Ti C MXene/porous g-C N ,
2 2
O
3 4
N
3
N
4
2
4
1
6
17
3
N
4
3
N
4
,
composite was successfully applied for visible-light-driven PEC
1
8
19
production of value-added commodity chemicals of H O /p-AP, as
3
4
3
2
3
4
2 2
2
0
pyromellitic diimide incorporated g-C N , nitrogen-vacancy and well as the degradation of LOM, and the mechanism of photo-
3
4
2
1
carbon-vacancy enriched g-C N
and benzene-substituted g- electrocatalysis is revealed in detail. Owing to its superior features,
production through photo- 3D MoS @CoMoS could be engaged in some scientic activities
catalytic technology. However, the low yield of photocatalytic for energy production and environmental pollution treatment.
production of H is still far from satisfactory due to the rapid
recombination of e –h aer excitation, and the homogeneous
photocatalyst is difficult to separate and recycle from the H
3
4
22
C N
3 4
have shown enhanced H
2
O
2
2
4
2 2
O
ꢀ
+
2
O
2
2. Experiment section
.1 Chemicals
product, so the types of effective catalysts are scarce. To overcome
the photocarrier recombination and the problems of recycling
powder catalysts and so on, the sunlight-driven PEC technique has
been proven to be an effective way to promote the separation of
2
CoCl $6H O,
(NH ) Mo O $4H O,
Na S$9H O,
NH F,
4
2
2
4 6
7
24
2
2
2
CO(NH ) , thiourea (CH N S), p-aminophenol (p-AP), p-nitro-
2 2
4 2
ꢀ
+
phenol (p-NP) and lomeoxacin (LOM) were obtained from
Sinopharm Chemical Reagent Co., Ltd (China), and carbon
cloth was provided by Suzhou Dasheng Electronic Materials Co.,
Ltd (China).
photo-generated e /h pairs and enhance the catalytic property.
Recently, PEC technology has been widely used in the
23
24
2 2 2
reduction of CO , the production of H and O , as well as in
5
the degradation of organic pollutants. The promising PEC
reaction is highly dependent on catalysts with a suitable band
gap energy, good sunlight-harvesting ability, efficient separa-
tion and long charge-carrier lifetime. Transition-metal suldes
generally have superior photoelectric properties and relative
2
.2 Catalysts and photoelectrode preparation
Synthesis of 3D CoMoS micro-owers. The CoMoS micro-
4
4
narrow band energy, and they favor adsorption of molecular owers were fabricated according to the following method:
25
oxygen due to the presence of sulfur, which accelerates the CoCl $6H O (0.5 mmol), (NH ) Mo O $4H O (0.071 mmol),
2
2
4 6
7
24
2
2 2 2 2 4
catalytic reaction process by modulating the electron transfer CO(NH ) (5 mmol), Na S$9H O (3 mmol) and NH F (2.5 mmol)
26,27
numbers in ORR.
were dissolved in 36 mL of deionized (DI) water and stirred to
The construction of a Z-scheme heterostructure has been paid form a clear solution at room temperature. The as-formed
much attention by researchers because of its more advantageous homogenous solution was then transferred into a Teon-lined
ꢁ
charge-carrier transfer mechanism. The Z-scheme model not only steel autoclave, which was sealed, maintained at 120 C for
signicantly promotes the separation efficiency of photo-induced 12 h, and then naturally cooled to room temperature. The
ꢀ
+
e
and h pairs, but also maintains the stronger redox ability of product was collected by centrifugation at 4000 rpm for 5 min,
ꢀ
+
photo-generated e and h , which will result in enhanced PEC washed a few times with DI water and ethanol, and then dried at
performance. So far Z-scheme metal sulde heterostructures, such 60 C for 12 h.
as CdS/CdO,
ꢁ
28
29
30
Bi
2
S
3
/MoS
2
/TiO
2
and ZnIn
2
S
4
/TiO
2
,
have
2 4 4
Synthesis of MoS @CoMoS . 0.149 g of CoMoS , 0.5 mmol of
successfully displayed potential applications in various scientic (NH ) Mo O $4H O and 15 mmol of thiourea were dispersed
4
6
7
24
2
activities for the production and storage of energy, in various and dissolved in 35 mL of DI water, magnetically stirred for
devices and for environmental pollution abatement. To our 20 min, and then transferred to a Teon-lined steel autoclave
ꢁ
knowledge, there has not been a study on proposing and fabri- with a volume of 50 mL and heated at 180 C for 24 h. Subse-
cating 3D hierarchical Z-scheme heterojunction composites with quently, the autoclave was naturally cooled down to room
2 2
the aim of PEC production of H O . It was previously reported that temperature.
compared with crystalline Mo-based material, amorphous Mo-
based materials, especially ternary transition metal sulde, have same method (heating at 180 C for 24 h).
For comparison, pure MoS
2
was also obtained using the
ꢁ
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Construction of photoelectrode. A 3D MoS
Journal of Materials Chemistry A
ower- evaluated by H
2
O
2
/p-AP production under a 300 W xenon lamp
2
@CoMoS
4
ꢀ2
like array electrode was synthesized as follows: rstly, carbon with a 420 nm cutoff lter at 100 mW cm . The initial pH was
2
cloths with an average size of 2 ꢂ 3 cm were pretreated on the adjusted to 3.0 with 1.0 M HClO
(if producing H
basis of previous work. Subsequently, 1 mL of solution con- continuously bubbled into the 0.1 M Na SO solution; when
(5 mg mL ) was uniformly producing p-AP, the solution was 0.1 M Na SO containing
O , the O was
2 2 2
4
33
2
4
ꢀ
1
taining 5 mg of MoS
2
@CoMoS
4
2
4
2
ꢁ
ꢀ1
deposited onto a carbon cloth (2 ꢂ 2 cm ) and dried at 60 C for 10 mg L p-NP), and then the prepared photoelectrode was put
2
h to form a uniform lm. All examined photoelectrodes were into the electrolytic cell for 30 min ensuring the adsorption–
3
4
fabricated by the same method.
desorption equilibrium of the solution before irradiation. The
evolved H /p-AP was monitored by KMnO redox titration/
2
O
2
4
HPLC (Shimadzu LC-16, Japan) equipped with an SB-C18
2
.3 Material characterization
column (4.6 mm ꢂ 150 mm, 5 mm) using a VWD detector at
ꢀ1
A scanning electron microscope (SEM, SU8000, Hitachi Co., Japan)
and transmission electron microscope (TEM, Oxford, TSR, USA)
with an EDS detector attached were operated to investigate the
morphology, structure and chemical information of the as-
prepared materials. X-ray photoelectron spectroscopy (XPS,
Thermo Electron, ESCALAB 250 Xi., USA) was used to analyze the
chemical state of the samples. Powder X-ray diffraction patterns/
Raman spectra were collected on a diffractometer (XRD, D5000,
Siemens Co., Germany)/micro-Raman spectra (Renishaw inVia
system equipped with an integral microscope (Leica)). A UV-vis
spectrophotometer (Shimadzu, UV-2600) was used to record the
UV-vis diffuse reectance spectra (DRS) of the prepared samples.
