Unprecedentedly enhanced solar photocatalytic activity of a layered titanate simply integrated with TiO2 nanoparticles

Article abstract of DOI:10.1039/c6cp05635k

We report a simple, low-cost methodology for unprecedentedly enhancing the photocatalytic activity of layered inorganic semiconductors. A layered titanate with a lepidocrocite-type structure scarcely showed photocatalytic activity for a test reaction, the

Full text of DOI:10.1039/c6cp05635k

View Article Online
View Journal
PCCP
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: K. Saito, M.
Kozeni, M. Somiya, K. Komaguchi, M. Ogawa, Y. Sugahara and Y. Ide, Phys. Chem. Chem. Phys., 2016,
DOI: 10.1039/C6CP05635K.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/pccp

Please do not adjust margins
Physical Chemistry Chemical Physics
Page 1 of 6
View Article Online
DOI: 10.1039/C6CP05635K
Journal Name
ARTICLE
Unprecedentedly enhanced solar photocatalytic activity of a
layered titanate simply integrated with TiO nanoparticles
2
Received 00th January 20xx,
Accepted 00th January 20xx
a,b
b
b
c
ab
Kanji Saito, Misa Kozeni, Minoru Sohmiya, Kenji Komaguchi, Makoto Ogawa , Yoshiyuki
*
ade
*af
Sugahara
and Yusuke Ide
DOI: 10.1039/x0xx00000x
We report a simple, low-cost methodology for unprecedentedly enhancing the photocatalytic activity of layered inorganic
semiconductors. A layered titanate with a lepidocrocite-type structure scarcely showed photocatalytic activity for a test
www.rsc.org/
reaction, the oxidative decomposition of formic acid in water into CO
enhanced photocatalytic activity upon mixing with a much smaller amount (approximately 10 wt%) of commercially
available TiO nanoparticle (P25) in water. The photocatalytic activity of the mixture was approximately 5 times that of P25,
2
, under simulated solar light, but it showed highly
2
a benchmark photocatalyst. From various analyses, the enhancement resulted from a transfer of photoexcited electrons
from the layered titanate to P25 at their particle interfaces and retardation of the charge recombination. When applied to
2
a photocatalyst for H production from water containing methanol under simulated solar light, the layered titanate/P25
mixture showed considerably enhanced activity and the apparent quantum yield was 23 % (at 320 nm). By replacing P25
with Pt co-catalyst-loaded P25, the apparent quantum yield of the mixture increased from 23 to 73 %, although extremely
small amount (below 0.06 %) of Pt was used in the system.
photocatalysts synthesized via layer-by-layer assembly of two
kinds of layered semiconductor nanosheets resulting from
enhanced charge separation efficiency due to efficient
lntroduction
Development of highly active solid photocatalysts has been
extensively investigated for efficient use of solar energy for
fuel production, fine chemical synthesis and removal of
9
,10
coupling based on their 2D structures.
In addition, with
tuning of their interlayer structures, they show such unique
and useful phenomena as substrate or product selective
1
-5
hazardous organic compounds. Extensive efforts have been
directed to modifying existing photocatalysts and synthesizing
new ones in consideration of enhancement of their surface
area and charge separation efficiency, which largely affect the
activities of photocatalyst particles. Layered inorganic
semiconductors such as layered titanates and niobates have
been utilized as scaffolds for designing highly efficient
photocatalysts, because they possess an interlayer space that
is expandable (or exfoliatable) via intercalation reactions and
can therefore provide huge nanospaces for reactants and
1
1-15
photocatalytic reactions,
that are difficult to achieve with
conventional semiconducting particles. Unmodified layered
inorganic semiconductors, however, often show negligible
1
1,13
photocatalytic activity;
photocatalysts often show photocatalytic activity lower than
that of such commercial photocatalysts as P25 TiO which is
as a result, the obtained hybrid
2
often used as a benchmark photocatalyst. To remarkably
enhance the photocatalytic activity of layered inorganic
semiconductors more easily and cheaply without intercalation
1
6
6
-8
reactions is thus challenging issue.
functional units for hybridization. Typical example is the
enhanced photocatalytic activity observed for hybrid
Herein, we report on a new methodology for enhancing
the photocatalytic activity of layered inorganic semiconductors
remarkably by making unique use of P25. P25 is one of the
most active photocatalysts; therefore, the modification of P25
with co-catalysts has often been conducted to synthesize
1
6-18
photocatalysts with high activity.
