General Synthesis of Ordered Mesoporous Carbonaceous Hybrid Nanostructures with Molecularly Dispersed Polyoxometallates

Article abstract of DOI:10.1002/anie.202104028

Hybrid nanomaterials with controlled dimensions, intriguing components and ordered structures have attracted significant attention in nanoscience and technology. Herein, we report a facile and green polyoxometallate (POM)-assisted hydrothermal carbonization strategy for synthesis of carbonaceous hybrid nanomaterials with molecularly dispersed POMs and ordered mesopores. By using various polyoxometallates such as ammonium phosphomolybdate, silicotungstic acid, and phosphotungstic acid, our approach can be generalized to synthesize ordered mesoporous hybrid nanostructures with diverse compositions and morphologies (nanosheet-assembled hierarchical architectures, nanospheres, and nanorods). Moreover, the ordered mesoporous nanosheet-assembled hierarchical hybrids with molecularly dispersed POMs exhibit remarkable catalytic activity toward the dehydration of tert-butanol with the high isobutene selectivity (100 %) and long-term catalytic durability (80 h).

Full text of DOI:10.1002/anie.202104028

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: General Synthesis of Ordered Mesoporous Carbonaceous Hybrid
Nanostructures with Molecularly Dispersed Polyoxometallates
Authors: Chaoliang Tan, Chunhong Chen, Shanjun Mao, Zhe Wang,
Yiyao Ge, Qinglang Ma, Xiao Zhang, Guodong Qi, Jun Xu,
Zhanxi Fan, and Yong Wang
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.202104028
Link to VoR: https://doi.org/10.1002/anie.202104028

10.1002/anie.202104028
Angewandte Chemie International Edition
RESEARCH ARTICLE
General Synthesis of Ordered Mesoporous Carbonaceous Hybrid
Nanostructures with Molecularly Dispersed Polyoxometallates
Chunhong Chen,[a,d] Shanjun Mao,[a] Chaoliang Tan,[c]* Zhe Wang,[a] Yiyao Ge,[d] Qinglang Ma,[d] Xiao
Zhang,[d] Guodong Qi,[e] Jun Xu,[e] Zhanxi Fan,[f] and Yong Wang[a,b]
*
[a]
Dr. C. Chen, Dr. S. Mao, Dr. Z. Wang, Prof. Dr. Y. Wang
Advanced Materials and Catalysis Group, Institute of Catalysis, Department of Chemistry, Zhejiang University
Hangzhou 310028, P. R. China.
E-mail: chemwy@zju.edu.cn
[b]
[c]
Prof. Dr. Y. Wang
College of Chemistry and Molecular Engineering, Zhengzhou University
Zhengzhou 450001, China
Prof. Dr. C. Tan
Department of Electrical Engineering, City University of Hong Kong
83 Tat Chee Avenue, Kowloon, Hong Kong, China
E-mail: chaoltan@cityu.edu.hk
[d]
[e]
Dr. C. Chen, Dr. Y. Ge, Dr. Q. Ma, Dr. X. Zhang
Center for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University
50 Nanyang Avenue, Singapore 639798, Singapore
Dr. G. Qi, Prof. Dr. J. Xu
National Centre for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of
Physics and Mathematics, Chinese Academy of Sciences
Wuhan 430071, P. R. China
[f]
Prof. Dr. Z. Fan
Department of Chemistry, City University of Hong Kong
83 Tat Chee Avenue, Kowloon, Hong Kong, China
Abstract: Hybrid nanomaterials with controlled dimensions, intriguing
components and ordered structures have attracted significant
attention in nanoscience and technology. Herein, we report a facile
and green polyoxometallate (POM)-assisted hydrothermal
carbonization strategy for synthesis of carbonaceous hybrid
nanomaterials with molecularly dispersed POMs and ordered
mesopores. By using various polyoxometallates such as ammonium
phosphomolybdate, silicotungstic acid, and phosphotungstic acid, our
approach can be generalized to synthesize ordered mesoporous
hybrid nanostructures with diverse compositions and morphologies
(nanosheet-assembled hierarchical architectures, nanospheres, and
nanorods). Moreover, the ordered mesoporous nanosheet-
assembled hierarchical hybrids with molecularly dispersed POMs
exhibit remarkable catalytic activity toward the dehydration of tert-
butanol with the high isobutene selectivity (100 %) and long-term
catalytic durability (80 h).