Photoluminescence (PL) spectra of the samples were collected on
a uorescence spectrometer (RF-5301PC, SHIMADZU, Japan). The
electron spin resonance (ESR) signals of the radicals were collected
on a Bruker ER200-SRC instrument. Electrochemical impedance
spectra (Nyquist plots) of the different samples in 50 mM of
K [Fe(CN) ] solution was collected by applying 5 mV amplitude in
3 6
a frequency range from 10 000 to 0.1 Hz and recorded at open
circuit potential.
All electrochemical measurements were performed in the
standard three-electrode system by a computer-controlled
workstation (CHI 660D, Shanghai ChenHua Instruments Co.,
China).
2
90 nm; the ow rate of the mobile phase was 1.0 mL min ,
and the mobile phase was methanol/water (60/40, v/v). The
was selected as 2 mM to
initial concentration (pH ¼ 3) of H
2 2
O
investigate the decomposition behavior of H
2 2
O over the
photocathode under irradiation for 120 min.
PEC LOM degradation. The PEC performance of the catalyst as
a photoanode (at 0.8 V bias voltage (vs. SCE)) was investigated by
ꢀ
1
the degradation of LOM (5 mg L ) in 0.1 M Na SO supporting
2
4
ꢀ
2
electrolyte (pH ¼ 10) under a 300 W xenon lamp at 100 mW cm
.
The adsorption–desorption equilibrium was reached aer 30 min
in the dark; 3 mL of aliquot was separated and used to monitor the
concentration of targets with a spectrophotometer (Shimadzu UV-
2550, Japan) in the same time interval. Aer the measurement, the
aliquots were promptly poured back into the reaction system.
2.5 Free radical trapping experiments
The process was the same as the PEC activity test mentioned
above except for adding scavengers. During the PEC reaction,
(
NH ) C O (AO), AgNO , p-benzoquinone (PBQ) and isopropyl
4 2 2 4 3
35
+
ꢀ
ꢀ
ꢀ
alcohol (IPA) were used to capture h , e , cO (e + O /
2
2
ꢀ
2
cO ) and cOH, respectively.
36
3. Results and discussion
3
.1 Catalyst characterization
The fabrication schematic diagram of the 2D/3D MoS
/p-AP production. The PEC activity of the catalyst CoMoS heterojunction is shown in Scheme 1. The 2D MoS
as a photocathode (at ꢀ0.5 V bias voltage (vs. SCE)) was nanosheets were successfully merged into the nano-leaves of 3D
2.4 Photoelectrochemical tests
2
@-
PEC H
2
O
2
4
2
2 4
Scheme 1 The preparation process of MoS @CoMoS .
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4 2 4
Fig. 1 (a–c) SEM images of CoMoS micro-flowers; (d–f) SEM images of 2D/3D hierarchical MoS @CoMoS .
CoMoS
method.
As shown in the SEM images in Fig. 1a–c, 3D CoMoS
4
micro-owers by a simple two-step hydrothermal the specic surface area of CoMoS
4
. Moreover, each nanosheet
as a support could offer a good contact interface to load other
4
with semiconductors in forming heterojunction hybrids. The SEM
2 4
a uniform hierarchical ower-shaped structure and an average images of 2D/3D MoS @CoMoS are shown in Fig. 1d–f, where
size of about 3 mm was assembled from 2D CoMoS nanosheets, uniform growth of the few-layered 2D MoS2 akes is inter-
4
which crossed each other to form a large amount of open-free spersed into the surface of 3D CoMoS , which proved that 2D
4
2 4
space in the micro-ower which would signicantly enlarge MoS was successfully assembled on the surface of CoMoS via
Fig. 2 TEM image of MoS
CoMoS (c); SAED spectrum of amorphous CoMoS
the MoS @CoMoS (f).
2
@CoMoS
4
(a), enlarged TEM image of the nanosheet edge (b) and HRTEM image of MoS
2
encapsulated at the edge of
4
4
(d) and 2D/3D hierarchical MoS @CoMoS (e); EDS elemental mapping of Co, Mo and S of
2
4
2
4
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the hydrothermal process. The SEM image of the pure MoS
2
vibration modes of the MoS
2 2
, indicating that the MoS @-
nanosheets stacked is also shown in Fig. S1.†
CoMoS4 composite photoelectrocatalyst was successfully
39
The detailed structure and morphology of the as-prepared prepared.
Raman analysis further proved the effective
composites were further revealed by TEM. As shown in combination of the two semiconductors to form MoS @CoMoS4
2
Fig. 2a, the edges of the MoS
a large number of obvious nanosized ake-like structures. The
curled aky edges were selected for further magnication, composition of MoS
revealing that hybrids of CoMoS nanosheet-supported MoS be detected in the survey spectrum (Fig. 3c). The Co 2p spec-
2D MoS @2D CoMoS ) were synthesized. The MoS nanosheets trum exhibited ve peaks including one at about 779.11 eV
2
@CoMoS
4
composites exhibited heterojunctions.
XPS was employed to further characterize the chemical
@CoMoS . Signals of Co, Mo and S could
2
4
4
2
(
2
4
2
were uniformly distributed on the CoMoS nanosheets, leading belonging to the CoMoS phase (Co–Mo–S), two peaks at 781.34
4
to a large specic surface area and good electrical conductivity and 797.68 eV belonging to Co 2p3/2 and Co 2p1/2, and another
(
Fig. 2b). In addition, dense interconnected ripples could also two peaks at 794.09 and 802.77 eV denoted as Sat., suggesting
2
+
2ꢀ
40–42
be observed, suggesting the edge-rich feature of the MoS
2
that Co ions were bonded with [MoS
4
]
(Fig. 3d).