We demonstrate that a
simple (particle-level) mixing of a layered titanate and a much
smaller amount of P25 (like a co-catalyst) produces a
composite showing considerably higher photocatalytic activity
than P25 for different reactions as a result of a transfer of
photoexcited electrons from a layered titanate to P25 and
retardation of the charge recombination, without intercalation
reactions. We highlight that a high level (apparent quantum
yield of 73% at 320 nm) of photocatalytic activity for H
2
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Physical Chemistry Chemical Physics
Page 2 of 6
View Article Online
DOI: 10.1039/C6CP05635K
ARTICLE
Journal Name
production from water containing methanol is achieved when
the P25 component is replaced by Pt-loaded P25, although
unusually small amount of Pt is used in the composite.
Results and discussion
Preparation of a layered titanate
We selected a lepidocrocite-type layered titanate (A
x
Ti2-
M O : A, interlayer alkali metal cation; M, metal or vacancy)
y y 4
to enhance the photocatalytic activity, because lepidocrocite-
type layered titanates are most widely investigated layered
inorganic semiconductors due to their superior intercalation
1
9
abilities.
4
K0.8Ti1.73Li0.27O (KTLO) was prepared by solid-state
o
reaction at 600 C according to the method of the previous
2
0
report, and the interlayer K cations of the obtained titanate
were subsequently exchanged with protons by acid treatment.
0.27 4
The formation of the protonated form (H1.07Ti1.73□ O ,
hereafter abbreviated as HTO) was confirmed by the
composition, XRD pattern and SEM image of the product (Fig.
S1 in Supporting Information).
Mixing of HTO with P25
Fig. 1A shows the size distribution of HTO, P25 and the
HTO/P25 mixture in water determined by dynamic light
scattering (DLS) analysis. HTO and P25 showed peaks with a
size of ca. 1.3 μm and ca. 0.3 μm, respectively. They were
assigned to aggregated particles, since the primary particle
sizes of HTO and P25 were ca. 100-200 nm and ca. 20-50 nm,
respectively. The HTO/P25 mixture showed a peak with a size subsequent stirring under dark. The suspension was irradiated
of 2.2 μm, which was much larger than those of HTO and P25. with a solar simulator (λ > 300 nm otherwise mentioned)
2
In the TEM image of the HTO/P25 mixture after the under stirring (under these testing conditions, CO evolved
evaporation of water, we found that each component was linearly with irradiation time, and formic acid adsorption on
mixed homogeneously and possessed particle interfaces (Fig. both HTO and P25 scarcely affected the photocatalytic
1
B). These results indicate that HTO and P25 particles can activity).
contact each other when mixed in water. The isoelectric points As shown in Fig. 2A, P25 decomposed formic acid
2
1
22
28
of HTO and P25 are ~ 2. and 6.4 , respectively. Given that photocatalytically to evolve CO , as reported previously. HTO
2
the pH of the aqueous HTO/P25 mixture dispersion was 4.0, was completely inactive for the reaction. On the other hand,
HTO and P25 clearly charged oppositely in water. Therefore, the HTO/P25 composite showed about 5 times higher activity
2
3
electrostatic interactions between HTO and P25 particles than P25. (HTO/P25 mixing ratio was optimized to be 13
seemed to be the driving force for forming aggregated mg/2mg as shown in Fig. S2). P25 is one of the most active
particles. The simple mixing of HTO and P25 in water thus photocatalysts for the decomposition of organic compounds,
produced
structures of HTO and P25 (Fig 1C),
photoexcited HTO to P25 is thermodynamically favorable, and
P25 can thus enhance the charge separation of HTO (hole comparable to that of hydrothermal treated P25, which
transfer is implausible, as discussed below).
shows the best photocatalytic activity for oxidative
decomposition of formic acid among unmodified TiO
a
2
composite. Considering the electric band and only a limited number of TiO materials have shown
2
4,25
29-
electron transfer from photocatalytic activity considerably higher than that of P25.
