2D ultrathin CoP modified Mn: XCd1- xS with controllable band structure and robust photocatalytic performance for hydrogen generation

Article abstract of DOI:10.1039/c9dt02849h

Considerable efforts have been directed towards constructing high-efficiency, earth-abundant and low-cost photocatalysts for hydrogen evolution under visible light irradiation. In this work, 2D ultrathin CoP-decorated bimetallic Mn_xCd_1-xS photocatalysts were developed based on the combined strategies of controllable band structure and co-catalyst modification. An optimal H₂ production rate of 65324 μmol g^-1 h^-1 was obtained for the Mn_0.5Cd_0.5S/CoP-4% sample under visible light irradiation, which was 4.26 times higher than that of pure Mn_0.5Cd_0.5S as well as 38.7 times that of pure CdS. UV-vis and MS characterization results showed that the introduction of Mn into CdS could change the band potential towards a more negative direction, which would be beneficial for water reduction. Moreover, the added CoP could act as a co-catalyst to facilitate the electron transfer and restrain the recombination of photogenerated electron-hole pairs, which was testified by photocurrent, PL and EIS analyses. This work paves the way to offer a new direction towards designing efficient photocatalysts for hydrogen evolution.

Full text of DOI:10.1039/c9dt02849h

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Douglas W. Stephen et al.
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2
D ultrathin CoP modified Mn Cd S with controllable
x
1-x
band structure and robust photocatalytic performance for
hydrogen generation

Ran Chen, Yanhui Ao , Chao Wang, Peifang Wang
Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry
of Education, College of Environment, Hohai University, No.1, Xikang road, Nanjing, 210098,
China
Abstract:
Considerable efforts have been paid towards constructing high-efficiency,
earth-abundant and low-cost photocatalysts for hydrogen evolution under the
irradiation of visible light. In this work, 2D ultrathin CoP decorated bimetallic
Mn Cd S photocatalysts were developed based on combined strategies of
x
1-x
controllable band structure and co-catalyst modification. An optimal H production
2
-1
-1
rate was obtained up to 65324 μmol﹒g ﹒h for Mn Cd S/CoP-4% sample under
0
.5
0.5
the irradiation of visible light, which was 4.26 times higher than pure Mn Cd S as
0
.5
0.5
well as 38.7 times of pure CdS. UV-vis and MS characterization results showed the
introduction of Mn into CdS could change the band potential directed to a more
negative position, which would be beneficial for water reduction. Moreover, the
addition of CoP could act the role as co-catalyst to facilitate the electrons transfer and
restrain the recombination of photogenerated electron-hole pairs, which was testified
by photocurrent, PL and EIS analyses. This work paves the way to offer a new

Corresponding author. E-mail address: andyao@hhu.edu.cn (Yanhui Ao)
1

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direction towards designing efficient photocatalysts for hydrogen evolution.
Keywords: hydrogen evolution, Mn Cd S, band structure, co-catalyst.
x
1-x
1
. Introduction
Photocatalytic hydrogen production over semiconductors is a rapidly developed
technology and has been envisioned as a potential manner towards solving increasing
1
-3
energy consumption and serious environmental pollution . Hydrogen, as a promising
candidate to substitute fossil fuels, has received much attention for its clean, high
4
-6
calorific value and free from contamination to environment . Since the first use of
photocatalysis in H generation over semiconductors by Fujishima and Honda in
2
7
1
972 , tremendous efforts have been paid in the last few decades. To date, great
improvement have been made in developing high-efficiency photocatalysts like
chalcogenides8-12, metal oxides13-15 and nitrides16, 17
.
Recently, a newly ternary composites that combined broad bandwidth
semiconductors with narrow band gap photocatalysts have drawn great concentration
1
8
for the predominant light absorption and controllable band position . Among the
numerous studying, integrating MnS with CdS to form Mn Cd S compound system,
x
1-x
which shows superior optical character and could optimize band structure, is
1
9
20
considered as a preferable option for H evolution . For example, Ikeue firstly
2
synthesized Mn Cd S photocatalysts with suitable band position for hydrogen
x
1-x
evolution reaction, which showed great photocatalytic improvement comparing to
2
1
pure CdS and MnS by visible light irradiation. Additionally, Liu et al. synthesized
Mn Cd S photocatalyst by hydrothermal method. The controllable band gap of
1
-x
x
2

