Hexagonal microspindle of NH2-MIL-101(Fe) metal-organic frameworks with visible-light-induced photocatalytic activity for the degradation of toluene

Article abstract of DOI:10.1039/c5ra23154j

This work focuses on exploring metal-organic frameworks (MOFs) for degradation of gaseous pollutants. We demonstrate that NH₂-MIL-101(Fe) hexagonal micro-spindles, as a new photocatalyst, showed an improved performance for degradation of toluene under visible light irradiation. The structural and optical properties of the as-prepared NH₂-MIL-101(Fe) hexagonal micro-spindles were characterized. Furthermore, the catalytic reaction mechanism has been investigated on the basis of in situ Fourier Transform infrared spectroscopy (FTIR) technology. Meanwhile, some intermediates (benzoic acid) and the final product (CO₂) of the degradation of toluene were also identified.

Full text of DOI:10.1039/c5ra23154j

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Hexagonal microspindle of NH2-MIL-101(Fe)
metal–organic frameworks with visible-light-
induced photocatalytic activity for the degradation
of toluene†
Cite this: RSC Adv., 2016, 6, 4289
a
a
a
c
Zhiguang Zhang,ab Xinyong Li, Baojun Liu, Qidong Zhao and Guohua Chen
*
*
This work focuses on exploring metal–organic frameworks (MOFs) for degradation of gaseous pollutants.
We demonstrate that NH2-MIL-101(Fe) hexagonal micro-spindles, as a new photocatalyst, showed an
improved performance for degradation of toluene under visible light irradiation. The structural and
optical properties of the as-prepared NH2-MIL-101(Fe) hexagonal micro-spindles were characterized.
Furthermore, the catalytic reaction mechanism has been investigated on the basis of in situ Fourier
Transform infrared spectroscopy (FTIR) technology. Meanwhile, some intermediates (benzoic acid) and
the final product (CO2) of the degradation of toluene were also identified.
Received 4th November 2015
Accepted 17th December 2015
DOI: 10.1039/c5ra23154j
www.rsc.org/advances
exhibit large absorption coefficient in the region of visible light
due to the existence of iron oxo-clusters. Some groups demon-
1. Introduction
strate the Fe3-m3-oxo clusters with small sizes could improve
mobility of photo-induced carriers and thus suppress recom-
bination of electron–hole pairs. Furthermore, visible-light
response range could be tuned by substitution of amino
group for organic linkers and variation of morphologies due to
quantum connement effect.16 Therefore, more attentions have
been paid to preparation of nanostructured Fe(III)-MOFs
(MIL-88A, MIL-53) as well as their applications in photocatalytic
degradation of aqueous pollutants.17–19
Volatile organic compounds (VOCs) are a class of primary
gaseous pollutants in atmosphere and indoor environment,
which have raised wide attention on their greenhouse effect and
photochemical smog in the environment.20–22 Hence, the
development of degradation methods for these pollutants is in
urgent demand. Compared with physical, chemical-adsorption
and biological methods, photocatalysis technique has been
widely investigated due to its cost-effective and environmentally
friendly superiorities.23–25 Up to now, various photocatalysts,
including inorganic and organic–inorganic semiconductors,
have been prepared and simultaneously applied to photo-
degradation of liquid and gaseous pollutants.26–29 However,
photocatalytic degradation of VOCs over MOFs is rarely re-
ported, in spite of their better adsorption to gas, which could be
benecial to achieving quick mass diffusion.
Metal–organic frameworks (MOFs) are crystalline porous hybrid
materials made by multifunctional organic molecular building
blocks and metal or metal cluster connecting nodes.1 Because of
their well-ordered porous structures, large surface area, highly
diversied framework topologies and tunable organic func-
tionality, MOFs exhibit many potential applications, such as gas
separation and adsorption,2–4 hydrogen storage,5,6 catalysis,7,8
and molecular recognition.9 Especially in the eld of photo-
catalysis, organic linkers could act as antennas to absorb light,
activate metal clusters, and form organic-linker-to-metal-cluster
charge transfer (LCCT),10 leading to a lower charge recombina-
tion rate of photoinduced electron–hole pairs.11 More impor-
tantly, tunable organic functionality, such as excellent optical
properties and strong absorption of visible light could be ob-
tained by simple modifying the organic linkers of MOFs.12
Recently, it has been proved that MOFs, as alternative photo-
catalysts, show attractive performances in hydrogen produc-
tion,13 reduction of CO2,14 and degradation of dye,15 etc. In
addition, Fe-based MOF materials have been reported and
aKey Laboratory of Industrial Ecology and Environmental Engineering, School of
Environmental Science
& Technology, Dalian University of Technology, Dalian
116024, China. E-mail: xinyongli@hotmail.com; xyli@dlut.edu.cn; Fax: +86-411-
8470-7733; Tel: +86-411-8470-7733
In this study, we successfully fabricated hexagonal
microspindle-type MOFs photocatalyst of NH2-MIL-101(Fe) for
degradation of gaseous toluene (a typical component of VOCs)
under visible light illumination. Owing to its inherent absor-
bance of visible light and efficiently separated from one another
in a metal–organic framework, NH2-MIL-101(Fe) is a good
bSchool of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian,
Liaoning 116029, China
cDepartment of Chemical and Biomolecular Engineering, The Hong Kong University of
Science &Technology, Clear Water Bay, Kowloon, Hong Kong, China. E-mail:
kechengh@ust.hk; Fax: +852-2358-0054; Tel: +852-2358-7138
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c5ra23154j
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 4289–4295 | 4289

View Article Online
RSC Advances
Paper
ꢀ
candidate for the photocatalytic degradation of gaseous temperature is controlled as about 22–25 C. During the reac-
pollutants.30 Furthermore, the photocatalytic degradation tion process, the reaction mechanisms and intermediates were
mechanism of NH2-MIL-101(Fe) was investigated in details by in studied through FTIR spectrometer (Bruker VERTEX 70).
situ Fourier transform infrared spectroscopy (FTIR).
3. Results and discussion
3.1 The chemical and physical properties of NH2-MIL-
2. Experimental section
101(Fe)
2.1 Preparation of the NH2-MIL-101(Fe) hexagonal
microspindle
X-ray powder pattern of the NH2-MIL-101(Fe) hexagonal
microspindle is shown in Fig. 1a. The main diffraction peaks of
the as-prepared samples are similar to that of the previously
reported pattern of MIL-101 family.33,34 By referring to the fact of
the standard, here, the 3D crystal model has been used to
simulate XRD pattern. Meanwhile, the XRD patterns of the
synthesized samples exhibited at background and strong
intensity, indicating the high crystallinity of the samples.
Moreover, for the as-obtained product, no other peaks were
detected, indicating that pure phase of NH2-MIL-101(Fe) has
been obtained.
All the reagents and solvents were commercially available and
used as received. NH2-MIL-101(Fe) was prepared by following
previously reported procedures with some modications.31
Typically, FeCl3$6H2O and 2-aminoterephthalic acid (H2ATA)
were dissolved in DMF solution (the molar ratio was set to
2 : 1 : 156), and then the mixed solution was put into a 100 mL
Teon-lined autoclave at 120 ꢀC for 24 h. Aer the hydrothermal
processing, the brown powder was collected and repeatedly
washed with DMF and methanol, and then dried at 60 ꢀC
overnight.