The
nanosheets. The HRTEM image in Fig. 2c further showed that high-resolution spectrum of Mo 3d showed a small peak at the
the composite was composed of CoMoS and MoS . Two position of 235.32 eV (Mo 3d5/2), which was consistent with
different lattice fringes with d-spacings of 0.26 and 0.62 nm Mo in the (NH
could be assigned to the (100) and (002) planes, respectively, of and 232.16 eV could demonstrate the existence of Mo
4
2
6
+
4 6 7
) Mo O24 precursor, while the peaks at 228.77
4
+
40
MoS . Furthermore, only a few discontinuous lattice fringes (Fig. 3e). The peak located at 226.12 eV corresponded to the
2
were observed at the edge of the interface, and they gradually chemical state of S 2s of MoS , which was consistent with the
2
43
became inconspicuous or even disappeared, indicating that previous analysis. The measured S 2p peaks were located at
CoMoS might be an amorphous and rich-defect structure. The 161.68 and 162.88 eV, which could be indexed as the S 2p3/2 and
4
corresponding selected area electron diffraction (SAED) spec- S 2p1/2 binding energies from the typical Co–S bonds, respec-
trum with extremely blurry diffraction rings in Fig. 2d further tively, revealing that the chemical oxidation state of S was the
showed that the CoMoS
while in the SAED spectrum (Fig. 2e) of the MoS
array, the discernible ring was indexed to the (100) plane of MoS2.
MoS , further proving the successful assembly of MoS , which successful formation of MoS @CoMoS heterojunctions.
4
exhibited an amorphous structure, ꢀ2 state for CoMoS
4
(Fig. 3f). Meanwhile, the peak for S 2p3/2 at
@CoMoS 164.08 eV indicated the presence of bridging apical S for
2
ꢀ
2
4
43–45
The results of the XPS analysis conrmed the
2
2
2
4
was consistent with the subsequent results of XRD. According to
The DRS UV-vis spectra of 2D MoS , 3D CoMoS and 2D/3D
2 4
the EDS elemental mapping in Fig. 2f, this conrmed a uniform MoS
2
@CoMoS
4
were shown in Fig. 4a. Obviously, compared
, pure 2D MoS nanosheets had a strong
sample. These results conrmed the successful visible light absorption intensity (400–1000 nm). Aer the
preparation of 2D/3D hierarchical MoS @CoMoS arrays. formation of an MoS @CoMoS heterojunction, the visible light
distribution of Co, Mo and S elements throughout the to pristine 3D CoMoS
MoS @CoMoS
4
2
2
4
2
4
2
4
The detailed crystal structures of the prepared samples were absorption intensity was further improved. The increased light
studied by XRD. The XRD patterns of MoS @CoMoS , pristine absorption intensity was benecial for the utilization of visible
2
4
CoMoS and MoS were exhibited in Fig. 3a. As shown in the light, so it was expected to exhibit better visible-light-driven PEC
4
2
XRD diagram of pristine CoMoS , no diffraction peaks were activity. Moreover, the band gap values (E ) of MoS and CoMoS
4
g
2
4
presented, which implied that the CoMoS
4
structure was were estimated to be 1.28 eV and 2.76 eV, respectively (Fig. 4b)
amorphous and consistent with the result reported in the by the Kubelka–Munk theorem.
3
7
literature. Clearly, the MoS
tion peaks consistent with JCPDS no. 37-1492, indicating the CoMoS
purity of the as-prepared MoS , the smaller average crystallite Usually, a linear plot with a positive slope indicates that the
size and layers and well-stacked lamellar structure. Aer the material is an n-type semiconductor, while a negative slope
2
showed broad and short diffrac-
The semiconductor types and band-edges of pure MoS
2
and
38
4
can be acquired from the Mott–Schottky (M–S) results.
2
46
formation of the MoS @CoMoS composite, except for the indicates that the material is a p-type semiconductor. It could
2
4
corresponding MoS peak (002), the remaining peaks (100, 110) be observed from Fig. 5a and b that MoS and CoMoS were
2
2
4
were clearly veried, which may be due to the lower content of both n-type semiconductors and the corresponding at band
MoS (f
) values were calculated as ꢀ0.35 eV vs. SCE (ꢀ0.11 eV vs.
In order to conrm the successful growth of MoS
on NHE, ENHE ¼ ESCE + 0.24) and ꢀ0.13 eV vs. SCE (0.11 eV vs.
CoMoS , the Raman spectra were investigated and were shown NHE), respectively.
in Fig. 3b. The band at 924 cm corresponded to the Mo–S 0.3 eV higher than the conduction band (ECB) of the n-type
2
.
b
2
47,48
4
b
Moreover, the edge position of f is 0.1–
ꢀ
1
ꢀ
1
49
symmetric stretching mode. The bands at 868 cm
and semiconductor. Therefore, the ECB values of MoS2 and
ꢀ
1
8
06 cm were associated with the S asymmetric stretching CoMoS4 were ꢀ0.41 eV (vs. NHE) and ꢀ0.19 eV (vs. NHE),
ꢀ1
mode of the S–Mo–S bond. The band at 404 cm was attributed respectively. According to the formula (E ¼ E ꢀ E ) and the
g
VB
CB
to the out-of-plane vibration of S atoms in opposite directions.
E
g
of MoS
The band at 360 cm could be associated with the Co–S–Mo CoMoS could be further calculated to be 0.87 eV (vs. NHE) and
symmetric stretching mode. In the Raman spectrum of 2.57 eV (vs. NHE), respectively. The relative approximate energy
2 4 2
and CoMoS in Fig. 4b, the EVB value of MoS and
ꢀ
1
4
ꢀ
1
MoS
4
2
@CoMoS
4
, two new bands appearing at 376 cm and band diagrams of CoMoS
4
and MoS
2
were shown in Fig. 5c.
ꢀ
1
04 cm , respectively, could be assigned to the E2g and A1g
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4 2 2 4 2 4
Fig. 3 XRD patterns of the as-prepared samples (a); Raman spectra of CoMoS , MoS and MoS @CoMoS (b); XPS spectra of MoS @CoMoS (c),
Co 2p (d), Mo 3d (e) and S 2p (f).
In order to nd the separation efficiency and lifetime of the electrochemical impedance spectra (EIS) measurement was
ꢀ
+
photogenerated e /h , a photoelectrochemical test of the used to investigate the charge transfer resistance (Rct) and
ꢀ
+
samples was carried out. As shown in the amperometric I–t separation efficiency of photo-generated e /h pairs. The
curves in Fig. 6a, the MoS @CoMoS heterojunctions exhibited formed MoS @CoMoS heterojunction had a smaller arc radius
2
4
2
4
the highest photocurrent response compared to pristine MoS2 (R z 62 U) than pristine CoMoS (R z 127 U), indicating that
ct
4
ct
and CoMoS
4
2 4
, indicating that the composites have the highest the MoS @CoMoS heterojunction had an improved interface
ꢀ
+
separation efficiency of photo-generated e /h pairs, which charge transfer rate (Fig. 6b). The standard Randle's equivalent
might be attributed to the MoS @CoMoS heterojunction circuit model, including a constant phase element (CPE),
formed by the proper contact surface. Meanwhile, charge transfer resistance value (Rct), Warburg impedance (Z
2
4
w
)
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2
2 4
Fig. 4 (a) UV-vis absorption spectra; (b) plots of (ahn) versus the photon energy (hn) of MoS and CoMoS , respectively.