3
1
The photocatalytic activity of HTO/P25 composite was
3
2
2
Enhanced photocatalytic formic acid oxidation and the mechanism photocatalyst to the best of our knowledge. To our surprise,
moreover, the photocatalytic activity of HTO/P25 composite
First, photocatalytic activities were evaluated by the
was higher than that of Pt@HTO, an HTO with its outer particle
oxidative decomposition of formic acid in water to evolve CO
2
,
surface modified with 0.5 wt% Pt nanoparticle, one of the
most efficient co-catalysts (Fig. 2A). All the results indicate the
merits of using P25 as an additive for simple, low-cost
development of high photocatalytic activity in HTO and many
a representative reaction for checking the performance of
2
6,27
photocatalysts.
mixture (13 mg/2 mg) was dispersed in an aqueous solution of
formic acid (5 mL, 5 vol%, O saturated) by ultrasonication and
HTO (15 mg), P25 (15 mg) or an HTO/P25
2
2
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 6
Physi cP al el aC s he ed mo ins ot tr ya dC j uh set mm i ac rag li nP shysics
View Article Online
DOI: 10.1039/C6CP05635K
Journal Name
ARTICLE
other layered inorganic semiconductors with electric band surface of P25 is subsequently reduced. This hypothesis was
3
structures similar to that of HTO.
3
To discuss the mechanism of the high photocatalytic
activity of the HTO/P25 composite, we first conducted a
photocatalytic reaction under simulated solar light with a
wavelength of λ > 360 nm, at which HTO is not excited but P25
is (Fig. 2B). As shown in Fig. 2A-right, the photocatalytic
activity of the mixture was similar to that of P25 under these
conditions. In light of the fact that formic acid is decomposed
directly by photogenerated holes in TiO2 (or the
decomposition is initiated by the holes) in the presence of
3
4
molecular O2, this result indicates that under full-spectrum
solar light irradiation, scarcely any electron transfer from P25
to HTO occurs to enhance the photocatalytic activity of P25. It
is thus suggested that HTO, which is inactive without P25
because the photogenerated electron-hole pairs are easily
recombined (possibly because of its low crystallinity and/or
low O reduction ability, as discussed later), shows extremely
2
highly enhanced activity as a result of electron transfer from
HTO to P25 to retard the charge recombination on HTO (Fig.
3). It has been reported that a lepidocrocite-type layered
titanate shows photocatalytic activity for the decomposition of
alcohols to H only after modification of the outer particle
2
1
1
surface with Pt. This observation supports our hypothesis.
To confirm this electron transfer, we monitored the O
−
2
3
5
yield by a method proposed by Matsumura, et al., who had
−
quantified the O2 yield of TiO using Nitroblue tetrazolium
2
−
NBT), which reacts with O , generated by a reaction between
(
2
further discussed by examining photocatalytic activity of
HTO/WO mixture (Fig. S3). The fact that efficient charge
separation is occurred in P25 via inter-particle electron
O and photoexcited electrons of a photocatalyst, to form
2
3
insoluble Formazan deposits on TiO . As shown in Fig. 3A, HTO
2
−
did not generate any O . However, the HTO/P25 composite
2
32,36
−
transfer from rutile and anatase
suggests the remarkably
generated an approximately 3 times the higher amount of O2
enhanced charge separation efficiency on the HTO/P25
composite.
