Conjugated nanoporous polycarbazole bearing a cobalt complex for efficient visible-light driven hydrogen evolution

Article abstract of DOI:10.1039/d0nj01534b

A conjugated nanoporous polycarbazole (CNP) cross-linked by pyridine and coordinated to Co(iii) displays high catalytic performance for visible light-driven H₂generation. The hydrogen evolution rate was up to 410 μmol g^?1h^?1. Spectroscopic and electrochemistry studies indicate that the redox active cobalt reduces recombination of photoexcited-charge-carriers and enhances the transmission of photoexcited-charge, thereby enriching the catalytic activity of hybrid materialsx-Co/CNP-N (x= 5, 10, 15 and 20 wt%).

Full text of DOI:10.1039/d0nj01534b

NJC
View Article Online
View Journal
PAPER
Conjugated nanoporous polycarbazole bearing a
cobalt complex for efficient visible-light driven
hydrogen evolution†
Cite this:DOI: 10.1039/d0nj01534b
a
b
b
c
Bin Guo,
Hai-Yan Li, Jian-Ying Chen,* David James Young,
*
a
a
Jian-Ping Lang
and Hong-Xi Li
*
A conjugated nanoporous polycarbazole (CNP) cross-linked by pyridine and coordinated to Co(III)
Received 29th March 2020,
Accepted 7th May 2020
2
displays high catalytic performance for visible light-driven H generation. The hydrogen evolution rate
ꢀ1 ꢀ1
was up to 410 mmol g
h . Spectroscopic and electrochemistry studies indicate that the redox active
cobalt reduces recombination of photoexcited-charge-carriers and enhances the transmission of
photoexcited-charge, thereby enriching the catalytic activity of hybrid materials x-Co/CNP-N (x = 5, 10,
15 and 20 wt%).
DOI: 10.1039/d0nj01534b
rsc.li/njc
from an industrial perspective. Cobaloxime complexes have been
assembled with heterogeneous PSs such as cadmium chalcogenide
Introduction
42–45
46–48
Energy generation from hydrogen combustion produces only quantum dots (CdX QDs, X = S, Se or Te),
TiO2,
and metal–organic frame-
for H photogeneration. However, these hetero-
covalent
49
26,50
water as a by-product, and so this lightest of all gases is a much organic frameworks (COF), g-C N
3
4
51,52
cleaner energy vector than coal or hydrocarbons, if it can be works (MOFs)
2
1
produced sustainably. Among the various methods for H
2
geneous PSs suffer from narrow visible light absorption windows
production, visible-light-driven hydrogen evolution reaction and/or poor stability and often require an intricate synthesis.
HER) has been demonstrated as a green route from solar Conjugated nanoporous polycarbazoles (CNPs) have been
2
–7
(
8
53–56
energy to this renewable fuel. Photocatalytic H
2
evolution widely employed as optical materials,
typically requires a proton reducing catalyst, a photosensitizer and for separation technologies.
for gas adsorption
5
7–64
CNPs with strong visible-
(PS) and a sacrificial donor. Photocatalytic systems based on Pt, light absorption also act as heterogeneous photocatalysts
Pd, Ru and other noble metals in combination with a PS display with good activity for organic transformations, such as the C-3
2
,3,9–24
65
66
excellent catalytic activity and high selectivity for HER.
functionalization of indoles, oxidative C–H functionalization,
67
68
However, the expense and scarcity of noble metal catalysts limit aerobic oxidation, oxidative hydroxylation of arylboronic acids
6
9
their widespread use. Noble-metal-free co-catalysts for H
2
generation and degradation of lignin. Very recently, Han et al. reported
2
5,26
have recently been developed.
example, act as effective co-catalysts in photoenhanced HER light CO
Cobaloxime complexes, for rhenium-metalated porous polypyridyl polycarbazoles for visible-
7
0
2
photoreduction. We recently demonstrated visible-
Molecular devices comprising a cobaloxime light-promoted Suzuki–Miyaura reactions of aryl chlorides with
co-catalyst and a photosensitizer (PS) such as Ru, Ir, Pt or Re arylboronic acids in water catalyzed by Pd nanoparticles loaded on
2
5,27,28
systems.
2
9–33
34–36
71
organometallic complexes,
molecular organic dyes,
to a CNP framework. CNP matrices are attractive candidates for
or boron-dipyrromethene the HER because they are inexpensive, easily prepared with high
BODIPY) chromophores can be effective for photo-induced porosity, are chemically and thermally stable, and possess tunable
generation. Nevertheless, the development of heterogeneous electronic and optical properties. In this work, we selected a CNP
3
7–40
porphyrin photosensitizers
4
1
(
H
2
HER catalytic systems that possess the inherent advantages of with bridging pyridyl groups to anchor a cobaloxime complex by
easy catalyst separation and recyclability are highly desirable coordination. The resulting photocatalytic system exhibited high
ꢀ
1
ꢀ1
activity with a hydrogen evolution rate of 410 mmol g
h . The
a
b
c
College of Chemistry, Chemical Engineering and Materials Science,
Soochow University, Suzhou 215123, China. E-mail: lihx@suda.edu.cn
Analysis and Testing Centre, Soochow University, Suzhou 215123, China.