2 4 2 4 4 2
Fig. 5 The Mott–Schottky plots of (a) MoS and (b) CoMoS in 0.1 M Na SO solution; (c) energy-band diagram of CoMoS and MoS .
and the uncompensated solution resistance (R ), was used to t SCE) (Fig. S2†) and illumination. Fig. 7a displayed an efficient
s
the impedance data. The above I–t curves of photocurrent and visible-light-driven PEC performance on H O production with
2
2
EIS experimental results proved that the MoS
erojunction had a higher carrier separation efficiency and faster that 2D/3D hierarchical MoS
interfacial charge transfer.
2
@CoMoS
4
het- different photoelectrocatalysts as photocathode. It was found
@CoMoS produced more H
due to enhanced optical absorp-
with tion, charge-carrier separation and transfer. An H concen-
2
4
2 2
O
2 4
than 2D MoS or 3D CoMoS
The PL spectra (Fig. 6c) of CoMoS
4
and MoS
2
@CoMoS
4
2 2
O
an excitation wavelength of 310 nm were employed to further tration of 205 mM could be achieved aer 120 min of visible light
investigate the separation and recombination efficiency of irradiation, which was about 1.86 and 2.93 times that of
photo-generated carriers. Clearly, the PL emission intensity of CoMoS4 (110 mM) and MoS2 (70 mM). PEC activity was also
MoS @CoMoS (365 nm) was weaker than that of pure CoMoS , dependent on 2D MoS2 modifying dosage (Fig. S3†): H O2
2
4
4
2
indicating that higher separation efficiency and faster interfa- production on the modied CoMoS
cial charge transfer existed in the MoS @CoMoS hetero- in MoS
junction, which was conducive to enhancing its PEC activity.
Fig. 6d shows the light-on and light-off current–potential cover some catalytic sites and decrease the approachability of
4
increased with an increase
2
4
2
dosage due to its favorable effects on enhancing visible
light absorption. Nevertheless, excess surface modier would
50
curve. The increase in current under illumination indicated that
MoS @CoMoS had a better photoelectric performance with
O
2
, resulting in a reduction in H
Meanwhile, control experiments (Fig. 7b) revealed that H O2
2 2
O production.
2
4
2
either positive or negative bias potential exerted. That is to say, could hardly be detected in the absence of O environment and
2
the composite catalyst might be used as both a photocathode visible light radiation, indicating that O2 and visible light
and a photoanode.
catalysis were especially indispensable for the PEC H
production process. Moreover, the photoelectric-driven forma-
tion of H might also depend on the pH of the aqueous
solution, because H generation might be a proton-coupled
2 2
O
3.2 PEC specialized for H O /p-AP production using
2 2
O
2
2
MoS @CoMoS photocathode
2 2
O
2
4
electron transfer process on the photocathode. The pH values
2 2
PEC for H O production is an attractive strategy to address
of the PEC reaction system were investigated (pH ¼ 2, 3 and 5)
chemical resource demands. To investigate H O generation,
2
2
by adjusting with HClO solution in the presence of catalysts.
4
the PEC process was conducted in O dissolved in water without
2
From Fig. 7c, it was observed that the amount of H O attained
2
2
any co-catalyst or sacricial agent using a standard three-
electrode system at an optimal applied bias of ꢀ0.5 V (vs.
its maximum when pH ¼ 3, while the H
2
O
2
decreased relatively
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Fig. 6 (a) The periodic on/off photocurrent response at ꢀ0.5 V bias potential vs. SCE; (b) electrochemical impedance spectra (Nyquist plots) of
2 4
the different samples; (c) photoluminescence spectra of prepared samples; (d) the light-on and light-off current–potential curve (0.1 M Na SO
aqueous solutions).
2 2 2 4
Fig. 7 PEC-driven H O production over different catalysts (a); the PEC activity of 3D MoS @CoMoS in different gas environments (b) and at
different pH (c).
in content when the pH decreased to 2 or increased to 5, sug- (AgNO ), while the production of H O would increase aer the
3
2 2
+
+
gesting that it might be attributed to the excess protons that addition of an h scavenger (AO), because adding an h scav-
ꢀ
induced the gradual oxidization of the produced H
2
O
2
into H
2
O
enger would increase the utilization efficiency of e or inhibit
+
ꢀ
(H
2
O
2
+ 2H + 2e / 2H
leading to lower H
was the optimum pH value for PEC production of H
summary, under the conditions of pH ¼ 3, visible light irradi- affected the amount of H
ation, oxygen environment and ꢀ0.5 V bias voltage, the was speculated that the synthesis of H O may be an ORR of
2
O) or a less proton-rich environment the decomposition reaction of H
2 2
O , which indicated that the
ꢀ
2
O
2
production, which showed that pH ¼ 3 participation of e was crucial in the production process of
+
ꢀ
2
O
2
. In
H
2
O
2
. Combing with the above experiments, O
2
, H and e all
2 2
O
generated in this experiment, so it
2
2
photoelectric-driven H O yield by the composite material proton-coupled electron transfer. In order to further explore the
2
2
MoS @CoMoS reached its maximum.
detailed electron transfer path of the ORR, p-benzoquinone
2
4
ꢀ
Fig. 8a shows the free radical trapping experiments for the (PBQ, 1 mM) was added to scavenge cO
2
. As shown in Fig. 8a,
synthesis of H
2
O
2
. It could be found that the amount of H
2
O
2
less than 24% of the H
2
O
2
production decreased in the
ꢀ
ꢀ
generated decreased signicantly aer adding an e scavenger MoS
2
@CoMoS
4
system, indicating that cO
2
might affect the
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2ꢀ
Fig. 8 (a) Free radical trapping experiments producing H
2
O
2
; (b) the DMPO spin-trapping ESR technique was used to measure the cO
2 2 2 2 2 4
generated during H O production; (c) the influence of PBQ content on the production of H O on MoS @CoMoS .
