WO3/BiVO4 photoanode coated with mesoporous Al2O3 layer for oxidative production of hydrogen peroxide from water with high selectivity

Article abstract of DOI:10.1039/c7ra09693c

A WO₃/BiVO₄ photoanode coated with various metal oxides demonstrated high selectivity (faradaic efficiency) for hydrogen peroxide (H₂O₂) generation from water (H₂O) under irradiation of simulated solar light in a highly concentrated hydrogen carbonate (KHCO₃) aqueous solution. A mesoporous and amorphous aluminium oxide (Al₂O₃) layer significantly facilitated inhibition of the oxidative degradation of generated H₂O₂ into oxygen (O₂) on the photoanode, resulting in unprecedented H₂O₂ selectivity (ca. 80%) and the accumulation (>2500 μM at 50C).

Full text of DOI:10.1039/c7ra09693c

RSC Advances
View Article Online
View Journal | View Issue
PAPER
WO /BiVO photoanode coated with mesoporous
3
4
Al O layer for oxidative production of hydrogen
2
3
Cite this: RSC Adv., 2017, 7, 47619
peroxide from water with high selectivity†
a
ab
a
ab
Kojiro Fuku, * Yuta Miyase, Yugo Miseki,
Takahiro Gunji
ab
and Kazuhiro Sayama*
A WO
efficiency) for hydrogen peroxide (H
solar light in a highly concentrated hydrogen carbonate (KHCO
amorphous aluminium oxide (Al ) layer significantly facilitated inhibition of the oxidative degradation
of generated H into oxygen (O ) on the photoanode, resulting in unprecedented H selectivity (ca.
80%) and the accumulation (>2500 mM at 50C).
3
/BiVO
4
photoanode coated with various metal oxides demonstrated high selectivity (faradaic
) generation from water (H O) under irradiation of simulated
) aqueous solution. A mesoporous and
2
O
2
2
Received 31st August 2017
Accepted 3rd October 2017
3
2 3
O
DOI: 10.1039/c7ra09693c
2
O
2
2
2 2
O
rsc.li/rsc-advances
Chemical conversions using light energy have been performed
H O is an especially versatile and clean oxidation product
2 2
in various elds since the discovery of the Honda–Fujishima having the potential to generate instead of O2 from H O
2
1–25
effect.
Signicant efforts have recently been devoted to H
2
(eqn (1)).
production by water splitting using inexhaustible light for clean
+
ꢁ
1–4,8–29
2H O / H O + 2H + 2e (E(H O /H O) ¼
energy conversion processes.
widely recognised as a promising technology for H
because they operate at an electrolysis voltage lower than the
Photoelectrode systems are
2
2
2
2
2
2
+
1.77 V vs. RHE)
(1)
2
production
1,8–29
However, the accumulation of H
2
O
2
, generated oxidatively is
into O also
conventional photo-
electrochemical system i.e. the redox potential of H degra-
dation is more negative than the redox potential of H
production from H O (eqn (1) and (2)), resulting in low selec-
tivity for oxidative H O generation.
theoretical electrolysis voltage of water (<1.23 V).
Visible
extremely difficult because degradation of H
occurs easily and oxidatively in
2
O
2
2
light-responsive oxide photoanodes with a narrow bandgap
energy, such as WO , BiVO and Fe O , are desirable for the
a
3
4
2 3
2 2
O
efficient utilisation of solar light and economical synthetic
8–29
2 2
O
processes.
focused on BiVO
of light energy (ꢀ520 nm) and achieving efficient O
Most importantly, numerous efforts have been
photoanodes capable of utilising a wide range
generation
photoanode that
combines BiVO with a WO underlayer for the efficient transfer
2
4
2
2
2
9–21,28,29,32
by water splitting.
