Cooperative dehydrogenation coupling of isopropanol and hydrogenation coupling of acetone over a sodium tantalate photocatalyst

Article abstract of DOI:10.1002/cctc.201400032

Photocatalytic organic syntheses are often limited by their low system efficiency and product selectivity. We demonstrate herein that intermolecular hydrogen transfer from isopropanol to acetone can be achieved efficiently on the surfaces of NaTaO₃ photocatalysts, on which 2-hydroxyisopropyl radicals are produced selectively from both oxidation and reduction half-reactions and then coupled to form 2,3-dimethyl-2,3-butanediol. Such a process effectively increases the total reaction efficiency. We also found that the two half-reactions occur at different crystal facets and display a remarkably promotive interaction, which dramatically speeds up the reactions by one order of magnitude and significantly restrains side reactions. The sodium ions on the NaTaO₃ surfaces play an important role in the promotive effect, likely facilitating the proton transfer between the oxidation and reduction sites. These factors make the production rate of 2,3-dimethyl-2,3- butanediol reach a very high level (10.87 mmol g^-1 h^-1), emphasizing the potential of photocatalytic hydrogenation and dehydrogenation in improving system efficiency of photocatalytic organic syntheses. Double couple: Dehydrogenation coupling of isopropanol and hydrogenation coupling of acetone can be performed simultaneously on a single NaTaO₃ photocatalyst through intermolecular hydrogen transfer and display a remarkable promotive interaction, which speeds the reactions by one order of magnitude and restrains side reactions. CB=conduction band, VB=valence band.

Full text of DOI:10.1002/cctc.201400032

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DOI: 10.1002/cctc.201400032
Cooperative Dehydrogenation Coupling of Isopropanol
and Hydrogenation Coupling of Acetone Over a Sodium
Tantalate Photocatalyst
Baoyue Cao,[a, c] Jian Zhang,[a, c] Jianghong Zhao,[a] Zhijian Wang,[a] Pengju Yang,[a, c]
Hongxia Zhang,[b] Li Li,[a] and Zhenping Zhu*[a]
Photocatalytic organic syntheses are often limited by their low
system efficiency and product selectivity. We demonstrate
herein that intermolecular hydrogen transfer from isopropanol
to acetone can be achieved efficiently on the surfaces of
NaTaO3 photocatalysts, on which 2-hydroxyisopropyl radicals
are produced selectively from both oxidation and reduction
half-reactions and then coupled to form 2,3-dimethyl-2,3-buta-
nediol. Such a process effectively increases the total reaction
efficiency. We also found that the two half-reactions occur at
different crystal facets and display a remarkably promotive
interaction, which dramatically speeds up the reactions by one
order of magnitude and significantly restrains side reactions.
The sodium ions on the NaTaO3 surfaces play an important
role in the promotive effect, likely facilitating the proton trans-
fer between the oxidation and reduction sites. These factors
make the production rate of 2,3-dimethyl-2,3-butanediol reach
a very high level (10.87 mmolgÀ1 hÀ1), emphasizing the poten-
tial of photocatalytic hydrogenation and dehydrogenation in
improving system efficiency of photocatalytic organic
syntheses.
Introduction
In the context of the global concerns on energy and environ-
mental problems, driving chemical reactions with renewable
solar energy has drawn growing attention and is inspired by
the powerful chemical derivation ability of the natural photo-
synthesis.[1] This ambition is also energized by the recent pro-
gresses in the fields of artificial semiconductors or molecular
photocatalysts and selective photocatalytic organic reactions.[2]
Furthermore, photocatalytic organic reactions are usually medi-
ated with neutral radicals, which can readily couple together
to derivate chemicals by the formation of CÀC and CÀN bond-
s.[2a,d,3] A major challenge in the current photocatalysis research
is the low efficiency of light utilization. The current strategies
to address this issue are mainly by modulating or innovating
photocatalysts to adjust the redox potential and to promote
light absorption and the separation of light-excited electron–
hole pairs (eÀ/h+).[4] Although these strategies are quite effec-
tive, it is still necessary to find other ways to further optimize
the efficiencies of photocatalysis systems for sustainable
applications.