than P25 alone. This result confirms that photoexcited
electrons of HTO are transferred to P25, and the O on the
2
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Physical Chemistry Chemical Physics
Page 4 of 6
View Article Online
DOI: 10.1039/C6CP05635K
ARTICLE
Journal Name
We also investigated a possible transfer of photogenerated 73 % at 320 nm (at 3 h irradiation in Fig. S4). This enhanced
holes from HTO to P25, resulting in retardation of the charge activity was ascribable to the presence of Pt co-catalyst for H
recombination on HTO and enhancement of the photocatalytic production, in addition to the enhanced charge separation
activity. It is known that PbO is deposited on photocatalyst owned by P25 similar to photocatalytic formic acid oxidation
2
2
2
+
particles from Pb by oxidation with photogenerated holes, on the HTO/P25 composite. It should be noted here that the
and this phenomenon has often been used to determine the photocatalytic activity of the HTO/Pt@P25 composite was
3
7
oxidation sites of photocatalyst particles. When the HTO/P25 even higher than that of Pt@P25 with the same catalyst
composite was treated by the reported method, very small, amount (15 mg), although the amount of Pt contained in the
broad peaks due to PbO
Fig. 3B), while PbO nanoparticles were not observed on P25 smaller than that (0.5 wt%) contained in the Pt@P25 sole
particles adjacent to HTO particles in the TEM image (Fig. 3C). system. Intercalation of appropriate visible light sensitizers
No formation of PbO on the P25 component was further into the HTO component will make utilization of solar energy
confirmed by the TEM electron mapping as shown in Fig. 3D. more efficiently.
2
were observed in the XRD pattern HTO/Pt@P25 system was only 0.06 wt%, which was much
(
2
2
2
+
These results indicate that Pb was not oxidized on P25 but
was oxidized in the interlayer space of HTO, confirming that
hole transfer from HTO to P25 had not occurred (we cannot
Conclusions
rule out the possibility that quite small PbO particles formed
2
We have reported on the remarkably enhanced photocatalytic
activity of a composite of a lepidocrocite-type layered titanate
on HTO particle outer surface).
2
particles and a much smaller amount of P25 TiO particles,
2
Photocatalytic H production from aqueous methanol
prepared by simple mixing of these particle in reaction media,
for photocatalytic reactions such as oxidative decomposition
On the basis of the above mechanism, we thought that the
photocatalytic activity of HTO for reduction reactions can also
be enhanced upon mixing with P25 particles. Therefore, we
finally checked the photocatalytic activity of the HTO/P25
2
of formic acid in water and H production from aqueous
methanol solution. The enhancement was due to efficient
charge separation via transfer of photogenerated electrons
from the titanate to P25. The apparent quantum yield at 320
nm of the composite was up to 73 % when unusually small
amount of Pt co-catalyst was used. This simple, low-cost and
efficient methodology can be applied to other layered
inorganic semiconductors and their intercalation compounds,
making their applications in photocatalysis more effective and
realistic.
2
composite for H production from water, one of the most
desired reactions for fuel productions. HTO (15 mg), P25 (15
mg) or the HTO/P25 mixture (13 mg/2 mg) was dispersed in an
aqueous solution of methanol (deaerated by Ar bubbling) by
ultrasonication and subsequent stirring under dark. The
suspension was irradiated with a solar simulator (λ > 300 nm)
2
under stirring. As shown in Fig. 4A, H evolved linearly with
irradiation time with all the samples except for P25, consistent
with the previous report that showed negligible activity of P25
3
2
under the similar condition. Upon mixing with P25 particles,
the photocatalytic activity of HTO was considerably enhanced
EXPERIMENTAL
(
ca. 6 times) as we expected (Fig. 4B). The AQY of the Preparation of HTO
composite at 320 nm was 23 %. When P25 was replaced with
.5 wt% of Pt nanoparticle-modified P25 (Pt@P25), the activity
was further enhanced by up to 31 times and the AQY reached
H
1.07Ti1.73
□
0.27
O
4
(HTO) was prepared by solid-state reaction
and subsequent acid treatments. K0.8Ti1.73Li0.27 (KTLO) was
prepared according to the previous report by solid-state
reaction from K CO , Li CO and TiO (at the molar ratio of
.4:0.8:10.4). The starting materials were mixed by using
0
O
4
2
3
2
3
2
2
Planet M2-3 (Gokin Planetaring) and the mixture was calcined
o
in air at 600 C for 30 min. After cooling to room temperature,
the mixture was mixed and was heated again for 20 hours in
air. KTLO (400 mg) was dispersed in 0.1 M aqueous HCl
solution (200 mL) and the dispersion was shaken (160 rpm,
1
2h). The reaction was conducted for 3 times. The solid was
separated by centrifugation (3500 rpm, 20-60 min), washed
with deionized water, and dried under reduced pressure at
+
+
room temperature. Complete extraction of K and Li from
KTLO was confirmed by analyzing the supernatant with
inductivity coupled plasma atomic emission spectroscopy (ICP-
AES). XRD patterns and SEM images of the products are shown
in Fig. S1.