In order to further analyze the molecular structure and
identify the functional groups of NH2-MIL-101(Fe) sample, the
FTIR spectroscopy was obtained and the results are shown in
Fig. 1b. Strong bands at the region of 1600–1400 cmꢁ1 are due to
2.2 Characterizations
The morphology of the NH2-MIL-101(Fe) was characterized by
using eld emission scanning electron microscope (FE-SEM,
HITACHI SU-8010), and the elements were veried by energy
dispersive X-ray (EDX) spectroscopy detector, equipped with the
FE-SEM above. Transmission electron microscopy (TEM) anal-
yses were carried out on a JEOL-2010 electron microscope, using
a 200 kV accelerating voltage. The X-ray diffraction (XRD) data
for crystalline structure of the prepared samples were obtained
from 5ꢀ to 30ꢀ. Fourier transform infrared spectra (FTIR,
BRUKER VERTEX 70) were recorded in the range 4000–450
cmꢁ1 with 4 cmꢁ1 resolution. Simple FTIR collection was con-
ducted at room temperature in the open environment without
chamber, when the pellet of sample prepared with KBr was xed
vertically on the holder of the standard accessory accompanied
with instrument. The surface properties and composition are
conducted by X-ray photoelectron spectroscopy (XPS, ESCA Lab
250, VG Scientic Ltd.). The UV-vis absorption spectra were
measured using UV-vis absorption spectrophotometer (JASCO,
UV-550) in the spectral range of 200–800 nm.
2.3 Photocatalytic activity test
Photocatalytic activity of the NH2-MIL-101(Fe) hexagonal
microspindle was evaluated by conversion of toluene under
visible light in a home-made in situ quartz infrared reaction
cell.32 The sample piece (0.02 g) was set in the sample holder,
and then a volume of 4 mL liquid toluene was injected into the
sealed reaction cell using a micro syringe. Aer an hour in the
dark, the gaseous toluene would reach adsorption equilibrium
on the surface of the catalyst prepared. At that time, the amount
of toluene was designated as the initial concentration. As light
resource, a 500 W xenon lamp with a UV-cutoff lter (l >
400 nm) (Shanghai Lansheng Electronic Co., Ltd.) was turned
on, and the toluene concentration for photocatalytic degrada-
tion was calculated by the integral area in the region of 3100–
Fig. 1 XRD patterns (a) and FTIR spectra (b) of the NH2-MIL-101(Fe)
2900 cmꢁ1 for characteristic peaks of toluene. The reactor (red) and MIL-101(Fe) (black) samples.
4290 | RSC Adv., 2016, 6, 4289–4295
This journal is © The Royal Society of Chemistry 2016

View Article Online
Paper
RSC Advances
the presence of the asymmetrical and symmetrical stretching and broad single ESR signal is observed for the samples (Fig. S2
modes of the framework O–C–O in the MIL-101, which are the in the ESI†), indicating that the valence state of iron ion in the
typical characteristic peaks of MIL-101 MOFs.35 In addition, the crystal is FeIII.44,45 Moreover, during the fabricated process, the
apparent peak at 540 cmꢁ1 is related to the Fe–O vibration,36 state of Fe element did not change.
and the peaks at 3456 cmꢁ1 and 3373 cmꢁ1 were ascribed to the
The morphology and particle sizes of the NH2-MIL-101(Fe)
asymmetrical and symmetrical stretching vibration absorption sample were observed by FE-SEM. As shown in Fig. 3a, the
of the amine groups, respectively. Meanwhile, the bands at microspindle NH2-MIL-101(Fe) has been successfully fabricated
1626 cmꢁ1 and 1337 cmꢁ1 are attributed to s (N–H) and n (C–N), on a large scale. Fig. 3b shows that the fabricated material
respectively.37 NH2-MIL-101(Fe) structure has been further consists of hexagonal microspindle crystals with 0.5–1.2 mm of
demonstrated by using Raman spectrum analysis (Fig. S1 in the the length, and 100–300 nm of the width. The composition
ESI†). The band at 1611 cmꢁ1 is due to the C–O stretching, and analysis by EDX measurement (Fig. S3 in the ESI†) shows the
the 1425 cmꢁ1 is associated with the out-of-phase stretching presence of Fe, C and O elements in the as-prepared sample,
modes of the carboxylate group. In addition, a new band at and the apparent atomic ratio of C to O is about 2 : 1, which is
1133 cmꢁ1, is probably due to a deformation mode involving the consistent with the stoichiometric composition of organic
carboxylate group, coupled with a C–C stretching mode and the linkers H2ATA. The morphology of NH2-MIL-101(Fe) was further
C–H stretching region, where only three components are conrmed by the transmission electron microscopy (TEM)
observed at 860, 810 and 630 cmꢁ1
XRD analysis, FTIR, and Raman spectra clearly conrm the of hexagonal microspindle with solid structure. From the side
formation of NH2-MIL-101(Fe) structure. view, it can be seen that the outline is regular hexagon, which is
To further study the surface components and chemical states consistent with the SEM results.