3 4
A WO /BiVO
+
+ 2H + 2e (E(O
ꢁ
H
2
O
2
/ O
2
2
/H
2
O
2
) ¼ +0.68 V vs. RHE) (2)
4
3
of excited electrons on BiVO to the F-doped SnO conductive
4
2
Recently, we reported that a photoelectrochemical system
glass (FTO) substrate shows exceptional photoelectrochemical
combining the WO /BiVO photoanode and aqueous electrolyte
3
4
10–13,17–20,28,29,32
performance for water splitting into H
However, most previous investigations, containing electro-
chemical reactions, focused solely on the recovery of H energy
2 2
and O .
of KHCO3 under CO2 bubbling could achieve simultaneous
generation and accumulation of H O and H from H O (eqn
2
2
2
2
2
28,29
(
3)).
an excellent oxidative catalyst for generating H
Moreover, H could be produced at no external bias on both
a WO /BiVO photoanode (from H O) and an Au cathode (from
) via a two-photon process (eqn (4)).
In this system, the aqueous electrolyte of KHCO acts as
3
generated on the cathode and little attention was paid to the
recovery of the oxidation products simultaneously evolved
2 2 2
O from H O.
2 2
O
24–31
during water splitting.
3
4
2
29
O
2
a
Research Center for Photovoltaics (RCPV), National Institute of Advanced Industrial
Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki
2H O / H O + H (two-photon process)
(3)
(4)
2
2
2
2
3
05-8565, Japan. E-mail: k.sayama@aist.go.jp
b
Department of Pure and Applied Chemistry, Tokyo University of Science, 2641
Yamasaki, Noda, Chiba 278-8514, Japan
2 2 2 2
2H O + O / 2H O (two-photon process)
†
Electronic supplementary information (ESI) available: Experimental section,
SEM images, XRD spectra, LHE spectra, applied voltage properties, I–V
characteristic of photoanodes, pore size distribution of the MeO particles,
effect of Al amount on WO /BiVO and dependence of applied voltage. See
DOI: 10.1039/c7ra09693c
Although the selectivity (faradaic efficiency: h(H O )) of
2
2
reductive H O production from O on cathodes such as Au was
2
2
2
x
very high, almost 100%, the maximum selectivity (h(H O )) for
2
O
3
3
4
2 2
2 2 3 4
oxidative H O production on WO /BiVO photoanodes was still
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 47619–47623 | 47619

View Article Online
RSC Advances
Paper
low, only ca. 54%. The design of novel photoanodes capable of
achieving efficient H O generation and inhibiting oxidative
2
2
degradation of generated H O is absolutely imperative for
2
2
building a clean and breakthrough technology, by accumulating
H
H
2
O
2
and H
O as the raw material.
Here, we focused on a surface modication of the metal
oxide (MeO ) layers on the WO /BiVO photoanode surface to
2 2 2
with unprecedented H O selectivity using only
2
x
3
4
achieve excellent selectivity of generation and accumulation of
H O in the KHCO aqueous solution under simulated solar
2
2
3
light irradiation (Fig. 1). The MeO layers were prepared by spin-
x
Fig. 2 Oxidative H O2 generation on photoanodes (WO /BiVO /
2
3
4
coating of metal organic solutions and calcination. Introducing MeO ) modified various metal oxides on a WO /BiVO at an electric
x
3
4
charge of 0.9C (900 s at steady photocurrent of 1 mA) in a 0.5 M
a porous Al
generation and accumulation with exceptional selectivity
in an aqueous KHCO electrolyte because of the blocking effect
2 3
O layer was found to specically permit oxidative
ꢂ
KHCO
3
aqueous electrolyte (35 mL) in an ice bath (below 5 C) under
2 2
H O
simulated solar light.
3
of oxidative degradation of the generated H
photoanode.
Details regarding experimental procedures for preparation
and photoelectrochemical reactions of photoanodes are
provided in the ESI†.
