A solar-charged photoelectrochemical wastewater fuel cell for efficient and sustainable hydrogen production

Article abstract of DOI:10.1039/c7ta08112j

It is of great practical significance to realize the efficient treatment of wastewater and the comprehensive utilization of chemical energy from wastewater. Therefore, a WO₃ NFs-C/Cu₂O nanowire arrays (NWAs) visible-light response dual-photoelectrodes solar-charged photoelectrochemical wastewater fuel cell (scPEWFC) was constructed for efficient hydrogen production based on the promotion of phenol oxidation at the anode. The hydrogen production reaches as high as 93.08 μmol cm^-2 by the photoelectrocatalytic oxidation of phenol (TOC removal rate reached 82.12%) of WO₃ NFs-C/Cu₂O NWAs under visible light irradiation for 8 h without additional bias, which is 3.02 times higher than that of pure photocatalytic water splitting. The excellent photoelectrochemical performance can be attributed to the less endergonic process of phenol oxidation compared to water oxidation, which indicated that phenol oxidation can promote the hydrogen generation at the cathode. Isotopic labelling experiments show that protons were derived from the splitting of water rather than phenol. Interestingly, WO₃ (with great electrons storage property) and photoelectrochemical cell (PEC) were combined to construct a scPEWFC, the hydrogen production (4 h to produce 7.50 μmol cm^-2) was still carried out at the cathode under the dark owing to the stored electrons of WO₃ under the light, which realized the ideal effect of full-day and high-efficiency hydrogen production. Besides, the mechanism of scPEWFC operation was investigated in detail. This paper provides a new research idea for scPEWFC wastewater treatment, energy recovery, electron storage, and simultaneous full-day hydrogen production.

Full text of DOI:10.1039/c7ta08112j

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Kun Chang, Zhaorong Chang et al.
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Solar-charged Photoelectrochemical Wastewater Fuel Cell
for Efficient and Sustainable Hydrogen Production
Received 00th January 20xx,
Accepted 00th January 20xx
Zhaoyu Zhou,‡a Zhongyi Wu,‡a Qunjie Xu*b and Guohua Zhao*a
DOI: 10.1039/x0xx00000x
It is of great practical significance to realize the efficient treatment of wastewater and the comprehensive utilization of
chemical energy of wastewater. Thus, a WO3 NFs-C/Cu2O NWAs visible-light response dual-photoelectrodes solar-charged
photoelectrochemical wastewater fuel cell (scPEWFC) was constructed for efficient hydrogen production based on the
promotion of phenol oxidation at the anode. The hydrogen production reaches as high as 93.08 μmol cm-2 by the
photoelectrocatalytic oxidation of phenol (TOC removal rate reached 82.12%) of WO3 NFs-C/Cu2O NWAs under visible light
irradiation for 8 h without additional bias, which is 3.02 times higher than that of pure photocatalytic water splitting. The
excellent photoelectrochemical performance can be attributed to the less endergonic process of phenol oxidation
compared to water oxidation, which indicated that phenol oxidation can promote the hydrogen generation at the cathode.
Isotopic labelling experiments show that protons were derived from the splitting of water rather than phenol.
Interestingly, the effective combination of photochargeable properties of WO3 with PEC, the hydrogen production (4 h to
produce 7.50 μmol cm-2) was still carried out at the cathode under the dark owing to the stored electrons of WO3 under
the light, which realized the ideal effect of full-day and high-efficiency hydrogen production. Besides, the mechanism of
scPEWFC operation was investigated in detail. This paper provides a new research idea for scPEWFC wastewater
treatment, energy recover, electron storage, and simultaneous full-day hydrogen production.
www.rsc.org/
is the main purpose of traditional wastewater treatment methods,
which ignored a huge amount of chemical energy in the wastewater.
Therefore, it is also a hot issue for how to efficiently process
wastewater and to reuse the electrons produced by wastewater
oxidation12.
Microbial fuel cell (MFC) is a kind of device that utilizes
microorganisms to convert chemical energy from organic matter
directly into electrical energy, which has wide application prospect
in wastewater treatment and new energy development13ꢀ19. However,
due to the relatively low current efficiency, the electrons are difficult
to store, thus researchers have switched to produce hydrogen with
MFC combined with electrocatalysis or photocatalysis effectively.
Photoelectrochemical cell (PEC) and MFC were combined to
achieve for electricity or hydrogen generation, using wastewater and
solar light as the only energy sources20. A selfꢀbiased solarꢀdriven
Introduction
With industrialization, globalization and manufacturing is expanding
at an alarming rate in the past descends, the large amount of organics
discharged into the waterꢀbody caused serious environmental
pollution, especially those low concentrate and highly toxic
pollutants in the water seriously threaten human health and social
development, so the development highly efficient methods of
purifying water pollutants is the focus of research and attention from
both industry and academia1ꢀ7. In fact, the researchers found that
wastewater containing high levels of organics and as an excellent
electron donor, which can be seen as an ideal available energy
source8ꢀ10
. In addition, the traditional wastewater treatment
technology, such as activated carbon adsorption, membrane
separation, Fenton and ozone oxidation technology11, have obtained
excellent treatment results. Unfortunately, strategy of reꢀprocessing,
light utilization was adopted, only the separation, enrichment,
degradation and destruction of pollutants, and pollutant degradation
microbial photoelectrochemical cell that coupled
a bacterialꢀ
colonizing bioanode with a semiconductor nanowire cathode to
achieve the goal of microbial electricity generation were also
reported21. However, it’s difficult to deal with some persistent and
biodegradable organic matter with MFC, such as azo dyes, due to its
biological tolerance. In addition, the performance of MFC is still
limited by the internal resistance of proton mass transfer and oxygen
reduction kinetics. The harsh conditions of microbiological culture,
enrichment, training and operating environment, low efficiency of
electronic transmission, the complex research mechanism limited
MFC actual largeꢀscale application22ꢀ24
.
Photoelectrochemical cell (PEC) provide a powerful means of
harnessing solar energy for the production of clean hydrogen fuels
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by photoelectrochemical reactions, without additional energy input25ꢀ WO3 or MoO3 for specific reactions in the dark45. In most research
27. The early studies focused on single semiconductor electrode work, TiO2 and WO3 were combined into
composite
a
PEC.28. Subsequently, researchers have proposed ZꢀScheme type photoelectrode41, 46ꢀ49. The electrons in the TiO2 conduction band
dual photoelectrode photocatalytic fuel cell (PFC) 29ꢀ32, which was were implanted and stored in the WO3 framework under UV
mainly composed of n, pꢀtype semiconductors as the photoanode and irradiation, and then the stored electrons were released from WO3 to
photocathode, respectively. The Fermi level of nꢀtype semiconductor reduce oxygen to H2O2 and H2O in the dark. Similar charge storage
was more negative than that of pꢀtype semiconductor, an interior phenomena have been reported in the dyeꢀsensitized TiO2ꢀWO3
bias can be produced to drive the electrons to combine with the holes system. Upon illumination, excited electrons in the dye are injected
of photocathode from the external circuit from photoanode33. A into TiO2 and WO3 for electron storage. A solar rechargeable battery
visibleꢀlight responsive photocatalytic fuel cell was constructed (solar water battery) was reported based on photoelectrochemical
based on WO3/W or TiO2/Ti photoanode and C/Cu2O photocathode water oxidation, which is environmentally friendly and can provide
for simultaneous wastewater treatment and electricity generation by an alternative to conventional photoelectrochemical water splitting50.