formation of H
exist in the path of H
2
O
2
and a two-step single-electron ORR might
It can be seen from Fig. 7a that the amount of H
, ꢀ0.33 V produced gradually increased with time, and the formation rate
tended to stabilize,
production was hindered at high
. This phenomenon might be caused by
2 2
O
ꢀ
ꢀ
2
ꢀ
O
2
production ((i) e + O
2
¼ cO
2
ꢀ
+
vs. NHE; (ii) cO
2
+ e + 2H / H
2
O
2
, 1.44 V vs. NHE). There- gradually slowed down and the yield of H
2
O
2
fore, DMPO spin-trap ESR technology was used to further detect suggesting that PEC H
2
O
2
ꢀ
2ꢀ
cO
2
. As shown in Fig. 8b, the characteristic peaks of DMPO– concentrations of H
2
O
2
cO were clearly observed during H
2
O
2
production employing the in situ decomposition behavior of H
2
O
2
. Usually, H
2
O
2
can
ꢀ
+
ꢀ
MoS @CoMoS , which indicated that cO
was a probable be decomposed in two ways ((i) H O + H + e / H O + OH*,
2
4
2
2
2
2
+
ꢀ
þ
þ
*
2
intermediate during the H O generation process. The ESR H O + 2H + 2e / 2H O; (ii) H2O2 þ h /H þ HO ; H O +
2
2
2
+
2
2
2 2
+
+
ꢀ
results strongly implied the existence of the two-step single- 2h / 2H + O
2
), where H /e is the main cause of H
decomposition at lower pH and light-induced h is the main
2
O
2
ꢀ
+
electron ORR using an cO
The yields of H
none (PBQ, 1 mM) were also investigated in Fig. 8c. When the In Fig. 7c, when the pH was further decreased to 2, the H
content of PBQ gradually increased, the yield of H gradually decreased relatively in content, suggesting that a lower pH
decreased, and when the content of PBQ continued to increase induced the gradual oxidization of the produced H into H
to 7 mL, the amount of H O was almost unchanged, indicating due to excess protons (H O + 2H + 2e / 2H O). The above
2
radical as an intermediate.
1
6,20,51–53
2 2 2 2
O with different amounts of p-benzoqui- cause of H O decomposition at higher concentration.
2 2
O
2 2
O
2
O
2
2
O
+
ꢀ
2
2
2
2
2
ꢀ
that cO2 would affect the production of H O within a certain phenomena showed that although increasing the protonic acid
2
2
small range, but it could not completely suppress the produc- concentration in the solution would increase the content of
tion of H . Therefore, it was speculated that there might also formation, it would also greatly aggravate the in situ
exist a one-step two-electron ORR during the production of decomposition behavior of H , resulting in a decrease in the
. In order to further understand the in situ
Based on the above test results, the two-electron one-step decomposition behavior of H , H (2 mM) decomposition
oxygen reduction route might dominate the entire H tests were performed with all the catalysts under light illumi-
2
O
2
2 2
H O
2 2
O
+
ꢀ
H
2
O
2
(O
2
+ 2H +2e / H
2
O
2
, 0.68 V vs. NHE).
2 2
content of H O
2
O
2
2 2
O
2 2
O
production process, but the sequential one-electron two-step nation. As shown in Fig. 9a, there were 17%, 13% and 10% H O2
2
oxygen reduction route may also exist. Therefore, it could be decomposition over MoS @CoMoS , CoMoS and MoS2 aer
2
4
4
clearly proved that the in situ H
dominant two-electron one-step oxygen reduction route with only 2% without a catalyst. The kinetic behaviors of H
the assistance of a sequential one-electron two-step oxygen formation and decomposition could be evaluated by tting the
reduction route. Therefore, the H production reaction in this data of Fig. 7a and 9a. The formation and decomposition of
2 2 2 2
O generation pathway was the 120 min of illumination, but the decomposition of H O was
2 2
O
2 2
O
PEC process could be described as follows:
2 2
H O could be well tted with the pseudo-zero-order and rst-
order kinetic models (Fig. 9b and c). The values of production
ꢀ
2e
one-step ORR
rate (K ) and decomposition rate (K ) were obtained, and
f
d
+
ꢀ
O
2
+ 2H + 2e / H
2
O
2
(1)
comparison results were shown in Fig. 9d. The K value was
f
greatly improved aer 2D MoS
D/3D MoS @CoMoS exhibited the largest K
lower K , leading to the highest conversion efficiency of H
while MoS and CoMoS presented lower K and relatively larger
, causing the worst yield of H . The results indicated that
the increased specic surface area of CoMoS due to the
merging of 2D MoS2 could enhance H O production and
2
coupling with 3D CoMoS
4
, and
ꢀ
1e
two-step ORR
2
2
4
f
and a relatively
ꢀ
ꢀ
ꢀ
ꢀ
+
d
2 2
O ,
(
i) e + O / cO ; (ii) cO2 + e + 2H / H O
(2)
2
2
2
2
2
4
f
K
d
2 2
O
Enhanced PEC performance of 2D/3D MoS
likely to be attributable to the unique structural features
reducing the charge transfer path length, the higher specic
surface area of MoS
of PEC active sites and the optimal loading of MoS restraining
the recombination of e /h pairs.
2
@CoMoS
4
was
4
2
2
stabilize the formed H O under light irradiation.
2
2
2 4
@CoMoS providing an increased number
As a dangerous chemical, p-nitrophenol (p-NP) is highly toxic
and carcinogenic, and can cause irreversible harm to the
2
ꢀ
+
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Fig. 9 The PEC decomposition of H
2
O
2
(2 mM) (a); The kinetic curves of PEC H
) for H (d).
O
2 2
formation (b) and decomposition (c); formation rate
constants (K ) and decomposition rate constants (K
f
d
2 2
O
environment and human health. Therefore, the PEC conversion irradiation time. Clearly, compared to pure MoS and CoMoS ,
2
4
of toxic p-NP into value-added commodity chemical p-AP has the MoS @CoMoS hybrid showed the highest PEC perfor-
2
4
become a top priority. p-AP as an organic intermediate can be mance (pH ¼ 3) (Fig. 10b). The reduction efficiency for p-NP was
widely used in the production of various medicines, dyes, 92% aer 180 min on the 2D/3D MoS @CoMoS photo-
antioxidants and oil additives. Therefore, reducing p-NP to p-AP electrode. Moreover, the reduction reaction kinetic data over
is very valuable for environmental protection and industrial MoS @CoMoS composites in Fig. 10c were consistent with
2
4
2
4
production. The transformation of toxic organic pollutants to pseudo-rst-order kinetics based on the Langmuir–Hinshel-
low-cost and green synthetic regimes is socioeconomically wood model, and the corresponding kinetic constant (k) was
ꢀ1
important, underpinning the sustainable energy and environ- estimated to be 0.0147 min , which was 6.13 and 3.27 times
ꢀ
1
mental future that deserves the increasing attention of scientic higher than for pure MoS (k ¼ 0.0024 min ) and CoMoS (k ¼
2
4
ꢀ1
communities.