E-mail: chenjianying@suda.edu.cn
Co–N coordination bond provided channels for photoexcited
electron transmission reducing recombination of photoexcited-
charge-carriers and thereby enhancing transmission of photo-
excited-charge. The mechanism of reaction was elucidated by
steady-state photoluminescence spectroscopy, electrochemical
impedance spectroscopy and cyclic voltammetry.
College of Engineering, Information Technology and Environment,
Charles Darwin University, Darwin NT 0909, Australia. E-mail: david.young@cdu.edu.au
Electronic supplementary information (ESI) available. See DOI: 10.1039/d0nj01534b
†
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2020
New J. Chem.

View Article Online
Paper
NJC
Results and discussion
Synthesis and characterization
the pyridyl moiety and the twelve protons of the four methyl
groups from dmgH, respectively (Fig. S2, ESI†). Other resonances
at d = 8.14–8.16, 7.50–7.53, and 7.39–7.44 ppm are assignable to
protons of the carbazolyl moiety (Fig. S2, ESI†).
Reaction of CoCl ꢁ6H O with dimethylglyoxime (dmgH ) and
2
2
2
7
1–73
3,5-di(9H-carbazol-9-yl)pyridine (3,5-Cz)
in refluxing EtOH
Metallated polymers x-Co/CNP (x = 5, 10, 15 and 20 wt%)
2
yielded Co(dmgH) (3,5-Cz)Cl in 77% isolated yield (Scheme 1).
This complex’s positive-ion electrospray ionization mass spec-
trum (ESI-MS) contained signals at m/z = 756.1518, which are
2
ascribed to the cationic species [Co(dmgH) (3,5-Cz)Cl + Na]
were synthesized by reaction of CoCl
dmgH ) with the polymer of 3,5-Cz (CNP) in refluxing ethanol
solution for 12 hours (Scheme 1). The powder X-ray diffraction
PXRD) patterns of all x-Co/CNP materials clearly indicated that Co
2 2
ꢁ6H O and dimethylglyoxime
(
2
+
(
and matched well with the simulated isotopic pattern (Fig. S1,
loading didn’t change the structure of the parent CNP, which
remained amorphous in nature (Fig. S3, ESI†). Inductively coupled
plasma atomic emission spectroscopy (ICP-AES) revealed that the
as-prepared 5-Co/CNP, 10-Co/CNP, 15-Co/CNP and 20-Co/CNP
materials contained 4.56, 9.88, 13.76 and 18.32 wt% of Co,
respectively (Table S1, ESI†). FT-IR absorption bands at approxi-
1
ESI†). In the H NMR spectra, the singlets at d = 8.67, 8.29, and
2.56 ppm are assignable to the two ortho and one para proton of
ꢀ
1
mately 3050, 1580, 1450 and 1230 cm (Fig. 1a) correspond to the
stretching vibrations of the C–H, CQN, CQC and C–N bonds,
ꢀ1
respectively. Extra peaks at 3450 and 1090 cm correspond to the
stretching vibrations of the O–H and C–O bonds of the dmgH
13
ligand indicating coordination of the Co complex. The C CP/MAS
NMR spectra showed three different signals between 100 and
150 ppm, indicating the presence of (i) an aromatic carbon atom
adjacent to a nitrogen atom (140–135 ppm), (ii) an aromatic carbon
with a carbon substituent (125 ppm) and (iii) an aromatic carbon
atom with a hydrogen (110 ppm) (Fig. 1b). Two additional signals
in the metallated x-Co/CNP at 153 and 11 ppm corresponding to
the oxime carbons and methyls of the dmgH groups. The Co 2p
X-ray photoelectron spectra (XPS) of x-Co/CNP (Fig. 1c) contained
III
III
peaks at 781.45 and 796.48 eV assignable to Co 2p1/2 and Co
3/2, respectively. These frequencies are consistent with those
of Co(dmgH) (3,5-Cz)Cl. Signals with electron-binding energy
2p
2
Scheme 1 Synthesis of Co(dmgH) (3,5-Cz)Cl and x-Co/CNP (x = 5, 10, 15
and 20 wt%).
2
13
Fig. 1 (a) FT-IR spectra, (b) C NMR spectra, (c) Co 2p, (d) N 1s XPS spectra of Co(dmgH)
2
(3,5-Cz)Cl, CNP and x-Co/CNP (x = 5, 10, 15 and 20 wt%),
(e) scanning TEM high-angle annular dark-field (STEM-HAADF) image and energy-dispersive X-ray spectroscopy (STEM-EDS) elemental mappings of 15-
2
Co/CNP, and (f) UV-vis spectra of 3,5-Cz, Co(dmgH) (3,5-Cz)Cl, CNP and x-Co/CNP (x = 5, 10, 15 and 20 wt%).
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2020

View Article Online
NJC
Paper
400.55 ꢂ 0.05 eV were attributed to pyrrolic N (Fig. 1d and
Table S1, ESI†). The positive shift in the N 1s binding energies of
the pyridinic N of x-Co/CNP, compared with the corresponding
values in the parent CNP, indicate N coordination to Co.
Additionally, the new peak at 401.25 ꢂ 0.2 eV corresponding
to N–O confirmed the presence of dmgH groups. TEM images
indicated that CNP and Co/CNP are amorphous (Fig. S4, ESI†).