simulating ZꢀScheme system 22, 34. Early research was mainly used to The TiO2 as photoelectrode was excited and generated electronꢀhole
treat wastewater and electricity production, but because of the pair. Then the photogenerated electrons in the TiO2ꢀPE were
unstable energy output, so it can’t be utilized directly. A solarꢀdriven transferred to the WO3ꢀSE through an external circuit and stored in
photocatalytic fuel cell with dual photoelectrode for simultaneous situ and then release electrons to the PtꢀCE for the reduction of
wastewater treatment and hydrogen production was constructed in hydrogen production in the dark. DyeꢀTiO2/electrolyte/Ni/WO3 dyeꢀ
our previous study8. In addition, the influencing factors of PEC such sensitized solar rechargeable batteries were constructed by solꢀgel
as electrode materials and target pollutants were investigated. The Zꢀ method, which possessed higher energy density than similar
Scheme structure of the simulated dual photoelectrode can materials51.
effectively separate electrons and holes for simultaneous degradation
Therefore, in our work, a solarꢀcharged photoelectrochemical cell
of pollutants and hydrogen production to achieve the effective (scPEWFC) was constructed for the phenol oxidization and
utilization of electrons of pollutants oxidation in the wastewater hydrogen production and simultaneous electrons storage, which
under the light and without additional power supply and accordingly performed in a single chamber photoelectrochemical cell quartz
hydrogen production efficiency was also significantly greater than reactor. Visible light response WO3 NFs, CꢀCu2O NWAs as
MFC35ꢀ37. As is known to us, this construction of heterostructures photoanode and photocathode, respectively. The potential of the
can effectively facilitate the charge separation and transfer, shorter WO3 NFs photoanode was higher than that of the C/Cu2O NWAs
radial transfer path, and effectively reduce the charge recombination. photocathode, resulting in the potential difference to spontaneously
Highly efficient photocatalytic H2 generation under visibleꢀlightꢀ drive the photogenerated electrons of the WO3 NFs photoanode to
driven was investigated based on MoS2/CdS nanosheetsꢀonꢀnanorod C/Cu2O NWAs photocathode from the external circuit to combine
and MoS2/CdS nanodotsꢀonꢀnanorods, which exhibit excellent H2 with the holes at the photocathode under the light, the holes of
evolution rate and apparent quantum yield38, 39
.
photoanode and electrons of photocathode thus can be released for
Though the excellent performance was achieved in PEC organics degradation and water reduction. At the same time, the
applications, the formed electrons and holes must be consumed remaining photogenerated electrons were stored in the framework of
immediately and require continuous illumination to ensure the WO3 NFs structure for continuous discharge and hydrogen
photocatalytic reaction can be carried out throughout the reaction production throughout the day.
period. Therefore, the biggest limitation of the traditional
photocatalysts is the need for continuous light energy input. But in
Experimental Section
reality, the photocatalytic efficiency is closely related to the solar
intensity of the day, while the light is not always present, and the
electrons cannot be stored. So we envisioned the simultaneous
collection and storage of solar energy for using in the dark. If the
excited photogenerated electrons can be stored under the light
illumination, it can not only reduce the recombination of
photogenerated carriers, but also can continue to release the stored
electrons for hydrogen production in the dark to convert solar energy
into chemical energy, to enhance the efficiency of solar energy
conversion, and further expand the application of solar energy in a
certain extent.
2.1. Materials
The tungsten foil (99.95%, 0.05 mm thick) and copper mesh (100
mesh, 0.11 mm dia wire) were purchased from Alfa Aesar (China)
Chemical Co., Ltd. Sulphuric acid (AR, 98%), sodium hydroxide
(AR, 99%), sodium fluoride (AR, 99%), sodium sulfate (AR, 98%),
ethanol (AR, 99.5%), acetone (AR, 99.5%) and isopropanol (AR,
99%) were purchased from Sinopharm Chemical Reagents Co., Ltd.,
SCRC, China. Phenol (D6, 98%) was purchased from CIL
Cambridge isotope laboratories Inc.
2.2 Preparation of WO3 NFs Photoelectrode
Recently, the applicability of solar energy is extended to the dark
stage by integrating the light harvesting and the energy storage
system. A selfꢀphotorechargeability of WO3 film was fabricated
under visible light irradiation40ꢀ43, which can store and release onꢀ
demand44. Photocatalysts with storage capacity such as WO3 or
MoO3 have been developed, and photoelectrons of TiO2 can be
transferred and stored in the conduction band of WO3 or MoO3
under UV irradiation and then the stored electrons are released from
WO3 NFs photoanode was prepared by anodizing according to the
literature44. The tungsten foil (Alfa Aesar, 99.95%, 0.05 mm thick)
was cut into 1.5 x 5.0 cm pieces and then polished to a mirror with
180 Cw, 300 Cw, 600 Cw and metallographic sandpaper to remove
rust and oxide on the surface, rinsed with distilled water, and
ultrasonically cleaned in distilled water, acetone, ethanol,
isopropanol and distilled water for 10 min, respectively. The
anodizing device is composed of two electrode systems with a
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platinum foil as the counter electrode (cathode) and the tungsten foil China) was used as a simulated solar light source (wavelength
as the working electrode (anode); the distance was kept constantly at range of 420ꢀ800 nm, light intensity of 100 mW cmꢀ2) in a
2 cm between the cathode and the anode. The tungsten foil was single chamber photoelectrochemical quartz reactor. No further
anodized at a constant potential (+50 V) using a DC power supply description, all experiments are carried out under the AM1.5
(Sovotek, E5200ꢀ3 75v/2A DC Power Supply, Da Hua Electronic, filter. Photoanode and photocathode working area are 2 cm2,
China) for 70 min (50 min, 60 min, 80 min, 90 min) under controlled moderate agitation and no external voltage. Before the test, it is
magnetic stirring at a temperature of 15 °C and the electrolyte necessary to continuously pass nitrogen into the electrolyte for
solution containing 1 mol Lꢀ1 H2SO4 and 0.5 wt.% NaF. After the 30 min to remove other impurities such as dissolved oxygen in
anodization process, the samples were soaked in distilled water and the solution. The IꢀV characteristic curve was measured by
ethanol for 30 min, then rinsed with distilled water, and dried in air. linear sweep voltammetry (LSV) with a sweep speed of 0.02 V
Hereafter the WO3 films were calcined at 400 °C for 4 h in air sꢀ1. The power density (P) is calculated as follows: P= I×V.
atmosphere, the rate of heating was maintained at 2 °C minꢀ1 and Under the irradiation of AM 1.5, the degradation of the organic
naturally cooled to room temperature.