Photocatalytic oxidative decomposition of formic acid
4
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 6
Physi cP al el aC s he ed mo ins ot tr ya dC j uh set mm i ac rag li nP shysics
View Article Online
DOI: 10.1039/C6CP05635K
Journal Name
ARTICLE
Oxidative decomposition of formic acid was performed in a with authentic sample. The number of incident photons was
stainless steel container (75 mL) equipped with a Pyrex determined by using S1337-1010BQ silicon photodiode
window as followed: the sample (layered titanate or both (Bunkoukeiki). AQY was defined by the following equation:
2
layered titanate and additive powders) was added in an O -
saturated aqueous solution (5 mL) containing 5 vol% of formic
acid, and the suspension was ultrasonicated for 1 min and
ꢆꢇꢈꢉꢊꢋꢃꢌꢍꢃꢋꢊꢎꢏꢐꢊꢑꢃꢊꢒꢊꢏꢐꢋꢌꢓꢔ
ꢆꢇꢈꢉꢊꢋꢃꢌꢍꢃꢕꢓꢏꢕꢑꢊꢓꢐꢃꢖꢗꢌꢐꢌꢓꢔ
ꢀ
ꢁꢂꢃꢄ%ꢅ =ꢃ
× ꢃꢘꢙꢙꢃ%
then irradiated by a solar simulator (San-Ei Electric, λ
>300
−
2
nm, 1000 Wm ) under stirring. The gas in the grass tube
was withdrawn with a gas-tight syringe and quantified
using a BID gas chromatograph (ShimadzuBID-2010 plus)
equipped with a Micropacked ST column. Argon gas was
used as a career gas.
ꢃ
ꢆꢇꢈꢉꢊꢋꢃꢌꢍꢃꢊꢚꢌꢒꢚꢊꢑꢃꢛ ꢃꢈꢌꢒꢊꢏꢇꢒꢊꢔ
ꢜ
ꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃ=
ꢃ× ꢃꢘꢙꢙꢃ%
ꢆꢇꢈꢉꢊꢋꢃꢌꢍꢃꢕꢓꢏꢕꢑꢊꢓꢐꢃꢖꢗꢌꢐꢌꢓꢔ
−
Quantitative analysis of O
2
−
O
2
yield of the photocatalysts were quantified according to
Acknowledgements
the previous report. HTO (15 mg), P25 (2 mg) or HTO/P25
mixture (13 mg/2 mg) was dispersed in an aqueous 2-propanol
This work was partly supported by JSPS KAKENHI Grant
Number 26708027. This paper was also a part of the outcome
of research performed under Waseda University Grant for
Special Research Projects (Project number: 2015S-033). We
thank Mr. Shinpei Enomoto for TEM observation.