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Mn Cd S plays the key role in improving hydrogen production. Thus, it is feasible to
1
-x
x
hybridize MnS with CdS towards water splitting reaction. Nevertheless,
photocatalytic H2 evolution under visible light irradiation over Mn Cd S
x
1-x
photocatalysts is still restricted by the fast recombination of photo-induced
electron-hole pairs. Thereafter, some strategies like adding co-catalysts22 or
modifying with other metals23 have been developed to enhance the photocatalytic
hydrogen production. Among the numerous methods, assemble Mn Cd S with a
x
1-x
co-catalyst could be an effective approach. In general, the coupling of co-catalyst
could enhance the electrons transfer capacity, which may in favor of reducing the
possibility of photogenerated electron-hole pairs recombination and thus promote H2
evolution. Graphene oxide and reduced graphene oxide24-27 have been studied
widely for their superior conductivity and electron mobility by acting
important role as electron collector and transporter as well as co-catalyst, which
could prolong the lifetime of photoinduced electrons and thus reduce the
recombination possibility of photogenerated electron-hole pairs. Currently, 2D
transition metal phosphides (TMPs) materials have aroused great attention for their
superior conductivity for water splitting reaction compare to bulk materials28-31
.
Among various metal phosphides, CoP was found to be the most typical catalyst for
its good capability in electrons transferring which could retard the
recombination of photogenerated electron-hole pairs and the existence of CoP
could improve the light absorption32, 33
.
For insistence, Zhou synthesized two
28
dimensional (2D) ultrathin CoP with other metals doping through electrocatalysis
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method and showed enhanced catalytic performance. The reports mentioned above
implied that cobalt phosphides could be served as potential noble metal-free
co-catalysts. However, no works in studying 2D ultrathin CoP modified Mn Cd S
x
1-x
photocatalyst apply to hydrogen production reaction have been reported.
In this paper, we firstly fabricated CoP decorated Mn Cd S photocatalysts for
x
1-x
water splitting. As expected, the Mn Cd S/CoP photocatalysts exhibited
x
1-x
significantly enhanced photocatalytic performance in comparison with pure CdS and
Mn Cd S. Physicochemical properties of Mn Cd S/CoP samples and the
x
1-x
x
1-x
mechanism for enhanced photocatalytic performance are studied in detail. Preferable
electro-conductibility and controllable band position of the cocatalyst may responsible
for the increased H generation performance.
2
2
2
Experimental section
.1 Synthesis of Mn Cd S
x
1-x
Mn Cd S photocatalysts (x = 1, 0.9, 0.75, 0.5, 0.25, 0.1, 0) were prepared by
x
1-x
hydrothermal method. Typically, 6mmol Mn(CH COO) ·4H O and a certain amount
3
2
2
of C H NS were added into 60ml deionized (DI) water with continuous stirring for
2
5
half an hour. Afterwards, a proportional amount of Cd(CH COO) ·2H O were
3
2
2
dropped into the mixed solution. After that, the mixed solution was shifted into a 100
o
ml Teflon-lined stainless steel autoclave and heated at 160 C in an oven for 24 h.
2
.2 Preparation of Co(OH)2
2
g L-arginine and 1.3658 g cobalt nitrate were added in 60 mL DI water. Next, kept
the solution in a 100 mL Teflon-lined autoclave for a whole day in an oven. Finally,
4