Elemental mapping of Co/CNP showed the Co to be evenly
dispersed throughout the CNP matrix (Fig. 1e and Fig. S5–S9,
ESI†). The Co/CNP composite absorbed more visible light
relative to the parent polymer, (Fig. 1f) due to charge transfer
7
4
between CNP and cobalt. The band-gap energy (E ) of x-Co/
g
CNP decreased relative to CNP as the loading of cobalt increased
(Fig. S10 and Table S1, ESI†).
Catalytic performance
The photocatalytic performance of CNP and x-Co/CNP (x = 5,
10, 15 and 20 wt%) were evaluated by suspending these photo-
catalysts in CH CN containing HBF (0.5 M) under the irradiation
3
4
of a 300 W Xe lamp equipped with a 400 nm cutoff filter and
using triethanolamine (TEOA, 10 vol%) as the sacrificial electron
donor. The time-dependent hydrogen-evolution curves for CNP
and x-Co/CNP (x = 5, 10, 15 and 20 wt%) over the first 5 hours all
displayed a roughly linear increase with time (Fig. 2a) and 15-Co/
ꢀ1
CNP displayed the highest hydrogen production of 2050 mmol g
after 5 hours. Photocatalytic activity was calculated by normal-
izing the amount of product formed over time relative to the
photocatalyst weight (Fig. 2b). The parent CNP produced a
ꢀ
1
ꢀ1
negligible amount of H (58 mmol g
h
). An increase of Co
loading from 5-Co/CNP to 10-Co/CNP and 15-Co/CNP resulted
in much enhanced H production rates of 179, 294 and
, respectively, indicating that the Co complex
is essential for photocatalysis. However, the photocatalytic
2
2
ꢀ
1
ꢀ1
410 mmol g
h
ꢀ
1
ꢀ1
activity of 20-Co/CNP dropped to 248 mmol g
h
indicating
a ‘volcano’ plot with a peak at 15-Co/CNP. Interestingly,
Co(dmgH) (3,5-Cz)Cl produced a negligible amount of H under
2
2
the same conditions, (Fig. 2a, b and Fig. S11, ESI†) possibly due
to poor absorption of visible-light (Fig. 1f). Control experiments
indicated that both TEOA and light were indispensable for
hydrogen production (Fig. 2b). The reusability of 15-Co/CNP
catalyst was demonstrated with no significant loss of catalytic
ꢀ1
activity after three cycles, during which more than 2000 mmol g
of hydrogen was produced (Fig. 2c). This catalytic activity of Fig. 2 (a) Time-dependent photocatalytic hydrogen production and
b) average hydrogen-production rates on CNP and x-Co/CNP (x = 5,
(
1
5-Co/CNP is higher than some reported noble metal contained
7
5–80
10, 15 and 20 wt%), (c) recycling performance of 15-Co/CNP.
systems for photocatalytic HER
dcbdt)(CO)
benzene-2,3-dithiolate, bpy = 2,2 -bipyridine), Co@NH
and similar to that of Fe (m-
2
2
+
ꢀ1 ꢀ1
6
/Ru(bpy)
3
(280 mmol g
h , dcbdt = 1,4-dicarboxyl-
0
81
2
-MIL-125
ꢀ
1
ꢀ1 51
II
compared with those of fresh 15-Co/CNP, presumably due to
some reduction.
(Ti) (375 mmol g
h ), and [Co (TPA)Cl][Cl]@MIL-125-NH
2
ꢀ1
ꢀ1
52
(553 mmol g
h , TPA = tris(2-pyridylmethyl)amine) (Table S2,
ESI†). ICP-AES analysis indicated that 87% of Co remained after
three cycles suggesting minimal leaching. Analysis of the reused
Mechanistic study
15-Co/CNP by PXRD, FT-IR, XPS and EDS elemental mapping To gain insight into the high photocatalytic performance of Co/CNP
revealed no discernible structural or compositional changes, and probe its internal electron transfer dynamics, we performed
attesting to structural stability (Fig. S12 and S13, ESI†). The steady-state photoluminescence (PL) spectroscopy in acetonitrile
binding energies of Co 2p and N 1s (Fig. S13, ESI†) in the reused (Fig. 3a). CNP showed strong PL emission between 460 and 650 nm
15-Co/CNP composite shifted slightly to lower binding energies with a maximum at 505 nm, stemming from the fast-radiative
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2020
New J. Chem.

View Article Online
Paper
NJC
14
was effectively retarded. Transient photocurrent measurements
and electrochemical impedance spectroscopy (EIS) were conducted
to further verify activity of x-Co/CNP (x = 5, 10, 15 and 20 wt%). As
expected, 15-Co/CNP exhibited the highest photocurrent response
in this series, (Fig. 3c) implying that this optimized Co loading is
ideal for efficient separation of photogenerated electron–hole
pairs. This proposition is further supported by the electrochemical
impedance spectroscopy (EIS) results (Fig. 3d) which indicated that
15-Co/CNP possessed the smallest radius, manifesting in the
lowest charge-transfer resistance. Combined with the results
above, it is proposed that 15 wt% Co loading is the optimized
value for reducing recombination of photoexcited-charge-carriers
and enhancing transmission of photoexcited-charge, leading to
higher HER performance. However, 20-Co/CNP exhibited a lower
ꢀ
1
ꢀ1
photocatalytic activity of 248 mmol g
h , suggesting that excess
Fig. 3 (a) Steady-state PL emission spectra (lex = 410 nm) in CH
(
profiles of CNP and x-Co/CNP (x = 5, 10, 15 and 20 wt%).