2
solution (5 mL, 4 vol%, O saturated), to which Nitroblue
tetrazolium (NBT) had been added at a concentration of 1 mM,
by ultrasonication. The suspension was irradiated with a 350
W mercury lamp (USHIO) for 3 min. This reaction was
conducted in a glass tube (>300 nm). After the irradiation, the
photocatalyst was replaced by centrifugation (45000 rpm, 15
References
min), and the supernatant was analyzed by UV-vis
−
1
A. Fujishima, X. Zhang and D. A. Tryk, Surf. Sci. Rep., 2008,
, 515-582.
spectroscopy. NBT reacts with O
between O
2
, generated by a reaction
6
3
2
and photoexcited electrons of a photocatalyst, at
2
3
A. Kudo and Y. Miseki, Chem. Soc. Rev., 2009, 38, 253-278.
Y. Shiraishi and T. Hirai, J. Photochem. Photobiol. C, 2008,
the molar ratio of 1:4 to form insoluble Formazan deposits on
the photocatalyst. Therefore, by quantifying the amount of
9
,
1
57-170.
NBT replaced from aqueous media, the amount of generated
−
4
5
6
7
8
9
J. L. Vivero-Escoto, Y.-D. Chiang, K. C-W Wu and Y. Yamauchi,
Sci. Tech. Adv. Mater., 2012, 13, 13003-13012.
Y.-T. Liao, C.-W. Huang, C.-H. Liao and J. C.-S. Wu, Appl.
Energy, 2012, 100, 75-80.
W. J. Youngblood, S.-H. A. Lee, K. Maeda and T. E. Mallouk,
Accounts Chem. Res., 2009, 42, 1966-1973.
O
2
can be quantified.
Determination of the oxidation site in HTO/P25 composite
The oxidation site in HTO/P25 composite was determined
according to the previous report. The HTO/P25 mixture (15
J. L. Gunjakar, I. Y. Kim, J. M. Lee, Y. K. Jo and S.-J. Hwang, J.
Phys. Chem. C, 2014, 118, 3847-3863.
mg) was dispersed in 0.1 M Pb(NO
saturated) by ultrasonication in a glass tube (>300 nm) . The
pH of the dispersion was adjusted at 1.0 by adding HNO . After
photoirradiation for 24 hours, the solid was separated by
3 2 2
) solution (5 mL, O
T. Okada, Y. Ide and M. Ogawa, Chem. Asian. J., 2012,
980-1992.
7,
1
3
S. Ida, A. Takeshiba, S. Koga, H. Hagiwara and T. Ishihara, J.
Am. Chem. Soc., 2014, 136, 1872-1878.
centrifugation (3500 rpm, 20 min), dried under reduced 10 D. Mochizuki, K. Kumagai, M. M. Maitani and Y. Wada,
Angew. Chem. Int. Ed., 2012, 51, 5452-5455.
pressure at room temperature and observed by TEM-EDS.
1
1
1 Y. Ide, Y. Nakasato and M. Ogawa, J. Am. Chem. Soc., 2010,
32, 3601-3604.
2 Y. Ide, M. Matsuoka and M. Ogawa, J. Am. Chem. Soc., 2010,
132, 16762-16764.
1
Photocatalytic H
Photocatalytic H
2
production
2
production from water was performed in a
Pyrex glass tube (34 mL) as follows: the sample (layered 13 B. Ohtani, S. Ikeda, H. Nakayama and S. Nishimoto, Phys.
Chem. Chem. Pyhs., 2002, 2, 5308-5313.
4 R. Abe, K. Shinmei, N. Koumura, K. Hara and B. Ohtani, J. Am.
Chem. Soc., 2013, 135, 16872-16884.
5 Y. Il Kim, S. Salim, M. J. Huq and T. E. Mallouk, J. Am. Chem.
Soc., 1991, 113, 9561-9563.
titanate or both layered titanate and additive powders) was
added in aqueous solution (5 mL) containing 50 vol% of
methanol, and the suspension was ultrasonicated for 1 min
and then deaerated by argon bubbling. The glass tube was
1
1
sealed with a rubber septum and irradiated by a solar 16 Y. Ide and K. Komaguchi, J. Mater. Chem. A, 2015, 3, 2541-
−
2
2
546.