2.3. Preparation of C/Cu2O NWAs Photoelectrode
compound was carried out in a quartz reactor. Phenol (20 mg Lꢀ
1) as the target organic compound with the electrolytes solution
Copper mesh (Alfa Aesar, 100 mesh, 0.11 mm dia wire) was cut into containing 0.1 mol Lꢀ1 Na2SO4. The removal rate of phenol total
pieces about 1.5 cm×5 cm and sonicated in acetone, deoxygenated organic carbon was monitored by the N/C3100 TOC/TNb
deionized water and absolute ethanol for 15 min and dried in air. The analyzer (Analytikjena, Germany). The total hydrogen amount
Cu(OH)2NWs were prepared by the constant current anodic method produced was calculated by multiplying the hydrogen content
in
a conventional three electrodes system using CHI 660C in a 1 mL gas sample by the headspace volume of the PEC
electrochemical workstation (CH Instruments Inc., USA ) with the reactor (200 mL). Hydrogen is qualitatively measured by gas
electrolytes solution containing 3 mol Lꢀ1 sodium hydroxide solution chromatography (GC 7900, Techcomp, Shanghai, China), N2 as
at room temperature52. Ag/AgCl was used as the reference electrode, carrier gas, TCD detector, column temperature of 80 °C,
Pt as the counter electrode and the copper mesh as the working detector temperature of 150 °C, Inlet port temperature of 130
electrode. Cu(OH)2 NWs were produced by anodizing at a constant °C and sample volume of 1 ml. Gas chromatographyꢀmass
current of 10 mA cmꢀ2 for 30 min, and the electrode potential is spectrometry (GCꢀMS, Agilent 6890/5973 N, Agilent Co) were
stabilized at ꢀ0.24 V (vs Ag/AgCl) at the initial stage. When the utilized to detect the D2, DH and H2.
potential was changed suddenly, it can be considered anodizing has
been completed. The prepared Cu(OH)2NWs were rinsed with
Results and discussion
deionized water, dried in vacuum and then immersed in a glucose
solution at a concentration of 3 g Lꢀ1 for 1 min, then taken out and
dried at room temperature. The glucoseꢀloaded Cu(OH)2 NWs were
calcined at 550 °C for 4 h in N2 atmosphere, the rate of heating was
maintained at 4 °C minꢀ1, finally at a rate of 5 °C minꢀ1 decreased to
room temperature to obtain the C/Cu2O NWAs photocathode.
2.4. Materials characterization
The detailed morphology and microstructure feature of the samples
were observed by field emission scanning electron microscopy (FEꢀ
SEM, Hitachi Sꢀ4800, Japan) and high resolution transmission
electron microscopy (HRꢀTEM, JEM2100, JEOL, Japan, using a
JEMꢀ2000EX electron microscope operated at 200 kV).The
composition and structure of the samples were characterized via Xꢀ
ray diffraction (XRD, D8 Focus Xꢀray diffractometer, Bruker,
Germany), using a Cu target: λ = 1.540598 Å; tube voltage 40 kV;
tube current 60 mA; scanning speed 2º minꢀ1. The composition,
structure and bonding conditions of the samples were characterized
and tested by Raman (514 nm laser with RM100). UVꢀVis diffuse
reflectance spectroscopy (UVꢀVis DRS, Avantes, Netherlands) was
used to determine the optical absorption properties of the sample
electrodes.
3.1. Anode oxidation for phenol efficient conversion
As shown in Fig. 1A, the TOC removal rate of phenol of WO3
NFsꢀ C/Cu2O NWAs was 82.12% in the first 8 h under AM 1.5
illumination, which is higher than that of WO3 NFsꢀPt (TOC
removal rate 52.5%).The reason for this efficient oxidation is
similar to that reported in the literature. Under such conditions,
a simulated ZꢀScheme type dual photoelectrode solarꢀcharged
photoelectrochemical wastewater fuel cell (scPEWFC) was
constructed. Due to the presence of the Fermi level difference,
the photogenerated electrons of the photoanode were migrate to
the photocathode to combine the holes at the photocathode, so
that the photogenerated electrons and holes were difficult to
recombine, so the catalytic oxidation efficiency of phenol has
been greatly improved. After the illumination for 8 h, the whole
system were kept in the dark for 8 h. The TOC removal of
phenol have not changed whether the photoanode and
photocathode were disconnected or not. It is speculated that in
the absence of light source, without holes were produced in the
anode, the entire anode filed lacks the oxide species, so the
phenol won’t be further removed under the drak.
In Fig. 1C, it’s also show that the photocurrent of the single
WO3 NFs photocathode is very small, but the photocurrent
density of C/Cu2O NWAs can reach 0.37 mA cmꢀ2, and the
short circuit current (JSC) of scPEWFC is 0.42 mA cmꢀ2, which
is greater than the sum of the two, and these values are also
larger than the literature34. So it can be inferred that the cathode
and anode of the constructed scPEWFC have a synergistic
effect, which confirm that the cell performance of WO3 NFs–
2.5. Photoelectrochemical measurements
The photoelectrochemical properties of these sample electrodes
were tested on a CHI660C electrochemical station (CH
Instruments Inc., USA) by using a conventional threeꢀelectrode
system at room temperature. Sample electrode, Pt, Ag/AgCl
electrode as the working electrode, counter electrode and the
reference electrode, respectively. PEC is achieved using a twoꢀ
electrode device. A 300W high voltage Xe lamp (Changtuo,
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Fig. 1 The TOC removal rate (A) of phenol (20 mg Lꢀ1) for scPEWFC under light illumination and dark. The I–V characteristic curve (B) (red) and power
density curve (blue) of WO3 NFsꢀC/Cu2O NWAs scPEWFC. The I–V curves were performed by linear sweep voltammetry with a two electrode system in
one typical cycle. The scan rate was 0.05 V sꢀ1. The photocurrent density (C) and the openꢀcircuit voltage (D) of WO3 photoanode and C/Cu2O
photocathode were measured in the dark and under AM1.5 (100 mW cmꢀ2) illumination. The I−t characteristics curves (E), LSV (F) were recorded with
no external bias from the scPEWFC using two electrode configuration under AM1.5 illumination in the 0.1 mol Lꢀ1 Na2SO4 solution containing 20 mg Lꢀ1
phenol ( the red solid line ) and without phenol ( the black solid line). The amount of hydrogen production and TOC removal rate (G) were recorded in
the 0.1 mol Lꢀ1 Na2SO4 solution containing different concentration phenol. The deuteriumꢀlabelling phenol (D6, 20 mg Lꢀ1) and noꢀlabelling phenol (H)
were performed to prove the source of hydrogen.