Inherently, a photocatalytic reaction consists of two half-re-
actions: hole-induced oxidation and electron-induced reduc-
tion. In the traditional photocatalytic systems, the oxidation or
reduction half-reaction was normally designed alternately as
a target reaction for the generation of desirable products,
whereas the other half-reaction was sacrificed and produced
wastes or even pollutants. Interestingly, Ohtani et al.[5] reported
in 1996 that upon the function of photocatalyst PtÀTiO2, a hy-
drogen transfer can effectively take place from isopropanol to
Schiff bases, leading to the production of acetone and secon-
dary amines. Recently, the groups of Maldotti and Kisch dem-
onstrated a photocatalytic reduction of nitrobenzene into
C6H5N(O)=NC6H5, C6H5N=NC6H5, C6H5NH2, and C6H5N(H)C6H9 in
the presence of cyclohexene, which was simultaneously cou-
pled or oxidized as bicyclohexene, cyclohex-2-en-1-one, and
cyclohex-2-en-1-ol.[6,7] These reports demonstrated the possibil-
ity of simultaneously profiting from both hole-induced oxida-
tion reaction and electron-induced reduction reaction through
a combination between hydrogenation and dehydrogenation
reactions, although such a concept was not mentioned by the
authors. Unlike the traditional photocatalytic organic synthesis,
such a design would double the total efficiency of photocataly-
sis systems, at least, and can shun the arduous processes for
hydrogen transport and storage, which make photocatalytic
organic syntheses more efficient and clean. Further design and
search of new photocatalytic hydrogenation-dehydrogenation
reaction systems and the understanding of the interaction be-
tween the half-reactions are interesting.
[a] B. Cao, J. Zhang, Dr. J. Zhao, Dr. Z. Wang, P. Yang, L. Li, Prof. Z. Zhu
State Key Laboratory of Coal Conversion
Institute of Coal Chemistry
Chinese Academy of Sciences
Taiyuan, 030001 (P.R. China)
Fax: (+86)0351-4048433
E-mail: zpzhu@sxicc.ac.cn
[b] Dr. H. Zhang
Institute of Application Chemistry
Shanxi University
Taiyuan, 030006 (P.R. China)
[c] B. Cao, J. Zhang, P. Yang
University of Chinese Academy of Sciences
Beijing, 100049 (P.R. China)
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/cctc.201400032.
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Herein we report that the dehydrogenation coupling (DHC)
of isopropanol and the hydrogenation coupling (HC) of ace-
tone can be performed synchronously on NaTaO3 photocatalyst
by an intermolecular hydrogen transfer, by which 2-hydroxyiso-
propyl radicals are produced from both the oxidation and re-
duction half-reactions and then coupled as 2,3-dimethyl-2,3-
butanediol (DMB, also called pinacol), as showed in Scheme 1.
More interestingly, the reaction combination leads to a notable
stimulative interaction between the two reactions and dramati-
cally speeds up the reaction rate and improves the reaction
selectivity.
Figure 1. a) SEM image, b) XRD pattern, c) TEM image, and d) HRTEM image
of the NaTaO3 photocatalyst. Inset of (c) is a selected area electron diffrac-
tion pattern taken from the labelled area.
Scheme 1. The combination of isopropanol DHC and acetone HC reactions
on light-excited NaTaO3 surfaces. CB=conduction band, VB=valence band.
Table 1. The photocatalytic data obtained from different reactant
recipes.[a]
Results and Discussion
Entry
Reactant [mol]
Conversion [%]
Selectivity [%]
Alkali tantalate crystals have been well proved to exhibit good
catalytic ability for water splitting under UV irradiation.[8] The
NaTaO3 photocatalyst employed here was produced by a hydro-
thermal Ta2O5–NaOH reaction at 1808C for 24 h, similarly to the
method reported previously.[9] After a water washing treatment
to remove unreacted NaOH and drying at 608C under vacuum,
the photocatalyst was directly used for further characteriza-
tions and photocatalysis tests, without any further treatments.
SEM images reveal that the prepared NaTaO3 photocatalyst ex-
hibits plate and cubic shapes, with sizes up to 220 nm (Fig-
ure 1a). XRD analysis (Figure 1b) indicates that it has a typical
orthorhombic structure, with high crystallization degree. Se-
lected area electron diffraction pattern of the catalyst (inset of
Figure 1c) further confirms the orthorhombic structure of
NaTaO3 and reveals a single crystalline structure. High-resolu-
tion TEM (HRTEM) images also show that the NaTaO3 particles
are well crystallized, with clear lattice fringes corresponding to
the (020) and (301) planes of orthorhombic lattice (Figure 1d).
The UV/Vis absorption spectrum of the NaTaO3 photocatalyst
reveals an electron absorption edge at approximately 310 nm
(Supporting Information, Figure S1), corresponding to a band
gap of 4.0 eV.
Isopropanol Acetone Isopropanol Acetone DMB
HXD
1
2
3
4
5
6
7
0.50
0.00
0.08
0.17
0.25
0.33
0.42
0.00
0.50
0.42
0.33
0.25
0.17
0.08
4.30
0.00
0.00
4.40
74.40
18.22
64.07
90.99
91.25
91.93
92.08
0.00
16.34
27.12
4.17
3.32
2.12
48.95
52.43
53.12
43.90
23.72
33.71
43.75
61.25
55.26
86.60
1.94
[a] Reaction conditions: 1.0 g NaTaO3 photocatalyst, 200 mL total volume
of reactant aqueous solution, 300 W high-pressure Hg lamp (l=365 nm),
Tꢀ258C, t=12 h.
Under the same conditions, acetone preferably display a pho-
tolysis behavior,[11] which releases large amounts of CO and
CH4 gases (Figure S3). Additionally, as indicated by the analyses
of liquid products, acetone can be also converted to DMB and
2,5-hexanedione (HXD), in spite of its low selectivity (entry 2).
The formation of the two compounds likely follows a dispro-
portion CÀC coupling mechanism, as shown in Figure S4, in
which acetone partially undergoes a DHC reaction towards
HXD and partially displays a HC reaction towards DMB. Note
that although both isopropanol and acetone solo reactions
can produce DMB, they exhibit much lower rates of DMB for-
mation, 0.67 and 0.17 mmolgÀ1 hÀ1 for isopropanol and ace-
tone, respectively (Figure 2). Interestingly, if the two solo reac-
tions perform together on the NaTaO3 photocatalyst, the reac-
tant (isopropanol and acetone) conversion and DMB produc-
tion dramatically increase by more than one order of magni-
tude within the same reaction duration (Table 1, Figure 2).
Based on a quantitative evaluation, it is certain that DMB is
produced from both the isopropanol DHC reaction and the
The evaluations of the photocatalytic reactions were per-
formed in an argon-degassed aqueous medium at ambient
temperature, by using a 200 mL-volume photoreactor (Fig-
ure S2). In Table 1, the experimental data obtained from differ-
ent reactant recipes are presented. Isopropanol solo reaction
(entry 1 in Table 1) majorly produces DMB and H2, with less for-
mation of acetone, CH4, CO, and CO2. The formation of DMB is
logically from a one-hole-induced DHC of isopropanol, similar
to the formation suggested over the other photocatalysts.[10]
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propanol (Figure 3a, Table 1). The other factor is the substitu-
tion of H+ with acetone as a more active electron acceptor
(versus isopropanol in the solo reaction), which can be wit-
nessed by the continuous decline of molecular H2 release with
increasing molar fraction of acetone (Figure 3b). These two
factors essentially improve electron injection into valence band
and electron extraction from conduction band and thus play
a synergistic action in blocking eÀ/h+ recombination. In this
sense, the promotive interaction should be an intrinsic conse-
quence of the combined photocatalytic reaction systems.
Furthermore, the combination of the isopropanol DHC reac-
tion and the acetone HC reaction on the single NaTaO3 photo-
catalyst also significantly improves reaction selectivity, because
more than 90% of the converted isopropanol and acetone are
coupled as target DMB (Table 1). This effect links with multiple
functions, which tune well the reaction kinetics and channels.
a) A single-charge (hole or electron) process is required for the
production of DMB from both isopropanol dehydrogenation
and acetone hydrogenation. Although two-charge reactions
occur possibly in the combination process, they would not
affect DMB selectivity because the two-charge reactions form
a product–reactant internal cycle between isopropanol and
acetone. Note that the multihole oxidations of isopropanol
occur rarely over the present NaTaO3 photocatalyst, even for
the isopropanol solo reaction, because only small amounts of
multihole oxidation products such as acetic acid and CO2 were
detected. b) The formation of byproduct HXD, through ace-
tone dehydrogenation at valence band (Figure S4), is kinetical-
ly competitive with the isopropanol DHC reaction in the com-
bination process. As isopropanol is more active than acetone
in electron-donated dehydrogenation, the production of HXD
is greatly restrained in the presence of high-concentration iso-
propanol (Figure 3a, Table 1). c) The HC reaction of acetone ki-
netically competes with its photolysis reaction. In the presence
of isopropanol, the HC reaction is promoted as described
above, whereas the photolysis reaction is obviously restrained,
as indicated by the obviously reduced rate of CH4 release
(Figure 3a).
Figure 2. The DMB production–time functions in different reaction systems.
Conditions: amounts of 0.5 mol acetone or isopropanol for solo reactions;
0.25 mol acetone and 0.25 mol of isopropanol for the combination reaction.
acetone HC reaction. Moreover, the rate of DMB production
highly depends on the molar fraction of the reactants and dis-
plays a volcano-like relationship, with the maximum rate
(10.87 mmolgÀ1 hÀ1) at a molar fraction of 0.5 (Figure 3a), ap-
proximately 16 times of the value for isopropanol solo reaction
and 64 times of the value for acetone solo reaction.
The dehydrogenation–hydrogenation combination reaction
is theoretically mediated by an intermolecular hydrogen trans-
fer from isopropanol to acetone. It can be witnessed by the re-
action episode: the presence of acetone promotes isopropanol
conversion but greatly reduces the rate of H2 release (Fig-
ure 3b). The intermolecular hydrogen transfer seems to pro-
ceed by H+ protons rather than molecular H2 because molecu-
lar H2 has been proved inert for acetone solo reaction under
the employed photocatalytic conditions (Figure S5). Further-
more, as described in Figure S6, acetone should directly cap-
ture H+ protons in the hydrogenation reduction half-reaction,
Figure 3. a) Production rates of DMB, HXD, and CH4 as a function of isopro-
panol molar fraction. b) Effect of molar fraction of acetone on isopropanol
conversion and H2 generation.
These events clearly show that the isopropanol DHC reaction
and acetone HC reaction cannot only occur simultaneously on
a single photocatalyst but also display a good kinetic collabo-
ration and a remarkable promotive interaction. This promotive
interaction can be assigned to the substitution of acetone with
isopropanol as a more active electron donor (versus acetone in
the solo reaction), which can be verified by the obvious de-
crease in HXD formation with increasing molar fraction of iso-
prior to the reaction of H+ protons with electrons into H radi-
C
cals. This reaction implies a kinetic competition between the
H+ capture with acetone and the reduction of H+ into H2. The
competition is further confirmed by probing the effect of plati-
num cocatalyst on reaction scenery. As it is well known, plati-
num exhibits a significant promotion effect on the reduction
of H+ protons to H2,[12] which is also evident in the NaTaO3-cat-
alyzed isopropanol solo reaction (Figure S7). For the combina-
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tion reaction, the platinum loaded on NaTaO3 surfaces obvious-
ly gives a negative effect on acetone conversion and DMB for-
mation because it speeds up the competitive H+-to-H2 reac-
tion (Figure 4). Notably, in the combination reaction over bare
NaTaO3, the rates of acetone and isopropanol conversions
(12.76 and 11.06 mmolgÀ1 hÀ1, respectively) are approximately
three orders of magnitude higher than the H2 release rate
(0.012 mmolgÀ1 hÀ1), implying a high reactivity of acetone in
H+ capture and a quick intermolecular hydrogen transfer from
isopropanol to acetone.
Figure 5. a) A typical SEM image and b, c) TEM images, which reveal that
one facet of the NaTaO3 plate is occupied with platinum particles (arrowed
objects) and the other facet is free. d) Magnification of the region labeled in
part c, displaying a platinum particle loaded on the (220) plane of the
NaTaO3 crystal.
Figure 4. Platinum loaded over NaTaO3 promotes H2 generation but restrains
acetone conversion and DMB formation. Conditions: amounts of 0.25 mol
acetone and 0.25 mol isopropanol.
(Figure 5a and S9), the platinum nanoparticles are selectively
deposited on certain planes of the NaTaO3 crystals, whereas
other planes are totally free of them. Such a phenomenon can
be seen from TEM images more clearly (Figure 5b,c, S10).
HRTEM images (Figure 5d, S10) further reveal that platinum is
mainly located on the (220) and (020) facets. These observa-
tions provide additional support for the conjecture that the
DHC reaction and HC reaction take place on different facets of
NaTaO3 crystals.
We also performed both ethanol DHC and acetone HC reac-
tions over NaTaO3, from which 2,3-butanediol and DMB are
produced as expected (Table S1), reflecting the generality of
the DHC–HC combination reaction. It is also interesting that
the hydroxyethyl and 2-hydroxyisopropyl radicals, formed from
ethanol dehydrogenation and acetone hydrogenation, respec-
tively (Figure S8), seem to preferably undergo self-coupling
rather than cross-coupling, as indicated by the less pro-
nounced formation of cross-coupling product, 2-methyl-2,3-bu-
tanediol (Table S1). A similar situation is also evident for the
acetone solo reaction, in which the formed acetonyl and 2-hy-
droxyisopropyl radicals rarely undergo a cross-coupling reac-
tion to produce 4-methyl-4-hydroxy-2-pentanone (Figure S3).
These events can be well explained by the recent observations
that electron-induced reduction and hole-induced oxidation
occur on different planes of semiconductor photocatalyst crys-
tals.[13] On the present NaTaO3 photocatalyst with regular plate
or cubic shape (Figure 1a), it is possible that the dehydrogena-
tion and hydrogenation sites are isolated from each other,
which leads to a small probabili-
Additionally, the efficient combination reaction must be
mediated by a fast H+ transfer from dehydrogenation facets to
hydrogenation facets and implies the existence of H+ express
channels on the NaTaO3 surfaces, although an H+ transfer by
liquid phase diffusion is also possible. On the NaTaO3 surfaces,
the NaÀOÀTa species might construct the channel to convey
H+ by ion exchange with Na+ ions (Scheme 2). This guess is
also supported by the following experimental observations.
The rate of DMB formation declines strongly upon a surface
exchange of Na+ ions with HCl and nearly recovers upon a re-
exchange with NaOH (Figure 6a). As measured by X-ray photo-
ty of radical cross-coupling. This
conjecture is supported by the
microscopic observations on the
Pt/NaTaO3 photocatalyst ob-
tained from an in situ 12 h re-
duction of H2PtCl6 in the isopro-
panol–acetone reaction system.
As observed by SEM images of
the Pt/NaTaO3 photocatalyst Scheme 2. Conveying H+ on the surface of NaTaO3 by Na+/H+ ion exchange.
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and acetone is more efficient both in reaction rate and product
selectivity.
Conclusions
We have demonstrated that a hole-induced isopropanol dehy-
drogenation coupling and an electron-induced acetone hydro-
genation coupling can harmoniously perform on a single
NaTaO3 photocatalyst, mediated by a single hydrogen transfer,
by which 2,3-dimethyl-2,3-butanediol (DMB) forms as the only
stoichiometric product. In this combination reaction, both pho-
togenerated electrons and holes are profited from, and all of
the atoms involved in the reactants move into products, ex-
pressing an atom- and energy-economic process. Furthermore,
we found that the two reactions occur on the different facets
of NaTaO3 crystals and exhibit a dramatic promotive interac-
tion, which speeds the reactions by one order of magnitude
and notably restrains side reactions. These effects enable DMB
to be selectively produced at a high rate (10.87 mmolgÀ1 hÀ1),
reaching the commercialization requirement as preliminarily
evaluated. This result not only provides an efficient and green
approach for DMB synthesis but also demonstrates another
paradigm of combining photocatalytic hydrogenation and de-
hydrogenation reactions for the improvement of light utiliza-
tion efficiency.
Figure 6. Effect of surface Na+ ions on DMB formation. a) Response of DMB
formation to an exchange of Na+ ions on NaTaO3 surfaces with HCl and to
a subsequent re-exchange with NaOH. b) Correlation between DMB forma-
tion rate and Na+ ion concentration on the surface of the NaTaO3 photoca-
talysts, which were prepared from different NaOH concentrations.
Experimental Section
electron spectroscopy, the NaTaO3 photocatalysts prepared
from different NaOH concentrations exhibit different concen-
trations of surface Na+ ion (Figure S11, Table S2). The DMB for-
mation rates over these photocatalysts clearly exhibit a positive
correlation with surface Na+ ion concentration (Figure 6b), al-
though all of the catalysts tested display the same crystalline
structure (Figure S12). These observations indicate an impor-
tant role of surface Na+ ions in the combination reaction,
likely associated with a fast exchange and travel of H+ ions on
surface NaÀOÀTa species caused by the ionization nature of
NaÀOÀTa species. This assignment also agrees with the fact
that KTaO3, like NaTaO3, is much more active than Ta2O5
(Table S3).
Preparation of NaTaO3 photocatalysts
As-purchased analytically pure Ta2O5 and NaOH were employed for
the hydrothermal synthesis of NaTaO3 photocatalysts, similarly to
the method reported elsewhere.[9] In a typical synthesis procedure,
Ta2O5 (4.42 g) was mixed with NaOH aqueous solution (30 mL) of
the desired concentration and stirred at RT for 2 h. The mixture
was then filled into a Teflon reactor (50 mL) that was fitted in
a sealed stainless steel autoclave. The autoclave was heated up to
1808C and kept at the temperature for 24 h for a full reaction.
After the reaction, the autoclave was cooled to RT in air, and the
resulted solid products were collected by centrifugation and
washed with deionized water and ethanol thoroughly to remove
unreacted NaOH, and finally dried at 808C for 12 h. The procedure
for the synthesis of KTaO3 photocatalysts was similar to that of
NaTaO3. The deposition of Pt on the NaTaO3 surfaces was per-
formed in situ by the photoreduction method similar to the previ-
ous reports.[14] Shortly, hexachloroplatinic acid (H2PtCl6·6H2O) 1m
aqueous solution (0.02 mL) was added into isopropanol–acetone
aqueous solution (200 mL, amounts of both reactants were
0.25 mol) dispersed with NaTaO3 photocatalyst (1.0 g). The resulted
solution was irradiated with a 300 W Hg lamp in argon atmosphere
for 12 h to allow reduction of H2PtCl6 into platinum nanoparticles,
which deposited on NaTaO3 surfaces.
As described above, the unique structural characteristics of
NaTaO3 photocatalysts give their excellent performance in the
DHC–HC combination reaction of isopropanol and acetone. We
have also tested the performances of the TiO2 photocatalysts
with different phase structures such as commercial TiO2 (P25,
Degussa) and rutile TiO2. The P25 photocatalyst exhibited very
high activity if noble-metal cocatalysts were loaded on its sur-
faces, but it showed a poor selectivity for DMB formation, with
a majority of isopropanol overoxidized into CO2, similarly to
the situation reported for the photocatalytic hydrogen genera-
tion from alcohol aqueous solution.[15] Although rutile TiO2 has
a relatively high selectivity, it exhibited a strongly decreased
activity. Indeed, photocatalytic pinacol couplings of alcohols or
aryl aldehydes were previously reported, by using conjugated
polymers[16] and ZnS.[10b] Comparatively, the present NaTaO3
photocatalytic DHC–HC combination reaction of isopropanol
Characterization of NaTaO3 photocatalysts
The morphologies of the NaTaO3 photocatalysts were observed by
field-emission scanning electron microcopy on a JSM-7001F, JEOL,
operated at 10.0 kV. Catalyst structures were analyzed by TEM on
a JEM-2010F, JEOL, equipped with an electron diffractometer, oper-
ated at 200 kV. For the TEM analyses, the samples were ultrasoni-
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Photocatalytic experiments were performed by using an inner-irra-
diation-type Pyrex reactor (250 mL) equipped with a 300 W high-
pressure Hg lamp, as shown in Figure S2. The lamp was cooled
with water to keep the reactions proceeding at RT (ꢀ258C). All
the photocatalytic tests were performed in aqueous solutions
(200 mL) of the reactants with desired concentrations, by using
photocatalyst amounts of 1.0 g. The reactions were performed in
argon atmosphere (10 mLminÀ1) and the reaction solution was
magnetically stirred to fully disperse the catalysts. Liquid samples
were analyzed by a gas chromatograph (Haixin; GC-950) equipped
with a flame ionization detector. Gaseous samples were analyzed
with a gas chromatograph (Fuli; GC-9790) equipped with a thermal
conductivity detector, a flame ionization detector, and a methane
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Acknowledgements
This work was supported by the National Natural Science Foun-
dation of China (No. 21173250) and Chinese Academy of Scien-
ces, following the Solar Energy Plan Project (No. KGCX2.EW.311).
Keywords: cooperative
hydrogenation · photochemistry · tantalum
effects
·
dehydrogenation
·
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Received: January 13, 2014
Published online on && &&, 0000
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ChemCatChem 0000, 00, 1 – 7
&
6
&
ÞÞ
These are not the final page numbers!

FULL PAPERS
Double couple: Dehydrogenation cou-
pling of isopropanol and hydrogenation
coupling of acetone can be performed
simultaneously on a single NaTaO3 pho-
tocatalyst through intermolecular hy-
drogen transfer and display a remarkable
promotive interaction, which speeds the
reactions by one order of magnitude
and restrains side reactions. CB=con-
duction band, VB=valence band.
B. Cao, J. Zhang, J. Zhao, Z. Wang,
P. Yang, H. Zhang, L. Li, Z. Zhu*
&& – &&
Cooperative Dehydrogenation
Coupling of Isopropanol and
Hydrogenation Coupling of Acetone
Over a Sodium Tantalate
Photocatalyst
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 0000, 00, 1 – 7
&
7
&
ÞÞ
These are not the final page numbers!