.
38–40 Therefore, the results of observation. Fig. 2c and d indicate that the sample is composed
of as-prepared NH2-MIL-101(Fe) hexagonal microspindle, the
The optical properties of the NH2-MIL-101(Fe) hexagonal
samples are characterized by XPS. From the survey spectrum in microspindles are characterized by UV-vis absorption spec-
Fig. 2a, it is obvious that the sample contains Fe, N, O and C troscopy. In Fig. 4a, NH2-MIL-101(Fe) displays more broad and
elements, which is well consistent with the EDS results. In intense absorption in the region of visible light than that of
Fig. 2b, the deconvolution of the C 1s peak results in three peaks MIL-101(Fe). Meanwhile, it could be observed that the color of
at about 284.8, 286.1, and 288.6 eV, corresponding to C–C, C–O NH2-MIL-101(Fe) is darker than that of MIL-101(Fe), suggesting
and C]O groups, respectively.41 Fig. 2c exhibits a single and that NH2-MIL-101(Fe) possesses better photo-response ability
strong peak at a binding energy of about 531.6 eV, attributed to than MIL-101(Fe). The band at around 260–310 nm can be
O 1s. In Fig. 2d, the spectrum of Fe 2p for NH2-MIL-101(Fe) ascribed to electron transfer from the oxygen to iron charge of
shows two peaks at 711.9 and 725.4 eV are Fe 2p3/2 and Fe isolated iron in an octahedral coordination environment, while
2p1/2, respectively, which indicates the presence of Fe(III), and the other band in the visible-light region can be ascribed to the
the satellite peak at the binding energy of 717.2 eV is also cor- ligand-based absorption and existence of Fe3O clusters in
responding to Fe(III).42 To evaluate the electron spin state of the NH2-MIL-101(Fe).46 The band gap energies of the samples can
NH2-MIL-101(Fe) hexagonal microspindle, ESR measurement be calculated from Tauc's plots using (ahn) ¼ A(hn ꢁ Eg)n/2
,
was carried out, which is a sensitive measurement of the reso- where a is the absorption coefficient near the absorption edge, h
nant eld and a good way of characterizing the local chemical is Planck's constant, A is a constant, n is the light frequency, Eg
(i.e. electronic) environment of the unpaired electron.43 A strong
Fig. 2 FESEM (a and b) and TEM spectra (c and d) of the NH2-MIL- Fig. 3 The XPS spectra of the NH2-MIL-101(Fe). (a) Survey of the
101(Fe) sample.
sample, (b) C 1s spectrum, (c) O 1s spectrum and (d) Fe 2p spectrum.
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 4289–4295 | 4291

View Article Online
RSC Advances
Paper
Fig. 5 (a) Photocatalytic degradation of toluene over the NH2-MIL-
101(Fe) hexagonal microspindles, and (b) the degradation kinetic
dynamics of toluene over the NH2-MIL-101(Fe) hexagonal
microspindles.
Fig. 4 (a) UV spectra of MIL-101(Fe) and NH2-MIL-101(Fe). (b) The
main absorption edge of NH2-MIL-101(Fe).
is the absorption band-gap energy, and n is 1 and 4 for a direct-
and indirect-band-gap semiconductor, respectively.47 The
Fig. 4b shows the plot of (ahn)1/2 versus hn of the samples, and
the equation gives Eg by estimating the intercept of the tangent
according to the plot. The band gap of NH2-MIL-101(Fe)
hexagonal microspindles is estimated to be about 1.32 eV.
NH2-MIL-101(Fe) hexagonal microspindles exhibited much
higher activity than P25 under visible light irradiation. The
reasons of enhanced photocatalytic ability include: (1)
NH2-MIL-101(Fe) hexagonal microspindles exhibit signicantly
improved photo-response in the region of visible light; (2)
organic linker to metal cluster charge transfer (LCCT) of
NH2-MIL-101(Fe) would increase photo-charge separation
efficiency.
3.2 Photocatalytic activity analysis
Fig. 5a illustrates the photocatalytic degradation of toluene over
different samples under visible light irradiation. For P25
(Degussa), the toluene conversion was about 11% aer 10 h
3.3 Mechanism of enhanced photocatalytic activity
reaction time, while for the obtained NH2-MIL-101(Fe) hexag- In situ FTIR technique could be employed to monitor the
onal microspindles photocatalyst, the toluene conversion could surface adsorbed species of catalysts and their transient events
reach about 79.4% aer 10 h. The activity of NH2-MIL-101(Fe) occurring on the catalyst during the reaction, which will give an
catalyst is higher than nano-BiVO4/TiO2 and quantum-BiVO4, important insight into the reaction mechanism.49 Fig. 6 shows
but lower than quantum-BiVO4/TiO2 reported recently.48 In the FTIR spectra collected during the degradation of gaseous
Fig. 5b, the kinetic curves of the different samples follow the toluene over the NH2-MIL-101(Fe) hexagonal microspindles.
model of pseudo-rst-order reaction. The observed kinetic The peaks of 3079 and 3038 cmꢁ1 can be attributed to the C–H
constants over NH2-MIL-101(Fe) hexagonal microspindles stretching vibration of aromatic ring, while 2937 and 2881 cmꢁ1
(0.273 hꢁ1) are approximately 13 times as large as P25 (0.021 could be ascribed to the symmetric and asymmetric C–H
hꢁ1), which are superior to the previously reported nano-BiVO4/ stretching vibrations of methyl groups, respectively. In addi-
TiO2 (0.203 hꢁ1), quantum-BiVO4 (0.252 hꢁ1), but lower than tion, the vibration of aromatic ring is associated with bands at
quantum-BiVO4/TiO2(0.365 hꢁ1).48 The result indicates that the 1609 and 1496 cmꢁ1
.
50
4292 | RSC Adv., 2016, 6, 4289–4295
This journal is © The Royal Society of Chemistry 2016

View Article Online
Paper
RSC Advances
Fig. 6 The FTIR spectra of degradation process for gaseous toluene over the NH2-MIL-101(Fe) hexagonal microspindles in the different regions
(a–c) and the corresponding time-domain IR spectra (d–f).
Upon irradiation, the characteristic peaks of toluene gradu- attributed to asymmetric stretching vibration of the carboxylate
ally decreased during the catalytic degradation process. Aer group COOꢁ, implies the presence of some benzoic acid.48,52,53
10 h reaction, the toluene degradation ratio is as high as 79.4%.
On the basis of the above analysis, the mechanism of the
Meanwhile, the characteristic peak area corresponding to CO2 photocatalytic degradation for gaseous toluene over the
(2362 and 2337 cmꢁ1) increased gradually. Furthermore, some NH2-MIL-101(Fe) hexagonal microspindles can be illustrated in
intermediate products also formed during the reaction process Fig. 7. Generally, there are two excitation pathways in the
aer 2 h. Generally, the process of toluene oxidation may amine-functionalized metal (M)-containing MOFs:46 (1) the NH2
include the step of forming benzaldehyde as the reaction pro- functionality can absorb visible light and then the photoelec-
ceeded.51 However, the weakly adsorbed benzaldehyde could trons would transfer from the organic linker to the M–O clus-
easily be oxidized to benzoic acid by reacting with induced ters, which is denoted as LCCT mechanism; (2) the M–O
hydroxyl groups on the surface of the catalyst, which would then clusters can directly absorb visible light, leading to photo-
retain on it rmly, leading to the inactivation of catalyst. The generated charge carriers.12 The two pathways can play syner-
observed new peaks at 1504, 1545 and 1562 cmꢁ1, which are getic roles in exciting these amino-functionalized Fe-based
Fig. 7 Proposed mechanism for photodegradation of toluene over the NH2-MIL-101(Fe) hexagonal microspindles under visible light irradiation.
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 4289–4295 | 4293

View Article Online
RSC Advances
Paper
MOFs. When the NH2-MIL-101(Fe) hexagonal microspindles
was irradiated by visible light, both of amine-functionalized
organic linker and Fe–O clusters could be excited to produce
photo-induced electrons and holes. Then the photo-generated
electrons produced at amine-clusters transfer to the surface of
Fe–O clusters based on LCCT mechanism, meanwhile Fe–O
clusters could be excited like semiconductor photocatalyst.
Aer that, the charge carriers transfer to the surface of catalyst,
and generate some active species ($OH and $O2ꢁ), which then
6 L. Hamon, P. L. Llewellyn, T. Devic, A. Ghou, G. Clet,
V. Guillerm, G. D. Pirngruber, G. Maurin, C. Serre and
G. Driver, J. Am. Chem. Soc., 2009, 131, 17490–17499.
7 C.-C. Wang, J.-R. Li, X.-L. Lv, Y.-Q. Zhang and G. Guo, Energy
Environ. Sci., 2014, 7, 2831–2867.
8 L. H. Wee, N. Janssens, S. P. Sree, C. Wiktor, E. Gobechiya,
R. A. Fischer, C. E. Kirschhock and J. A. Martens,
Nanoscale, 2014, 6, 2056–2060.
9 H. L. Jiang and Q. Xu, Chem. Commun., 2011, 47, 3351–3370.
react with adsorbed toluene, leading to some intermediate 10 M. Alvaro, E. Carbonell, B. Ferrer, F. X. Llabres i Xamena and
products, such as benzoic acid and benzaldehyde. Finally, these
species would be mineralized to H2O and CO2.
H. Garcia, Chem.–Eur. J., 2007, 13, 5106–5112.
´
11 F. X. Llabres i Xamena, A. Corma and H. Garcia, J. Phys.
Chem. C, 2007, 111, 80–85.
12 D. Sun, L. Ye and Z. Li, Appl. Catal., B, 2015, 164, 428–432.
13 Y. Horiuchi, T. Toyao, M. Saito, K. Mochizuki, M. Iwata,
H. Higashimura, M. Anpo and M. Matsuoka, J. Phys. Chem.
C, 2012, 116, 20848–20853.
14 Y. Lin, C. Kong and L. Chen, RSC Adv., 2012, 2, 6417–6419.
15 M. C. Das, H. Xu, Z. Wang, G. Srinivas, W. Zhou, Y. F. Yue,
V. N. Nesterov, G. Qian and B. Chen, Chem. Commun.,
2011, 47, 11715–11717.
16 H. R. Abid, H. M. Ang and S. Wang, Nanoscale, 2012, 4, 3089–
3094.
17 W. T. Xu, L. Ma, F. Ke, F. M. Peng, G. S. Xu, Y. H. Shen,
J. F. Zhu, L. G. Qiu and Y. P. Yuan, Dalton Trans., 2014, 43,
3792–3798.
18 Y. Zhang, G. Li, H. Lu, Q. Lv and Z. Sun, RSC Adv., 2014, 4,
7594–7600.
19 K. G. Laurier, F. Vermoortele, R. Ameloot, D. E. de Vos,
J. Hoens and M. B. Roeffaers, J. Am. Chem. Soc., 2013,
135, 14488–14491.
20 H.-J. Sedjame, C. Fontaine, G. Lafaye and J. Barbier Jr, Appl.
Catal., B, 2014, 144, 233–242.
21 L. Malherbe and C. Mandin, Atmos. Environ., 2007, 41, 6322–
6330.
22 H. M. Liang and C. M. Liao, Chemosphere, 2007, 68, 781–789.
23 Q. Wang, M. Zhang, C. Chen, W. Ma and J. Zhao, Angew.
Chem., Int. Ed., 2010, 49, 7976–7979.
24 K. Parida, N. Sahu, A. Tripathi and V. Kamble, Environ. Sci.
Technol., 2010, 44, 4155–4160.
25 B. Liu, X. Li, Q. Zhao, J. Ke, J. Liu, S. Liu and M. Tade, J.
Colloid Interface Sci., 2015, 438, 1–6.
26 W. Hou and S. B. Cronin, Adv. Funct. Mater., 2013, 23, 1612–
1619.
4. Conclusions
In summary, the NH2-MIL-101(Fe) hexagonal microspindles
were synthesized via the solvothermal method. The
results demonstrate that 2-amine-1,4-benzene dicarboxylate
(NH2-BDC) anions and inorganic trimmers link together to form
basic mesoporous cages unit and then assemble to grow
hexagonal microspindles by coordinating interaction. Further-
more, we applied NH2-MIL-101(Fe) in photocatalytic degrada-
tion of gaseous toluene under visible light irradiations for the
rst time. The as-prepared NH2-MIL-101(Fe) hexagonal micro-
spindles exhibit great photocatalytic activity for gaseous toluene
under visible light illumination. The conversion efficiency is up
to 79.4% under the adopted experimental condition, which is as
high as that of the commercial photocatalysts. In addition, the
catalytic reaction of gaseous toluene was explored by in situ
FTIR, which could clearly display production of the interme-
diate such as benzaldehyde, benzoic acid, and nal mineralized
production such as CO2 and H2O during the degradation
procedure. These results highlight the great potential of MOFs
as photocatalysts for VOCs removal, which may be applied to air
purication.
Acknowledgements
This work was supported nancially by National Nature Science
Foundation of China (No. 21377015) and the Key Laboratory of
Industrial Ecology and Environmental Engineering, China
Ministry of Education.
27 L. Rizzo, D. Sannino, V. Vaiano, O. Sacco, A. Scarpa and
D. Pietrogiacomi, Appl. Catal., B, 2014, 144, 369–378.
28 B. Qiu, M. Xing and J. Zhang, J. Am. Chem. Soc., 2014, 136,
5852–5855.
29 X. An, J. C. Yu, Y. Wang, Y. Hu, X. Yu and G. Zhang, J. Mater.
Chem., 2012, 22, 8525–8531.
Notes and references
1 N. Stock and S. Biswas, Chem. Rev., 2012, 112, 933–969.
2 D. N. Dybtsev, H. Chun, S. H. Yoon, D. Kim and K. Kim, J. Am.
Chem. Soc., 2004, 126, 32–33.
¨
3 O. K. Farha, A. O. Yazaydın, I. Eryazici, C. D. Malliakas,
B. G. Hauser, M. G. Kanatzidis, S. T. Nguyen, R. Q. Snurr 30 D. Wang and Z. Li, Catal. Sci. Technol., 2015, 5, 1623–1628.
´
and J. T. Hupp, Nat. Chem., 2010, 2, 944–948.
4 A. M. Ebrahim, J. Jagiello and T. J. Bandosz, J. Mater. Chem. A,
2015, 3, 8194–8204.
31 S. Bauer, C. Serre, T. Devic, P. Horcajada, J. Marrot, G. Ferey
and N. Stock, Inorg. Chem., 2008, 47, 7568–7576.
32 Y. Shen, Q. Zhao, X. Li, D. Yuan, Y. Hou and S. Liu, J. Hazard.
Mater., 2012, 241–242, 472–477.
5 B. Chen, C. Liang, J. Yang, D. S. Contreras, Y. L. Clancy,
E. B. Lobkovsky, O. M. Yaghi and S. Dai, Angew. Chem., Int. 33 J. Sun, G. Yu, Q. Huo, Q. Kan and J. Guan, RSC Adv., 2014, 4,
Ed., 2006, 118, 1418–1421.
38048–38054.
4294 | RSC Adv., 2016, 6, 4289–4295
This journal is © The Royal Society of Chemistry 2016

View Article Online
Paper
RSC Advances
34 E. V. Ramos-Fernandez, C. Pieters, B. van der Linden, J. Juan- 43 S. Guo, X. Li, H. Wang, F. Dong and Z. Wu, J. Colloid Interface
˜
Alcaniz, P. Serra-Crespo, M. W. G. M. Verhoeven,
H. Niemantsverdriet, J. Gascon and F. Kapteijn, J. Catal., 44 M. Nishikawa, Y. Mitani and Y. Nosaka, J. Phys. Chem. C,
2012, 289, 42–52. 2012, 116, 14900–14907.
35 T. A. Vu, G. H. Le, C. D. Dao, L. Q. Dang, K. T. Nguyen, 45 S. Hernandez-Anzaldo, N. Sanchez-Morales, R. Zamorano-
Sci., 2012, 369, 373–380.
´
´
´
P. T. Dang, H. T. Tran, Q. T. Duong, T. V. Nguyen and
Ulloa, R. Escudero, M. de Jesus Rosales Hoz and Y. Reyes-
G. D. Lee, RSC Adv., 2014, 4, 41185–41194.
Ortega, J. Mol. Struct., 2013, 1040, 39–46.
36 A. Modrow, D. Zargarani, R. Herges and N. Stock, Dalton 46 D. Wang, R. Huang, W. Liu, D. Sun and Z. Li, ACS Catal.,
Trans., 2012, 41, 8690–8696. 2014, 4, 4254–4260.
37 L. Shen, S. Liang, W. Wu, R. Liang and L. Wu, Dalton Trans., 47 S. Li, Y.-H. Lin, B.-P. Zhang, Y. Wang and C.-W. Nan, J. Phys.
2013, 42, 13649–13657. Chem. C, 2010, 114, 2903–2908.
38 O. V. Zalomaeva, K. A. Kovalenko, Y. A. Chesalov, 48 J. Sun, X. Li, Q. Zhao, M. O. Tade and S. Liu, J. Mater. Chem.
M. S. Mel'gunov, V. I. Zaikovskii, V. V. Kaichev, A, 2015, 3, 21655–21663.
A. B. Sorokin, O. A. Kholdeeva and V. P. Fedin, Dalton 49 X. Li, X. Zou, Z. Qu, Q. Zhao and L. Wang, Chemosphere,
Trans., 2011, 40, 1441–1444. 2011, 83, 674–679.
39 S. S. Balula, C. M. Granadeiro, A. D. S. Barbosa, 50 X. Li, Z. Zhu, Q. Zhao and L. Wang, J. Hazard. Mater., 2011,
´
I. C. M. S. Santos and L. Cunha-Silva, Catal. Today, 2013,
210, 142–148.
40 S. Bordiga, C. Lamberti, G. Ricchiardi, L. Regli, F. Bonino,
186, 2089–2096.
51 Q. Yan, X. Li, Q. Zhao and G. Chen, J. Hazard. Mater., 2012,
209–210, 385–391.
A. Damin, K.-P. Lillerud, M. Bjorgen and A. Zecchina, 52 A. J. Maira, J. M. Coronado, V. Augugliaro, K. L. Yeung,
Chem. Commun., 2004, 2300–2301. J. C. Conesa and J. Soria, J. Catal., 2001, 202, 413–420.
41 Y. Wu, H. Luo and H. Wang, RSC Adv., 2014, 4, 40435–40438. 53 M. D. Hernandez-Alonso, I. Tejedor-Tejedor, J. M. Coronado
´
42 H. Wang, F. Yin, G. Li, B. Chen and Z. Wang, Int. J. Hydrogen
Energy, 2014, 39, 16179–16186.
and M. A. Anderson, Appl. Catal., B, 2011, 101, 283–293.
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 4289–4295 | 4295