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the product was washed repeatedly via DI water and ethanol followed by drying at 60
oC for 10h.
2
.3 Preparation of CoP
0
.001 mol of above obtained Co(OH) and 0.005 mol of NaH PO ·H O were ground
2
2
2
2
o
uniformly together in a mortar. Then annealed the mixture at 300 C (heating rate 2
oC/min) for 2 h under the atmosphere of argon. At last, the product was collected and
washed before use.
2
.4 Preparation of Mn Cd S/CoP
0.5 0.5
In a typical procedure, certain amount of the as-prepared CoP (2 mg, 4 mg, 8 mg and
2 mg) were added in 10 mL ethanol and kept ultra-sonicated for 30min to form A
solution, respectively. At the meantime, 0.2 g Mn Cd S were added in another 20
1
0
.5
0.5
ml ethanol and kept ultra-sonicated for 30min to form B solution. Then, transferred B
solution into A solution with fierce stirring for 2h. At last, rotary evaporators was
o
used to remove ethanol and then dried in an oven at 60 C for further using. The as
prepared Mn Cd S/CoP-x (x = mCoP/m 0.5 0.5 ) was marked as MCSCP-x.
0
.5
0.5
Mn Cd S
3
. Results and discussion
3
.1 Characterization of samples
X-ray diffraction (XRD) characterization was employed to study the crystallinity
and structure of pure CdS, MnS, CoP, Mn Cd S as well as MCSCP-x photocatalysts.
x
1-x
o
o
o
o
o
o
In pure CdS sample (Fig. 1a), peaks at 2θ = 25.0 , 26.6 , 28.2 , 36.6 , 43.9 , 48.0 ,
o
5
2.0 of (100), (002), (101), (102), (103), (112) planes corresponding to hexagonal
3
4
o
o
phase CdS (JCPDS No. 41-1049) . For MnS catalysts, several peaks at 29.6 , 34.4 ,
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o
o
o
o
4
1.9 , 49.3 , 61.5 , 72.4 can be observed and correspond well with hexagonal MnS
3
5
(
JCPDS 72-1534) . Obviously, all Mn Cd S samples show similar diffraction
x 1-x
patterns, testifying the hexagonal structure of CdS has not been changed after the
o
o
o
o
addition of Mn. With the adding of Mn, peaks at 2θ = 29.6 , 49.3 , 61.5 and 72.4
belong to MnS become stronger. Similar results can be observed in Fig. 1b, pure CoP
o
o
o
exhibits peaks at 2θ = 31.8 , 34.6 and 49.3 match well with orthorhombic CoP
3
6
(
JCPDS 29-0497) . Comparing to Mn Cd S, MCSCP-x photocatalysts, MCSCP-x
0.5 0.5
display analogical patterns except for several peaks supposed to CoP occur at 2θ =
o
o
o
3
1.8 , 34.6 and 49.3 , stating the successfully preparation of MCSCP-x
photocatalysts.
The surface chemical composition and valence state of elements in Mn Cd S
0
.5
0.5
and MCSCP-4% catalysts was tested by X-ray photoelectron spectroscopy (XPS) in
order to further study electronic interactions. As can be seen in Fig. 2a, the Cd 3d
spectrum of Mn Cd S and MCSCP-4% composites show a similar trend with two
0
.5
0.5
binding energy at 411.7 eV and 404.8 eV ascribe to Cd 3d3/2 and Cd 3d , which
5/2
signifies the existence of Cd2+37, 38 in both samples. In the high-resolution XPS
spectrum of Mn 2p in Mn Cd S (Fig. 2b), a strong doublet at binding energy of
0
.5
0.5
6
52.0 eV and 640.8 eV with satellite peaks at 654.7 eV as well as 644.5 eV in
accordance with Mn 2p1/2 and Mn 2p3/2 of Mn2+39. In the MCSCP-4% composite, the
high-resolution XPS spectrum of Mn 2p keeps well with Mn Cd S excepts a slight
0
.5
0.5
movement shifting towards higher energy, testifying the doping of CoP could affect
the Mn core level electrons by forming chemical interaction during the preparation
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2
2
process . Fig. 2c exhibits the high-resolution XPS spectrum of P 2p of MCSCP-4%,
4
0
peak locates at 134.3 eV attributes to P-O , while another peaks at 129.7 eV and
1
27.7 eV identify with the P 2p1/2 and P 2p3/241. Additionally, peaks at 777.4 eV and
81.3 eV as well as a satellite peak can be observed in Co 2p (Fig. 2d) region in
7
MCSCP-4% photocatalyst. Characteristic peak at 781.3 eV may ascribe to the partial
oxidized of Co that results in the formation of Co-O bonding. Moreover, peaks at
7
77.4 eV in the high-resolution XPS spectrum of Co 2p and at 127.7 eV of P 2p3/2
4
2
represents Co-P, which signifies the presence of CoP . The above results demonstrate
the existence of CoP in the MCSCP-4% photocatalyst. Moreover, the interaction
between CoP and Mn Cd S are chemically bonded rather than physical mixture.
0
.5
0.5
Scanning electron microscopy (SEM) images with low and high
magnification of MCSCP-4% sample is shown in Fig. S1. As shown in Fig. S1,
there are numerous of small nanoparticles corresponding to Mn Cd S cover
0
.5
0.5
the surface of CoP in the low magnification image of MCSCP-4% sample. From
the high magnification image, some bloomed particles (in the circle), different
with light ones (in the square), can be seen under the CoP nanosheet, testifying
the ultrathin morphology of CoP. Transmission electron microscope (TEM) and
high-resolution TEM (HRTEM) analysis are useful method to obtain the information
about microscopic morphology of the as-prepared photocatalyst. As can be seen in
Fig. 3a, Mn Cd S nanoparticles keep a close contact with flake-like CoP. A
0
.5
0.5
magnified image of MCSCP-4% sample is displayed in Fig. 3b, the lattice spacing of
.34 nm assigns to Mn Cd S (002) and the other lattice fringe of 0.23 nm
0
0
.5
0.5
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corresponding to CoP (201) can be acquired43, 44. Additionally, the EDX analysis of
MCSCP-4% is showed in Fig. S2, testifying the coexistence of Mn, Cd, S, Co and P.
The consequences matches well XPS and XRD results, which demonstrates the
successful synthesis of MCSCP-4% photocatalyst.
The comparison of the optical properties by using UV-vis diffuse reflectance spectra
(
DRS) between CdS, MnS, CoP, MCSCP-4% and a series of Mn Cd S
x 1-x
photocatalysts are shown in Fig. 3a and b. Clearly in Fig. 3a, the original CdS
possesses a band gap of about 2.21 eV that shows the absorption edge located at 560
4
5
nm, and the result identifies well with the previous report . For MnS sample, an
absorption edge at about 406 nm can be found and the band gap is 3.05 eV, which
shows fluctuation within the scope of visible light and the reason may due to the
2
1
internal transitions of Mn and defects . However, the absorption exhibits a
continuous blue shift comparing to pure CdS with the adding of Mn in Mn Cd S
x
1-x
photocatalysts. Besides, band gap for CdS, Mn Cd S and MCSCP-4% are
0
.5
0.5
estimated to be 2.21 eV, 2.23 eV and 2.36 eV, respectively, according to (ahv)2
hv - Eg39. The above results further certifies the successfully incorporation of Mn
into the lattice of CdS by chemical process rather than a simple commixture of CdS
=
4
6
and MnS . In Fig. 3b, the MCSCP-x composites keep similar absorption trend and
exhibit a red shift towards visible light region comparing to Mn Cd S,
0
.5
0.5
demonstrating that CoP doped on the surface of Mn Cd S as well as the adding of
0
.5
0.5
CoP could extend the visible light absorption.
.2 Photocatalytic performance
3
8

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Photocatalytic H generation performance over Mn Cd S (x=0, 0.14, 0.25, 0.5,
2
x
1-x
0
.75, 0.86, 1) and Mn Cd S with different CoP loading under the irradiation of
0.5 0.5
2
-
2-
visible light via using S /SO as sacrificial reagents are exhibited in Fig. 5. As can
3
be seen in Fig. 5a, no H evolution catalytic activity can be detected in pure MnS. A
2
wide band gap is mainly responsible for the poor photocatalytic performance. And
-1
-1
CdS sample exhibits lower catalytic performance of about 1687 μmol·g ·h , which
4
7
may for fast photo-generated electron-holes pair recombination and less active sites .
Notably, the hydrogen evolution rate increases with the adding of Mn content into
-1
-1
CdS and reaches a maximum H evolution up to 15340 μmol·g ·h over Mn Cd S
2
0.5
0.5
sample. However, the photocatalytic activity decreases rapidly when Mn content
exceeds 50%. On one hand, a higher loading of Mn would induce more formation of
MnS that cover the surface of CdS, which could shield the light absorption. On the
other hand, too much MnS would aggregate and turn into recombination center of
electron-holes. In Fig. 5b, H evolution rate increases remarkably after the further
2
loading of CoP, which testifies CoP could act as an efficient co-catalyst to shift
electrons and thus enhance photocatalytic activity. A prominent H generation rate is
2
-1
-1
obtained of 65324 μmol·g ·h for MCSCP-4% composite by coupling 4 wt% CoP
with Mn Cd S with an apparent quantum efficiency (AQE) of 22.6% (420 nm). The
0
.5
0.5
catalytic activity will descend when further adds CoP, which due to overmuch CoP
will prejudice the electrons transfer. Also, CoP/CdS sample was tested as a
comparison. Clearly, CoP/CdS sample shows an enhanced photocatalytic performance
than pure CdS.
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Furthermore, the recycling measurement of MCSCP-4% sample is tested to
study the stability and reusability, which is a significant factor for widespread
application. As revealed in Fig. 6, the MCSCP-4% keeps a steady catalytic
performance during three cycles and no deactivation is found, which demonstrates
MCSCP-4% sample is quite efficient and stable during the whole test.
XPS analysis was employed to characterize the stability of the MCSCP-4%
photocatalyst after the reaction (Fig. S3). Comparing to fresh MCSCP-4%
sample, nearly no changes can be seen in XPS spectrum of Cd 3d, Mn 2p, P 2p
and Co 2p, testifying the perfect stability of the MCSCP-4% photocatalyst.
3
.3 Proposed photocatalytic H -production mechanism
2
Separation of photogenerated electron-hole pairs is an important aspect affects
photocatalytic performance towards water splitting. Photoluminescence (PL)
measurement was measured at an excitation wavelength of 380 nm. In Fig. 7a, pure
CdS photocatalyst exhibits the highest peak emission located at about 590 nm
4
8
corresponding to the intrinsic band edge of CdS , which illustrates a poor electrons
transfer and leads to a lower photocatalytic H performance. For Mn Cd S sample,
2
0.5
0.5
a reduced peak intensity can be observed after the incorporation of MnS, which
explains a faster separation of photo-generated electron holes pair. Notably, peak
intensity for MCSCP-4% composite quenches much in comparison with neither CdS
or Mn Cd S, stating the further adding of CoP could play a critical role as an
0
.5
0.5
efficient co-catalyst to transfer electrons and thereafter promotes H generation
2
4
9
reaction . Besides, time-resolved photoluminescence (TPRL) was carried out to
1
0