The PEC reduction performances of the prepared 2D/3D MoS
MoS @CoMoS as a photocathode was also investigated by performance in reducing p-NP.
reducing p-NP to p-AP under irradiation for 180 min. It could be The reduction products of p-NP at different times were
0.0045 min ). The above results strongly indicated that the
2
@CoMoS thin-lm electrode exhibited satisfactory PEC
4
2
4
observed from Fig. 10a that the UV absorption spectrum peak of explored by HPLC analysis. The chromatographic peaks
p-NP (ꢃ318 nm) gradually decreased with a prolongation of the appearing at 2.98 and 1.98 min corresponded to p-NP and p-AP
Fig. 10 (a) UV spectrum of MoS
2
@CoMoS
4
for p-NP reduction; (b) the PEC activities of as-prepared different samples and (c) the corresponding
kinetic analysis.
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external standard method, the yield of p-AP was calculated to be
about 83%. The deduced equation of the chemical reaction
process has been inserted in Fig. 11.
3
.3 PEC activity towards LOM degradation using an
MoS @CoMoS photoanode
The PEC degradation performance of as-obtained 2D/3D
MoS @CoMoS as a photoanode was evaluated by LOM degra-
2
4
2
4
dation under visible light illumination for 180 min. The corre-
sponding UV characteristic peaks of LOM were located at
2
80 nm and 327 nm, and the peak intensities decreased grad-
Fig. 11 Evolution of HPLC chromatograms during reduction of p-NP ually with prolonged irradiation time (Fig. 12a). It could be seen
to p-AP with MoS @CoMoS
that the MoS @CoMoS composite exhibited an improved PEC
2
4
.
2
4
activity compared to pure MoS2 and CoMoS , and the
4
percentage of LOM degradation over MoS @CoMoS was found
2
4
standards (Fig. S4†). As shown in Fig. 11, the chromatographic to be 79% (Fig. 12b) within 180 min of irradiation. Meanwhile,
peak appearing at 2.98 min gradually decreased as the irradia- the oxidation reaction kinetic data over MoS @CoMoS4
2
tion time increased, indicating that p-NP was rapidly reduced. composites in Fig. 12c were consistent with pseudo-rst-order
Simultaneously, a new chromatographic peak appeared at kinetics based on the Langmuir–Hinshelwood model, and the
1
.98 min and gradually increased along with the increase in corresponding kinetic constant (k) was estimated to be
ꢀ1
irradiation time, indicating that the p-AP yield was gradually 0.00863 min , which was about 1.87 and 3.17 times higher
increased. The above experimental results showed that p-NP than those of pure CoMoS (0.00461 min ) and MoS2
was successfully converted into p-AP in the presence of (0.00272 min ). In addition, the degradation products of LOM
MoS @CoMoS under visible light irradiation. In addition, the aer 180 min of reaction were also detected by ion chroma-
ꢀ1
4
ꢀ
1
2
4
resolution (R) of p-AP and p-NP was 3.93, indicating that the two tography. As shown in Fig. 12d, with the increase in visible light
compounds could be separated under the same HPLC condi- irradiation time, two new ion peaks appeared at 7.1 min and
ꢀ
2ꢀ
tions to quantify the content of the product. According to the 10.4 min, which were found to be NO3 and SO4 , respectively.
Fig. 12 (a) UV-vis spectrum of MoS
corresponding kinetic analysis; (d) ion chromatogram of the LOM solution during degradation for 180 min.
2
@CoMoS
4
for LOM degradation (pH ¼ 10); (b) The PEC activity of as-prepared different samples and (c) the
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2 4 2 2
Fig. 13 Cycling runs over MoS @CoMoS for (a) H O /(b) p-AP production and LOM degradation.
These results suggested that the LOM molecules were gradually found to be the active species in the process of H
converted to CO , H O and some harmless ions. and LOM degradation. Based on the above analyses, a Z-scheme
PEC mechanism was proposed (Scheme 2), which is consistent
2 2
O production
2
2
54
with the principle of interfacial band bending. In the tight
solid–solid contact heterojunction interface between MoS and
CoMoS , the E of CoMoS is very close to the E of MoS2,
3
.4 Stability
To research the stability of MoS
driven H /p-AP production and LOM degradation, recycling
2
2
4
@CoMoS for photoelectron-
4
CB
4
VB
2 2
O
providing a shorter electron transfer path, and the photo-
tests were carried out. First, the photoelectrode was washed and
dried, and subsequently reused in a new system for monitoring
H O /p-AP generation and LOM degradation under the same
ꢀ
generated e at the ECB of CoMoS could quickly migrate to
4
+
the EVB of MoS
2
and immediately combine with the h there.
2
2
ꢀ
+
Thereby, the longevity of the remaining e (ECB,MoS2)/h
VB,CoMoS4) pairs was greatly prolonged, giving the hetero-
junction excellent oxidation and reduction activity. When
MoS @CoMoS was applied as a photocathode, the H was
conditions. Fig. 13 shows that MoS @CoMoS had excellent
2
4
(E
stability aer four cycles. All of these results indicated that the
PEC activity of CoMoS had been further improved aer form-
ing a Z-scheme 2D/3D MoS @CoMoS hybrid.
4
2
4
2 2
O
2
4
ꢀ
produced in two ways, one was by combining O with 2e to
2
directly synthesize H O , and the other one was rst combining
2
ꢀ
2
3
.5 PEC mechanism
ꢀ
1
H
e
to produce cO2 medium, and then indirectly generating
ꢀ
Based on the band gap values in Fig. 5c, MoS
could be activated under visible light to generate e and h
2
and CoMoS
4
+
2
O
2
. At the same time, the photoexcited e le at the ECB of
ꢀ
2
MoS could also be acquired by p-NP to form p-AP, while the
+
simultaneously. Generally, if the heterojunction formed photogenerated h in the EVB of CoMoS
4
would be neutralized
ꢀ
between CoMoS
4
and MoS
2
was type-II, the photo-generated e
by the electrons from the carbon cloth electrode, and then the
on the ECB of MoS would be transferred to the E of CoMoS4 charge carriers would be effectively separated for the further
2
CB
+
and the photo-generated h on the E of CoMoS would be enhancement of PEC efficiency of H
transferred to the EVB of MoS . In this way, the e accumulated contrast, when MoS
on the ECB of CoMoS
O
/p-AP production. In
VB
4
2
2
ꢀ
2ꢀ
ꢀ
@CoMoS
was used as photoanode, the e
would combine with O
for LOM degradation. Simultaneously, the photogenerated
to enhance the PEC degra-
2
2
4
to cO , owing to the accumulated on the ECB of MoS
to form
4
could not reduce O
2
2
2
ꢀ
ꢀ
E (O
E
2
/ cO
2
) (ꢀ0.33 eV vs. NHE) being more negative than the cO
2
+
CB of CoMoS
4
(ꢀ0.19 eV vs. NHE), which was inconsistent with h were le on the EVB of CoMoS
4
ꢀ
trapping experiments (Fig. 14). As shown in Fig. 14, cO
2
was dation efficiency of LOM (Scheme 2). Based on the analysis of
the above results, the possible reaction equations could be
proposed as follow:
+
ꢀ
CoMoS + hv / h
+ e(CB)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
4
(VB)
+
(CB)ꢀ
MoS
2
+ hv / h(VB) + e
+
ꢀ
O + 2H + 2e / H O
2
2
2
ꢀ
¼ cO2ꢀ; (ii) O + e + 2H / H
2ꢀ
ꢀ
+
(
i) e + O
2
2 2
O
ꢀ
+
p-NP + 2e + 2H /p-AP
ꢀ
cO2 + LOM / CO + H O
2
2
+
Fig. 14 The effects of various scavengers on the production of H
2 2
O ,
h + LOM / CO
2
+ H O + harmless ions
2
2 4
reduction of p-NP and degradation of LOM over MoS @CoMoS .