C/Cu2O NWAs is superior53,54. In such a simulated ZꢀScheme estimated that the EFB of WO3 NFs is 0.30 V (vs. Ag/AgCl) in
system, the electron/hole pairs were separated effectively at the Na2SO4 solution. Meanwhile, WO3 NFs electrode photocarrier
two photoelectrodes. The holes of WO3 NFs photoanode and density can be calculated and presented ND values of 4.47×1020
the electrons of C/Cu2O NWAs photocathode can be released cmꢀ3. Compared with other materials, WO3 NFs have a higher
for the oxidation of the phenol and the reduction of proton to carrier concentration55. The results show that WO3 NFs
produce hydrogen, respectively. In addition, after five cycle photoelectrode has a very high photocatalytic oxidation ability,
tests of dark and light, the photocurrent density almost keeps excellent photoresponse and rapid charge transfer rate.
stable, which indicated that the WO3 NFs photoanode has a 3.2 Cathode reduction for sustainable hydrogen production
good photoelectrochemical response, photocurrent stability, In the system, oxidation of phenol was performed at the anode,
antiꢀcorrosive properties. However, when Pt foil as cathode, the meanwhile efficient hydrogen production was operated at the
photocurrent is relatively low, due to without Zꢀscheme cell cathode. Many literatures were reported that the hydrogen
was constructed. At the same time, the photovoltage was also production efficiency of the cathode is limited by anodic
measured. As shown in Fig. 1D, the photovoltage of WO3 NFs oxidation54,56,57, in other words, the whole system, the oxidation
photoanode is almost low, and exhibit a relatively slow of anode phenol is the rateꢀlimiting step.
photoresponse. But the C/Cu2O NWAs photocathode display
From the thermodynamic point of view, the oxidation
excellent photoresponse (photovoltage increases instantly to potential of lots of organic pollutants is lower than that of
0.15 V and keeps stable). The openꢀcircuit voltage (VOC) of water. Therefore, phenol was selected as a representative
WO3 NFsꢀC/Cu2O NWAs scPEWFC is 0.26 V. In other words, organic pollutant to study the degradation performance of the
WO3 NFs photoanode provide a negative bias for C/Cu2O scPEWFC. In fact we are also very interested in studying the
NWAs photocathode, while C/Cu2O NWAs photocathode effect of different pollutants oxidation on the hydrogen
offered a positive bias for WO3 NFs photoanode. Because the production of the cathode, and the relevant work was also
WO3 NFs photoanode Fermi level is more negative than that of carried out. In the previous work, two classes of typical
C/Cu2O NWAs photocathode, an interior bias can be produced pollutants, phenols and alkylbenzenes, were treated using a
to drive the electrons of WO3 NFs to C/Cu2O NWAs electrode selfꢀbiasing photoelectrochemical (PEC) cell to reveal the
without the external conditions.
intrinsic relationships between the redox properties of the
The MottꢀSchottky curve of WO3 NFs photoelectrode is pollutants and hydrogen production58. The photocatalytic
shown in Fig. S1 (ESI†), which illustrate the relationship oxidation of phenol and simultaneous hydrogen production
between 1/C2 and the applied potential. WO3 NFs electrode is were studied by using phenol as the oxidizing substrate and
characterized by a positive slope in the MottꢀSchottky plot, WO3 NFs electrode as the photoanode and C/Cu2O NWAs as
which means the sample is an nꢀtype semiconductor material. the photocathode.
The tangent portion of the curve intersects with 1/C2=0 is the
flat potential EFB of the WO3 NFs photoelectrode and it can be hydrogen production were studied by using phenol as the
The photocatalytic oxidation of phenol and simultaneous
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oxidizing substrate and WO3 NFs electrode as the photoanode 3.3 The relationship between electrons storage of WO3 and
and C/Cu2O NWAs as the photocathode. The iꢀt curve was hydrogen production
determined in the twoꢀelectrode system in 0.1 mol Lꢀ1 Na2SO4 In the Fig 1E, when the cathode and anode were disconnected
solution containing 20 mg Lꢀ1 phenol under the AM1.5 filter and remained in the dark for 8 h, and then connected the
irradiation (100 mW cmꢀ2), without an external bias as shown in cathode and the anode again, and it was apparent that the
Fig. 1E. With the prolongation of illumination time, the photocurrent was observed significantly, and higher than the
photocurrent density tends to increase gradually. In the initial initial dark current. WO3 NFs photocharging characteristics are
absence of light, the photocurrent density was almost zero, and reported in many literatures, so it was can be speculate that part
then applied the light, the photocurrent density increases slowly of the excited electrons were stored within the WO3 NFs
with the time, then gradually stabilized and remained at 0.523 electrode in the system (the shaded area below the discharge
mA cmꢀ2 after 4 h operation. For comparison, without phenol curve corresponds to the total stored charges) and were
was added into the 0.1 mol Lꢀ1 Na2SO4 electrolyte solution. discharged in the dark. Therefore, it was concluded that when
Correspondingly, the photocurrent density was significantly the WO3 NFs as scPEWFC anode material, the characteristics
lower than the presence of phenol. After keeping in dark for 8 of lightꢀcharging was still remained and the mechanism is
h, the photocurrent was measured again, a similar result occurs. explained as follows:
In the test of hydrogen production, it was notable that the
amount of hydrogen production was about 30.74 ꢁmol cmꢀ2 in
the absence of phenol. In contrast, in the presence of phenol (20
mg Lꢀ1), the amount of hydrogen production reached 79.58
ꢁmol cmꢀ2 as shown in Fig.1G. Some literatures also reported
that the nature of the pollutions as well as its concentration also
had great influence on the performance for PEC hydrogen
production from the biomass derivative and water57. With the
increase of pollutant concentration, the hydrogen production
effect was obviously enhanced. This also illustrates that the
oxidation of phenol at the anode did play a decisive role in the
hydrogen production of the cathode, the electrons of the anodic
WO3+hν→WO3
ʠ
h++eꢀʡ
h++eꢀʡ
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
Cu2O+hν→Cu2O
ʠ
WO3+xNa++xeꢀ→NaXWO3
C6H5OH+H2O+28h+→6CO2+28H+
eꢀ+h+→hν
2H++2eꢀ→H2
NaXWO3→WO3+xNa++xeꢀ
2H++2eꢀ→H2
C6H5OH+11H2O→6CO2+14H2
Fig. S2 (ESI†) describes the schematic plots of
oxidation transferred to the cathode to raise the photocurrent photocharging and discharging processes of WO3 NFs during
density, and accordingly enhance the efficiency of hydrogen light and dark conditions. The photogenerated electronꢀhole
production Therefore, the oxidation reaction of the anode was pairs were formed under simulative solar light illumination.
easier to proceed, and the efficiency of hydrogen production When the WO3 NFs were excited (Eqn 1) the part of the photoꢀ
was more obvious.
excited electrons can be neutralized by the intercalation of
In order to understand the effect of phenol and optimize existing Na+ in the electrolyte solution in the form of NaXWO3,
scPEWFC activity for phenol oxidation over the WO3 NFs which stored within the WO3 framework in situ (Eqn 3). The
photoanode, the linear sweep voltammetry (LSV) plots of the phenol molecules adsorbed on the electrode surface were
asꢀprepared photoanode was performed in 0.1 mol Lꢀ1 Na2SO4 oxidized to CO2 by the holes generated on the WO3 electrode
solution containing 20 mg Lꢀ1 phenol whether with illumination (Eqn 4). The carbonꢀcoated C/Cu2O NWAs/Cu mesh also
or not. As shown in Fig. 1F, the WO3 NFs showed higher generated electronꢀhole pairs under the simulative solar light
current density in the phenol solution (0.09 mA cmꢀ2) than that illumination (Eqn 2). The nꢀtype semiconductor WO3 NFs
of without phenol (0.04 mA cmꢀ2) under dark at 0.8 V (vs
.