7 Q. Xiang, J. Yu and M. Jaroniec, Chem. Soc. Rev., 2012, 41
82-796.
simulator (San-Ei Electric, λ >300 nm, 1000 Wm ) under
stirring. For AQY calculation, the glass tube was irradiated by a
monochromated light (320 nm) for 3 h using a 500 W Xe lamp
1
1
,
,
7
8 H. Tada, T. Kiyonaga and S. Naya, Chem. Soc. Rev., 2009, 38
1849-1858.
(
Ushio) and SM-25 monochrometer (Bunkokeiki). The gas in
the glass tube was withdrawn with a gas-tight syringe and 19 Y. Ide, M. Sadakane, T. Sano and M. Ogawa, J. Nanosci.
Nanotech., 2014, 14, 2135-2147.
quantified using a TCD gas chromatograph (Shimadzu GC-8A)
2
0 M. Ogawa, M. Morita, S. Igarashi and S. Sato, J. Solid State.
Chem., 2013, 206, 9-13.
equipped with SHINCARBON-ST 50-80 columns. Argon gas was
used as a career gas. The H concentrations were calibrated
2
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Physical Chemistry Chemical Physics
Page 6 of 6
View Article Online
DOI: 10.1039/C6CP05635K
ARTICLE
Journal Name
2
2
2
2
1 S. Tsukahara, N. Soh and K. Kamada, J. Phys. Chem. C, 2012,
16, 19285-19289.
2 B. Ohtani, Y. Okugawa, S. Nishimoto and T. Kagiya, J. Phys.
Chem., 1987, 91, 3550-3555.
3 N. Siedl, S. O. Baumann, M. J. Elser and O. Diwald, J. Phys.
Chem. C, 2012, 116, 22967-22973.
4 N. Sakai, Y. Ebina, K. Takada and T. Sasaki, J. Am. Chem. Soc.,
1
2
5 D. E. Scaife, Solar Energy, 1980, 25, 41-54.
004, 126, 5851-5858.
2
2
6 H. Kominami, A. Tanaka and K. Hashimoto, Chem. Commun.,
2
010, 46, 1287-1289.
7 O.-O. Prieto-Mahaney, N. Murakami, R. Abe and B. Ohtani,
Chem. Lett., 2009, 38, 238-239.
2
2
8 H. Kominami, J. Kato, Y. Takada, Y. Doushi, B. Ohtani, S.
Nishimoto, M. Inoue, T. Inui and Y. Kera, Catal. Lett., 1997,
46, 235-240.
2
9 F. Amano, O.-O. Prieto-Mahaney, Y. Terada, T. Yasumoto, T.
Shibayama and B. Ohtani, Chem. Mater., 2009, 21, 2601-
2
603.
3
3
3
0 S. Ito, S. Inoue, H. Kawada, M. Hara, M. Iwasaki and H. Tada,
J. Colloid Interface Sci., 1999, 216, 59-64.
1 Z. Bian, T. Tachikawa and T. Majima, J. Phys. Chem. Lett.,
2
012, 3, 1422-1427.
2 Y. Ide, N. Inami, H. Hattori, K. Saito, M. Sohmiya, N. Tsunoji,
K. Komaguchi, T. Sano, Y. Bando, D. Goldberg and Y.
Sugahara, Angew. Chem. Int. Ed., 2016, 55, 3600-3605.
3 K. Akatsuka, G. Takanashi, Y. Ebina, M. Haga and T. Sasaki, J.
Phys. Chem. C, 2012, 116, 12426-12433.
3
3
3
3
3
4 B. Ohtani, Y. Nohara and R. Abe, Electrochemistry, 2008, 76
47-149.
5 H. Goto, Y. Hanada, T. Ohno and M. Matsumura, J. Catal.,
004, 225, 223-229.
,
1
2
6 D. C. Hurum, A. G. Alexander, G. Agrios and K. A. Gray, J.
Phys. Chem. B, 107, 4545-4549.
7 T. Ohno, K. Sarukawa and M. Matsumura, New J. Chem.,
2
002, 26, 1167-1170.
6
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins