Strategy for stabilizing noble metal nanoparticles without sacrificing active sites

Article abstract of DOI:10.1039/c9cc03066b

We report a facile surface fluorination strategy for restricting Pt nanoparticle sintering through providing anchoring sites on the TiO₂ support and enhancing metal-support interaction via improved electronic interaction without sacrificing the active sites. The fluorine-tailored Pt/TiO₂ exhibits excellent sintering resistance and significant activity enhancement in the catalytic oxidation of toluene.

Full text of DOI:10.1039/c9cc03066b

View Article Online
View Journal
ChemComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: W. Ji, X. Wang, M.
Tang, L. Yang, Z. Rui, Y. Tong and J. Lin, Chem. Commun., 2019, DOI: 10.1039/C9CC03066B.
This is an Accepted Manuscript, which has been through the
Volume 52 Number
1 4 January 2016 Pages 1–216
Royal Society of Chemistry peer review process and has been
accepted for publication.
ChemComm
Accepted Manuscripts are published online shortly after
Chemical Communications
www.rsc.org/chemcomm
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
author guidelines.
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, outlined
in our author and reviewer resource centre, 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.
ISSN 1359-7345
COMMUNICATION
Marilyn M. Olmstead, Alan L. Balch, Josep M. Poblet, Luis Echegoyenet al.
Reactivity differences of Sc3N@C2n (2n 68 and 80). Synthesis of the
first methanofullerene derivatives of Sc N@D5h-C80
=
3
rsc.li/chemcomm

Please do not adjust margins
Page 1 of 4
ChemComm
View Article Online
DOI: 10.1039/C9CC03066B
Journal Name
COMMUNICATION
Strategy for Stabilizing Noble Metal Nanoparticles without
Sacrificing Active Sites
Weikang Ji,a Xuyu Wang,b Minni Tang,b Le Yang,a Zebao Rui, *a Yexiang Tong,b Jerry Y.S. Linc
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
We report a facile surface fluorination strategy for restricting Pt HCHO or NaBH4 solution reduction strategy for inducing SMSI in
nanoparticles sintering through providing anchoring sites on TiO2 Pt/TiO2. Recently, a sacrificial coating strategy was also employed to
support and enhancing metal-support interaction via electronic protect Au NP against sintering during SMSI formation 16
.
metal-support interaction improvement without sacrificing the
In spite of different routes for inducing SMSI and stabilizing NP
active sites. The fluorine tailored Pt/TiO2 exhibits excellent reported by now, the as-developed catalysts show some identical
sintering-resistant property and significant activity enhancement characters, such as partial physical coverage of noble metal NP by
in the catalytic toluene oxidation process.
an oxide thin layer and formation of electronic metal-oxide
interaction
10,
14-16. Although the oxide barrier formation is one
Supported noble metal nanoparticles (NP) with well-designed size,
morphology and chemical state are crucial for their applications in
important reason for the stabilization of noble metal NP through
2
SMSI and in some cases catalytically correlated 2, 17, the barrier
1,
catalysis 2. However, these noble metal NP normally hold high
coverage unavoidably sacrifices NP or active sites exposure and
suppresses the overall catalytic activity 6, 15, 18. While removal of the
barrier layers requires additional steps under harsh conditions and
surface energy and tend to sinter by particle migration/coalescence
or Ostwald ripening when employed at a high temperature or a
prolonged time 2, 3. Various strategies were proposed to stabilize
normally leads to NP sintering and functional metal-support
10, 18,
interface destruction
19. This inherent trade-off between
these active NP on the support, including introduction of physical
2, 6, 7
barriers 4, 5, rational design of metal-support interactions
modification of the active phase itself
and
catalyst stability and activity makes the construction of efficient
supported noble metal catalysts through SMSI a daunting challenge.
9. In particular, strong
2, 8,
metal-support interaction (SMSI) was considered as one of the most
promising ways to stabilize noble metal NP through the
combination between electronic and geometric modification 2, 10, 11
.
The traditional route to stabilize noble metal NP by SMSI is
through sequential steps of NP loading, calcination and high-
temperature H2 reduction to activate metal oxide support (such as
TiO2) and form thin barriers around/over the noble metal NP for
Scheme 1. Schematic representations of the Pt nanoparticles growth on the TiO2
surface and fluorinated TiO2 surface.
12
anchoring them (Scheme 1)
10, 11, except for those SMSI in ZnO
and hydroxyapatite 13 induced under oxidizing conditions. The harsh
Herein, we report a facile surface fluorination strategy for
enhancing SMSI without blocking active sites. In this route
(Scheme 1), anatase TiO2 surface was first fluorinated to form
anchoring sites for Pt NP loading. SMSI between Pt NP and
fluorinated TiO2 (F-TiO2) occurred via H2 reduction at 300 °C, a
relatively mild condition. The SMSI formed here is different
from those classic SMSI in the literature, in which the Pt NP
stabilization and enhanced Pt NP-F-TiO2 interaction are
achieved by enhanced electronic metal−support interactions
(EMSI) without sacrificing the active sites. TiO2 surface
fluorination is the key to this process, which leads to TiO2
surface properties change, such as charges, defects and
roughness 20-22. The induced negative and defect sites assure
calcination and reduction condition usually causes aggregation of
NP before the formation of SMSI
14,
15. A number of new routes
were developed to induce SMSI and avoid the negative effect of
14
high temperature reduction process. Rui et al. reported a mild
a. School of Chemical Engineering and Technology, Sun Yat-sen University, Southern
Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082,
P.R. China. E-mail: ruizebao@mail.sysu.edu.cn
b. MOE Laboratory of Bioinorganic and Synthetic Chemistry, The Key Lab of Low-
Carbon Chemistry and Energy Conservation of Guangdong Province, School of
Chemistry, Sun Yat-sen University, Guangzhou 510275, China.
c. School for Engineering of Matter, Transport and Energy, Arizona State University,
Tempe, AZ 85287, USA.
†
Electronic Supplementary Information (ESI) available: Experimental, XRD
patterns, TEM images, DFT calculation, Exclusion of diffusion effects and strong binding for positive Pt ions 23, 24, which is essential to
evaluation of activation energy. See DOI: 10.1039/x0xx00000x
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
ChemComm
Page 2 of 4
COMMUNICATION
Journal Name
anchoring Pt NP during SMSI formation and enhancing EMSI controlled F loading amount, i.e. 0.4Pt/1F-TiO2, resulting in a
View Article Online
between Pt NP and F-TiO2 support. Particularly, such an better Pt NP distribution. Interestingly,DfOoIr: 100..410P3t9//TCiO9C2C, 0th30e66PBt
interaction relies on the formation of ≡Ti-F species not the TiOx NP size measured by CO chemisorption (~4.0 nm) is greatly
barrier formation, thus keeping Pt NP exposure. Owing to the larger than that observed by TEM (~3.1 nm), while the Pt NP
enhanced EMSI at no cost of active sites, Pt/F-TiO2 size of 0.4Pt/1F-TiO2 calculated by TEM (~2.3 nm) is close to
demonstrates excellent sintering-resistance and activity that determined by CO chemisorption (~2.5 nm). Thus, we can
enhancement in catalytic toluene combustion process.
propose that H2 reduction leads to a blocking effect for CO
Anatase TiO2 surface fluorination was achieved through adsorption on 0.4Pt/TiO2, which is consistent with the classic
2,
post HF solution treatment with a HF concentration aiming for SMSI phenomenon reported in the literature
1 wt.% and 2 wt.% F loading (named as 1F-TiO2 and 2F-TiO2), blockage effect is not obvious on 0.4Pt/1F-TiO2.
followed by the calcination at 500 °C in air. Then, 0.1 or 0.4 wt.
10. Such
(b)
(a)
TiO2
1F-TiO2
142
g=1.992
% Pt (referred as 0.1Pt or 0.4Pt) was introduced onto TiO2 and
fluorinated TiO2 by impregnating with H2PtCl6 solution
followed by calcination at 400 °C in air. Before activity test and
characterization, the as-prepared samples were reduced in H2
atmosphere at 300 °C for 3 h. The experimental details are
provided in ESI†. Due to the corrosion effect of HF acid 22, the
BET-surface areas of 0.4Pt/1F-TiO2 and 0.4Pt/2F-TiO2 are lower
while their average pore sizes are larger than those of the
reference 0.4Pt/TiO2 (Table S1, ESI†). The 0.4Pt/xF-TiO2 (x=0,
1, 2) all only present the main characteristic peaks of anatase
structured TiO2 (JCPDS 21-1272) in the XRD patterns (Fig. S1,
ESI†). The platinum based species are all under the detect limit
due to their low loading and good dispersion.
0.4Pt/TiO2
0.4Pt/1F-TiO2
1F-TiO2
0.4Pt/1F-TiO2
196
394
0.4Pt/TiO2
TiO2
100
200
300
400
500
310
320
330
340
350
Magnetic field /mT
360
370
Raman shift (cm-1
)
Pt 4f
(d)
458.7
Ti 2p
(c)
70.61
70.96
458.9
464.5
0.1Pt/1F-TiO2
0.1Pt/TiO2
0.1Pt/1F-TiO2
0.1Pt/TiO2
464.7
70.57
70.64
458.6
458.6
0.4Pt/1F-TiO2
0.4Pt/TiO2
464.5
0.4Pt/1F-TiO2
0.4Pt/TiO2
464.5
475
470
465
460
455
73
72
71
70
69
68
Binding Energy (eV)
Binding Energy (eV)
Fig. 2. (a) Raman spectra and (b) EPR of 0.4Pt/xF-TiO2 and xF-TiO2, and XPS
profiles of 0.1Pt/xF-TiO2 and 0.4Pt/xF-TiO2 (x= 0, 1): (c) Ti 2p and (d) Pt 4f.
Raman spectra of TiO2, 1F-TiO2, 0.4Pt/TiO2 and 0.4Pt/1F-
TiO2 in Fig. 2a show three characteristic bands at 142, 196 and
394 cm-1, belonging to the O-Ti-O bending vibration 25. As
compared, both the fluorine modification and Pt NP loading
weaken the intensity of O-Ti-O bands, which relate with the
25
formation of F-Ti-O
and Pt-O-Ti on the TiO2 surface.
However, their intensity in 0.4Pt/1F-TiO2 is greatly stronger
than that over 0.4Pt/TiO2, indicating the formation of Pt-F-Ti
bond and its effect on Pt-O-Ti bond formation. The
modification of titania was further characterized by electron
paramagnetic resonance (EPR). As shown in Fig. 2b, the
characteristic EPR signals of Ti3+ center with g values around
1.992 are observed 26. The fluorine modification remarkably
enhances Ti3+ signals in 1F-TiO2 and 0.4Pt/1F-TiO2 in
comparison with those in TiO2 and 0.4Pt/TiO2 due to the
formation of F-Ti-O, agreeing well with the Raman results.
Besides, the Pt NP loading weakens the Ti3+ signals in 0.4Pt/1F-
TiO2, indicating the interaction of Pt-F-TiO2.
XPS spectra were measured to check the chemical states
of surface elements and SMSI in the samples. The successful
introduction of fluorine species is demonstrated by F1s XPS
spectra (Fig. S5, ESI†), showing a characteristic peak at 684.4
eV for the fluorine modified samples, which is ascribed to the
formation of surface fluoride or Ti-F species 24. A surface F/Ti
atom ratio of 0.0328 for 0.4Pt/1F-TiO2 and 0.0675 for 0.4Pt/2F-
TiO2 were estimated from XPS analysis. For O1s spectra (Fig. S5
ESI†), in addition to the main peak (OI) at 530.0 eV, a shoulder
peak (OII) around 531.3-531.8 eV appears on these samples,
which represents the chemisorbed oxygen 14. In Fig. 2c, Ti2p
Fig. 1. STEM images, elemental mapping and high-resolution TEM images of (a-c)
0.4Pt/TiO2 and (d-f) 0.4Pt/1F-TiO2.
The successful introduction of fluorine and Pt NP is
demonstrated by the STEM and TEM images (Fig. 1 and Fig.
S2&3, ESI†). Uniform Pt distribution is observed on 0.4Pt/1F-
TiO2 with an average Pt NP size of 2.3 nm. Comparatively, the
reference 0.4Pt/TiO2 holds Pt NP size around 3.1 nm and
0.4Pt/2F-TiO2 shows Pt NP size of 4.3 nm. In addition, lower
oxide barrier coverage of Pt NP on 0.4Pt/1F-TiO2 than
0.4Pt/TiO2 is demonstrated though the Pt NP embedment is
observed in both 0.4Pt/TiO2 and 0.4Pt/1F-TiO2. The elemental
mapping analysis in Fig. 1e and Fig. S3 (ESI†) indicates the
overlap of Pt and F species on 0.4Pt/1F-TiO2. At a low Pt
loading of 0.1 wt. %, atomic-scale Pt NP sites are obtained on
0.1Pt/1F-TiO2 (Fig. S4, ESI†). CO chemisorption test was
performed to evaluate the Pt NP dispersion on the samples. A
unit ratio of CO/Pt was assumed during the calculation of Pt
NP dispersion and size. Thus, the large measured Pt NP size
corresponds to a low CO chemisorption amount. By this way,
an average Pt NP size of 4.0 nm for 0.4Pt/TiO2, 2.5 nm for
0.4Pt/1F-TiO2 and 4.6 nm for 0.4Pt/2F-TiO2 were measured.
Both TEM observation and CO chemisorption characterization
clearly indicate appropriate TiO2 surface fluorination with
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 4
ChemComm
Please do not adjust margins
Journal Name
COMMUNICATION
spectra of 0.1Pt/1F-TiO2 shows an obvious negative peak shift the charge of Pt is 0.17 eV, while it is 0.20 eV in Pt/TViOiew2,AirntidcliecOatnilninge
in comparison with 0.1Pt/TiO2, assigning to the Ti3+ formation the Pt atom in Pt/F-TiO2 configuration is more close to the metallic
DOI: 10.1039/C9CC03066B
27. Due to the high electronegativity of F, the formation of state. In addition, the charge of Ti atoms nearby the Pt atom and
strong ≡Ti-F bond is favorable for localizing the extra electron the corresponding Pt-Ti distance are enlarged by the surface
in the Ti 3d orbital and inducing the Ti3+ formation for the fluorination. Since the migration of reduced metal oxide (e.g. TiO2-x
)
charge compensation 21. On the other hand, the electrons can onto the noble metal NP surface is the main route for barrier layer
transfer from TiO2 (or F-TiO2) to Pt NP due to the difference in formation 11, these results indicate surface fluorination can inhibit
the electrochemical potentials 14. The negligible negative Ti2p the formation of such a barrier layer. Additionally, TiO2 (101) and F-
peak shift over 0.4Pt/1F-TiO2 is attributed to the effective TiO2 (101) supported two Pt atoms are also modeled (Fig. S7, ESI†),
charge transfer from 1F-TiO2 to Pt NP and good charges and the same prediction that surface fluorination provides an
storage ability of Pt NP due to the relatively higher Pt NP anchoring site for Pt NP with an intense EMSI effect is obtained,
content in comparison with that in 0.1Pt/1F-TiO2. Pt 4f7/2 which is consistent with the experimental findings, especially those
spectra of 0.4Pt/xF-TiO2 and 0.1Pt/xF-TiO2 (x=0, 1) in Fig. 2d for 0.1Pt/xF-TiO2 (x=0, 1) with atomic-scale Pt NP dispersion.
and 0.4Pt/2F-TiO2 in Fig. S5 (ESI†) present peaks located at
70.61~70.96 eV, which show a negative transfer in comparison
with that for metallic Pt (71.1 eV) 14. The negative shift extent
indicates the intensity of EMSI 14. As compared, the measured
Pt NP charge difference between 0.4Pt/1F-TiO2 or 0.4Pt/2F-
TiO2 and 0.4Pt/TiO2 (70.57 or 70.60 VS 70.64 eV) is not as
obvious as that between 0.1Pt/1F-TiO2 and 0.1Pt/TiO2 (70.61
VS. 70.96 eV). In addition, the TiO2 surface fluorination or the
formation of strong ≡Ti-F bond can prevent the migration of
Ti3+ and TiOx barrier layer formation over Pt NP to some
content and improve Pt NP exposure. The surface Pt/Ti ratios
on 0.4Pt/TiO2, 0.4Pt/1F-TiO2 and 0.4Pt/2F-TiO2 are 0.0018, Fig. 3. Optimized structures of (a) Pt/ TiO2 (101) and (b) Pt/F-TiO2 (101) surfaces.
0.0080 and 0.0086, respectively. Thus, TiO2 surface
The Pt/F-TiO2 catalyst was then evaluated in toluene
fluorination promotes Pt dispersion and exposure, and combustion reaction, which is SMSI sensitive and important in the
strengthens the EMSI for anchoring Pt NP. Furthermore, the field of environmental catalysis 5, 14. As compared in Fig. 4a, TiO2
electrons enrichment over ≡Ti-F species (or negative and surface fluorination enhances the activity of 0.4Pt/1F-TiO2 and
defect sites) assure the strong adsorption of positive Pt ions 0.1Pt/1F-TiO2 in comparison with the reference samples. Complete
and Pt−F interaction, which benefits for anchoring Pt NP toluene conversion using 0.4Pt/1F-TiO2 is achieved at 190°C with a
during the post thermal process, promoting Pt NP dispersion low 0.4 wt.% Pt loading, which is 30 °C lower than that using
and enhancing EMSI. However, when concentrated HF is 0.4Pt/TiO2. After excluding the diffusion effects (Table S2, ESI†), the
employed, e.g., the case of 0.4Pt/2F-TiO2, the surface activation energy (Ea) is evaluated, which reveals that Ea of
fluorination of TiO2 with excess fluorine ions in the solution 0.4Pt/1F-TiO2 (~42 kJ/mol) is lower than that of 0.4Pt/TiO2 (~57
results in physically adsorbed fluorine anions at F-TiO2 surface kJ/mol) (Fig. 4b & Table S3, ESI†). The Ea value of 0.4Pt/1F-TiO2 (~42
and the formation of Ti–F–F- 28, which shows no promotion kJ/mol) is also remarkably lower than those state of the art Pt based
effect on Pt NP dispersion and EMSI of the sample.
catalysts, such as Pt/A-TiO2 (75~119 kJ/mol) 14, Pt/ATiO2 (58.6
Density functional theory (DFT) calculations were carried out kJ/mol ) 5, Pt/TiNT (73.2 kJ/mol) 5 and 110~142 kJ/mol for Pt/SiO2
to further explain the effect of surface fluorination on EMSI of as compared in Table S4 (ESI†). The comparison indicates that
Pt/TiO2 (S2, ESI†). Two kinds of surface structures, i.e., anatase TiO2 surface fluoridation is an effective way for tailoring the
(101) and F-TiO2 (101) with an F ion occupied the two coordinate performance of Pt/TiO2. The repeatability and stability of 0.4Pt/1F-
oxygen (O2C) site, were first constructed and optimized (Fig. S6, TiO2 are demonstrated in five continuous heating-cooling
ESI†). Then the loading of a Pt atom on TiO2 (101) and F-TiO2 (101) performance cycles (Fig. 4c). For each cycle, the temperature is
were studied (Fig. 3), respectively. The corresponding Pt loading raised from 100 to 190 °C (or T99, at which a toluene conversion of
energy on TiO2 and F-TiO2 supports was calculated by the following 99% is obtained) with a heating rate of 20°C/h, held at 190 °C for 50
,
29
equations 23
,
h, and then cooled to 100 °C with a cooling rate of 20 °C/h to 100
°C. As shown, there is no obvious activity decrease in the five cycles
on-stream test (> 300 h). In addition, no apparent change in surface
EL1 = ETiO2 + EPt – EPt/TiO2
EL2 = EF-TiO2 + EPt – EPt/F-TiO2
(1)
(2)
Herein, EL1 and EL2 represent adsorption energy, EPt is the energy of fluorine anion amount (Fig. S8a, ESI†), crystalline structure (Fig.
a Pt atom under vacuum, ETiO2 and EF-TiO2 correspond to TiO2 and F- S8b, ESI†) and Pt NP distribution (Fig. S9, ESI†) of 0.4Pt/1F-TiO2
TiO2 surface energy, EPt/TiO2 and EPt/F-TiO2 are the total system after the stability test was observed. As a comparison, cyclic test
energies after the Pt atom loading. By this definition, the higher Pt was also performed for 0.4Pt/TiO2 between 100 and 220°C (or
loading energy of 1.89 eV (EL2) on F-TiO2 with the connection of F-Pt initial T99) with a ramping rate of 20 °C/h and an intervening stay at
than the EL1 value (1.65 eV) indicates that the surface fluorination 220 °C for 44 h (Fig. S10, ESI†), showing the toluene conversion
enhances the metal-support interaction. The Hirshfeld charge of the decreases from an initial value of 99% to ~93% at 220 °C and the
two configurations were calculated. In the Pt/F-TiO2 configuration, end of second cycle. Critical aging treatments under the reactant
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
ChemComm
Page 4 of 4
COMMUNICATION
Journal Name
gaseous conditions and 500 °C for 8 h were performed for 0.4Pt/xF-
TiO2 and 0.1Pt/xF-TiO2 (x=0, 0.1). After aging treatment, Pt NP
dispersion slightly decrease from 44.1% to 37.8% for 0.4Pt/1F-TiO2,
while it remarkably decreases from 28.3% to 16.1% for the
reference 0.4Pt/TiO2 (Table S5, ESI†). Meanwhile, less toluene
oxidation activity loss of 0.4Pt/1F-TiO2 and 0.1Pt/1F-TiO2 is
observed after aging treatment in comparison with 0.4Pt/TiO2 and
0.1Pt/TiO2, respectively (Fig. S11, ESI†). STEM images and the
corresponding Pt particle size distribution of the aged 0.4Pt/TiO2
and 0.4Pt/1F-TiO2 show more serious Pt NP sintering for 0.4Pt/TiO2
from ~3.1 nm to ~5.7 nm than that for 0.4Pt/1F-TiO2 from ~2.3 nm
to ~3.1 nm after aging test (Fig. S12, ESI†). Obviously, the surface
fluorination improves the stability of Pt/TiO2. The applicability of
0.4Pt/1F-TiO2 is further evaluated under various space velocities
(Fig. 4d). Even at a high space velocity of 75,000 mL h-1 g-1, a (>) 95%
toluene conversion is obtained with 0.4Pt/1F-TiO2 at 200°C.
According to the toluene combustion scheme over titania
View Article Online
DOI: 10.1039/C9CC03066B
(NSFC No. 21576298 and 21776322), and Science and Technology
Program of Guangzhou (201804010154) is acknowledged.
Financial support of national natural science foundation of China
Conflicts of interest
There are no conflicts to declare.
Notes and references
1
2
3
4
5
6
7
Y. Xia, H. Yang and C. T. Campbell, Acc. Chem. Res., 2013, 46,
1671-1672.
E. D. Goodman, J. A. Schwalbe and M. Cargnello, ACS. Catal.,
2017, 7, 7156-7173.
T. W. Hansen, A. T. DeLaRiva, S. R. Challa and A. K. Datye, Acc.
Chem. Res., 2013, 46, 1720-1730.
H. Arandiyan, Y. Wang, H. Sun, M. Rezaei, H. Dai, Chem.
Commun., 2018, 54, 6484-6502.
Z. B. Rui, M. N. Tang, W. K. Ji, J. J. Ding and H. B. Ji, Catal. Today,
2017, 297, 159-166.
P. Sonström, D. Arndt, X. Wang, V. Zielasek and M. Bäumer,
Angew. Chem. Int. Ed., 2011, 50, 3888-3891.
C. Wang, M. Yang and M. Flytzani-Stephanopoulos, AIChE. J.,
2016, 62, 429-439.
5
supported Pt catalysts developed in our previous study , that the
decomposing of the main intermedium species (such as aliphatic
carboxylate species and benzoate species) is taken as the rate-
controlling step and relates to the density and chemical state of the
active sites, the unique performance of Pt/1F-TiO2 correlates with
its special surface properties, such as rich active sites due to the
good Pt NP dispersion and exposure (Table S1, ESI†), negative Pt
8
9
Q. Fu, F. Yang and X. Bao, Acc. Chem. Res., 2013, 46, 1692-1701.
X. L. Zou, Z. B. Rui and H. B. Ji, ACS. Catal., 2017, 7, 1615-1625.
10 S. J. Tauster, S. C. Fung and R. L. Garten, J. Am. Chem. Soc., 1978,
100, 170-175.
11 K. Fujiwara, K. Okuyama and S. E. Pratsinis, Environ. Sci. Nano.,
2017, 4, 2076-2092.
12 X. Liu, M. H. Liu, Y. C. Luo, C. Y. Mou, S. D. Lin, H. Cheng, J. M.
Chen, J. F. Lee and T. S. Lin, J. Am. Chem. Soc., 2012, 134, 10251-
10258.
13 H. Tang, J. Wei, F. Liu, B. Qiao, X. Pan, L. Li, J. Liu, J. Wang and T.
Zhang, J. Am. Chem. Soc., 2015, 138, 56-59.
14 Z. B. Rui, L. Y. Chen, H. Y. Chen and H. B. Ji, Ind. Eng. Chem. Res.,
2014, 53, 15879-15888.
15 L. Wang, J. Zhang, Y. Zhu, S. Xu, C. Wang, C. Bian, X. Meng and F.
Xiao, ACS. Catal., 2017, 7, 7461-7465.
16 W. Zhan, Q. He, X. Liu, Y. Guo, Y. Wang, L. Wang, Y. Guo, A. Y.
Borisevich, J. Zhang, G. Lu and S. Dai, J. Am. Chem. Soc., 2016,
138, 16130-16139.
17 N. J. Divins, I. Angurell, C. Escudero, V. Perez-Dieste and J. Llorca,
Science, 2014, 346, 620-623.
18 J. Silvestre-Albero, A. Sepffllveda-Escribano, F. Rodrı́guez-
Reinoso, J. A. Anderson, J. Catal., 2004, 223, 179-190.
19 S. Bernal, J. J. Calvino, J. M. Gatica, C. Larese, C. López-Cartes and
J. A. Pérez-Omil, J. Catal., 1997, 169, 510-515.
20 S. Liu, J. Yu, B. Cheng and M. Jaroniec, Adv. Colloid. Interfac.,
2012, 173, 35-53.
5,
state and enriched chemisorbed oxygen induced by EMSI (Fig. 2)
14. Meanwhile, the enhanced EMSI leads to Pt NP sintering-
resistance and superior stability of Pt/1F-TiO2 in toluene oxidation.
(a)
(b)
0.4Pt/1F-TiO2
100
80
60
40
20
0
-3.2
-3.6
-4.0
-4.4
-4.8
0.4Pt/2F-TiO2
0.4Pt/TiO2
0.1Pt/1F-TiO2
0.1Pt/TiO2
1F-TiO2
0.4Pt/TiO2 Ea= 57 kJ/mol
0.4Pt/1F-TiO2 Ea= 42 kJ/mol
0.4Pt/2F-TiO2 Ea= 45 kJ/mol
TiO2
120
160
200
240
280
320
2.25
2.30
2.35
2.40
)
2.45
2.50
Temperature (oC)
1000/T (K-1
200
180
160
140
120
100
(c)120
(d)
heating cooling
100
80
60
40
20
0
100
30000 mL h-1 g-1
60000 mL h-1 g-1
75000 mL h-1 g-1
80
60
40
20
0
Cycle5
250
Cycle4
200
Cycle3
Cycle2
100
Cycle1
50
0
150
Time (h)
300
100
120
140
160
180
200
Temperature (oC)
Fig. 4. (a) Light-off curves of 0.4Pt/xF-TiO2 (x=0, 1, 2), 0.1Pt/xF-TiO2 (x=0, 1), 1F-
TiO2 and TiO2, (b) Arrhenius fitting lines of 0.4Pt/xF-TiO2 for catalytic toluene
oxidation, (c) cyclic stability test for catalytic toluene oxidation over 0.4Pt/1F-TiO2
at 190°C and (d) effect of space velocities on the performance of 0.4Pt/1F-TiO2.
In summary, we demonstrated a facile surface fluorination
route for dispersing and stabilizing Pt nanoparticles on TiO2
support. The introduction of surface fluorine provides anchoring
sites for Pt nanoparticles and strengthens the interaction between
Pt nanoparticles and TiO2 substrate. Such strong metal-support
interaction is induced via electronic metal-support interaction,
showing negligible sacrificing effect on Pt exposure. This results in
significantly improved Pt nanoparticles sintering-resistance and
catalytic performance of TiO2 supported Pt catalyst. Such an
electronic metal-support interaction tailor strategy provides an
effective catalyst design way to stabilize and disperse noble metal
nanoparticles with enhanced catalytic performance.
21 A. M. Czoska, S. Livraghi, M. Chiesa, E. Giamello, S. Agnoli, G.
Granozzi, E. Finazzi, C. D. Valentin and G. Pacchioni, J. Phys.
Chem. C., 2008, 112, 8951-8956.
22 X. F. Cheng, W. H. Leng, D. P. Liu, Y. M. Xu, J. Q. Zhang, C. N. Cao,
J. Phys. Chem. C., 2008, 112, 8725-8734.
23 X. Y. Wang, Z. B. Rui, Y. Q. Zeng, H. B. Ji, Z. Du, Q. L. Rao, Catal.
Today, 2017, 297, 151-158.
24 X. X. Lin, F. Rong, D. G. Fu, C. W. Yuan, Powder. Technol., 2012,
219, 173-178.
25 J. Ding, J. Lin, J. Xiao, Y. Zhang, Q. Zhong, S. Zhang, L. Guo and M.
Fan, J. Alloy. Compd., 2016, 665, 411-417.
26 A. Giannakas, M. Antonopoulou, C. Daikopoulos, Y. Deligiannakis,
I. Konstantinou, Appl. Catal. B-Environ., 2016, 184, 44-54.
27 H. Huang and D. Leung, J. Catal., 2011, 280, 60-67.
28 J. Kim, W. Choi, H. Park, Res. Chem. Intermed., 2010, 36, 127-140.
29 J. Uchisawa, K. Kosuge, T. Nanba, S. Masukawa and A. Obuchi,
Catal. Lett., 2009, 133, 314-320.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins