Photocatalytic aerobic oxidation of toluene and its derivatives to aldehydes on Pd/Bi2WO6

Article abstract of DOI:10.1016/S1872-2067(17)62757-8

The selective oxidation of toluene and its derivatives is extremely important in the chemical industry. The use of photocatalysis in organic synthesis has attracted considerable attention among synthetic chemists because of its “green” environmental characteristics. In this study, nanoscale Bi₂WO₆ with a flower-like morphology was found to be a highly efficient photocatalyst in the catalytic oxidation of toluene and its derivatives using O₂ as the oxidant. The loading of Pd nanoparticles as a cocatalyst onto the flower-like Bi₂WO₆ was found to produce a significant enhancement in the catalytic activity. Mechanistic investigation showed that the superior performance of Pd/Bi₂WO₆ could be attributed to the improvement of both the reductive and oxidative abilities of Bi₂WO₆ by the loading of the cocatalyst.

Full text of DOI:10.1016/S1872-2067(17)62757-8

Chinese Journal of Catalysis 38 (2017) 440–446
a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h n j c
Article (Special Column on Novel Catalysts for Energy and Environmental Issues)
Photocatalytic aerobic oxidation of toluene and its derivatives to
aldehydes on Pd/Bi2WO6
Bo Yuana,b, Bao Zhanga,b, Zhiliang Wanga,b, Shengmei Lua, Jun Lia, Yan Liua,*, Can Lia,#
a State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
b University of Chinese Academy of Sciences, Beijing 100049, China
A R T I C L E I N F O
A B S T R A C T
Article history:
The selective oxidation of toluene and its derivatives is extremely important in the chemical indus‐
try. The use of photocatalysis in organic synthesis has attracted considerable attention among syn‐
thetic chemists because of its “green” environmental characteristics. In this study, nanoscale Bi2WO6
with a flower‐like morphology was found to be a highly efficient photocatalyst in the catalytic oxida‐
tion of toluene and its derivatives using O2 as the oxidant. The loading of Pd nanoparticles as a co‐
catalyst onto the flower‐like Bi2WO6 was found to produce a significant enhancement in the catalytic
activity. Mechanistic investigation showed that the superior performance of Pd/Bi2WO6 could be
attributed to the improvement of both the reductive and oxidative abilities of Bi2WO6 by the loading
of the cocatalyst.
Received 27 October 2016
Accepted 20 November 2016
Published 5 March 2017
Keywords:
Flower‐like Bi2WO6
Toluene oxidation
Benzaldehyde
Cocatalyst
Palladium nanoparticle
© 2017, Dalian Institute of Chemical Physics, Chinese Academy of Sciences.
Published by Elsevier B.V. All rights reserved.
1. Introduction
extremely important in the chemical industry, because the
oxidized products are commercially versatile intermediates in
The use of heterogeneous photocatalysis for organic
synthesis has attracted considerable attention among synthetic
chemists because of its “green” environmental characteristics
[1‒4]. The development of new catalytic systems with high
efficiency has been the subject of numerous studies [5‒8].
Metal oxides [9‒18], plasmonic photocatalysts [19‒29] and
polymeric graphitic carbon nitride [30‒33] have been
demonstrated to be efficient heterogeneous photocatalysts in
certain valuable selective redox organic transformations. De‐
spite the significant progress made so far, the development of
new strategies to discover additional heterogeneous
photocatalysts for challenging organic transformations remains
an important goal.
the manufacture of pharmaceuticals, dyestuffs, preservatives,
perfumes, plasticizers and flame retardants [34]. Industrial
processes for the selective oxidation of toluene rely on metal
catalysts under harsh conditions, including high temperature,
high oxygen pressure and the use of acid as the solvent [35].
Recently, heterogeneous photocatalysis was demonstrated to
be an efficient way to realize the oxidation of toluene and its
derivatives under very mild conditions [36,37]. In 2012, Yuan
et al. [38] applied surface‐chlorinated BiOBr/TiO2 as the
photocatalyst in the selective oxidation of toluene, achieving
the highest reactivity reported to date. The group of Xu
[39,40] reported that cubic‐phase CdS could achieve the
oxidation of toluene and its derivatives with high activity and
The selective oxidation of toluene and its derivatives is
selectivity as a visible‐light‐driven photocatalyst, using
* Corresponding author. Tel: +86‐411‐84379302; Fax: +86‐411‐84694447; E‐mail: yanliu503@dicp.ac.cn
# Corresponding author. Tel: +86‐411‐84379070; Fax: +86‐411‐84694447; E‐mail: canli@dicp.ac.cn
This work was supported by the National Natural Science Foundation of China (21322202, 21472187) and the National Basic Research Program of
China (2010CB833300).
DOI: 10.1016/S1872‐2067(17)62757‐8 | http://www.sciencedirect.com/science/journal/18722067 | Chin. J. Catal., Vol. 38, No. 3, March 2017

Bo Yuan et al. / Chinese Journal of Catalysis 38 (2017) 440–446
441
molecular oxygen as the oxidant. Recently, Yin’s group [41]
found that the use of Bi2WO6 as a photocatalyst allowed the
conversion of saturated C‒H bonds into aldehydes. In spite of
these notable achievements, however, industry still requires
the development of a stable, non‐toxic and more efficient
photocatalyst for this important transformation.
Very recently, our group has found BiVO4 to be an efficient
photocatalyst under visible‐light irradiation for the selective
oxidation of amines to imines [42]. Subsequently, we described
the first colloidal synthesis of single‐crystalline, ultrathin
nanosheets of BiOCl with strong absorption in the visible range,
which displayed higher reactivity in the selective oxidation of
amines than previously reported catalytic systems [43]. As part
of our ongoing interest in developing more efficient Bi‐based
heterogeneous photocatalysts for organic transformations, we
found that a flower‐like morphology of Bi2WO6 loaded with 0.1
wt% Pd could dramatically increase the activity of toluene oxi‐
dation. In this paper, we report the detailed optimization of the
conditions for this reaction, the substrate scope and the results
of control experiments to elucidate the reaction mechanism.
Ultraviolet–visible (UV‐vis) diffuse reflectance spectra were
collected on a JASCO V‐550 spectrometer. X‐ray diffraction
(XRD) patterns of these samples were obtained at room
temperature on an X‐ray diffractometer (Rigaku) using Cu Kα
as the X‐ray radiation source at 40 kV and 30 mA. Scanning
electron microscopy (SEM) images were taken on a Quanta 200
FEG scanning electron microscope. N2 adsorption‐desorption
isotherms to quantify the Brunauer‐Emmett‐Teller (BET) sur‐
face areas were measured at −196 °C using a Micromeritics
ASAP 2000 analyzer.
2.3. Electrochemical measurements
Photoelectrochemical measurements were conducted in a
three‐electrode quartz cell using a CH Instruments 760D
potentiostat. A Pt plate was used as the counter electrode, and
saturated calomel electrode (SCE) was used as the reference
electrode, while the working electrode was prepared on
fluoride–tin oxide (FTO) conductor glass. The sample powder
(50 mg) was ground with water and triton X‐100 to obtain an
even slurry. The slurry was spread onto FTO glass. The working
electrode was dried in the oven at 550 °C for 1 h. The
electrolyte was a saturated aqueous solution of K2SO4. The light
irradiation source was a 300 W Xe arc lamp system with a
current of 20 A, and the light was directed through the conduc‐
tor glass to the interface of the substrate and the catalyst.
2. Experimental
2.1. Catalyst preparation
The procedures for the synthesis of Bi2WO6 in the present
work were based on a hydrothermal approach as described
previously [44]. In a typical procedure, 0.98 g (2 mmol) of
Bi(NO3)3·5H2O was ultrasonicated in 30 mL of an HNO3 solution
with a pH value of 5.61, 3.33, 2.75, or 0.49 until complete dis‐
solution; the resulting solutions were denoted Bi2WO6‐1, 2, 3, 4,
respectively. Separately, 0.33 g (1 mmol) of Na2WO4·2H2O was
dissolved in 30 mL of water. Then, the solution of Na2WO4 was
added dropwise into the above solution with vigorous stirring,
and a white precipitate was formed. After another 24 h
vigorous stirring, the mixture was transferred into a 100 mL
Telfon‐sealed autoclave, which was heated at 160 °C for 12 h in
the oven and cooled naturally to room temperature. The
resulting solid powder was obtained by filtration, washed with
deionized water to remove the residual ions and dried at 60 °C
in the oven for further use.
2.4. Evaluation of photocatalytic activity
The photocatalytic reactions were carried out under
irradiation by a 300 W Xe lamp with continuous stirring in a 15
mL Pyrex glass bottle (light with wavelengths below 400 nm
was excluded using 1 mol/L NaNO2 solution as a filter). The
Pyrex glass bottle was sealed with a glass stopper, connected to
an O2 balloon and surrounded with water to maintain the
temperature between 14 and 17 °C. A typical reaction system
contained 1 mL substrate and 50 mg Bi2WO6 with a stirring bar.
The products were analyzed by GC and characterized using
standard samples and GC‐MS.
3. Results and discussion
Photodeposition was used to load the Pd cocatalyst onto the
Bi2WO6. 861 μL PdCl2 aqueous solution (0.581 mg (Pd)/mL)
and 500 mg Bi2WO6 were added to a mixture of 50 mL H2O and
25 mL CH3OH. After stirring under Ar flow to extract the air, the
suspension was irradiated by a 300 W Xe lamp under Ar
atmosphere for 1 h. The Pd‐loaded Bi2WO6 was recovered by
filtration, washed with water and dried at 60 °C in the oven.
The as‐obtained powder was used for characterization of the
product and testing of its catalytic activity.
3.1. Catalyst preparation and characterization
The XRD patterns of the Bi2WO6‐1,2,3,4 samples are shown
in Fig. 1. The predominant phase of Bi2WO6 detected in the
prepared samples was orthorhombic (JCPDS 73‐2020), with
(113) as the preferred orientation, along with (006), (200),
(020), (206), (026), (220), (018), (119), (313), (208), (226) and
(0110) reflections. No other likely impurities, such as Bi2O3 or
WO3, were detected. The XRD data reveal that the structure of
Bi2WO6 was unaffected by changing the pH during synthesis.
SEM images of the samples are presented in Fig. 2. Their
morphologies were strongly dependent on the pH values. Fig.
2(b)‒(d) shows that the products consisted of a large quantity
of nanoplates. Fig. 2(a) shows an SEM micrograph of the
Bi2WO6 sample prepared at pH 0.49, which was evidently
2.2. Characterization
All reagents and solvents were obtained commercially and
toluene was distilled prior to use. Gas chromatography (GC)
measurements were made with a GC7890 equipped with an
FID detector and β‐DEX 225 column, using Ar as the carrier gas.

442
Bo Yuan et al. / Chinese Journal of Catalysis 38 (2017) 440–446
Table 1
Oxidation of toluene over various photocatalysts.
Bi2WO6-1
Bi2WO6-2
Bi2WO6-3
SBET
(m2/g)
—
11
14
Conversion
(%) a
trace
0.42
2a
(μmol/g/h)
—
Selectivity of
Entry
Catalyst
2a (%) a
—
1
2
3
4
5
None
Bi2WO6‐1
Bi2WO6‐2
Bi2WO6‐3
Bi2WO6‐4
140
252
320
500
90
88
87
92
0.76
0.99
1.47
Bi2WO6-4
19
35
Reaction conditions: λ > 400 nm, catalyst 50 mg, toluene 1 mL,
irradiation time: 5 h, oxygen balloon 1 atm.
a Determined by gas chromatography.
JCPDS 73-2020
40 50 60
10
20
30
70
80
2(o )
Fig. 1. XRD patterns of different Bi2WO6 samples.
transition rather than transitions from impurity levels.
We performed the model reaction in the absence of an or‐
ganic solvent, because solvent‐free conditions are environ‐
mentally friendly and simplify the separation of the desired
product from the reaction system. The photocatalytic activity
and selectivity of toluene oxidation over the various Bi2WO6
catalysts are summarized in Table 1. Bi2WO6‐1, which was
prepared in the least acidic environment, proved able to cata‐
lyze the model reaction, providing benzaldehyde with 0.42%
conversion and 90% selectivity. Several previous studies have
shown that the crystallinity and specific surface area of Bi2WO6,
which can be controlled by the pH value during its hydrother‐
mal preparation [45,46], strongly influence its catalytic activity
in the photocatalytic degradation of contaminants [47]. Thus,
four samples of Bi2WO6, namely, Bi2WO6‐1, Bi2WO6‐2, Bi2WO6‐3
and Bi2WO6‐4, were prepared at different pH values and ap‐
plied in the photocatalytic oxidation of toluene to compare
their effectiveness. However, the flower‐like Bi2WO6‐4 (Fig.
3(a)), which was prepared in the most acidic environment
(with a pH value of 0.49), achieved both the highest activity
(producing benzaldehyde at a rate of 500 μmol/g/h) and the
highest selectivity (Table 1, entry 5).
(a)
(b)
(d)
(c)
Fig. 2. SEM images of Bi2WO6‐4 (a), Bi2WO6‐3 (b), Bi2WO6‐2 (c),
Bi2WO6‐1 (d).
In sharp contrast, the samples Bi2WO6‐1–3 (Fig. 3(b)–(d)),
with sheet‐like morphologies, supplied benzaldehyde at lower
formed of aggregated nanoplates and possessed
a
well‐dispersed flower‐like structure. These nanoplates were
aligned to the spherical surface at a specific angle with clearly
oriented layers. More importantly, abundant pores with vary‐
ing diameters were formed, which may serve as transport
channels for small molecules. From Table 1 it can be seen that
the Bi2WO6‐4 sample (Fig. 2(a)) had a much larger surface area
than the other three samples.
Bi2WO6-4
Bi2WO6-3
Bi2WO6-2
Bi2WO6-1
The optical absorption of the Bi2WO6 samples was
measured using a UV‐vis spectrometer. Fig. 3 shows diffuse
reflectance spectra of Bi2WO6‐1, 2, 3, 4. The optical absorption
properties of Bi2WO6‐1, 2, 3 were nearly identical. The spectra
show that the Bi2WO6 samples displayed photoabsorption from
the ultraviolet region to visible light as far as wavelengths up to
450 nm. All of the samples were light yellow in color. Each
spectrum features an intense absorption band with a steep
edge in the visible‐light region. These indicate that the
visible‐light absorption corresponded to the band gap
250 300 350 400 450 500 550 600 650 700 750 800
Wavelength (nm)
Fig. 3. UV‐vis spectra of different Bi2WO6 samples.

Bo Yuan et al. / Chinese Journal of Catalysis 38 (2017) 440–446
443
reaction rates (Table 1, entries 2–4). By careful investigation of
the XRD patterns (Fig. 1), UV‐vis spectra (Fig. 3) and BET sur‐
face areas (Table 1) of Bi2WO6‐1–4, the higher activity of
Bi2WO6‐4 can be attributed to its larger BET surface area (35
m2/g), which is about 3 times that of Bi2WO6‐1 (11 m2/g).
tion [51]. It should be noted that, with a reaction rate of 1140
μmol/g/h, the catalytic activity of Pd/Bi2WO6‐4 for the oxida‐
tion of toluene was superior to that observed for any previous‐
ly reported photocatalytic system [52]. Further screening of the
amount of Pd loading (Table 2, entries 5–7) showed that,
among the four values compared, 0.1 wt% Pd on Bi2WO6‐4 was
the optimal cocatalyst loading in terms of reactivity and selec‐
tivity.
3.2. Effect of cocatalyst
In previous studies of photocatalytic water‐splitting and the
decomposition of environmental organic contaminants, the
loading of a cocatalyst onto a semiconductor photocatalyst has
been shown to be an effective means to enhance the photo‐
catalytic performance by improving the charge separation effi‐
ciency [48]. However, this strategy has seldom been utilized to
prepare photocatalysts for use in synthetic chemistry. Bi2WO6
has a sufficiently positive valence band level (+2.94 V) for tol‐
uene oxidation [49,50]. However, its positive conduction band
(+0.24 V) hinders the efficient consumption of photoexcited
electrons. Therefore, to further improve the reactivity of
Bi2WO6, the loading of reductive cocatalysts onto its surface
was explored.
3.3. Oxidation products of toluene derivatives
The photocatalytic oxidation of various substituted toluenes
was performed in the presence of Pd/Bi2WO6‐4 and O2 (Table
3). Oxidation of these toluenes proceeded efficiently to provide
the corresponding substituted benzaldehydes with 85–95%
selectivities and excellent functional group tolerance of both
electron‐donating and electron‐withdrawing groups (2a–2f).
Moreover, o‐, m‐ and p‐xylene were selectively oxidized to the
corresponding monoaldehydes, and no dialdehydes were de‐
tected at all.
Metal‐nanoparticle‐loaded Bi2WO6 samples (M‐Bi2WO6‐4)
were prepared by photodeposition from metal precursors onto
the as‐prepared Bi2WO6 under visible‐light irradiation in a
mixture of CH3OH and H2O. To ensure that the intrinsic effects
of the cocatalysts were measured, each cocatalyst was depos‐
ited at the ultra‐low loading of 0.1 wt%. The photocatalytic
activity of each M‐Bi2WO6‐4 in the model reaction was assessed
and the results are listed in Table 2. Compared with neat
Bi2WO6‐4, the Bi2WO6‐4 loaded with Ni nanoparticles showed
lower reactivity (Table 2, entry 2). The introduction of Pt as the
cocatalyst led to a slight increase in reactivity, with 89% selec‐
tivity for the photocatalytic oxidation of toluene (Table 2, entry
3). Pd nanoparticles proved to be the most effective cocatalyst
in this reaction system, affording benzaldehyde with 3.42%
conversion and 90% selectivity (Table 2, entry 4). Although the
loading of nanoparticles on the Bi2WO6 samples may have
blocked part of the active site, the higher charge separation
efficiency and enhanced reduction reaction made Pd/Bi2WO6 a
more effective catalyst than neat Bi2WO6 for toluene oxida‐
3.4. Recyclability of photocatalyst
Recycling experiments were carried out to evaluate the sta‐
bility of Pd/Bi2WO6‐4 as a catalyst for toluene oxidation under
visible‐light irradiation. After 5 h of photocatalytic toluene oxi‐
dation, the photocatalyst was separated from the reaction solu‐
tion, washed with deionized water and dried in the oven for 12
h. As seen in Fig. 4, the solid catalyst retained almost all of its
activity and selectivity through up to seven cycles of this pro‐
cess. XRD (Fig. 5) and SEM (Fig. 6) measurements were per‐
Table 3
Oxidation products of toluene and its derivatives.
O
H
X
X
Pd/ Bi2WO6-4
O2
+ H2O
+
> 400 nm
5 h
1a
2
1 mL
Balloon
Yield
(μmol/g/h)
948
Reactant
Product
Selectivity (%)
90
O
H
Table 2
2b
Effect of cocatalysts in the photocatalytic oxidation of toluene.
642
306
90
86
O
H
2c
O
H
Metal load‐ Conversion a Yield of 2a Selectivity
2d
Entry
Catalyst
ing (wt%)
—
(%)
1.47
0.99
1.52
3.42
1.17
2.31
1.66
(μmol/g/h) of 2aa (%)
O
H
432
724
85
95
MeO
Cl
MeO
Cl
1
2
3
4
5
6
7
Bi2WO6‐4
500
337
517
1140
380
740
580
92
92
89
90
88
86
94
Ni/ Bi2WO6‐4
Pt/ Bi2WO6‐4
Pd/ Bi2WO6‐4
Pd/ Bi2WO6‐4
Pd/ Bi2WO6‐4
Pd/ Bi2WO6‐4
0.1
0.1
0.1
2e
O
H
0.001
0.01
0.3
2f
Reaction conditions: λ > 400 nm, Pd/Bi2WO6‐4 50 mg, toluene 1 mL,
irradiation time: 5 h, oxygen balloon 1 atm, loading of metal on Bi2WO6:
0.1 wt%; Conversions and selectivities determined by gas chromatog‐
raphy.
Reaction conditions: λ > 400 nm, catalyst 50 mg, toluene 1mL, irradia‐
tion time: 5 h, oxygen balloon 1 atm.
a Determined by gas chromatography.

444
Bo Yuan et al. / Chinese Journal of Catalysis 38 (2017) 440–446
Table 4
Activity
Selectivity
1800
1600
1400
1200
1000
800
600
400
200
0
112.5
100.0
87.5
75.0
62.5
50.0
37.5
25.0
12.5
0.0
Results of the controlled experiments.
Conversion Al selectivity
Al activity
(μmol/g/h)
Time
(h)
Additive
(%)
(%)
None
AgNO3 (no O2)
AO
2
0.5
2
0.93
0.04
0.07
93
—
—
300
12
24
added, the oxidation reaction was terminated, indicating that
the photocatalytic oxidation was driven by photogenerated
holes. A similar cessation of activity was observed when AgNO3,
an electron‐trapping species, was added, which suggests that
the activation of O2 by electrons was also involved in the reac‐
tion system. These results clearly show that both photogener‐
ated electrons and holes played important roles in this reac‐
tion.
1
2
3
4
5
6
7
Times
Fig. 4. Recycling experiment of Pd/Bi2WO6‐4.
A photo‐electron experiment was conducted to elucidate the
effect of cocatalyst loading on the Bi2WO6 material. As seen in
Fig. 7, when a bias of −0.2 V was applied to the catalysts, the
Bi2WO6 by itself, with no cocatalyst, showed no photocurrent
response, because its conduction band is not negative enough.
In contrast, the Bi2WO6 catalysts loaded with Pt or Pd nanopar‐
ticles both responded with similar reductive currents, indicat‐
ing that both Pt and Pd as cocatalysts were able to promote the
reductive ability of Bi2WO6. Interestingly, when a bias of +1 V
was applied to the catalysts, the Bi2WO6 loaded with Pd, Pt, and
Ni responded with a stronger oxidative current than Bi2WO6
which suggests that the cocatalysts were also beneficial for the
oxidation reaction. Pd/Bi2WO6 promoted a stronger oxidative
current than Pt/Bi2WO6 and Ni/Bi2WO6, which is in accord with
its activity in the photocatalytic oxidation of toluene.
(2)
(1)
10
20
30
40
2/(o )
50
60
70
80
Fig. 5. XRD patterns of Pd/Bi2WO6‐4 before (1) and after (2) one reac‐
tion cycle.
(a)
(b)
Based on the above results, we propose a possible reaction
mechanism, as shown in Fig. 8. Under visible‐light irradiation,
electron–hole pairs are generated in Pd/Bi2WO6. The toluene
adsorbed on the surface of the catalyst is oxidized to the corre‐
sponding cationic radicals by the positive holes. Meanwhile, O2
Bi2WO6
Bi2WO6
-0.2 V
+1.0 V
Ni/ Bi2WO6 -0.2 V
Ni/ Bi2WO6 +1.0 V
Pt/ Bi2WO6 -0.2 V
Pt/ Bi2WO6 +1.0 V
Pd/ Bi2WO6 -0.2 V
Pd/ Bi2WO6 +1.0 V
Fig. 6. SEM images of Pd/Bi2WO6. (a) Before reaction; (b) After one
reaction cycle.
6
4
On
Off
formed to discern the crystal structure and morphology of
Pd/Bi2WO6‐4 after being used as a photocatalyst. The XRD pat‐
terns revealed that the crystal structure of Pd/Bi2WO6‐4 re‐
mained completely unchanged, with no detectable impurity
phase, after one cycle. The TEM images confirmed that the
flower shape of Pd/Bi2WO6‐4 was also retained. These results
clearly demonstrate that Pd/Bi2WO6‐4 exhibits excellent stabil‐
ity.
2
0
-2
-4
Off
20
On
3.5. Mechanistic investigation of the reaction
40
60
Time (s)
80
100
To further investigate the mechanism of photocatalytic tol‐
uene oxidation over the Bi2WO6 photocatalyst, controlled ex‐
periments were performed (Table 4). When ammonium oxalate
(AO), a radical species that acts as a scavenger of holes, was
Fig. 7. Photocurrent transient response of the as‐prepared Bi2WO6,
Ni/Bi2WO6, Pt/Bi2WO6 and Pd/Bi2WO6 samples in a Na2SO4 aqueous
solution (0.5 mol/L) with bias −0.2 and +1 V versus SCE.

Bo Yuan et al. / Chinese Journal of Catalysis 38 (2017) 440–446
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446
Bo Yuan et al. / Chinese Journal of Catalysis 38 (2017) 440–446
Graphical Abstract
Chin. J. Catal., 2017, 38: 440–446 doi: 10.1016/S1872‐2067(17)62757‐8
Photocatalytic aerobic oxidation of toluene and its
derivatives to aldehydes on Pd/Bi2WO6
Bo Yuan, Bao Zhang, Zhiliang Wang, Shengmei Lu, Jun Li,
Yan Liu*, Can Li*
Dalian Institute of Chemical Physics, Chinese Academy of
Sciences; University of Chinese Academy of Sciences
Flower‐like Bi2WO6 loaded with Pd nanoparticles as cocatalyst is
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μmol/g/h, 96%, Ref. [41]); Niobium hydroxide grafted with ben‐
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