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better explore the capability of electrons transfer of the different catalysts and the
results are shown in Fig. 7b. The PL lifetime of MCSCP-4% (1.42 ns) increased
comparing to Mn Cd S (1.19 ns), which testifies the coupling of CoP could restrain
0
.5
0.5
the recombination of photo-induced electron-holes pair to allow more electrons attend
3
9
the H generation process .
2
Electrochemical impedance spectroscopy (EIS) was carried out to explore the
transferring efficiency of electrons. In Fig. 8, MCSCP-4% composite shows a much
quenched arc radius in comparison with pure CdS and Mn Cd S, which means a
0
.5
0.5
much lower level of resistance and a superior electrons transfer. Photocurrent
characterization is an effective method to understand the electrons transportation
under the irradiation of visible light. In Fig. 9, pure CdS and Mn Cd S as well as
0
.5
0.5
MCSCP-4% composites show visible light response and maintain good repeatability
in the whole several on/off cycles test. As expected, pure CdS exhibits relative low
photocurrent intensity, which means an inferior electrons transfer ability.
Nevertheless, Mn Cd S exhibits an increased photocurrent intensity, illustrating the
0
.5
0.5
modifying of MnS could facilitate the migration of electrons. It is obviously,
MCSCP-4% displays much more intense photocurrent response, proving the further
modifying of CoP could act as an effective co-catalyst to accelerate the electrons
transfer and reduce the recombination possibility of photo-generated electron-holes
pair.
The energy band structure was concluded by means of ultraviolet-visible
(UV-vis) spectroscopy and Mott-Schottky (M-S) analysis (Fig. S3) to assess the effect
1
1

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of Mn species in CdS. The band gaps of CdS, MnS and Mn Cd S composites were
x
1-x
elucidated from the Tauc’s plot by taking into account the transmittance and
reflectance of the samples. It is known that band gap and construction band position
are two key factors that influence the photocatalytic activity. In Fig. 10, all the
catalysts are semiconductors with a direct band gap more than 1.23 eV, which are
larger than the required minimum band gap for water splitting reaction, testifying the
potential application of Mn Cd S composites as a visible light photocatalysts. The
x
1-x
construction band of pure CdS is -0.45 V, while Mn Cd S composites all shifted to
x
1-x
more negative potential with the adding of Mn. In general, a more negative CB
5
0
position of Mn Cd S implies a fast electrons shifting and a stronger ability in
x
1-x
5
1
reducing water to generate hydrogen , which will be of great significance in
promoting the H production reaction. As a result, the doping of Mn could change the
2
band gap position towards a more negative position, accelerating the hydrogen
generation. Furthermore, Mott-Schottky analysis (Fig. S5) and the energy band
structure (Fig. S6) of Mn Cd S with different amount of CoP modifying are
0
.5
0.5
studied, respectively. Clearly, the coupling of CoP resulted in a reduced band gap and
the conduction band directed to a negative position with the continuous adding of
CoP.
Based on the above results, photocatalytic H generation under the irradiation of
2
visible light over MCSCP-4% photocatalyst is proposed in Fig. 11. As illustrated,
photo-generated electrons from the valance band of Mn Cd S will move to the
0
.5
0.5
conduction band of Mn Cd S upon excitation, leaving holes in the valance band.
0
.5
0.5
1
2

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5
2
The CB and VB site of CoP is -0.43eV and 1.3eV , while Mn Cd S located at
0
.5
0.5
-
0.68 eV and 1.55 eV, respectively. Therefore, the electrons on the CB of Mn Cd S
0.5 0.5
will further move to the CB of CoP due to the better electrons assemble ability and
+
low Fermi level of CoP. The H will be captured by CoP to form H-CoP, then the
intermediate H-CoP would react with electrons that transferred from the CB of
5
3
Mn Cd S to form hydrogen . The detail steps are listed as follows:
0
.5
0.5
+
-
MnxCd1 - xS + hν → h + e
CoP + e + H + → H - CoP
-
+
-
H - CoP + H + e → CoP + H2
Meanwhile, the holes leaved on the VB of Mn Cd S would be captured by
0
.5
0.5
2
-
2-
S /SO . Therefore, the introduction of CoP could effectively act as the role of
3
cocatalyst to transmit electrons, leading to the relative low recombination of
photo-induced electron-holes pair and ultimately greatly boost the H generation rate.
2
4
. Conclusions
In brief, a series of MCSCP-x photocatalysts were successfully prepared to study
the hydrogen production reaction under the irradiation of visible light and have been
attested to be high-efficiency for water splitting. The optimal hydrogen production
-1
-1
rate was 65324 μmol﹒g ﹒h for MCSCP-4% photocatalyst, which is 4.26 times higher
than Mn Cd S and 38.7 times of original CdS. On one hand, the introduction of Mn
0
.5
0.5
could change the construction band potential directs to a more negative position. On
the other hand, the adding of CoP could play the role as co-catalyst, efficiently
transfer the photoinduced electrons from the construction band of Mn Cd S,
0
.5
0.5
1
3

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resulting in a relative low possibility of photogenerated electron-hole pairs
recombination. The result offers a new direction to the preparation of high-efficiency
and low-cost co-catalyst for producing hydrogen from water.
Acknowledgements
We are grateful for grants from National Science Funds for Creative Research Groups
of China (No.51421006), the Fundamental Research Funds for The Central
Universities (2018B14514), the World-Class Universities (Disciplines) and
Characteristic Development Guidance Funds for the Central Universities, Natural
Science Foundation of China (51679063), the Key Program of National natural
Science Foundation of China (No. 91647206), the National Key Plan for Research
and Development of China (2016YFC0502203), PAPD.
References
1
.
H. G. Yu, X. Huang, P. Wang and J. G. Yu, J. Phys. Chem. C, 2016, 120,
722-3730.
3
2
3
.
.
F. X. Xiao and B. Liu, Nanoscale, 2017, 9, 17118-17132.
Y. C. Nie, F. Yu, L. C. Wang, Q. J. Xing, X. Liu, Y. Pei, J. P. Zou, W. L. Dai,
Y. Li and S. L. Suib, Appl. Catal.B-Environ., 2018, 227, 312-321.
J. F. Wang, J. Chen, P. F. Wang, J. Hou, C. Wang and Y. H. Ao, Appl.
Catal.B-Environ., 2018, 239, 578-585.
4
5
6
.
.
.
J. F. Wang, P. F. Wang, J. Hou, J. Qian, C. Wang, Y. H. Ao, Catal. Sci.
Technol., 2018, 8, 5406-5415.
J. F. Wang, P. F. Wang, C. Wang and Y. H. Ao, Int. J. Hydrogen Energy,
1
4

Page 15 of 30
Dalton Transactions
View Article Online
DOI: 10.1039/C9DT02849H
2
018, 43, 14934-14943.
A. Fujishima and K. Honda, Nature 1972, 238, 37-38.
R. Chen, P. Wang, J. Chen, C. Wang, Y. Ao, Appl. Surf. Sci., 2019, 473,
1-19.
7
8
.
.
1
9
1
1
1
1
1
1
.
X. H. Zhang, J. Xiao, M. Hou, Y. G. Xiang and H. Chen, Appl.
Catal.B-Environ., 2018, 224, 871-876.
0.
1.
2.
3.
4.
5.
P. F. Wang, T. F. Wu, C. Wang, J. Hou, J. Qian and Y. H. Ao, ACS
Sustainable Chem. Eng., 2017, 5, 7670-7677.
Y. P. Du, B. Chen, Z. Y. Yin, Z. Q. Liu and H. Zhang, Small, 2014, 10,
4
727-4734.
P. Wang, Y. Sheng, F. Z. Wang and H. G. Yu, Appl. Catal.B-Environ., 2018,
20, 561-569.
2
L. Yang, X. Li, G. Zhang, P. Cui, X. Wang, X. Jiang, J. Zhao, Y. Luo and J.
Jiang, Nat. Commun., 2017, 8, 16049.
K. X. Wang, Z. F. Yu, V. Li, M. L. Brongersma, T. F. Jaramillo and S. H. Fan,
ACS Photonics, 2014, 1, 235-240.
M. M. Shao, Y. F. Shao, J. W. Chai, Y. J. Qu, M. Y. Yang, Z. L. Wang, M.
Yang, W. F. Ip, C. T. Kwok, X. Q. Shi, Z. G. Lu, S. J. Wang, X. S. Wang and
H. Pan, J. Mater. Chem. A, 2017, 5, 16748-16756.
1
6.
7.
X. F. Yang, L. Tian, X. L. Zhao, H. Tang, Q. Q. Liu and G. S. Liu, Appl.
Catal.B-Environ., 2019, 244, 240-249.
1
L. Tian, X. F. Yang, Q. Q. Liu, F. Q. Qu and H. Tang, Appl. Catal.B-Environ.,
1
5

Dalton Transactions
Page 16 of 30
View Article Online
DOI: 10.1039/C9DT02849H
2
018,455, 403-409.
1
1
8.
9.
Q. Li, H. Meng, P. Zhou, Y. Q. Zheng, J. Wang, J. G. Yu and J. R. Gong, ACS
Catal., 2013, 3, 882-889.
M. C. Liu, Y. C. Du, L. J. Ma, D. W. Jing and L. J. Guo, Int. J. Hydrogen
Energy, 2012, 37, 730-736.
2
2
0.
1.
K. Ikeue, S. Shiiba and M. Machida, Chem. Mater., 2010, 22, 743-745.
M. Y. Liu, L. Q. Zhang, X. X. He, B. Zhang, H. F. Song, S. N. Li and W. S.
You, J. Mater. Chem. A, 2014, 2, 4619-4626.
22.
23.
24.
25.
26.
27.
28.
H. Liu, Z. Z. Xu, Z. Zhang and D. Ao, Appl. Catal.A-Gen., 2016, 518,
1
50-157.
K. Ikeue, Y. Shinmura and M. Machida, Appl. Catal.B-Environ., 2012,
23-124, 84-88.
1
G. Xie, L. Guan, L. Zhang, B. Guo, A. Batool, Q. Xin, R. Boddula, S. U.
Jan and J. R. Gong, Nano Lett., 2019, 19, 1234-1241.
G. Xie, K. Zhang, B. Guo, Q. Liu, L. Fang and J. R. Gong, Adv. Mater.,
2
013, 25, 3820-3839.
J. Zhang, J. Yu, M. Jaroniec and J. R. Gong, Nano Lett., 2012, 12,
584-4589.
4
Q. Li, B. Guo, J. Yu, J. Ran, B. Zhang, H. Yan and J. R. Gong, J. Am.
Chem. Soc., 2011, 133, 10878-10884
L. Zhou, M. F. Shao, J. B. Li, S. Jiang, M. Wei and X. Duan, Nano Energy,
2
017, 41, 583-590.
1
6

Page 17 of 30
Dalton Transactions
View Article Online
DOI: 10.1039/C9DT02849H
29.
30.
31.
32.
33.
34.
35.
Y. P. Hu, F. Li, Y. Long, H. D. Yang, L. L. Gao, X. F. Long, H. G. Hu, N. Xu,
J. Jin and J. T. Ma, J. Mater. Chem. A, 2018, 6, 10433-10440.
E. L. Hu, J. Q. Ning, D. Zhao, C. Y. Xu, Y. Y. Lin, Y. J. Zhong, Z. Y. Zhang,
Y. J. Wang and Y. Hu, Small, 2018, 14.
S. Hao, L. B. Yang, D. N. Liu, R. M. Kong, G. Du, A. M. Asiri, Y. C. Yang
and X. P. Sun, Chem. Commun. (Camb), 2017, 53, 5710-5713.
W. Gao, M. Yan, H. Y. Cheung, Z. Xia, X. Zhou, Y. Qin, C. Y. Wong, J. C.
Ho, C. R. Chang and Y. Qu, Nano Energy, 2017, 38, 290-296.
D. S. Dai, H. Xu, L. Ge, C. C. Han, Y. Q. Gao, S. S. Li and Y. Lu, Appl. Catal.
B-Environ., 2017, 217, 429-436.
X. Y. Zhang, Z. Zhao, W. W. Zhang, G. Q. Zhang, D. Qu, X. Miao, S. R. Sun
and Z. C. Sun, Small, 2016, 12, 793-801.
X. Y. Fang, L. F. Cui, T. T. Pu, J. L. Song and X. D. Zhang, Appl. Surf. Sci.,
2
018, 457, 863-869.
3
3
6.
7.
X. Yue, S. Yi, R. Wang, Z. Zhang and S. Qiu, Small, 2017, 13.
X. Chen, X. J. Huang, L. T. Kong, Z. Guo, X. C. Fu, M. Q. Li and J. H. Liu, J.
Mater. Chem., 2010, 20, 352-359.
3
3
4
8.
9.
0.
J. He, L. Chen, F. Wang, Y. Liu, P. Chen, C. T. Au and S. F. Yin,
ChemSusChem, 2016, 9, 624-630.
Q. Z. Huang, Z. J. Tao, L. Q. Ye, H. C. Yao and Z. J. Li, Appl Catal
B-Environ., 2018, 237, 689-698.
L. F. Xiong, J. L. Bi, L. Q. Wang and S. C. Yang, Int. J. Hydrogen Energy,
1
7

Dalton Transactions
Page 18 of 30
View Article Online
DOI: 10.1039/C9DT02849H
2
018, 43, 20372-20381.
41.
42.
43.
44.
45.
B. L. Qiu, A. L. Han, D. C. Jiang, T. T. Wang and P. W. Du, ACS Sustainable
Chem. Eng., 2018, 7, 2360-2369.
Q. Mo, W. Zhang, L. He, X. Yu and Q. Gao, Appl. Catal.B-Environ, 2019,
2
44, 620-627.
L. Li, G. N. Liu, S. P. Qi, X. D. Liu, L. Y. Gu, Y. B. Lou, J. X. Chen and Y.
X. Zhao, J. Mater. Chem. A, 2018, 6, 23683-23689
Y. Y. Zhong, Y. Z. Wu, B. Chang, Z Z.. Ai, K. Zhang, Y. L. Shao, L.
Zhang and X. P. Hao, J. Mater. Chem. A, 2019, 7, 14638-14645.
X. Z. Zhou, H. Sun, H. Z. Zhang and W. X. Tu, Int. J. Hydrogen Energy,
2
017, 42, 11199-11205.
4
4
4
6.
7.
8.
K. Ikeue, S. Shiiba and M. Machida, ChemSusChem, 2011, 4, 269-273.
H. F. Lin, Y. Y. Li, H. Y. Li and X. Wang, Nano Res., 2017, 10, 1377-1392.
S. Hong, D. P. Kumar, E. H. Kim, H. Park, M. Gopannagari, D. A. Reddy and
T. K. Kim, J. Mater. Chem. A, 2017, 5, 20851-20859.
4
5
9.
0.
H. Zhao, P. Jiang and W. Cai, Chem Asian J, 2017, 12, 361-365.
X. B. Chen, S. H. Shen, L. J. Guo and S. S. Mao, Chem. Rev., 2010,
6
503-6570.
5
5
1.
2.
G. Liu, J. Pan, L. C. Yin, J. T. S. Irvine, F. Li, J. Tan, P. Wormald and H. M.
Cheng, Adv. Funct. Mater., 2012, 22, 3233-3238.
D. Zhao, B. Sun, X. Q. Li, L. X. Qin, S. Z. Kang, Dong Wang, RSC Adv,
2
016, 6, 33120-33125.
1
8

Page 19 of 30
Dalton Transactions
View Article Online
DOI: 10.1039/C9DT02849H
5
3.
Z. Liang, X. Zhong, T. Li, M. Chen and G. Feng, ChemElectroChem, 2019, 6,
2
60-267.
Figure Captions
Figure 1. X-ray diffraction (XRD) patterns of (a) CdS, MnS and a series of Mn Cd S catalysts
x
1-x
(
b) Mn Cd S with different CoP loading
0.5 0.5
Figure 2. X-ray photoelectron spectra (XPS) of Mn Cd S and MCSCP-4% photocatalysts,
0
.5
0.5
high-resolution signals of Cd 3d(a); Mn 2p(b); P 2p(c); Co 2p(d)
Figure 3. (a-b) TEM and HR-TEM images of MCSCP-4% photocatalysts
Figure 4. (a) UV-vis diffuse reflectance spectra (DRS) of all samples and (b) CoP and MCSCP-x
Figure 5. (a) Photocatalytic H evolution over Mn Cd S (x=0, 0.14, 0.25, 0.5, 0.75, 0.86, 1); (b)
2
x
1-x
Comparison of photocatalytic H evolution over Mn Cd S with different CoP loading and
2
0.5
0.5
CoP/CdS sample
Figure 6. Recycling photocatalytic H evolution measurement of MCSCP-4% photocatalyst
2
Figure 7. (a) Photoluminescence (PL) spectra of CdS, Mn Cd S and MCSCP-4% catalysts; (b)
0
.5
0.5
TPRL spectra of Mn Cd S and MCSCP-4% catalysts
0
.5
0.5
Figure 8. EIS Nyquist plots of CdS, Mn Cd S and MCSCP-4% catalysts
0
.5
0.5
Figure 9. Transient photocurrent response of CdS, Mn Cd S and MCSCP-4% catalysts
0
.5
0.5
Figure 10. Energy band structure schematic of origin CdS, MnS and Mn Cd S (x = 0.14, 0.25,
x
1-x
0
.5, 0.75 and 0.86)
Figure 11. Proposed mechanism of MCSCP-4% for hydrogen evolution under the irradiation of
visible light
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Figure 1. X-ray diffraction (XRD) patterns of (a) CdS, MnS and a series of Mn Cd S catalysts;
x
1-x
(
b) Mn Cd S with different CoP loading
0.5 0.5
2
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Figure 2. X-ray photoelectron spectra (XPS) of Mn Cd S and MCSCP-4% photocatalysts,
0
.5
0.5
high-resolution signals of Cd 3d(a); Mn 2p(b); P 2p(c); Co 2p(d)
2
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Figure 3. (a-b) TEM and HRTEM images of MCSCP-4% photocatalysts
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Figure 4. UV-vis diffuse reflectance spectra (DRS) of all Mn Cd S samples (a) and (b) CoP and
x
1-x
MCSCP-x
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Figure 5. (a) Photocatalytic H evolution over Mn Cd S (x=0, 0.14, 0.25, 0.5, 0.75, 0.86, 1); (b)
2
x
1-x
Comparison of photocatalytic H evolution over Mn Cd S with different CoP loading and
2
0.5
0.5
CoP/CdS sample
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Figure 6. Recycling photocatalytic H evolution measurement of MCSCP-4% photocatalyst
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Figure 7. (a) Photoluminescence (PL) spectra of CdS, Mn Cd S and MCSCP-4% catalysts;
0
.5
0.5
(
b) TPRL spectra of Mn Cd S and MCSCP-4% catalysts
0.5 0.5
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Figure 8. Electrochemical impedance spectroscopy (EIS) Nyquist plot of CdS,
Mn Cd S and MCSCP-4% catalysts.
0
.5
0.5
2
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Figure 9. Transient photocurrent response of CdS, Mn Cd S and MCSCP-4% catalysts
0
.5
0.5
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Figure 10. Energy band structure schematic of origin CdS, MnS and Mn Cd S (x = 0.14, 0.25,
x
1-x
0
.5, 0.75 and 0.86)
2
9