2 2 2
O into O on the
diffraction peaks derived from MeO
x
were observed in all WO
3
/
BiVO
modied on WO
4
/MeO
x
photoanodes, suggesting that all tried MeO
/BiVO
x
3
4
photoanode possess amorphous-like
structure. As shown in Fig. S3; ESI,† little change of the light
harvesting efficiency (LHE) was also conrmed in tried all
photoanodes, suggesting that these MeO introduced on the
The effects of MeO
photoanode, for oxidative H
investigated at an applied electric charge of 0.9C (900 s at steady
photocurrent of 1 mA) in a 0.5 M KHCO aqueous electrolyte. As
shown in Fig. 2, all MeO -coated photoanodes, except CoO
enhanced the oxidative H O generation compared to a bare
x
layers, modied on the WO
3 4
/BiVO
2 2
O
generation properties were
x
WO
WO
3
3
/BiVO
/BiVO
4
4
have little effect to light absorption efficiency on
photoanode. The time courses of voltages applied
3
x
x
,
between photoanode and a counter electrode of Pt mesh at
steady photocurrent of 1 mA (Fig. 2) in oxidative H genera-
2
2
2 2
O
WO /BiVO photoanode, and the enhanced effect, ranked by the
3
4
tion reaction were also conrmed (Fig. S4; ESI†). The voltages
for applying steady photocurrent of 1 mA slightly increased by
introducing MeO on the WO /BiVO photoanode. In particular,
modied metal oxide, was Al O > ZrO > TiO > SiO >> CoO .
2
3
2
2
2
x
Little H
because CoO
quickly, or O
noted that the Al
anode achieved roughly twice the oxidative H
compared to the bare WO /BiVO photoanode. The Al O
2 3
2
O
2
was observed on the CoO
probably decomposed the generated H
may be evolved on CoO directly. It should be
modication on the WO /BiVO photo-
generation
x
coated photoanode,
x
3
4
x
2 2
O
WO /BiVO /Al O photoanode, coated uniformly, smoothly and
3
4
2
3
2
x

atly at Al
2
O
3
x
compared to other MeO , required highest
2
O
3
3
4
applied voltage. In order to conrm the effect introducing the
Al on the photoanode in more detail, the photocurrent
property of the WO /BiVO /Al photoanode was investigated
in a 0.5 M KHCO aqueous solution (Fig. S5; ESI†). The bare
WO /BiVO photoanode exhibited excellent photocurrent
property in all applied voltage ranges as with our past reported
2 2
O
2 3
O
3
4
3
4
2 3
O
uniformly, smoothly and atly covered the entire area of the
3
WO /BiVO photoanode as shown in the SEM images (Fig. 3),
3
4
3
4
x
whereas other MeO were granularly and uniformly supported
on that and possessed any crack holes (Fig. S1; ESI†). It was also
conrmed, from XRD measurement (Fig. S2; ESI†), that no
1
1,12,28,29
example,
and the photocurrent property slightly
layer. However, it should be
decreased by introducing the Al
2 3
O
noted that the decreasing degree of the photocurrent property
was slight, only ca. 9% and 5% at +1.23 V and +1.77 V vs. RHE,
respectively, although the Al
covered the entire area of the WO
2
O
3
, having an insulation property,
/BiVO photoanode. A similar
3
4
2 2
Fig. 1 Pattern and energy diagrams for photoelectrochemical H O
generation from H
light irradiation.
2
O on WO
3
/BiVO
4
/MeO
x
photoanodes under solar Fig. 3 SEM images of (A) WO
3 4 3 4 2 3
/BiVO and (B) WO /BiVO /Al O
photoanodes.