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Scheme 2 Possible PEC mechanism path.
3
4
Y. Shiraishi, S. Kanazawa, Y. Sugano, D. Tsukamoto,
H. Sakamoto, S. Ichikawa and T. Hirai, ACS Catal., 2014, 4,
4
. Conclusions
774–780.
Z-scheme 2D/3D MoS @CoMoS ower-shaped catalyzers were
2
4
Y. Fu, C.-L. Dong, W. Zhou, Y.-R. Lu, Y.-C. Huang, Y. Liu,
P. Guo, L. Zhao, W.-C. Chou and S. Shen, Appl. Catal., B,
fabricated via a hydrothermal process merging 2D MoS
sheets into the nano-leaves of 3D CoMoS micro-owers. The
construction of a rationally designed photocathode was bene-
cial for promoting the selective reduction of O and p-NP to
and p-AP, respectively. With MoS @CoMoS , this supplied
2
nano-
4
2020, 260, 118206.
5
6
7
8
J. Wang, C. Xue, W. Yao, J. Liu, X. Gao, R. Zong, Z. Yang,
W. Jin and D. Tao, Appl. Catal., B, 2019, 250, 369–381.
I. Yamanaka and T. Murayama, Angew. Chem. Int. Ed, 2008,

2
H
2
O
2
2
4
an economic, efficient and green route for the photoelectric-
driven high-value-added product of H O (about 205 mM H O
2 2
was produced under irradiation for 120 min)/p-AP (the corre-
sponding yield of p-AP was about 83% under irradiation for 180
min) by using 5.0 mg of catalyst without any co-catalyst. More-
over, rapid PEC degradation towards LOM (79%) was also ach-
ieved when MoS @CoMoS acted as a photoanode. This work
2 4
could provide new insights into the rational design of a PEC
system with efficient H O /p-AP production and capacity to
degrade contaminants.
47, 1900–1902.
2
2
Y. Jiang, P. Ni, C. Chen, Y. Lu, P. Yang, B. Kong, A. Fisher and
X. Wang, Adv. Energy Mater., 2018, 8, 1801909.
X. Shi, S. Siahrostami, G. L. Li, Y. Zhang, P. Chakthranont,
F. Studt, T. F. Jaramillo, X. Zheng and J. K. Norskov, Nat.
Commun., 2017, 8, 701.
A. Verdaguer-Casadevall, D. Deiana, M. Karamad,
S. Siahrostami, P. Malacrida, T. W. Hansen, J. Rossmeisl,
I. Chorkendorff and I. E. Stephens, Nano Lett., 2014, 14,
9
2
2
1603–1608.
1
0 S. Siahrostami, A. Verdaguer-Casadevall, M. Karamad,
D. Deiana, P. Malacrida, B. Wickman, M. Escudero-
Escribano, E. A. Paoli, R. Frydendal, T. W. Hansen,
I. Chorkendorff, I. E. Stephens and J. Rossmeisl, Nat.
Mater., 2013, 12, 1137–1143.
Conflicts of interest
There are no conicts to declare.
1
1 J. S. Jirkovsky, I. Panas, E. Ahlberg, M. Halasa, S. Romani and
D. J. Schiffrin, J. Am. Chem. Soc., 2011, 133, 19432–19441.
2 C. H. Choi, M. Kim, H. C. Kwon, S. J. Cho, S. Yun, H. T. Kim,
K. J. Mayrhofer, H. Kim and M. Choi, Nat. Commun., 2016, 7,
Acknowledgements
1
This project was supported by the National Natural Science
Foundation of China (NSFC 51672116 and 52072164), and Liao
Ning Revitalization Talents Program (No. XLYC1902066). The
authors also thank their colleagues and other students who
participated in this study.
10922.
1
1
1
3 R. Shen, W. Chen, Q. Peng, S. Lu, L. Zheng, X. Cao, Y. Wang,
W. Zhu, J. Zhang, Z. Zhuang, C. Chen, D. Wang and Y. Li,
Chem, 2019, 5, 2099–2110.
4 Z. Lu, G. Chen, S. Siahrostami, Z. Chen, K. Liu, J. Xie, L. Liao,
T. Wu, D. Lin, Y. Liu, T. F. Jaramillo, J. K. Nørskov and Y. Cui,
Nat. Catal., 2018, 1, 156–162.
5 P. Y. Kuang, Y. Z. Su, K. Xiao, Z. Q. Liu, N. Li, H. J. Wang and
J. Zhang, ACS Appl. Mater. Interfaces, 2015, 7, 16387–16394.
References
1
2
H. B. Gray, Nature Chem, 2009, 1, 7.
D. Kim, K. K. Sakimoto, D. Hong and P. Yang, Angew. Chem.
Int. Ed, 2015, 54, 3259–3266.
This journal is © The Royal Society of Chemistry 2020
J. Mater. Chem. A

View Article Online
Journal of Materials Chemistry A
Paper
16 L. Zhou, J. Feng, B. Qiu, Y. Zhou, J. Lei, M. Xing, L. Wang, 34 L. Zhang, Y. Hu and J. Zheng, J. Mater. Chem. A, 2017, 5,
Y. Zhou, Y. Liu and J. Zhang, Appl. Catal., B, 2020, 267,
18396–118404.
7 Y. Kofuji, S. Ohkita, Y. Shiraishi, H. Sakamoto, S. Ichikawa,
18664–18673.
1
35 L. Jing, Y. Xu, S. Huang, M. Xie, M. He, H. Xu, H. Li and
Q. Zhang, Appl. Catal., B, 2016, 199, 11–22.
1
S. Tanaka and T. Hirai, ACS Sustainable Chem. Eng., 2017, 36 X. Yang, F. Qian, G. Zou, M. Li, J. Lu, Y. Li and M. Bao, Appl.
, 6478–6485. Catal., B, 2016, 193, 22–35.
8 Y. Kofuji, S. Ohkita, Y. Shiraishi, H. Sakamoto, S. Tanaka, 37 M. Wei, C. Wang, Y. Yao, S. Yu, W.-H. Liao, J. Ren, R. Sun and
S. Ichikawa and T. Hirai, ACS Catal., 2016, 6, 7021–7029. C.-P. Wong, Chem. Eng. J., 2019, 355, 891–900.
9 Y. Yang, Z. Zeng, G. Zeng, D. Huang, R. Xiao, C. Zhang, 38 S. Wang, D. Zhang, B. Li, C. Zhang, Z. Du, H. Yin, X. Bi and
C. Zhou, W. Xiong, W. Wang, M. Cheng, W. Xue, H. Guo, S. Yang, Adv. Energy Mater., 2018, 8, 1801345.
X. Tang and D. He, Appl.Catal., B, 2019, 258, 117956–117966. 39 X. Xu, Y. Song, R. Xue, J. Zhou, J. Gao and F. Xing, Chem. Eng.
0 Y. Kofuji, Y. Isobe, Y. Shiraishi, H. Sakamoto, S. Tanaka, J., 2016, 301, 266–275.
S. Ichikawa and T. Hirai, J. Am. Chem. Soc., 2016, 138, 40 X. Y. Yu, Y. Feng, Y. Jeon, B. Guan, X. W. Lou and U. Paik,
0019–10025. Adv. Mater., 2016, 28, 9006–9011.
1 S. Li, G. Dong, R. Hailili, L. Yang, Y. Li, F. Wang, Y. Zeng and 41 Y. R. Liu, X. Shang, W. K. Gao, B. Dong, X. Li, X. H. Li,
5
1
1
2
1
2
2
2
C. Wang, Appl.Catal., B, 2016, 190, 26–35.
2 H. Kim, S. Gim, T. H. Jeon, H. Kim and W. Choi, ACS Appl.
Mater. Interfaces, 2017, 9, 40360–40368.
J. C. Zhao, Y. M. Chai, Y. Q. Liu and C. G. Liu, J. Mater.
Chem. A, 2017, 5, 2885–2896.
42 J. Zheng and L. Zhang, Appl. Catal., B, 2018, 231, 34–42.
3 E. V. Kondratenko, G. Mul, J. Baltrusaitis, G. O. Larraz ´a bal 43 X. Dai, K. Du, Z. Li, M. Liu, Y. Ma, H. Sun, X. Zhang and
and J. P ´e rez-Ram ´ı rez, Energy Environ. Sci., 2013, 6, 3112–
135.
4 B. Klahr, S. Gimenez, F. Fabregat-Santiago, J. Bisquert and
Y. Yang, ACS Appl. Mater. Interfaces, 2015, 7, 27242–27253.
44 Y.-R. Liu, X. Shang, W.-K. Gao, B. Dong, J.-Q. Chi, X. Li,
K.-L. Yan, Y.-M. Chai, Y.-Q. Liu and C.-G. Liu, Appl. Surf.
Sci., 2017, 412, 138–145.
3
2
T. W. Hamann, J. Am. Chem. Soc., 2012, 134, 16693–16700.
25 Y.-J. Yuan, Z. Li, S. Wu, D. Chen, L.-X. Yang, D. Cao, 45 Q. Li, X.-Q. Qiao, Y. Jia, D. Hou and D.-S. Li, ACS Appl. Nano
W.-G. Tu, Z.-T. Yu and Z.-G. Zou, Chem. Eng. J., 2018, 350,
35–343.
6 J. Liang, Y. Jiao, M. Jaroniec and S. Z. Qiao, Angew. Chem. Int.
Ed, 2012, 51, 11496–11500.
Mater, 2019, 3, 68–76.
46 J. Luo, G. Dong, Y. Zhu, Z. Yang and C. Wang, Appl. Catal., B,
2017, 214, 46–56.
47 Q. Li, X.-Q. Qiao, Y. Jia, D. Hou and D.-S. Li, Appl. Surf. Sci.,
2019, 498, 143863.
3
2
2
7 L. Zheng, H. Su, J. Zhang, L. S. Walekar,
H. V. Molamahmood, B. Zhou, M. Long and Y. H. Hu, 48 S. Hua, D. Qu, L. An, W. Jiang, Y. Wen, X. Wang and Z. Sun,
Appl. Catal., B, 2018, 239, 475–484.
Appl. Catal., B, 2019, 240, 253–261.
2
2
8 K.-H. Cho and Y.-M. Sung, Nano Energy, 2017, 36, 176–185.
9 Q. A. Drmosh, A. Hezam, A. H. Y. Hendi, M. Qamar,
49 W. Shi, F. Guo, H. Wang, M. Han, H. Li, S. Yuan, H. Huang,
Y. Liu and Z. Kang, Appl. Catal., B, 2017, 219, 36–44.
Z. H. Yamani and K. Byrappa, Appl. Surf. Sci., 2020, 499, 50 W. Zou, Y. Shao, Y. Pu, Y. Luo, J. Sun, K. Ma, C. Tang, F. Gao
43938. and L. Dong, Appl. Catal., B, 2017, 218, 51–59.
0 G. Yang, D. Chen, H. Ding, J. Feng, J. Z. Zhang, Y. Zhu, 51 X. Wang, Z. Han, L. Yu, C. Liu, Y. Liu and G. Wu, ACS
1
3
3
S. Hamid and D. W. Bahnemann, Appl. Catal., B, 2017,
19, 611–618.
1 J. Staszak-Jirkovsky, C. D. Malliakas, P. P. Lopes,
Sustainable Chem. Eng., 2018, 6, 14542–14553.
52 S. Thakur, T. Kshetri, N. H. Kim and J. H. Lee, J. Catal., 2017,
345, 78–86.
2
N. Danilovic, S. S. Kota, K. C. Chang, B. Genorio, 53 Y. Shiraishi, S. Kanazawa, Y. Kofuji, H. Sakamoto,
D. Strmcnik, V. R. Stamenkovic, M. G. Kanatzidis and
N. M. Markovic, Nat. Mater., 2016, 15, 197–203.
S. Ichikawa, S. Tanaka and T. Hirai, Angew. Chem. Int. Ed,
2014, 53, 13454–13459.
3
3
2 Y. Sun, C. Wang, T. Ding, J. Zuo and Q. Yang, Nanoscale, 54 Z.-F. Huang, J. Song, X. Wang, L. Pan, K. Li, X. Zhang,
2
016, 8, 18887–18892.
3 L. Yang, Y. Hu and L. Zhang, Chem. Eng. J., 2019, 378,
22092.
L. Wang and J.-J. Zou, Nano Energy, 2017, 40, 308–316.
1
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