(Eg=2.75 eV), pꢀtype semiconductor C/Cu2O NWAs (Eg=2.4
Ag/AgCl). When the surface of the electrode was irradiated eV), and the relative band positions for the WO3 NFsꢀC/Cu2O
with simulated sunlight, the current density of the WO3 NFs NWAs visibleꢀlight response dualꢀphotoelectrodes as shown in
photoelectrode was significantly increased to 0.92 mA cmꢀ2 at Fig. S3 (ESI†). According to the principle of energy level
0.8 V (vs Ag/AgCl). The results indicated that phenol was more matching, the Fermi level of the nꢀtype semiconductor WO3
easily oxidized under simulated solar excitation, and the NFs was higher than that of the pꢀtype semiconductor C/Cu2O
oxidation potential was 0.35 V (vs. Ag/AgCl) (lower than water NWAs, Accordingly, the potential of the WO3 NFs photoanode
oxidation), which explained the reason of phenol oxidation at was higher than that of the C/Cu2O NWAs photocathode under
the anode to promote cathode hydrogen production at the AM 1.5 illumination, and the interior bias was generated and to
cathode.
In addition, it is possible that hydrogen can be derived from the holes of C/Cu2O NWAs photocathode from the external
the splitting of water or degradation of phenol, so circuit (Eqn 5). The holes of WO3 NFs photoanode and the
drive the electrons of WO3 NFs photoanode to combine with
a
comparative experiment is carried out by using deuteriumꢀ electrons of C/Cu2O NWAs photocathode can be released for
labeled phenol (D6, 20 mg Lꢀ1) to prove the source of the oxidation of the phenol at the anode and the reduction of
hydrogen. By GCꢀMS analysis, only H2 is detected and no DH proton to produce hydrogen at the cathode (Eqn 6,8).
or D2 is detected during the photoelectrocatalysis experiment Afterwards, Na+ deꢀintercalate from the WO3 NFs structure
(as shown in Fig. 1H), so it can be illustrated that hydrogen is (Eqn 7), then stored electrons were released and transferred to
derived from the water splitting.
C/Cu2O NWAs counter electrode to produce hydrogen (Eqn 8).
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Meanwhile, the structure of Zꢀscheme is more favorable for the
separation of photogenerated electrons and holes, and enhance
the efficiency of photoelectrocatalysis conversion.
In order to prove that Na+ was embedded into the framework
of WO3 NFs under AM 1.5 illumination. XRD was used to
characterize the variety of WO3 NFs framework before and
after charging and discharging process in 0.1 mol Lꢀ1 Na2SO4
electrolyte solution containing 20 mg Lꢀ1 phenol as shown in
Fig. 2A. The three peaks of 2θ=23.119°, 23.586° and 24.380°
corresponding to the (002), (020) and (200) planes are
characteristic peaks of the monoclinic phase WO3. After
performing three chargeꢀdischarge cycle, the characteristic
peaks shift to a lower 2θ value, which is associated with the
structural change of tetragonal structure and which is related to
the embedding of the alkaline cations as discussed in the
literature59, 60. Thus, the results further demonstrate that the
presence of trapped alkali cations in the framework of WO3
NFs in situ. Raman spectroscopy was also used to study the
structural variety in higher symmetry caused by intercalation of
the alkaline cations. Fig. 2B shows the Raman spectra of the
WO3 NFs photoelectrode after the three chargeꢀdischarge cycle
in the Na2SO4 electrolyte containing 20 mg Lꢀ1 phenol. The
Raman shift peak at 807 cmꢀ1 and 714 cmꢀ1 are attributed to the
stretching modes arising from the WꢀO framework in
monoclinic WO361, 62. It is possible to determine initially that
the electrode was monoclinic phase γꢀWO3. The peak at 807
cmꢀ1 is hardly altered by the phase transition, while the mode at
714 cmꢀ1 is highly sensitive to the embedded ions, which
reflects the structural changes caused by the embedded ions.
When the WO3 NFs were irradiated for 8 h, the peak intensity at
714 cmꢀ1 decreased which is associated with the changes in the
WO3 host [to a more symmetrical structure (tetragonal)] and
ascribed to the symmetrisation of WꢀO bonds along the a–b
plane of the WO6 octahedron59, 63, 64.When the WO3 NFs were
discharged for 4 h, the intensity of the peak at 714 cmꢀ1
restores to the original state. Therefore, the greater the decrease
in the Raman intensity of the 714 cmꢀ1 peak, the more
trappedalkali cations stored within the WO3 structure, and the
more electrons stored.
Fig. 3 Amount of hydrogen produced under different conditions. The
cathode and cathode were disconnected (A) or connected (B) for 8 h
under the dark.
The mechanism of scPEWFC photoꢀcharging and
discharging (Na+ intercalation and deintercalation from the
WO3 framework) was studied by using cyclic voltammetry. Fig.
2C depicts the CV response of WO3 before and after 10 min
illumination. A significant oxidized peak (0.40 V vs. Ag/AgCl)
was presented under the visible irradiation for 10 min, which
was attributed to the phenol oxidization at the photoanode. The
presence of other anode peaks (0.82 V vs. Ag/AgCl) may be
caused by the localised oxidation of W4+ to W5+ or W5+ to W6+,
and was related to the photoꢀcharging phenomenon, which
reflected the discharging of stored electrons and simultaneous
deꢀintercalation of alkali cations65. Fig. 2D is UVꢀvisible
diffuse reflectance absorption spectra of the WO3 NFs
photoelectrode. It show that the prepared of WO3
photoelectrode. It show that the prepared WO3 NFs absorption
band edge can reach about 450 nm, barely enter the visible light
response range. The bandgap of 2.75 eV was calculated
according to the formula, which is the same as reported in the
literature66. While, the absorption band is clearly redshift to 550
nm and the absorption band of visible light section is present,
which speculate that Na+ in the electrolyte solution were
intercalated into the WO3 structure in situ in the form of
tungsten bronze.
In addition, it can be speculate that the Na+ has been
successfully embedded into the structural framework of
WO3after 10 min light from the EDS energy spectrum (as
shown in Fig. 4H), which can explain the chargeꢀdischarge
Fig. 2 XRD patterns (A), Raman patterns (B), Cyclic voltammetry curve(C)
and UVꢀVis absorption spectra (D) of WO3 NFs before and after three
chargeꢀdischarge cycles performed in 0.1mol Lꢀ1 Na2SO4 electrolyte
solution containing 20 mg Lꢀ1 phenol.
6 | J. Name., 2012, 00, 1-3
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Fig. 4 (A), (B), (C), (D) and (E) are the SEM image of WO3 NFs at the time of anodized 50, 60, 70, 80 and 90 min, respectively. (F) and (G) are the SEM
and SAD spectrum of C/Cu2O NWAs. (H) is EDS elemental analysis of WO3 NFs after 10 min charging.
principle of the WO3 NFs electrode to a certain extent.
C/Cu2O NWAs; meanwhile, the photoelectrons were stored in
When the charges is being stored at the anode, hydrogen is situ to achieve the purpose of hydrogen production throughout
also being produced at the cathode simultaneously. The the day even in the absence of light, and the utilization rate of
research method of hydrogen production process is the same as stored electrons was 98.23%.
the TOC removal. The amount of hydrogen production was
Thus, it can found that the construction of csPEWFC can not
79.58 ꢁmol cmꢀ2 and showed a significant linear increase for 8 only efficient oxidation of phenol, store the electrons, but also
h under the AM 1.5 illumination. The anode and cathode were obtain hydrogen, with great significance of environmental and
disconnected and kept in the dark for 8 h, and then connected energy. The part of the photoelectrons generated by WO3 under
the cathode and the anode again, the hydrogen production photoexcitation was stabilized by the alkaline cations and
increased to 12.5 ꢁmol cmꢀ2 for 4 h gradually as shown in Fig. stored within the WO3 framework in situ, and this charges of
3A. In contrast, the dark process was not disconnected for 8 h, lightꢀinduced storages were utilized subsequently under dark
it can show that the amount of hydrogen were maintained at conditions in a controllable manner. Therefore, the factors that
about 10 ꢁmol cmꢀ2 for 4 h without any change as shown in Fig. affect the directional movement of alkaline cations can affect
3B. Considering the variety of TOC, it can speculate the main the WO3 NFs charging and discharging capacity, such as the
reason is that, the photoelectrons of WO3 NFs photocathode type of alkaline cation, the size, the concentration of electrolyte,
were separated from the holes after the illumination, and some the surface resistance of semiconductor WO3 NFs photoanode.
of the photoelectrons of WO3 NFs photoanode were driven to The properties of the interface between the scPEWFC electrode
combine with the holes of C/Cu2O NWAs photocathode from and the electrolyte solution by using the electrochemical
the external circuit to increase the utilization of cathode impedance spectroscopy (EIS) were investigated. First, the
photogenerated electrons. The other part of the photoelectrons morphological structure of WO3 were studied by adjusting the
was stored in the lattice of the anode WO3 NFs in situ. If the anodizing time (50 min, 60 min, 70 min, 80 min, 90 min) to
anode and cathode were not connected in the dark for 8 h, then obtain the different structure of WO3.
the electrons stored in the WO3 NFs will be transferred to the
Fig. S4 (ESI†) is the Nyquist curve of WO3 photocathode
cathode for hydrogen production in situ, which has been stored prepared at different anodizing times. As it can be seen from
in the reactor all the time, so the amount of hydrogen remained the Fig. S4 (ESI†), WO3 photoanode exhibits the minimum
stable essentially when it was detected. On the contrary, if the diameter of the semicircle under the condition of 70 min, which
dark process was disconnected for 8 h, it can be seen that the indicated the optimal conductivity and fast electron transfer
amount of hydrogen production increased gradually after process occurring at its surface. This can also be speculated
connecting the two electrode. During the process of from its appearance as shown in Fig. 4. When the anodizing
disconnection, the electrons at the anode have been stored time was 50 min (Fig. 4A), WO3 was mainly composed of
without discharging, then the electrons stored on the anode will broken nanotube network structure, and the pore structure was
be transferred to the cathode through the external circuit after very obvious, but the nanotube fracture was severe, so its
the reconnection, so that the stored electrons can continue be impedance increased evidently. When the anodizing time
utilized for hydrogen production under dark conditions. increased (60 min Fig. 4B), the morphology of the nanoflower
Therefore, it can be concluded that the photoelectrons can be was gradually displayed. Under the anodic conditions of 70 min
introduced into the cathode to combine with the holes on the (Fig. 4C), a dense nanostructure was formed, the surface was
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uniform and the resistance became smaller. The reason for this mesh surface, which greatly increases the surface area of the
is that the nanotube had a high specific surface area that can electrodes. The performance tests of the scPEWFC were carried
generate more photogenerated carriers and adsorb more out by using a twoꢀelectrode system. The IꢀV characteristic
contaminants on the surface. At the same time, the petal curve was measured by linear sweep voltammetry with a sweep
structure was also more conducive to the absorption and speed of 0.02 V sꢀ1. The power density (P) is calculated as
utilization of light energy. Whereas, with the extension of the follows: P = I×V.
anodizing time (80 min Fig. 4D), the nanoflower structure
In Fig. 1B, when the current density is 0.10 mA cmꢀ2, the
became scarce. The possible reason is that the anodizing time power density reaches a maximum (Pmax) of 0.015 mW cmꢀ2.
was too long, and the existing nanoflowers were further etched, The fill factor (FF) which is also an important indicator of
the lower part of the pipe network has been blocked. After output characteristics of a photoelectrochemical cell can be
increasing the anodizing time to 90 min (Fig. 4E), the calculated based on these parameters by the following equation:
Pmax
nanostructure disappeared completely, while the underlying
FF=
JSC·VOC
pipe network structure completely blocked, resulting in its
increasing impedance. Fig. 4(F) and (G) are the SEM and TEM
image of C/Cu2O NWAs, respectively. The diameter of C/Cu2O
NWAs was about 500 nm, and smooth surfaces with no
obvious fractures, the nanowires are densely grown on the Cu
Where Pmax and JSC•VOC represent the actual maximum
power density and the theoretical maximum power density,
respectively. JSC is the shortꢀcircuit current density, VOC is the
openꢀcircuit voltage. Table S1 (ESI†) lists the battery properties
of WO3 NFs ꢀC/Cu2O NWAs scPEWFC prepared at different
anodizing times. These results also demonstrate that JSC
exhibits a maximum value with the increase of anodic time.
The removal of TOC and the amount of hydrogen production
follow the same trend. The WO3 electrode (anodized of 70 min)
behave the best performance, which also be attributed to its
surface microscopic structure.
The factors influencing the charge and discharge properties
of WO3 were also investigated. As can be seen from Table. S2
(ESI†), the electrolyte concentration is not the larger the charge
and discharge performance is better. When the electrolyte
concentration is 0.1mol Lꢀ1, the optical photocurrent density
reached to the maximum. It is also indicate that WO3 stores
more charges in 0.1 mol Lꢀ1 Na2SO4 electrolyte solution and
the amount of hydrogen in the dark also reached the maximum.
To some extent, the charge stored in WO3 can be used
efficiently for hydrogen production in the dark. It is speculated
the main reason for this is that the size of the alkaline cations
themselves are different, so the rate of intercalation and deꢀ
intercalation of Na+ is different, so that the charge and
discharge capacity is different. While the discharge speed will
directly affect the dark current. Therefore, due to the different
discharge speed, the demand for alkaline cations concentration
is different, as for Na+ itself, 0.1 mol Lꢀ1 is the optical
concentration.
It can be found that the degradation of pollutants and
hydrogen production systems remained stable in the solarꢀ
charged photoelectrochemical wastewater fuel cell (scPEWFC)
by performing three cycles testing of the hydrogen production
and TOC removal (as shown in Fig. 5). The WO3 electrode was
illuminated under the simulative solar light for 4.2 h and then
discharged in the dark for 4.2 h. After three cycles, the
electrodes showed good stability and recyclability for all three
cycles.
Conclusions
In summary, a visible responsive dual photoelectrode based on WO3
NFsꢀC/Cu2O NWAs scPEWFC was constructed for the simultaneous
treatment of wastewater and hydrogen production. The scPEWFC
Fig. 5 The stability of scPEWFC in hydrogen production (A), TOC removal
(B). and three cycles of onꢀoff visible light irradiation (C) were recorded.
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22. J. Li, J. Li, Q. Chen, J. Bai and B. Zhou, Journal of hazardous materials,
2013, 262, 304ꢀ310.
performance parameters, the ability of deal with pollutants, hydrogen
production and the mechanism of scPEWFC chargingꢀdischarging
were systematically investigated. In the work, the hydrogen
production of scPEWFC based on phenol oxidation is 3.02 times
higher than that of pure photocatalytic water splitting, which
indicated that the oxidation of phenol could effectively promote the
hydrogen production. In addition, it also show that WO3 NFs still
retain its photoꢀcharging characteristics after visible light irradiation,
and efficient and sustainable hydrogen production (7.50 ꢁmol cmꢀ2
in 4 h) in the dark, which realized the desired effect without external
power supply, fullꢀday efficient and sustainable hydrogen
production. The research work has extended the new application of
scPEWFC for simultaneous wastewater treatment and hydrogen
production in the dark, and provided some theoretical guidance for
developing a novel, sustainable and green energy production routes
in environmental and energy field.
23. B. H. Kim, I. S. Chang and G. M. Gadd, Appl Microbiol Biotechnol, 2007, 76,
485ꢀ494.
24. Bruce E. Logan, ‡, Bert Hamelers, René Rozendal, ǁ, Uwe Schröder, J.
Keller, S. Freguia, P. Aelterman, a. Willy Verstraete and K. Rabaey,
Environmental science & technology, 2006, 40, 5181ꢀ5192.
25. Z. Li, W. Luo, M. Zhang, J. Feng and Z. Zou, Energy & Environmental
Science, 2013, 6, 347ꢀ370.
26. X. Chen, S. Shen, L. Guo and S. S. Mao, Chemical reviews, 2010, 110,
6503.
27. M. G. Walter, E. L. Warren, J. R. Mckone, S. W. Boettcher, Q. Mi, E. A.
Santori and N. S. Lewis, 2011, 111, 6446ꢀ6473.
28. A. Paracchino, V. Laporte, K. Sivula, M. Grätzel and E. Thimsen, Nature
materials, 2011, 10, 456ꢀ461.
29. K. Li, Y. Xu, Y. He, C. Yang, Y. Wang and J. Jia, Environmental science &
technology, 2013, 47, 3490ꢀ3497.
30. K. Li, H. Zhang, T. Tang, Y. Xu, D. Ying, Y. Wang and J. Jia, Water
Research, 2014, 62, 1ꢀ10.
31. Q. Chen, J. Bai, J. Li, K. Huang, X. Li, B. Zhou and W. Cai, Chemical
Engineering Journal, 2014, 252, 89ꢀ94.
32. Y. Liu, J. Li, B. Zhou, X. Li, H. Chen, Q. Chen, Z. Wang, L. Li, J. Wang and
W. Cai, Water Res, 2011, 45, 3991ꢀ3998.
Acknowledgements
33. G. Ma, T. Hisatomi and K. Domen, Chemical Society Reviews, 2014, 43,
7520ꢀ7535.
This work was financially supported by the National Natural
Science Foundation of China (NSFC, No. 21477085,
21537003).
34. Q. Chen, J. Li, X. Li, K. Huang, B. Zhou, W. Cai and W. Shangguan,
Environmental science & technology, 2012, 46, 11451ꢀ11458.
35. H. Tada, T. Mitsui, T. Kiyonaga, T. Akita and K. Tanaka, Nature materials,
2006, 5, 782ꢀ786.
Notes and references
36. K. Maeda, Acs Catalysis, 2013, 3, 1486–1503.
37. P. Zhou, J. Yu and M. Jaroniec, Advanced Materials, 2014, 26, 4920ꢀ4935.
38. X. L. Yin, L. L. Li, W. J. Jiang, Y. Zhang, X. Zhang, L. J. Wan and J. S. Hu,
ACS Appl Mater Interfaces, 2016, 8, 15258ꢀ15266.
1. I. Ali, Chemical reviews, 2012, 112, 5073ꢀ5091.
2. C. C. Wang, J. R. Li, X. L. Lv, Y. Q. Zhang and G. Guo, Energy &
Environmental Science, 2014, 7, 2831ꢀ2867.
39. X.ꢀL. Yin, G.ꢀY. He, B. Sun, W.ꢀJ. Jiang, D.ꢀJ. Xue, A.ꢀD. Xia, L.ꢀJ. Wan and
J.ꢀS. Hu, Nano Energy, 2016, 28, 319ꢀ329.
3. C. Chen, W. Ma and J. Zhao, Chemical Society Reviews, 2010, 39, 4206.
4. L. Xia, J. Bai, J. Li, Q. Zeng, X. Li and B. Zhou, Applied Catalysis B:
Environmental, 2016, 183, 224ꢀ230.
40. C. Ng, Y. H. Ng, A. Iwase and R. Amal, Applied Materials & Interfaces,
2013, 5, 5269ꢀ5275.
5. H. Shi and G. Zhao, The Journal of Physical Chemistry C, 2014, 118,
25939ꢀ25946.
41. S. Higashimoto, T. Shishido, Y. Ohno, M. Azuma, M. Takahashi and M.
Anpo, Journal of the Electrochemical Society, 2007, 154, F48ꢀF54.
42. C. Ng, A. Iwase, Y. H. Ng and R. Amal, Journal of Physical Chemistry
Letters, 2012, 3, 913ꢀ918.
6. G. Yang, G. Zhang and H. Wang, Water Research, 2015, 78, 60ꢀ73.
7. M. Gao, L. Zhu, W. L. Ong, J. Wang and G. W. Ho, Catal. Sci. Technol.,
2015, 5, 4703ꢀ4726.
43. X. Lu, T. Zhai, X. Zhang, Y. Shen, L. Yuan, B. Hu, L. Gong, J. Chen, Y. Gao
and J. Zhou, Advanced Materials, 2012, 24, 938ꢀ944.
44. C. Ng, Y. H. Ng, A. Iwase and R. Amal, Physical chemistry chemical
physics : PCCP, 2011, 13, 13421ꢀ13426.
8. Z. Wu, G. Zhao, Y. Zhang, J. Liu, Y.ꢀn. Zhang and H. Shi, J. Mater. Chem.
A, 2015, 3, 3416ꢀ3424.
9. N. Strataki, M. Antoniadou, V. Dracopoulos and P. Lianos, Catalysis Today,
2010, 151, 53ꢀ57.
45. S. N. Lou, N. Yap, J. Scott, R. Amal and Y. H. Ng, Scientific reports, 2014,
4, 7428.
10. Y. Feng, H. Lee, X. Wang, Y. Liu and W. He, Bioresource Technology,
2010, 101, 632ꢀ638.
46. P. Ngaotrakanwiwat, T. Tatsuma, S. Saitoh, Y. Ohko and A. Fujishima,
Physical Chemistry Chemical Physics, 2003, 5, 3234ꢀ3237.
47. S. Kim and H. Park, RSC Advances, 2013, 3, 18424–18429.
48. M. Long, B. Tan, P. Hu, B. Zhou and Y. Zhou, J. Mater. Chem. A, 2015, 3,
10195ꢀ10198.
11. C. A. Martínezhuitle, M. A. Rodrigo, I. Sirés and O. Scialdone, Chemical
reviews, 2015, 115, 13362ꢀ13407.
12. D. Cambié, C. Bottecchia, N. J. W. Straathof, V. Hessel and T. Noël,
Chemical reviews, 2016, 116, 10276ꢀ10341.
13. A. Rinaldi, B. Mecheri, V. Garavaglia, S. Licoccia, P. D. Nardo and E.
Traversa, Energy & Environmental Science, 2008, 1, 417ꢀ429.
14. Y. Du, Y. Feng, Y. Qu, J. Liu, N. Ren and H. Liu, Environmental science &
technology, 2014, 48, 7634ꢀ7641.
49. D. Liu, F. Liu and J. Liu, Journal of Power Sources, 2012, 213, 78ꢀ82.
50. G. Kim, M. Oh and Y. Park, Scientific reports, 2016, 6, 33400.
51. W. Zhao, X.ꢀF. Wang, E. Zheng, Y. Wei, Y. Sanehira and G. Chen, Journal
of Power Sources, 2017, 350, 28ꢀ34.
15. B. E. Logan and K. Rabaey, Science, 2012, 337, 686ꢀ690.
16. W.ꢀW. Li, H.ꢀQ. Yu and Z. He, Energy & Environmental Science, 2014, 7,
911ꢀ924.
52. Z. Zhang, R. Dua, L. Zhang, H. Zhu, H. Zhang and P. Wang, Acs Nano,
2013, 7, 1709.
53. Y. Chang, K. Yu, C. Zhang, Z. Yang, Y. Feng, H. Hao, Y. Jiang, L. L. Lou,
W. Zhou and S. Liu, Applied Catalysis B Environmental, 2017, 215.
54. Z. Wu, J. Wang, Z. Zhou and G. Zhao, J. Mater. Chem. A, 2017, 5, 12407ꢀ
12415.
17. Y.ꢀK. Wang, G.ꢀP. Sheng, W.ꢀW. Li, Y.ꢀX. Huang, Y.ꢀY. Yu, R. J. Zeng and
H.ꢀQ. Yu, Environmental science & technology, 2011, 45, 9256ꢀ9261.
18. W. Yang, K. Y. Kim, P. Saikaly and B. E. Logan, Energy & Environmental
Science, 2017, 10, 1025ꢀ1033.
55. R. Levinas, N. Tsyntsaru, M. Lelis and H. Cesiulis, Electrochimica Acta,
2017, 225, 29ꢀ38.
19. X. Xie, C. Criddle and Y. Cui, Energy & Environmental Science, 2015, 8,
3418ꢀ3441.
56. Y. Zhang, B. Tang, Z. Wu, H. Shi, Y. Zhang and G. Zhao, Green Chem.,
2016, 18, 2424ꢀ2434.
20. H. Wang, F. Qian, G. Wang, Y. Jiao, Z. He and Y. Li, Acs Nano, 2013, 7,
8728ꢀ8735.
57. X. Lu, S. Xie, H. Yang, Y. Tong and H. Ji, Chemical Society Reviews, 2014,
43, 7581ꢀ7593.
21. Q. Fang, G. Wang and Y. Li, Nano letters, 2010, 10, 4686ꢀ4691.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 9
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Journal of Materials Chemistry A
Page 11 of 12
ARTICLE
View Article Online
DOI: 10.1039/C7TA08112J
Journal Name
58. Z. Wu, Z. Zhou, Y. Zhang, J. Wang, H. Shi, Q. Shen, G. Wei and G. Zhao,
Electrochimica Acta, 2017, 254, 140ꢀ147.
59. S. Balaji, Y. Djaoued, A. S. Albert, R. Z. Ferguson, R. Brüning and B. L. Su,
Journal of Materials Science, 2009, 44, 6608ꢀ6616.
60. K. Machida and M. Enyo, Cheminform, 1990, 137, 1169ꢀ1175.
61. C. Santato, M. Odziemkowski, M. Ulmann and J. Augustynski, Journal of
the American Chemical Society, 2001, 123, 10639ꢀ10649.
62. S. Balaji, Y. Djaoued, A. S. Albert, R. Z. Ferguson, R. Brüning and B. L. Su,
Journal of Materials Science, 2012, 44, 6608ꢀ6616.
63. S. H. Lee, M. J. Seong, H. M. Cheong, E. Ozkan, E. C. Tracy and S. K.
Deb, Solid State Ionics, 2003, 156, 447ꢀ452.
64. S. Balaji, A. S. Albert, Y. Djaoued and R. Brüning, Journal of Raman
Spectroscopy, 2010, 40, 92ꢀ100.
65. C. Ng, A. Iwase, Y. H. Ng and R. Amal, ChemSusChem, 2013, 6, 291ꢀ298.
66. K. A. Newton and F. E. Osterloh, Topics in Catalysis, 2016, 59, 750ꢀ756.
10 | J. Name., 2012, 00, 1-3
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Table of Contents Graphic
Solar-charged photoelectrochemical wastewater fuel cell for efficient and sustainable
hydrogen production based on the promotion of pollutant oxidation