3
CN, cobalt molecule catalysts could become recombination centres of
74
b) time-resolved PL spectra, (c) photocurrent responses and (d) EIS
photoexcited electrons and holes, and so the photocatalytic
activity of 20-Co/CNP is lower than that of 15-Co/CNP, consistent
with PL, transient photocurrent and EIS results.
Cyclic voltammetry (CV) of Co(dmgH) (3,5-Cz)Cl revealed an
2
recombination of photogenerated electron–hole pairs. As expected, irreversible reduction potential at E = ꢀ0.37 V and a reversible
p
the fluorescence of CNP was partly quenched by loading of reduction potential at E1/2 = ꢀ1.09 V vs. saturated calomel
cobaloxime complex, (Fig. 3a) which further confirmed the electrode (SCE) (Fig. S14a, ESI†). They are assigned to the
III
II
II
I
efficient transfer of photoexcited electrons from CNP to cobal- Co /Co and Co /Co couples, respectively. Irreversible reduction
III
II
II
I
oxime complex through coordination bonds. Time-resolved PL potentials of Co /Co and Co /Co couples in 15-Co/CNP were
spectra were recorded for all samples at an excitation wave- located at E
p
= ꢀ0.29 V and E = ꢀ1.01 V vs. SCE, respectively
p
length of 410 nm (Fig. 3b) and indicated average fluorescence (Fig. S14b, ESI†). The valence band (VB) and conduction band
lifetimes (t) of 1.30, 1.53, 2.23, 2.54 and 2.35 ns for CNP, 5-Co/ (CB) of CNP were calculated to be 1.02 and ꢀ1.28 V vs. SCE from
CNP, 10-Co/CNP, 15-Co/CNP and 20-Co/CNP, respectively. The the CV of CNP, respectively (Fig. S14d, ESI†). These results
III
I
attenuated PL emission and prolonged fluorescence lifetime of indicate that the excited state of CNP can reduce Co to Co
15-Co/CNP in comparison with other members in the family by a two-step single electron transfer. The absorption spectra of
2
clearly indicated that the radiative recombination of photoexcitons Co(dmgH) (3,5-Cz)Cl were acquired in the presence of TEOA
Scheme 2 Proposed mechanism for photocatalyzed hydrogen evolution.
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2020

View Article Online
NJC
Paper
II
with/without irradiation (4350 nm). The formation of Co
284.7 eV from hydrocarbon to compensate for effects. Co content
2
occurred within 10 min for the Co(dmgH) (3,5-Cz)Cl + TEOA was measured by inductively coupled plasma atomic emission
system as evidenced by the appearance of the characteristic spectroscopy (ICP-AES) using a Varian 710-ES instrument. Infra-
absorption at 430 nm, and the absorbed signal gradually red (IR) spectra were recorded on a Varian Scamiter-1000 spectro-
ꢀ1
decreased upon further light irradiation, (Fig. S15a, ESI†) infer- meter (4000–400 cm ). Elemental analyses for C, H, and N were
II
I 41
ring the change of Co to Co , consistent with CV results. No performed on a Carlo-Erba CHNO-S microanalyzer. The photo-
II
2
Co formation was observed for the mixtures of Co(dmgH) (3,5- luminescent spectra were obtained on a HORIBA QM-40 spectro-
Cz)Cl and TEOA at pH = 13.5 after photoirradiation; instead, fluorometer. UV-Vis spectra were obtained with a Shimadzu
expansion of the spectrum in the range of 600–850 nm clearly UV-2600 spectrometer.
I
showed a broad absorption peak of Co species (Fig. S15b, ESI†),
2 2
Synthesis of Co(dmgH) (3,5-Cz)Cl. Co(dmgH) (3,5-Cz)Cl was
III
I
73
indicating Co was reduced to Co by a single-step simulta- synthesized as previously reported. 3,5-Cz (0.44 g, 1.05 mmol)
4
3
neous two-electron transfer.
was added to a hot solution of CoCl ꢁ6H O (0.13 g, 0.53 mmol)
2
2
Analysing the above H2 production experiments, spectro- and dimethylglyoxime (0.14 g, 1.2 mmol) in 20 ml ethanol. The
scopic studies and previous literature reports,
2
8,41,43,50,82–84
we mixture was stirred in refluxing ethanol for 2 hours, cooled to
propose a reaction mechanism as depicted in Scheme 2. Under room temperature and stirred for a further 60 min. The brown
visible light irradiation, the excited electrons in the VB of CNP precipitate was collected by filtration, washed successively
move to the CB. The electrons in the CB of CNP reduce the with water, ethanol, and diethyl ether and recrystallized from
III
II
coordinated Co species of Co/CNP to form Co /CNP, with the dichloromethane and diethyl ether. Yield 0.30 g (77%). HRMS
+
+
elimination of chloride ion. Under visible light irradiation, (ESI) m/z: [M + Na] , calcd for C H ClCoN O Na : 756.1507;
Co /CNP was further reduced to Co /CNP by excited electrons. found: 756.1518. Anal. calcd for C H ClCoN O : C, 60.37; H,
Meanwhile, the holes generated inside the CNP combine with 4.79; N, 13.32. Found: C, 60.36; H, 4.68; N, 13.26. H NMR
electrons from TEOA. The photogenerated Co species are then (400 MHz, CDCl
protonated to obtain a Co –H/CNP intermediate, which finally 4H), 7.51 (t, J = 7.6 Hz, 4H), 7.41 (dd, J = 15.5, 7.8 Hz, 8H), 2.56
reacts with another proton to generate H
intermediates. These Co /CNP (I) intermediates are reduced 137.3, 131.9, 127.1, 124.9, 122.4, 121.2, 109.2, 13.5. IR (KBr
to Co /CNP under visible light irradiation completing the disk, cm ): 3475 (w), 3056 (w), 1582 (s), 1492 (m), 1477 (m),
3
7
35
7 4
II
I
3
7
35
7 4
1
I
3
) d 8.67 (s, 2H), 8.29 (s, 1H), 8.15 (d, J = 7.6 Hz,
III
III
13
2
and Co /CNP (I) (s, 12H). C NMR (101 MHz, CDCl
3
) d 153.2, 145.8, 139.3,
III
II
ꢀ1
catalytic cycle.
1445 (s), 1336 (m), 1307 (m), 1240 (s), 1220 (s), 1160 (w),
1
7
094 (m), 1018 (w), 999 (w), 980 (w), 923 (w), 753 (s), 720 (m),
00 (m), 653 (w), 511 (w).
Synthesis of x-Co/CNP (x = 5, 10, 15 and 20 wt%). x-Co/CNP
Conclusions
(
x = 5, 10, 15 and 20 wt%) were prepared in a similar method to
that described above for Co(dmgH) (3,5-Cz)Cl. CNP (100 mg)
was added a hot solution of CoCl O (amount calculated for
ꢁ6H
cobalt loadings of 5, 10, 15 and 20 wt%) and dimethylglyoxime
We have demonstrated efficient visible-light-promoted hydrogen
evolution catalyzed by cobalt complexes loaded on to a conjugated
nanoporous polycarbazole (CNP). This catalytic system showed
high efficiency, good stability and reusability. Spectroscopic and
electrochemical studies confirmed that cobalt loading promoted
photocatalytic hydrogen evolution by reducing recombination of
photoexcited-charge-carriers and enhancing transmission of
photoexcited-charge. Extending the application of this photo-
catalytic system to other reactions, e.g. CO2 reduction, is an
ongoing endeavour in our laboratory.
2
2
2
(
2.3 eq. for CoCl ꢁ6H O) in 30 ml ethanol. The mixture was
2
2
stirred in refluxing ethanol for 12 hours in air before cooling to
room temperature. The resulting brown precipitate was collected
by filtration, washed successively with water, ethanol, and diethyl
ether and dried at room temperature in vacuo.
Photocatalytic H
x-Co/CNP (x = 5, 10, 15 and 20 wt%, 15 mg), was dispersed in
7 ml of 0.5 M HBF CH CN solution and TEOA (3 ml, 10 vol%)
2
evolution reactions. Photocatalyst powder,
2
4
3
in a top-irradiation Pyrex vessel. This dispersion was ultra-
sonicated for 30 min and the resulting suspension purged with
nitrogen for 30 min to remove air. The reaction vessel was
Experimental
General information
All reagents were used as purchased without further purification. linked to a full glass automatic on-line trace gas analysis system
1
13
H and C NMR spectra were recorded at ambient temperature (Labsolar-6A, Beijing PerfectLight Technology Co., Ltd, China)
on a Varian UNITY plus-400 spectrometer. Transmission electron and the amount of H was determined using online gas
2
microscopy (TEM) was performed on a FEI Tecnai G20 electron chromatography (GC7900, Tianmei, China) with a TCD detector
microscope operating at 200 kV. Annular dark-field scanning using argon as carrier gas. The photocatalytic experiments
TEM (ADF-STEM) was performed on a FEI Tecnai F20 electron involved direct irradiation of the solution by a 300 W Xe-lamp
microscope operating at 200 kV, equipped with Genesis EDS with a cut-off filter (l 4 400 nm). The reaction temperature was
detector. Powder X-ray diffraction (PXRD) patterns were collected maintained at 15 1C using a water-cooling system.
on a PANalytical Aeris diffractometer (Cu-Ka). X-ray photoelectron
spectra (XPS) were recorded on an X-ray photoelectron spectrometer measurements were conducted using a CHI660E electrochemical
AXIS Ultra DLD) and binding energies were referenced to C 1s at system with a conventional three-electrode cell consisting of a Pt
Photoelectrochemical measurements. Photoelectrochemical
(
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2020
New J. Chem.

View Article Online
Paper
NJC
plate as the counter electrode, an Ag/AgCl electrode as the 14 W. Huang, Q. He, Y. Hu and Y. Li, Angew. Chem., Int. Ed.,
reference electrode and 0.01 M nBu NPF as electrolyte by
2019, 58, 8676–8680.
directly irradiating the working electrode from the back side 15 Q. Zuo, T. Liu, C. Chen, Y. Ji, X. Gong, Y. Mai and Y. Zhou,
using a 300 W Xe lamp with a 400 nm cut-off filter. The working
Angew. Chem., Int. Ed., 2019, 58, 10198–10203.
electrode was prepared on indium-tin oxide (ITO) glass pre- 16 E. Jin, Z. Lan, Q. Jiang, K. Geng, G. Li, X. Wang and D. Jiang,
viously cleaned by sonication in ethanol for 30 min and dried at
Chem, 2019, 5, 1632–1647.
4
6
6
0 1C. The boundary of the ITO glass was protected with Scotch 17 G. Lan, Y. Y. Zhu, S. S. Veroneau, Z. Xu, D. Micheroni and
tape. Catalyst (5 mg) was dispersed in isopropanol (1 ml) containing
W. Lin, J. Am. Chem. Soc., 2018, 140, 5326–5329.
3
0 ml 0.5 wt% Nafion solution by sonication for 0.5 h to obtain a 18 P. Pachfule, A. Acharjya, J. Roeser, T. Langenhahn,
slurry, and the slurry was spread onto the pretreated ITO glass,
and then dried at room temperature. EIS analysis was performed
M. Schwarze, R. Schomacker, A. Thomas and J. Schmidt,
J. Am. Chem. Soc., 2018, 140, 1423–1427.
at ꢀ0.5 V vs. Ag/AgCl condition at the frequency range 0.01 to 19 Y. Song, Z. Li, Y. Zhu, X. Feng, J. S. Chen, M. Kaufmann,
1
00 000 Hz using 0.5 M HBF as electrolyte.
C. Wang and W. Lin, J. Am. Chem. Soc., 2019, 141, 12219–12223.
0 H. Yang, J. Wang, J. Ma, H. Yang, J. Zhang, K. Lv, L. Wen and
T. Peng, J. Mater. Chem. A, 2019, 7, 10439–10445.
4
2
Conflicts of interest
21 X. Wang, L. Chen, S. Y. Chong, M. A. Little, Y. Wu, W. H.
Zhu, R. Clowes, Y. Yan, M. A. Zwijnenburg, R. S. Sprick and
A. I. Cooper, Nat. Chem., 2018, 10, 1180–1189.
There are no conflicts to declare.
22 V. S. Vyas, F. Haase, L. Stegbauer, G. Savasci, F. Podjaski,
C. Ochsenfeld and B. V. Lotsch, Nat. Commun., 2015,
Acknowledgements
6, 8508.
2
2
2
2
2
3 K. Mori, R. Osaka, K. Naka, D. Tatsumi and H. Yamashita,
ChemCatChem, 2019, 11, 1963–1969.
4 L. Guo, Y. Niu, H. Xu, Q. Li, S. Razzaque, Q. Huang, S. Jin
and B. Tan, J. Mater. Chem. A, 2018, 6, 19775–19781.
5 M. Wang, K. Han, S. Zhang and L. Sun, Coord. Chem. Rev.,
We thank the National Natural Science Foundation of China
(21771131 and 21971182), the ‘‘Priority Academic Program
Development’’ of Jiangsu Higher Education Institutions and
the Project of Scientific and Technologic Infrastructure of
Suzhou (SZS201708 and SZS201905) for financial support.
2015, 287, 1–14.
6 J. Dong, M. Wang, X. Li, L. Chen, Y. He and L. Sun,
ChemSusChem, 2012, 5, 2133–2138.
7 Y. Huang and B. Zhang, Angew. Chem., Int. Ed., 2017, 56,
14804–14806.
Notes and references
1
2
S. Chu and A. Majumdar, Nature, 2012, 488, 294–303.
G. G. Zhang, Z. A. Lan and X. C. Wang, Angew. Chem., Int. 28 J. Willkomm and E. Reisner, Bull. Jpn. Soc. Coord. Chem.,
Ed., 2016, 55, 15712–15727.
2018, 71, 18–29.
Y. Wang, A. Vogel, M. Sachs, R. S. Sprick, L. Wilbraham, 29 O. Schott, A. K. Pal, D. Chartrand and G. S. Hanan, Chem-
3
S. J. A. Moniz, R. Godin, M. A. Zwijnenburg, J. R. Durrant,
A. I. Cooper and J. Tang, Nat. Energy, 2019, 4, 746–760.
B. Zhu, R. Zou and Q. Xu, Adv. Energy Mater., 2018, 8, 1801193.
SusChem, 2017, 10, 4436–4441.
30 C. Lentz, O. Schott, T. Auvray, G. Hanan and B. Elias, Inorg.
Chem., 2017, 56, 10875–10881.
4
5
H. Zhong, C. Campos-Rold ´a n, Y. Zhao, S. Zhang, Y. Feng 31 P. Du, J. Schneider, G. Luo, W. W. Brennessel and
and N. Alonso-Vante, Catalysts, 2018, 8, 559.
R. Eisenberg, Inorg. Chem., 2009, 48, 4952–4962.
Y. Shi, A.-F. Yang, C.-S. Cao and B. Zhao, Coord. Chem. Rev., 32 B. Probst, A. Rodenberg, M. Guttentag, P. Hamm and
019, 390, 50–75.
R. Alberto, Inorg. Chem., 2010, 49, 6453–6460.
Y. Hua, X. Li, C. Chen and H. Pang, Chem. Eng. J., 2019, 370, 33 P. Du, K. Knowles and R. Eisenberg, J. Am. Chem. Soc., 2008,
6
7
2
37–59.
130, 12576–12577.
8
9
J. A. Turner, Science, 2004, 305, 972–974.
Z. Hu, X. Zhang, Q. Yin, X. Liu, X.-F. Jiang, Z. Chen, X. Yang,
F. Huang and Y. Cao, Nano Energy, 2019, 60, 775–783.
34 F. Lakadamyali, M. Kato, N. M. Muresan and E. Reisner,
Angew. Chem., Int. Ed., 2012, 51, 9381–9384.
35 T. Lazarides, T. McCormick, P. Du, G. Luo, B. Lindley and
R. Eisenberg, J. Am. Chem. Soc., 2009, 131, 9192–9194.
36 D. W. Wakerley and E. Reisner, Phys. Chem. Chem. Phys.,
2014, 16, 5739–5746.
10 N. Wang, G. Cheng, L. Guo, B. Tan and S. Jin, Adv. Funct.
Mater., 2019, 1904781.
11 H. Yu, R. Shi, Y. Zhao, T. Bian, Y. Zhao, C. Zhou, G. I. N.
Waterhouse, L. Z. Wu, C. H. Tung and T. Zhang, Adv. Mater., 37 P. Zhang, M. Wang, C. Li, X. Li, J. Dong and L. Sun, Chem.
017, 29, 1605148.
Commun., 2010, 46, 8806–8808.
2 L. Shang, B. Tong, H. Yu, G. I. N. Waterhouse, C. Zhou, 38 T. Lazarides, M. Delor, I. V. Sazanovich, T. M. McCormick,
2
1
1
Y. Zhao, M. Tahir, L.-Z. Wu, C.-H. Tung and T. Zhang, Adv.
Energy Mater., 2016, 6, 1501241.
I. Georgakaki, G. Charalambidis, J. A. Weinstein and
A. G. Coutsolelos, Chem. Commun., 2014, 50, 521–523.
3 X. Ma, L. Wang, Q. Zhang and H. L. Jiang, Angew. Chem., Int. 39 M. Natali, M. Orlandi, C. Chiorboli, E. Iengo, V. Bertolasi and
Ed., 2019, 58, 12175–12179.
F. Scandola, Photochem. Photobiol. Sci., 2013, 12, 1749–1753.
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2020

View Article Online
NJC
Paper
4
4
4
4
4
4
4
4
4
4
5
5
0 J. C. Manton, C. Long, J. G. Vos and M. T. Pryce, Dalton 63 F. Jiang, T. Jin, X. Zhu, Z. Tian, C.-L. Do-Thanh, J. Hu,
Trans., 2014, 43, 3576–3583.
D.-E. Jiang, H. Wang, H. Liu and S. Dai, Macromolecules,
2016, 49, 5325–5330.
64 Y. Liao, Z. Cheng, M. Trunk and A. Thomas, Polym. Chem.,
2017, 8, 7240–7247.
1 G. G. Luo, H. Lu, X. L. Zhang, J. C. Dai, J. H. Wu and J. J. Wu,
Phys. Chem. Chem. Phys., 2015, 17, 9716–9729.
2 X. B. Li, C. H. Tung and L. Z. Wu, Angew. Chem., Int. Ed.,
2
019, 58, 10804–10811.
65 W. Zhang, J. Tang, W. Yu, Q. Huang, Y. Fu, G. Kuang, C. Pan
and G. Yu, ACS Catal., 2018, 8, 8084–8091.
66 Y. Zhi, S. Ma, H. Xia, Y. Zhang, Z. Shi, Y. Mu and X. Liu,
Appl. Catal., B, 2019, 244, 36–44.
3 Y. Xu, Y. Ye, T. Liu, X. Wang, B. Zhang, M. Wang, H. Han
and C. Li, J. Am. Chem. Soc., 2016, 138, 10726–10729.
4 F. Wen, J. Yang, X. Zong, B. Ma, D. Wang and C. Li, J. Catal.,
2
011, 281, 318–324.
67 J. Luo, J. Lu and J. Zhang, J. Mater. Chem. A, 2018, 6,
15154–15161.
5 J. C. Hu, S. Sun, M. D. Li, W. Xia, J. Wu, H. Liu and F. Wang,
Chem. Commun., 2019, 55, 14490–14493.
68 J. Luo, X. Zhang and J. Zhang, ACS Catal., 2015, 5, 2250–2254.
6 F. Lakadamyali and E. Reisner, Chem. Commun., 2011, 47, 69 J. Luo, X. Zhang, J. Lu and J. Zhang, ACS Catal., 2017, 7,
695–1697. 5062–5070.
7 F. Lakadamyali, A. Reynal, M. Kato, J. R. Durrant and 70 H.-P. Liang, A. Acharjya, D. A. Anito, S. Vogl, T.-X. Wang,
E. Reisner, Chem. – Eur. J., 2012, 18, 15464–15475. A. Thomas and B.-H. Han, ACS Catal., 2019, 9, 3959–3968.
8 A. Reynal, F. Lakadamyali, M. A. Gross, E. Reisner and 71 B. Guo, H. X. Li, C. H. Zha, D. J. Young, H. Y. Li and
J. R. Durrant, Energy Environ. Sci., 2013, 6, 3291–3300. J. P. Lang, ChemSusChem, 2019, 12, 1421–1427.
9 T. Banerjee, F. Haase, G. Savasci, K. Gottschling, C. Ochsenfeld 72 S. Ding, C. Tian, X. Zhu, C. W. Abney, Z. Tian, B. Chen,
1
and B. V. Lotsch, J. Am. Chem. Soc., 2017, 139, 16228–16234.
0 X.-W. Song, H.-M. Wen, C.-B. Ma, H.-H. Cui, H. Chen and
C.-N. Chen, RSC Adv., 2014, 4, 18853–18861.
M. Li, D.-E. Jiang, N. Zhang and S. Dai, ChemSusChem, 2017,
10, 2348–2351.
73 G. N. Schrauzer, Inorg. Synth., 1968, 11, 61–70.
1 M. A. Nasalevich, R. Becker, E. V. Ramos-Fernandez, 74 J. S. Zhang and W. D. Zhang, ChemCatChem, 2019, 11,
S. Castellanos, S. L. Veber, M. V. Fedin, F. Kapteijn, J. N. H. 2657–2666.
Reek, J. I. van der Vlugt and J. Gascon, Energy Environ. Sci., 75 Y. Horiuchi, T. Toyao, M. Saito, K. Mochizuki, M. Iwata,
2
015, 8, 364–375.
H. Higashimura, M. Anpo and M. Matsuoka, J. Phys. Chem.
C, 2012, 116, 20848–20853.
5
5
2 Z. Li, J.-D. Xiao and H.-L. Jiang, ACS Catal., 2016, 6, 5359–5365.
3 S. Y. Byeon, J. H. Kim and J. Y. Lee, ACS Appl. Mater. 76 T. Toyao, M. Saito, S. Dohshi, K. Mochizuki, M. Iwata,
Interfaces, 2017, 9, 13339–13346.
4 C. Tang, R. Bi, Y. Tao, F. Wang, X. Cao, S. Wang, T. Jiang,
H. Higashimura, Y. Horiuchi and M. Matsuoka, Chem.
Commun., 2014, 50, 6779–6781.
5
C. Zhong, H. Zhang and W. Huang, Chem. Commun., 2015, 77 J. He, J. Wang, Y. Chen, J. Zhang, D. Duan, Y. Wang and
1, 1650–1653. Z. Yan, Chem. Commun., 2014, 50, 7063–7066.
5 X. Yang, G. Zhou and W. Y. Wong, Chem. Soc. Rev., 2015, 44, 78 L. Shen, M. Luo, L. Huang, P. Feng and L. Wu, Inorg. Chem.,
484–8575. 2015, 54, 1191–1193.
6 B. Wex and B. R. Kaafarani, J. Mater. Chem. C, 2017, 5, 8622–8653. 79 Z. L. Wu, C. H. Wang, B. Zhao, J. Dong, F. Lu, W. H. Wang,
5
5
8
5
5
7 Q. Q. Dang, H. J. Wan and X. M. Zhang, ACS Appl. Mater.
Interfaces, 2017, 9, 21438–21446.
W. C. Wang, G. J. Wu, J. Z. Cui and P. Cheng, Angew. Chem.,
Int. Ed., 2016, 55, 4938–4942.
58 X. Zhu, C. Tian, T. Jin, K. L. Browning, R. L. Sacci, 80 T. Toyao, M. Saito, Y. Horiuchi, K. Mochizuki, M. Iwata,
G. M. Veith and S. Dai, ACS Macro Lett., 2017, 6, 1056–1059.
9 T. Jin, Y. Xiong, X. Zhu, Z. Tian, D. J. Tao, J. Hu, D. E. Jiang,
H. Higashimura and M. Matsuoka, Catal. Sci. Technol.,
2013, 3, 2092–2097.
5
H. Wang, H. Liu and S. Dai, Chem. Commun., 2016, 52, 81 S. Pullen, H. Fei, A. Orthaber, S. M. Cohen and S. Ott, J. Am.
454–4457. Chem. Soc., 2013, 135, 16997–17003.
0 Q. Chen, M. Luo, P. Hammershoj, D. Zhou, Y. Han, B. W. 82 J. T. Muckerman and E. Fujita, Chem. Commun., 2011, 47,
4
6
Laursen, C. G. Yan and B. H. Han, J. Am. Chem. Soc., 2012,
34, 6084–6087.
1 Y. Zhang, S. A, Y. Zou, X. Luo, Z. Li, H. Xia, X. Liu and Y. Mu,
12456–12458.
1
83 A. Bhattacharjee, E. S. Andreiadis, M. Chavarot-Kerlidou,
M. Fontecave, M. J. Field and V. Artero, Chem. – Eur. J., 2013,
19, 15166–15174.
6
J. Mater. Chem. A, 2014, 2, 13422–13430.
6
2 Q. Chen and B. H. Han, Macromol. Rapid Commun., 2018, 84 B. H. Solis and S. Hammes-Schiffer, Inorg. Chem., 2011, 50,
9, 1800040. 11252–11262.
3
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2020
New J. Chem.