47620 | RSC Adv., 2017, 7, 47619–47623
This journal is © The Royal Society of Chemistry 2017

View Article Online
Paper
RSC Advances
28
2 2 2
phenomenon has also been observed in O and H generation generation via the two-electron oxidation of H O. Even in the
through water splitting on
a photoanode coated with case of using the WO /BiVO /Al O photoanode, the selectivity
3 4 2 3
32
amorphous-like Ta O . In addition, it was conrmed, from the (h(H O )) for H O generation was signicantly enhanced with
2
5
2
2
2 2
N absorption and desorption measurement of MeO particles increasing concentration of KHCO , and the h(H O ) in the
2
x
3
2 2
(
Fig. S6; ESI†), that almost all MeO
x
possess mesoporous 2.0 M KHCO
3
aqueous solution reached ca. 80% at 0.9C,
/BiVO photoanode was ca.
calculated 54%. It should be noted that the selectivity (h(H
) ¼ ca. 53%)
photoanode by XRF on the WO /BiVO /Al photoanode in lowly concentrated
(0.1 M) was comparable to that (ca. 54%) on the bare
investigate the effects of dense Al O on WO /BiVO on the WO /BiVO photoanode in highly concentrated KHCO (2.0 M).
structure at a pore size of ca. 4–20 nm. In particular, a pore size whereas that using the bare WO
of the Al was ca. 4.7 nm. The thicknesses of Al
from the coating amount on the WO /BiVO
measurement were ca. 100 nm (0.055 mg cm ). In order to also KHCO
3
4
2
O
3
2
O
3
2 2
O
3
4
3
4
2 3
O
ꢁ2
3
2
3
3
4
3
4
3
oxidative H O generation, increasing Al O amount on WO / This suggests that the Al O could effectively be contributing to
2
2
2
3
3
2 3
BiVO4 photoanode was performed by decreasing the spin oxidative H O generation from H O even in the lowly concen-
2
2
2
coating number (500 rpm) of precursor solution of EMOD trated KHCO
3
. Moreover, as shown in Fig. 4(B), the excellent
/BiVO /Al photoanode
photoanode was signicantly
00 rpm calculated from the XRF measurement was ca. 127 nm maintained even at high electric charge up to 50C. As a result,
solved in butyl acetate containing ethylcellulose when intro-
H
2
O
2
generation property on the WO
/BiVO
3
4
2 3
O
ducing Al layers. The thickness of Al introduced at compared to the WO
2
O
3
2
O
3
3
4
5
ꢁ
2
3 4 2 3
(0.070 mg cm ), suggested that the thickness increases with the accumulation amount, using the WO /BiVO /Al O photo-
decreasing the spin coating number. As shown in Fig. S7; ESI,† anode, reached >2500 mM at 50C, while that using the bare WO3/
little change of the H O generation amounts was observed on BiVO photoanode was >1300 mM at 50C. The dependency of the
2
2
4
these WO /BiVO /Al O photoanodes prepared at 500 and applied voltage on the oxidative H O generation was investi-
3
4
2
3
2 2
1
000 rpm, indicating that increasing Al
photoanode has little effect on the oxidative H
subsequent experiments, WO /BiVO /Al
prepared at 1000 rpm was utilized as the photoanode. These that the enhanced effect of introducing an Al
results indicate that the specic effect enhancing oxidative pendent of the voltages applied between a photoanode as the
H O generation property was achieved on the WO /BiVO working electrode and a Pt mesh as counter electrode using the
2
O
3
on WO
generation. In ESI†). A small change in H
photoanode observed in all ranges of applied voltages (0.8–1.8 V), suggesting
layer is inde-
3
/BiVO
4
gated to conrm the effect of the Al
2 3
O coating in detail (Fig. S8;
2
O
2
2 2
O
generation performance was
3
4
2 3
O
2 3
O
2
2
3
4
though the mesoporous and amorphous Al O layer covered aqueous electrolyte of the KHCO3.
2
3
uniformly, smoothly and atly the entire area.
Although little development with regards to highly selective
generation via two-photon oxidation of H O and accu-
layer, the concen- mulation using photoanodes has been reported, our method of
aqueous electrolytes on the Al coating on the WO /BiVO photoanode produced
generation property was investigated at an tremendous improvement in selective H generation and
applied electric charge of 0.9C (Fig. 4(A)). We have already re- accumulation from H O in a KHCO aqueous electrolyte. It is
ported that the oxidative H O generation property on the WO / speculated that the specic enhancement of selectivity for H O2
To track the specic performance enhancing effect of
generating H by introducing the Al
tration dependency of KHCO
oxidative H
H
2
O
2
2
2
O
2
2 3
O
3
2
O
3
3
4
2
O
2
2 2
O
2
3
2
2
3
2
BiVO photoanode was improved with increasing concentration generation on the WO /BiVO /Al O photoanode may be caused
4
3
4
2 3
of KHCO , which acts as an effective catalyst for H O
by a blocking effect, on the mesoporous Al O layer, that
2 3
3
2
2
inhibits oxidative H
investigate the blocking effect on the Al
property test of H was performed in a 2.0 M KHCO
solution containing H (550 mM) in the presence of the bare
WO /BiVO or WO /BiVO /Al photoanodes in presence or
2
O
2
degradation into O
layer, a degradation
aqueous
2 4
on the BiVO . To
2 3
O
2
O
2
3
2 2
O
3
4
3
4
2 3
O
absence of simulated solar light irradiation in an ice bath
ꢂ
(
below 5 C). In both cases, as shown in Fig. 5, almost all the
initial amount of H O was maintained in the dark condition,
2
2
however, the H
tion by simulated solar light, suggesting that the H
decomposed by photocarriers (excited electrons and holes)
produced on the BiVO . It should be noted that the H
degradation in the presence of the WO /BiVO /Al photo-
anode was dramatically inhibited compared to the degradation
in the presence of a bare WO /BiVO photoanode. The oxidative
2
O
2
amount drastically decreased with irradia-
2 2
O
was
4
2 2
O
3
4
2 3
O
Fig. 4 (A) Oxidative H
2
O
2
generation in KHCO
3
aqueous electrolytes
3
4
(
(
(
35 mL) of different concentrations at applied electric charges of 0.9C H O generation test was also conrmed in a 2.0 M KHCO
2 2
3
900 s at steady photocurrent of 1 mA) under simulated solar light and
aqueous electrolyte, initially containing H
bare WO /BiVO and WO /BiVO /Al
the generated H degradation behaviour in more detail
(Fig. 6). The generated rates of H were reduced by the initial
2 3
addition of H in both cases of presence or absence of Al O .
2
O
2
(210 mM) on the
B) accumulation of oxidative H generation in a 2.0 M KHCO
2
O
2
3
3
4
3
4
2 3
O photoanodes, to track
aqueous solution (35 mL) under visible light irradiation (l > 420 nm)
using an intense Xe lamp at an applied voltage of 1.5 V in an ice bath
(
2 2
O
ꢂ
2 2
O
below 5 C) on a (a) bare WO
3
/BiVO
4
and (b) WO
3
/BiVO
4
/Al
2
O
3
photoanodes.
O
2
2
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 47619–47623 | 47621

View Article Online
RSC Advances
Paper
h(H
2
O
2
) in lower KHCO
3
concentration, as shown in Fig. 4(A).
The tracking and contribution of these other mechanisms, on
the Al O layer, is currently under investigation.
2
3
Conclusions
3
In summary, various metal oxides were coated onto a WO /
BiVO
4
photoanode to enhance the selectivity (faradaic effi-
ciency) of oxidative H O generation, in an aqueous electrolyte
2
2
of KHCO , from water under solar light irradiation. Among the
3
various metal oxides, the Al
a mesoporous and amorphous structure on the WO
generation at
photoanodes at no applied a selectivity of ca. 80% and an accumulation of >2500 mM (50C).
Interestingly, the Al -coated WO /BiVO photoanode
dramatically inhibited oxidative degradation of H generated
on the WO /BiVO photoanode aer introducing the Al O3
2
O
3
coating, which produced
Fig. 5 Degradation properties of H
2
O
2
(550 mM) initially added in
ꢂ
/BiVO
a 2.0 M KHCO
3
aqueous solution in an ice bath (below 5 C) under CO
2
3
4
bubbling and simulated solar light irradiation in the presence of a (a) photoanode, achieved excellent oxidative H
WO /BiVO and (b) WO /BiVO /Al
voltage.
2 2
O
3
4
3
4
2 3
O
2
O
3
3
4
2 2
O
3
4
2
However, the decreasing rate of H O generation was signi-
2
2
layer. This study contributes to developing a promising design
for a clean H production system that uses only water as the
raw material under solar light irradiation. More effective
dreamy H generation, at an excellent selectivity close to
00%, can be expected by modifying the surface-treatment
cantly inhibited, from ca. 61% to ca. 39%, by introducing the
Al layer on the WO /BiVO photoanode. These results
suggest that introducing the Al layer signicantly contrib-
uted to the highly selective H generation and accumulation
from H O, with a high photocurrent property, by a blocking
2 2
O
2
O
3
3
4
2 3
O
O
2 2
2 2
O
1
2
technology, and it is currently under investigation.
effect that inhibited the oxidative degradation of generated
H O . The mechanism of blocking effect is proposed that the
2
2
Conflicts of interest
H O generated on the BiVO in the WO /BiVO /Al O photo-
2
2
4
3
4
2 3
anode diffuses in electrolyte of KHCO
through mesoporous of the Al , and contact of the H
diffused in electrolyte with the BiVO covered uniformly and
smoothly Al
that with bare BiVO
inhibition of oxidative H O degradation. Furthermore, there
3
aqueous solution
There are no conicts to declare.
2
O
3
2 2
O
4
2
O
3
may be signicantly inhibited compared with Acknowledgements
4
, resulting in the formation of effective
The present work was partially supported by JSPS KAKENHI
Grant Number 26810105 and the International Joint Research
Program for Innovative Energy Technology. We thank Dr Etsuko
Fujita (Brookhaven National Laboratory) for helpful
discussions.
2
2
may be other possible mechanisms such as a blocking effect of
a direct O evolution site via a 4-photon process covering by
2
Al
2 3
O , or an enrichment effect resulting from the increasing
KHCO
3
concentration around the photoanode based on the
ꢁ
acid–base adsorption between HCO
weakly acidic sites on the Al
3
(a weak base) and the
2
O
3
surface, related to the good
Notes and references
1
2
A. Fujishima and K. Honda, Nature, 1972, 238, 37.
Z. G. Zou, J. H. Ye, K. Sayama and H. Arakawa, Nature, 2001,
414, 625.
3
4
A. Kudo and Y. Miseki, Chem. Soc. Rev., 2009, 38, 253.
K. Maeda, K. Teramura, D. Lu, T. Takata, N. Saito, Y. Inoue
and K. Domen, Nature, 2006, 440, 295.
5
6
7
8
9
K. Fuku, K. Hashimoto and H. Kominami, Chem. Commun.,
2010, 46, 5118.
K. Fuku, T. Kamegawa, K. Mori and H. Yamashita, Chem.–
Asian J., 2012, 7, 1366.
K. Fuku, R. Hayashi, S. Takakura, T. Kamegawa, K. Mori and
H. Yamashita, Angew. Chem., Int. Ed., 2013, 52, 7446.
B. D. Alexander, P. J. Kulesza, I. Rutkowska, R. Solarska and
J. Augustynski, J. Mater. Chem., 2008, 18, 2298.
K. Sayama, A. Nomura, Z. Zou, R. Abe, Y. Abe and
H. Arakawa, Chem. Commun., 2003, 2908.
2 2 3
Fig. 6 Comparison of oxidative H O generation in a 2.0 M KHCO
aqueous electrolyte (a) in the absence of or (b) containing initially-
ꢂ
added H
and (B) WO
irradiation at steady photocurrent of 1 mA.
2
O
2
(210 mM) in an ice bath (below 5 C) on a (A) WO
3
/BiVO
4
10 P. Chatchai, Y. Murakami, S. Kishioka, A. Y. Nosaka and
3
4 2 3
/BiVO /Al O photoanodes under simulated solar light
Y. Nosaka, Electrochim. Acta, 2009, 54, 1147.
47622 | RSC Adv., 2017, 7, 47619–47623
This journal is © The Royal Society of Chemistry 2017

View Article Online
Paper
RSC Advances
1
1
1
1 R. Saito, Y. Miseki and K. Sayama, Chem. Commun., 2012, 48,
K. M. Yu, J. Yang, L. Chen, M. R. Shaner, J. Spurgeon,
F. A. Houle, K. A. Persson and I. D. Sharp, Nat. Commun.,
2016, 7, 12012.
3833.
2 I. Fujimoto, N. Wang, R. Saito, Y. Miseki, T. Gunji and
K. Sayama, Int. J. Hydrogen Energy, 2014, 39, 2454.
3 X. Shi, I. Y. Choi, K. Zhang, J. Kwon, D. Y. Kim, J. K. Lee,
22 J. Y. Kim, G. Magesh, D. H. Youn, J. W. Jang, J. Kubota,
K. Domen and J. S. Lee, Sci. Rep., 2013, 3, 2681.
S. H. Oh, J. K. Kim and J. H. Park, Nat. Commun., 2014, 5, 23 Q. Mi, A. Zhanaidarova, B. S. Brunschwig, H. B. Gray and
4775.
N. S. Lewis, Energy Environ. Sci., 2012, 5, 5694.
1
1
4 T. W. Kim and K. S. Choi, Science, 2014, 343, 990.
5 Y. Liu, Y. Guo, L. T. Schelhas, M. Li and J. W. Ager III, J. Phys. 25 K. Ueno and H. Misawa, NPG Asia Mater., 2013, 5, e61.
24 J. C. Hill and K. S. Choi, J. Phys. Chem. C, 2012, 116, 7612.
Chem. C, 2016, 120, 23449.
6 L. H. Hess, J. K. Cooper, A. Loiudice, C. M. Jiang,
26 K. Fuku, N. Wang, Y. Miseki, T. Funaki and K. Sayama,
ChemSusChem, 2015, 8, 1593.
1
1
1
1
R. Buonsanti and I. D. Sharp, Nano Energy, 2017, 34, 375.
7 J. Su, L. Guo, N. Bao and C. A. Grimes, Nano Lett., 2011, 11, 28 K. Fuku and K. Sayama, Chem. Commun., 2016, 52, 5406.
27 H. G. Cha and K. S. Choi, Nat. Chem., 2015, 7, 328.
1928.
29 K. Fuku, Y. Miyase, Y. Miseki, T. Funaki, T. Gunji and
K. Sayama, Chem.–Asian J., 2017, 12, 1111.
30 K. Fuku, Y. Miyase, Y. Miseki, T. Gunji and K. Sayama,
ChemistrySelect, 2016, 1, 5721.
8 P. M. Rao, L. Cai, C. Liu, I. S. Cho, C. H. Lee, J. M. Weisse,
P. Yang and X. Zheng, Nano Lett., 2014, 14, 1099.
9 I. Grigioni, K. G. Stamplecoskie, D. H. Jara, M. V. Dozzi,
A. Oriana, G. Cerullo, P. V. Kamat and E. Selli, ACS Energy 31 T. Shiragami, H. Nakamura, J. Matsumoto, M. Yasuda,
Lett., 2017, 2, 1362.
0 K. Mase, M. Yoneda, Y. Yamada and S. Fukuzumi, ACS
Energy Lett., 2016, 1, 913.
1 F. M. Toma, J. K. Cooper, V. Kunzelmann, M. T. McDowell,
J. Yu, D. M. Larson, N. J. Borys, C. Abelyan, J. W. Beeman,
Y. Suzuri, H. Tachibana and H. Inoue, J. Photochem.
Photobiol., A, 2015, 313, 131.
32 R. Saito, Y. Miseki, W. Nini and K. Sayama, ACS Comb. Sci.,
2015, 17, 592.
2
2
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 47619–47623 | 47623