great potential in heterogeneous catalysis and electrocatalysis.[8-
10]
Till now, various methods have been developed to prepare
carbonaceous hybrid nanomaterials. For example, the direct
thermal pyrolysis of biomass or biomass derivatives with metal
compounds is a typical route for synthesis of carbonaceous
hybrids due to its high efficiency and simplicity.[11-13] Unfortunately,
the aforementioned method suffers from the formation of
nonuniform structures[14-15] and generation of large amount
inaccessible pores.[16-17] Alternatively, hydrothermal carbonization
(HTC) of carbohydrates has been recognized as an effective
method for the controlled synthesis of functional carbonaceous
materials.[18-19] This straightforward water-based method
commonly yields nonporous materials. Considering practical
applications, carbonaceous hybrid nanostructures with
periodically arranged pore channels and high pore volume are
highly desirable and of great potential, in particular for
heterogenous catalysis.[20] The nanocasting method is good for
the proof of principles by direct negative replication from hard
templates; however, it suffers from inevitably tedious and harsh
process.[21] Generally, soft-templating method is a more prevailing
approach for the synthesis of ordered mesopores by using
organic surfactants as templates.[21-22] Yet the direct use of soft
templates for the HTC of biomass derivatives severely limits by
the difficulty in controlling assembly ability of a soft template and
biomass carbon resource at HTC temperatures (160–240 °C),
which is found to be critical for the ordered pore formation.[23-24]
Therefore, the HTC strategies for the synthesis of biomass-
derived ordered mesoporous carbonaceous nanomaterials are
still at an early stage of development, and exploring a general and
straightforward strategy to improve the HTC of biomass
derivatives is of scientific and technological importance.
Introduction
Hybrid nanomaterials with controlled compositions, structures,
and dimensionalities have emerged as an important class of
functional nanomaterials.[1-2] The synergistic effect between
different components with complementary functionalities in hybrid
nanomaterials could endow them with new functionalities, which
offers new opportunities in catalysis,[3] energy conversion and
storage,[4-5] sensor,[6] etc.[7] Among different types of hybrid
nanomaterials, carbonaceous hybrid nanomaterials are of
particular interest owing to their outstanding thermal and chemical
stabilities, and high electrical conductivity, which have shown
1
This article is protected by copyright. All rights reserved.

10.1002/anie.202104028
Angewandte Chemie International Edition
RESEARCH ARTICLE
Polyoxometallates (POMs), a class of well-defined molecular
clusters formed by early transition metal ions (Mo, W, V, U, Nb)
and oxo ligands, have been extensively investigated for
applications in catalysis,[25] electronics,[26] and energy storage[27]
because of their striking chemical and electronic properties.
However, these materials generally showed poor application
performance owning to their inaccessible active sites induced by
the low surface area (3 m2 g-1 for commercial phosphomolybdic
acid) and small pore volume.[28] Considering that the POMs are
known for their Brønsted acidity and our recent works found that
the addition of acid was indispensable to successfully obtain
ordered porous materials with HTC,[23] one has reason to address
the thorny problem by combination of HTC and POMs. Moreover,
POMs with oxygen-enriched surface have the potential to serve
as building blocks for the bottom-up assembly of hybrid materials,
allowing a molecularly controlled approach.[29]
Figure 1. Characterization of PMo1/OMHs. a-c, SEM images. d, TEM image.
e,f, TEM images viewed along the [001] axis (e) and [110] axis (f).
Herein, we report a facile and general POM-assisted HTC
strategy for the synthesis of ordered mesoporous carbonaceous
hybrid nanostructures with molecularly dispersed POMs as well
as different compositions and morphologies (nanosheet-
assembled hierarchical architectures, nanospheres and
nanorods) from ubiquitous, nontoxic, and low-cost natural
renewable resources. As a proof-of-concept application, the as
made hybrids are used as acid catalyst for the dehydration of tert-
butanol (TBA), exhibiting high activity and excellent long-term
stability (80 h).
Scanning electron microscopy (SEM) image (Figure 1a) shows
that the as-obtained material has a three-dimensional (3D)
hierarchical architecture assembled from nanosheets. The
nanosheets for assembling 3D hierarchical architectures have a
thickness of about 90 nm and lateral size of up to few micrometers
(Figure 1b). Interestingly, the high-magnification SEM image
(Figure 1c) clearly shows that the nanosheets possess well-
ordered cylindrical mesopores on the surface. The low-
magnification transmission electron microscopy (TEM) image
(Figure 1d) indicates that these mesopores are uniformly
distributed across the entire nanosheet. Furthermore, TEM
images viewed along the [001] direction (Figure 1e) and [110]
direction (Figure 1f) confirm that these sheets have a highly
ordered hexagonal p6m mesoporous pattern. The pore diameter
and wall thickness are estimated to be 7 nm and 9 nm,
respectively, yielding a cell parameter of 16 nm. The small-angle
X-ray scattering (SAXS) pattern of PMo1/OMHs also exhibits a
clear broad shoulder, well consistent with the periodic porous
structure (Figure S5a).
High-angle annular dark field scanning transmission electron
microscope (HAADF-STEM) image and the corresponding
energy-dispersive X-ray (EDX) mappings reveal that C, Mo, P,
and N elements distribute uniformly throughout the PMo1/OMHs
(Figure 2a, b). The molar ratio of Mo to P (Table S1) is close to
the theoretical stoichiometry in APMo (i.e. 12), indicating no
substantial decomposition of PMo during the HTC process.
Moreover, the zoom-in scanning transmission electron
microscopy (STEM) image (Figure 2c) shows distinct uniform
distributed bright dots (marked with purple arrows), suggesting
the uniform distribution of PMo units into the carbon matrix (Figure
S6). The diameter of the well-dispersed bright dots is estimated
to be ~1.14 nm (inset of Figure 2c), which is consistent with the
reported diameter of H3PMo clusters (~1.1 nm),[35-36] suggesting
the molecular dispersion of the PMo units within the matrix.
Powder X-ray diffraction (PXRD) pattern of the PMo1/OMHs
shows no peaks assigned to the parent crystalline APMo, further
validating the homogeneous dispersion of the PMo (Figure S5b).
The thermogravimetry (TG) curve of the PMo1/OMHs shows a
weight loss of 71 wt% at about 700 oC in air (Figure S5c), and the
residuals are confirmed to be MoO3 by the PXRD pattern (inset of
-
Results and Discussion
Commercially available poly(ethylene oxide)-poly(propylene
oxide)-poly(ethylene
oxide)
copolymer
Pluronic
F127
(EO106PO70EO106) and renewable ribose were used as the soft
template and carbon precursor, respectively. Ammonium
phosphomolybdate (APMo, (NH4)3PO4(MoO3)12) with a typical
Keggin structure (Figure S1) was chosen as the additive POMs.[30-
31]
It is widely known that the diethylether and other similar
polyethylene glycols can bind to the acidic POMs via the induced
dipole interactions between the hydronium cations of POMs and
the ether.[32-33] Here, the strong coordination interaction between
APMo and PEO blocks of F127 is confirmed by the formation of
porous APMo and UV-Vis analysis (Figure S2).[34] In a typical
synthesis, the aqueous mixture containing APMo, F127, and
ribose was stirred overnight at room temperature while a color
change of the mixture from yellow to green can be explained by
interaction between polyoxometallates and the saccharide
(Figures S3 and 4). Subsequently, the HTC step was carried out
at 140 oC for
8 h to synthesize ordered mesoporous
carbonaceous nanohybrids with molecularly dispersed
phosphomolybdic (PMo) units (denoted as PMo1/OMHs).
2
This article is protected by copyright. All rights reserved.

10.1002/anie.202104028
Angewandte Chemie International Edition
RESEARCH ARTICLE
Figure 2. Detailed structural characterization. a,b HAADF-STEM image (a) of PMo1/OMHs and the corresponding EDX mappings (b) as marked by the red
square in (a). c, High-magnification STEM image of PMo1/OMHs. Inset: statistical size distribution histogram of the PMo units. The arrows indicate the molecularly
dispersed PMo. d-f, FT-IR (d), XANES (e), and FT-EXAFS (f) spectra of the APMo and PMo1/OMHs.
Figure S5c). These results indicate that the weight percentage of
PMo blocks in PMo1/OMHs is about 31.5 wt%. Fourier transform
infrared spectroscopy (FT-IR) spectrum (Figure 2d) of
PMo1/OMHs shows the characteristic adsorption peaks at 1062,
958, 874, and 805 cm-1, which correspond to νas(P-Oa), νas(Mo-
Od), νas(Mo-Ob-Mo), and νas(Mo-Oc-Mo), respectively (Figure
S1).[37] The chemical state of Mo element in the nanostructured
framework was explored by X-ray photoelectron spectroscopy
(XPS) (Figure S5d). Usually, the Mo 3d core level spectrum of
pure APMo consists of a spin-orbit doublet with peaks located at
232.4 and 235.7 eV, associated with Mo atoms in their higher
oxidation state (i.e. Mo6+). As for the PMo1/OMHs, the Mo 3d core
level spectrum is considerably broader, owing to the presence of
small amount of lower oxidation state (i.e. Mo5+).[38] The Mo K-
edge X-ray absorption near-edge structure (XANES) spectra
were also recorded to further investigate the oxidation states and
space symmetry of Mo atoms in PMo1/OMHs at the atomic level.
Notably, there is a shoulder peak at around 20006 eV in the pre-
edge region, the intensity of which can reflect the distortion
degree of Mo atoms with octahedral coordination.[39] As shown in
Figure 2e, the PMo1/OMHs show similar intensity of the pre-edge
compared to the pristine APMo, suggesting the remained Keggin
structure. In addition, the absorption threshold position of Mo K-
edge has been utilized to confirm the valence state of Mo atom.
The slight shift of absorption edge toward lower energy value
indicates the partial reduction of Mo in PMo1/OMHs, in agreement
with the result from XPS analysis. Extended X-ray absorption fine
structure (EXAFS) technique was employed to investigate the
local structure of the molecule. The Fourier transformed EXAFS
spectra for the samples are shown in Figure 2f, demonstrating the
radial atomic distribution around Mo atoms. The bulk APMo
mainly exhibits four characteristic peaks, which can be assigned
to the Mo=O double bond, two types of Mo-O distances, and a
Mo-Mo distance, respectively.[40-41] The EXAFS spectrum of as-
prepared PMo1/OMHs shows similar peaks as that of APMo,
confirming a well-maintained local structure of PMo units (Figure
S5).
Figure 3. Characterization of other carbonaceous hybrid nanomaterials. a-c, TEM
image (a), STEM image (b), and FT-IR spectrum (c) of POMs/OMHs derived from
H4SiW12O40. d-f, TEM image (d), STEM image (e), and FT-IR spectrum (f) of
POMs/OMHs derived from H3PW12O40
.
3
This article is protected by copyright. All rights reserved.

10.1002/anie.202104028
Angewandte Chemie International Edition
RESEARCH ARTICLE
This facile HTC method can be also used for the synthesis of
other carbonaceous hybrid nanomaterials with molecularly
dispersed POMs with different compositions and morphologies by
S3). Thus, POM anions also play an important role for the
interaction between F127 and ribose. The oxide salt counterparts
of POMs like ammonium molybdate and ammonium
simply changing the types of used POMs (Figure 3 and Figure S7). metatungstate were chosen to replace POMs and a high yield of
Specifically, ordered mesoporous nanospheres and nanorods
can be synthesized by using tungstosilicic acid (H4SiW12O40) and
tungstophosphoric acid (H3PW12O40), respectively. In order to
further extend this synthetic protocol to other biomasses, we also
chose glucose, xylose and fructose as carbon precursors. All the
synthesized hybrid nanomaterials show the typical ordered
mesoporous flaky nanoarchitecture (Figures S8), demonstrating
the generality of this method. PEO-PPO-PEO surfactants with
different compositions (e.g. Pluronic F108 and P123) are also
explored as the surfactant, leading to the formation of well-defined
ordered mesoporous nanostructures as well (Figures S9 and
S10). All these results have proven that this facile HTC method is
a versatile strategy for the synthesis of carbonaceous hybrid
nanomaterials with molecularly dispersed POMs.
The weak affinity between ribose and soft template, which is
confirmed by dynamic light scattering (DLS, Figure S11), can be
easily destroyed during HTC process as the low-yield HTC
product shows no pores (Figure S12). To unveil whether the
protonic acid plays a key role in our strategy, a group of controlled
experiments with different pH values (~3.0, ~1.5, ~ 0.4 adjusted
by adding sulfuric acid) in F127 and ribose system were carried
out since POMs are also a strong Brønsted acid.[42-43] Little
amount of product could be obtained when the experiments were
conducted at pH = 3.0 and 1.5. TEM images demonstrate that the
products are irregular bulk or solid spheres (Figure S13). Only at
pH less than 0.4, ordered mesoporous materials can be fabricated
in high yield (Figure S14), which is consistent with our previous
results.[23, 44] These experimental evidences suggest that only the
high-concentration acids can work effectively for the synthesis of
ordered mesoporous materials. However, the pH values of the
PMo1/OMHs solutions at different reaction time established an
equilibrium at about 1.5, a much lower H+ concentration (Table
nanohybrids (~0.4 g) can still be obtained, indicating that the
inorganic metal-oxo anions can also facilitate the HTC process.
TEM images show that the resultant hybrids possess less ordered
pores compared to POM-derived hybrids (Figure S15). Such a
periodicity decrease is further certified by SAXS tests (Figures
S15c, f). These findings indicate that the inorganic anions, such
as molybdate and POM anions, can also promote the
carbonization of saccharide and act as enhancer like H+ ions to
enhance the interaction between the soft template and ribose,
partly because the metal-oxo anions can strongly coordinate with
both surfactants and carbon precursors (illustration of F127-
APMo-Ribose complex, Figure S16). Meanwhile, POM anions
with unique phosphates/silicates at the center of their 3D oxide
framework behaves better in promoting the formation of long-
range periodicity compared with their metal oxide counterparts.
To gain a deeper understanding of the self-assembly during the
synthesis process for the PMo1/OMHs, the reaction was
quenched at different HTC time. All the hybrids showed ordered
mesoporous flaky structures with increasing lateral size along
with HTC reaction time from 3 h to 12 h, as confirmed by various
characterizations (Figures S18-22). IR tests reveal that the
Keggin structures of PMo clusters in the composites are well
preserved all the time (Figure S23b). According to TG curves
(Figure S24a, b), the PMo content decreases notably from 61 wt%
to 42 wt% when the reaction time increases from 2 h to 6 h,
suggesting the gradual carbonization of ribose. Strikingly, for a
longer reaction time (i.e. from 6 h to 10 h), the as-synthesized
hybrids show a similar PMo mass fraction of about 30 wt% while
the product yield kept increasing. It is assumed that the building
blocks, i.e. cylindrical complex micelles (Figure S24c), consisting
of constant mass ratio among F127, PMo, and oligomers, took
part in the product assembly during this period.
Figure 4. Schematic illustration of the self-assembly process.
4
This article is protected by copyright. All rights reserved.

10.1002/anie.202104028
Angewandte Chemie International Edition
RESEARCH ARTICLE
Based on the aforementioned analysis, the formation
mechanism of PMo1/OMHs could be proposed as a POM-
assisted carbonization process (Figure 4). When the mixture is
stirred at room temperature, self-assembly and micellization
among F127, APMo, and ribose happen, which is driven by
hydrogen bond and coordination interaction. Upon heating,
complex structure of the hybrid cylindrical micelles (i.e. F127-
POMs-oligomers) can be well maintained with the assistance of
both anion and cation of POMs as enhancers to resist the high
HTC temperature. These building micelles can further assemble
and stack into hexagonal symmetry structures. After that, further
cross-linking carbonization of the oligomers, which is facilitated by
POMs, can solidify the ordered hybrid structure and
simultaneously incorporate the monodispersed POMs in
carbonaceous frameworks, resulting in the formation of hybrid
nanomaterials.
The triblock copolymer in as-obtained samples could be
removed by treatment in hot solvent and the subsequent
calcination in N2 atmosphere (Figure S25). After the removal of
the triblock copolymer, the ordered mesoporous architectures can
be well reserved (Figure S26a and Figure 5a). To keep the
Keggin-patterned POMs, a low pyrolysis temperature (350 oC)
was selected due to the relatively low decomposition temperature
of APMo (denoted as PMo1/OMHs-350 with 31 wt% content of
PMo unit, PMo1/OMHs-2-350 with 45 wt% content of PMo unit).[44]
Elemental mappings show homogeneous distribution of C, Mo, P,
and N elements within the hybrids (Figure S26b-d). XAFS and FT-
IR spectra further confirm the Keggin-structure after the treatment
(Figure 5b-d). The Brunauer-Emmett-Teller (BET) specific
surface area and pore volume of the product with calcination at
only 350 were estimated to be 80.4 m2 g-1 and 0.12 cm3 g-1, much
higher than that of pure APMo (Figure S27).
resonance peaks observed in the region of 50-70 ppm may be
assigned to TMPO bounded to Lewis acid sites and two TMPO
adsorbed on one protonic site. The peak centered at 45 ppm most
likely results from the physisorbed TMPO. Ammonia temperature-
programmed desorption (NH3-TPD) also indicates a suitable acid
property as shown in Figure S28b, which could increase the acid
catalytic activity, for example dehydration.[47] The dehydration of
tert-butanol was then chosen as a model reaction using a fix bed
reactor to evaluate the catalytic performance of the PMo1/OMHs-
350. Except isobutene, no other products were founded in these
reactions. Figure 5f shows the conversion of TBA slightly
decreased from 100 % to 85 % in an 80 h reaction. In contrast,
the composite prepared by wetness impregnation of PMo onto the
ordered mesoporous carbons (OMCs-PMo) shows inferior
catalytic activity and stability. This may result from carbon
deposits catalyzed by the strong acid sites,[48] corresponding to
NH3 desorption peak from 250-350 oC (Figure S28b). HTC-PMo
behaves much worse catalytic performance, indicating the
importance of mesopores to enhance the activity. These results
demonstrate the advantages of the molecularly dispersed POMs
and abundant ordered mesopores towards the catalytic
applications.
Conclusion
In summary, we have developed a facile and general POM-
assisted HTC strategy for the synthesis of ordered mesoporous
carbonaceous hybrids with molecularly dispersed POMs. To the
best of our knowledge, this is the first report on the synthesis of
such kind of unique hybrids with molecularly dispersed POMs.
The formation mechanism and structure of the novel composites
were thoroughly studied. Although the originally designed role of
POMs here was only to effectively enhance the reaction kinetics
of the HTC process as acidic catalyst, their unexpectedly versatile
properties originated from their coordination ability were quickly
recognized and enabled the formation of more diverse products.
For example, this approach was successfully coupled with
different kinds of POMs to directly produce novel ordered
mesoporous carbonaceous hybrids with molecularly dispersed
POM in matrix for the first time. Impressively, when used as a
catalyst, the ordered mesoporous POMs carbonaceous hybrids
show excellent catalytic activity and stability toward the
dehydration of TBA. We believe these unique hybrid materials
may demonstrate new possibilities for the design and construction
of well-ordered mesoporous hybrid nanomaterials towards a
variety of practical applications, especially for single-molecule
heterogeneous catalyst.
Figure 5. Structural and composition characterization of catalysts. a, STEM
image of PMo1/OMHs-2-350. b-d, XANES (b), FT-EXAFS (c), and FT-IR (d) spectra
of PMo1/OMHs-2-350 and APMo. e, 31P MAS NMR spectra of TMPO-PMo1/OMHs-
350 and TMPO-PMo1/OMHs-2-350. f, Catalytic performance of TBA dehydration on
selected catalysts.
Acknowledgements
To gain insight into the nature of catalytic sites, acid properties
were characterized by 31P solid-state magic-angle-spinning
(MAS) NMR of adsorbed trimethylphosphine oxide (TMPO).[37, 46]
As shown in Figure 5e and Figure S28a, the main chemical shifts
at -5.9 ppm and -8.1 ppm for all samples correspond to
phosphorus in the parent PMo. The broad resonance peaks in the
range of 70-95 ppm could be attributed to the TMPO bound to
Financial support from the National Key R&D Program of China
(2016YFA0202900), the National Natural Science Foundation of
China (21872121, 21908189), and the Key R&D Project of
Zhejiang Province (2020C01133) are greatly appreciated. C.T.
thanks the funding support from the Start-Up Grant (Project No.
9610495) from City University of Hong Kong. The XAS
experiments were conducted in the Shanghai Synchrotron
Radiation Facility (SSRF).
Brønsted acid site forming TMPOH+ ion complex, whereas the 31
P
5
This article is protected by copyright. All rights reserved.

10.1002/anie.202104028
Angewandte Chemie International Edition
RESEARCH ARTICLE
[35] T. Lunkenbein, D. Rosenthal, T. Otremba, F. Girgsdies, Z. Li, H. Sai, C.
Bojer, G. Auffermann, U. Wiesner, J. Breu, Angew. Chem. Int. Ed. 2012,
51, 12892-12896.
Keywords: Hydrothermal carbonization • Biomass • Ordered
mesopore • Molecularly dispersed polyoxometalates • Single-
molecule heterogeneous catalyst
[36] H. Omachi, T. Inoue, S. Hatao, H. Shinohara, A. Criado, H. Yoshikawa,
Z. Syrgiannis, M. Prato, Angew. Chem. Int. Ed. 2020, 59, 7836-7841.
[37] L. Dermeche, R. Thouvenot, S. Hocine, C. Rabia, Inorg. Chim. Acta 2009,
362, 3896-3900.
[1]
[2]
L. Lin, W. Zhou, R. Gao, S. Yao, X. Zhang, W. Xu, S. Zheng, Z. Jiang, Q.
Yu, Y.-W. Li, C. Shi, X.-D. Wen, D. Ma, Nature 2017, 544, 80-83.
Q. Lu, A.-L. Wang, Y. Gong, W. Hao, H. Cheng, J. Chen, B. Li, N. Yang,
W. Niu, J. Wang, Y. Yu, X. Zhang, Y. Chen, Z. Fan, X.-J. Wu, J. Chen, J.
Luo, S. Li, L. Gu, H. Zhang, Nat. Chem. 2018, 10, 456-461.
L. He, F. Weniger, H. Neumann, M. Beller, Angew. Chem. Int. Ed. 2016,
55, 12582-12594.
[38] E. Anderson, A. Crisci, K. Murugappan, Y. Román-Leshkov,
ChemSusChem 2017, 10, 2226-2234.
[39] H. Nair, J. T. Miller, E. A. Stach, C. D. Baertsch, J. Catal. 2010, 270, 40-
47.
[3]
[40] J. Wienold, O. Timpe, T. Ressler, Chem. - Eur. J. 2003, 9, 6007-6017.
[41] H. Wang, S. Hamanaka, Y. Nishimoto, S. Irle, T. Yokoyama, H.
Yoshikawa, K. Awaga, J. Am. Chem. Soc. 2012, 134, 4918-4924.
[42] I. V. Kozhevnikov, Chem. Rev. 1998, 98, 171-198.
[43] W. Deng, Q. Zhang, Y. Wang, Dalton. Trans. 2012, 41, 9817-9831.
[44] L. Xie, H. Wang, C. Chen, S. Mao, Y. Chen, H. Li, Y. Wang, Research
2018, 2018, 5807980.
[4]
[5]
J. Wang, F. Xu, H. Jin, Y. Chen, Y. Wang, Adv. Mater. 2017, 29, 1605838.
Q. Zhang, Y. Zhou, F. Xu, H. Lin, Y. Yan, K. Rui, C. Zhang, Q. Wang, Z.
Ma, Y. Zhang, K. Huang, J. Zhu, W. Huang, Angew. Chem. Int. Ed. 2018,
57, 16436-16441.
[6]
[7]
E. Lee, Y. S. Yoon, D.-J. Kim, ACS Sens. 2018, 3, 2045-2060.
G. Liu, V. Chernikova, Y. Liu, K. Zhang, Y. Belmabkhout, O. Shekhah, C.
Zhang, S. Yi, M. Eddaoudi, W. J. Koros, Nat. Mater. 2018, 17, 283-289.
J. Liu, Q. Ma, Z. Huang, G. Liu, H. Zhang, Adv. Mater. 2019, 31, 1800696.
Y. Cao, S. Mao, M. Li, Y. Chen, Y. Wang, ACS Catal. 2017, 7, 8090-
8112.
[45] M. Almohalla, I. Rodríguez-Ramos, A. Guerrero-Ruiz, Catal. Sci.
Technol. 2017, 7, 1892-1901.
[8]
[9]
[46] N. Feng, A. Zheng, S.-J. Huang, H. Zhang, N. Yu, C.-Y. Yang, S.-B. Liu,
F. Deng, J. Phys. Chem. C 2010, 114, 15464-15472.
[10] F. Cao, M. Zhao, Y. Yu, B. Chen, Y. Huang, J. Yang, X. Cao, Q. Lu, X.
Zhang, Z. Zhang, C. Tan, H. Zhang, J. Am. Chem. Soc. 2016, 138, 6924-
6927.
[47] H. Xin, X. Li, Y. Fang, X. Yi, W. Hu, Y. Chu, F. Zhang, A. Zheng, H. Zhang,
X. Li, J. Catal. 2014, 312, 204-215.
[48] I. Yarulina, K. De Wispelaere, S. Bailleul, J. Goetze, M. Radersma, E.
Abou-Hamad, I. Vollmer, M. Goesten, B. Mezari, E. J. M. Hensen, J. S.
Martínez-Espín, M. Morten, S. Mitchell, J. Perez-Ramirez, U. Olsbye, B.
M. Weckhuysen, V. Van Speybroeck, F. Kapteijn, J. Gascon, Nat. Chem.
2018, 10, 804-812.
[11] W. Cui, Q. Liu, Z. Xing, A. M. Asiri, K. A. Alamry, X. Sun, Appl. Catal. B-
Environ. 2015, 164, 144-150.
[12] Y. Li, G. Wang, T. Wei, Z. Fan, P. Yan, Nano Energy 2016, 19, 165-175.
[13] J. Wang, Z. Wei, S. Mao, H. Li, Y. Wang, Energ. Environ. Sci. 2018, 11,
800-806.
[14] B. Huang, Y. Liu, Z. Xie, J. Mater. Chem. A 2017, 5, 23481-23488.
[15] L.-H. Zhang, W.-C. Li, H. Liu, Q.-G. Wang, L. Tang, Q.-T. Hu, W.-J. Xu,
W.-H. Qiao, Z.-Y. Lu, A.-H. Lu, Angew. Chem. Int. Ed. 2018, 57, 1632-
1635.
[16] H. Nishihara, T. Kyotani, Adv. Mater. 2012, 24, 4473-4498.
[17] X. Ning, W. J. Koros, Carbon 2014, 66, 511-522.
[18] M.-M. Titirici, R. J. White, C. Falco, M. Sevilla, Energ. Environ. Sci. 2012,
5, 6796-6822.
[19] F. J. Martin-Martinez, K. Jin, D. López Barreiro, M. J. Buehler, ACS Nano
2018, 12, 7425-7433.
[20] P. Zhang, L. Wang, S. Yang, J. A. Schott, X. Liu, S. M. Mahurin, C. Huang,
Y. Zhang, P. F. Fulvio, M. F. Chisholm, S. Dai, Nat. Commun. 2017, 8,
15020.
[21] T.-Y. Ma, L. Liu, Z.-Y. Yuan, Chem. Soc. Rev. 2013, 42, 3977-4003.
[22] T. Zhao, A. Elzatahry, X. Li, D. Zhao, Nat. Rev. Mater. 2019, 4, 775-791.
[23] F. Xu, Y. Chen, M. Tang, H. Wang, J. Deng, Y. Wang, ACS Sustain.
Chem. Eng. 2016, 4, 4473-4479.
[24] J. Liu, L. Xie, J. Deng, Y. Gong, G. Tang, H. Bai, Y. Wang, Chem. Mater.
2019, 31, 7186-7191.
[25] B. Akram, B. Ni, X. Wang, Adv. Mater. 2020, 32, 1906794.
[26] Y. Ren, Y. Zou, Y. Liu, X. Zhou, J. Ma, D. Zhao, G. Wei, Y. Ai, S. Xi, Y.
Deng, Nat. Mater. 2020, 19, 203-211.
[27] J. W. Jordan, G. A. Lowe, R. L. McSweeney, C. T. Stoppiello, R. W.
Lodge, S. T. Skowron, J. Biskupek, G. A. Rance, U. Kaiser, D. A. Walsh,
G. N. Newton, A. N. Khlobystov, Adv. Mater. 2019, 31, 1904182.
[28] Y.-F. Song, R. Tsunashima, Chem. Soc. Rev. 2012, 41, 7384-7402.
[29] Q. Liu, P. He, H. Yu, L. Gu, B. Ni, D. Wang, X. Wang, Sci. Adv. 2019, 5,
eaax1081.
[30] A. Antonello, C. Benedetti, F. F. Pérez-Pla, M. Kokkinopoulou, K.
Kirchhoff, V. Fischer, K. Landfester, S. Gross, R. Muñoz-Espí, ACS Appl.
Mater. Interfaces 2018, 10, 23174-23186.
[31] J. He, H. Pang, W. Wang, Y. Zhang, B. Yan, X. Li, S. Li, J. Chen, Dalton.
Trans. 2013, 42, 15637-15644.
[32] J. Ettedgui, R. Neumann, J. Am. Chem. Soc. 2009, 131, 4-5.
[33] C. Wang, B. P. Zhou, X. P. Zeng, Y. Y. Hong, Y. B. Gao, W. J. Wen, J.
Mater. Chem. C 2015, 3, 177-186.
[34] G. Haight, V. J. A. C. Paragamian, Anal. Chem. 1960, 32, 642-644.
6
This article is protected by copyright. All rights reserved.

10.1002/anie.202104028
Angewandte Chemie International Edition
RESEARCH ARTICLE
Entry for the Table of Contents
A facile and green polyoxometallate (POM)-assisted hydrothermal carbonization strategy is developed for synthesis of carbonaceous
hybrid nanomaterials with molecularly dispersed POMs and ordered mesopores, which exhibit remarkable catalytic activity toward the
dehydration of tert-butanol.
7
This article is protected by copyright. All rights reserved.