Construction of a Nanoporous Highly Crystalline Hexagonal Boron Nitride from an Amorphous Precursor for Catalytic Dehydrogenation

Article abstract of DOI:10.1002/anie.201904996

Hexagonal boron nitride (h-BN) is regarded as a graphene analogue and exhibits important characteristics and vast application potentials. However, discovering a facile method for the preparation of nanoporous crystalline h-BN nanosheets (h-BNNS) is still a challenge. Herein, a novel and simple route for the conversion of amorphous h-BN precursors into highly crystalline h-BNNS was achieved through a successive dissolution–precipitation/crystallization process in the presence of magnesium. The h-BNNS has high crystallinity, high porosity with a surface area of 347 m² g^?1, high purity, and enhanced thermal stability. Improved catalytic performance of crystalline h-BNNS was evidenced by its much higher catalytic efficiency in the dehydrogenation of dodecahydro-N-ethylcarbazole, compared with its amorphous h-BN precursor, as well as other precious-metal-loaded heterogeneous catalysts.

Full text of DOI:10.1002/anie.201904996

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: A Strategy for Construction of a Nanoporous Highly Crystalline
Hexagonal Boron Nitride from an Amorphous Precursor
Authors: Hao Chen, Zhenzhen Yang, Zihao Zhang, Zitao Chen,
Miaofang Chi, Song Wang, Jie Fu, and Sheng Dai
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.201904996
Angew. Chem. 10.1002/ange.201904996
Link to VoR: http://dx.doi.org/10.1002/anie.201904996
http://dx.doi.org/10.1002/ange.201904996

10.1002/anie.201904996
Angewandte Chemie International Edition
COMMUNICATION
A Strategy for Construction of a Nanoporous Highly Crystalline
Hexagonal Boron Nitride from an Amorphous Precursor
Hao Chen, Zhenzhen Yang*, Zihao Zhang, Zitao Chen, Miaofang Chi, Song Wang, Jie Fu* and Sheng
Dai*
Abstract: Hexagonal boron nitride (h-BN) is regarded as a graphene
analogue and exhibits important characteristics and vast application
potentials. However, discovering a facile methodology for the
preparation of nanoporous crystalline h-BN nanosheets (h-BNNS) is
still a challenge. Herein, a novel and simple protocol for the
conversion of amorphous h-BN precursors to highly crystalline h-
different structural characteristics, such as size, surface area,
thickness, crystal phase, defects, vacancies, etc.[2, 8-10]
To date, Hermans et al. reported that bulk h-BN and boron nitride
nanotubes (BNNT) exhibited unique and highly efficient catalytic
properties for the oxidative dehydrogenation of propane, resulting in
great selectivity to olefins (79% propene and 12% ethene at 14%
12]
BNNS was achieved through
a
successive dissolution-
propane conversion).[11,
Although both bulk h-BN and BNNT
precipitation/crystallization process in the presence of magnesium.
The fabricated h-BNNS exhibited high crystallinity and high porosity
with a surface area of 347 m2 g-1, high purity, and enhanced thermal
stability. Improved catalytic performance of crystalline h-BNNS was
evidenced by its much higher catalytic efficiency in the
dehydrogenation of dodecahydro-N-ethylcarbazole, compared with its
amorphous h-BN precursor, as well as other precious metal loaded
heterogeneous catalysts. This work provides new insight into the
fabrication of nanoporous crystalline h-BNNS, expanding its
application in the field of energy storage and transformation.
exhibited analogous product distributions, BNNT showed a rate of
propane consumption more than one order of magnitude higher than
that of h-BN, partially because of the higher surface area of BNNT (97
m2 g-1) relative to bulk h-BN (16 m2 g-1), and thus a superior mass
transfer effect during the catalytic process. The thickness of the h-BN
materials (bulk vs. few layered) also had a significant effect on their
properties. Generally, few layered h-BNNS are preferred, which are
mostly prepared via either a solid-phase mechanical method[13] or
15]
liquid-phase exfoliation.[14,
Our group previously presented an
efficient strategy for the scalable synthesis of few-layered h-BNNS
using a gas exfoliation of bulk h-BN in liquid N2.[16] However, the final
few-layered h-BNNS obtained through these approaches often suffer
from low surface areas or amorphous/low crystalline structures.[15, 17]
Compared with amorphous materials, their highly crystalline
counterparts have ordered structures and fewer defects, thus leading
to enhanced performance in optoelectronics and catalysis,[18] as
shown by the significant development of crystalline metal–organic
framework (MOF) nanosheets,[19] and 2D covalent organic
frameworks (COFs).[20] In addition, the high crystallinity makes their
structures easier to be determined by using powder X-ray diffraction
(PXRD) and high-resolution transmission electron microscopy (HR-
TEM). Up to now, the lack of a controlled synthesis of quality h-BN
samples largely prevented the full potential of h-BN nanostructures
from being realized. Therefore, the development of novel and simple
synthetic methodologies for the fabrication of crystalline few-layered
h-BNNS with a high surface area would propel further advancement
in this field, despite still being a challenging task.
Two-dimensional (2D) nanomaterials have been the subject of much
research since the discovery of mechanically exfoliated graphene with
extraordinary physical and chemical properties.[1-5] Hexagonal boron
nitride (h-BN) has a layered honeycomb-like structure similar to that
of graphite, consisting of alternating B and N atoms. A single-layer h-
BN nanosheet (h-BNNS) can be regarded as a graphene analogue,
which is commonly known as the "white graphene". h-BN structures
are characterized by their excellent thermal and chemical stability,
and unique electronic and optical properties, which are widely applied
in the field of energy storage and transformation.[2, 6, 7] Generally, their
properties/functionality can vary tremendously depending on their
[a]
Dr. H. Chen, Dr. J. Fu, Z. Zhang
Key Laboratory of Biomass Chemical Engineering of Ministry of
Education, College of Chemical and Biological Engineering
Zhejiang University, Hangzhou, 310027, China.
E-mail: jiefu@zju.edu.cn
We hypothesized whether it was possible to construct highly
crystalline and porous h-BNNS from amorphous h-BN. Recently, this
protocol was utilized in the conversion of amorphous covalent organic
polymers (COPs) to COFs of high crystallinity and porosity by
replacing the linkers.[21] Herein, a novel strategy was developed for
the successful transformation of amorphous bulk h-BN to h-BNNS
with high crystallinity and porosity, which was fully characterized by
[b]
[c]
Dr. Z. Yang, Dr. H. Chen, Dr. S. Dai
Chemical Sciences Division, Oak Ridge National Laboratory, Oak
Ridge, TN 37831, United States.
E-mail: dais@ornl.gov
Dr. Z. Yang, Dr. H. Chen, Dr. S. Dai
Department of Chemistry, The University of Tennessee, Knoxville,
TN, 37996, United States.
E-mail: zyang17@utk.edu
powder
X-ray diffraction (PXRD), microscopy and N2
adsorption/desorption isotherms. The essence of this strategy lies in
the successive dissolution-precipitation/crystallization of amorphous
h-BN precursor in the presence of magnesium (Mg) (Figure 1A). The
produced crystalline h-BNNS consisted primarily of thin layers in a
high mass yield of 88%. The N2 sorption and desorption isotherm
exhibited a surface area of 347 m2 g-1 and total pore volume of 0.41
cm3 g-1 with a pore size distribution dominated by mesopores. The
[d]
[e]
S. Wang
Department of Chemistry, University of California, Riverside,
California 92521, United States.
Z. Chen, M. Chi
Center for Nanophase Materials Sciences, Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37831, United States
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/anie.201904996
Angewandte Chemie International Edition
COMMUNICATION
enhanced structure patterns and thermal stability render it as an
efficient catalyst in the dehydrogenation of dodecahydro-N-
ethylcarbazole, exhibiting a much higher catalytic efficiency compared
with the amorphous h-BN precursor, as well as other precious metal
loaded heterogeneous catalysts reported previously.
interplanar distance of 3.5 Å. Other relatively weaker diffraction peaks
at 2θ = 41.88, 42.93 ,44.46 and 54.08 degrees are assigned to (100),
(101), (002), and (004) crystal planes, respectively, suggesting the
formation of highly crystalline h-BN with an extended/ordered stacking
in the c direction.[27] These results confirm that this method can
effectively transform the bulk amorphous precursor into highly
crystalline h-BN.
In order to illustrate the morphological change after treatment with
Mg, scanning electron microscopy (SEM) images of the parent bulk
amorphous h-BN and obtained crystalline h-BN are shown in Figure
2A and 2B. The bulky h-BN precursor is mainly composed of big
blocks containing randomly packed layers of large lateral size and
thickness (>3.5 µm). Comparatively, the crystalline h-BN
demonstrates a petaloid flakes morphology of much smaller lateral
size (≈200 nm) with a thickness of about 12.9 nm. Meanwhile,
transmission electron microscopy (TEM) images of the h-BN
precursor and the crystalline h-BN also exhibit distinct differences.
Figure 2D shows that the crystalline h-BN has a transparent and
overlapped flat structure, whereas the parent amorphous h-BN has a
bulky and opaque structure with numerous wrinkles and crimps, as
shown in Figure 2C, which provides clear evidence that the bulky h-
BN precursor is reorganized into sheet-like patterns. In the region of
higher contrast in Figure 2D, the curved edge can be seen and the
thickness of one sheet-like structure is found to be approximately 13.1
nm, consistent with the thickness measured in the SEM image. Figure
2E and 2F are an enlarged selective area of Figure 2C and 2D,
respectively. HR-TEM images of the parent h-BN precursor showed
no lattice fringes, while HR-TEM images of the crystalline h-BN
exhibited one set of lattice fringes with a spacing of 0.35 nm,
corresponding to the (002) plane of the six-fold symmetry of h-BN.
Given that the thickness of a single-layered h-BN is about 0.4-0.5
nm,[28] the observation suggests that the as-prepared crystalline h-
BNNS consists about 15~20 atomic layers in each sheet. The electron
diffraction pattern suggests the amorphous structure of the h-BN
precursor (Figure 2G) and the typical six-fold symmetry structure of
the obtained crystalline h-BNNS (Figure 2H and 2I).
Figure 1. (A) The general strategy used in this work for the conversion of
amorphous h-BN to crystalline h-BNNS. (B) PXRD patterns of the bulk h-BN
precursor and (C) the obtained crystalline h-BNNS.
The amorphous h-BN precursor was first synthesized according to
a previously reported procedure with boric acid and urea (molar ratio
1:24) as the reactants, which was calcined at 900 oC for 2 h under N2
atmosphere (for details, see Supporting Information).[22] The PXRD
pattern of the bulk h-BN samples (Figure 1B) showed only one broad
tiny diffraction peak at 2θ = 42.5 degrees, which was indexed at (100)
planes of h-BN, and no obvious diffraction (002) peak at 2θ = 27.0
degree was observed, indicating almost no crystallinity of the h-BN
precursor. It is well known that catalysts such as metal elements,
oxides, and salts, can significantly lower the graphitization
temperature of soft carbons and enable the graphitization of hard
carbons.[23, 24] Our group has reported a simple electrochemical route
for the graphitization of amorphous carbons through cathodic
polarization in molten CaCl2, and the resultant nanostructured
graphite exhibited good performance as a superior cathode material
for batteries.[25] In this work, a crystallization strategy was adopted for
the transformation of h-BN material in the presence of molten metals.
Magnesium was selected as the reagent used to treat the amorphous
h-BN precursor, considering its appropriate melting point (650 oC) and
good performance in the fabrication of crystalline graphite powder
from renewable hard carbon precursors.[26] The recrystallization
process is illustrated in Figure 1A. The h-BN precursor was first mixed
with Mg powder, and then the mixture was sealed in stainless-steel
The Fourier transform infrared (FTIR) spectra of the raw h-BN
material and the crystalline h-BNNS are shown in Figure S1. In the
original h-BN, two characteristic peaks are observed at about 1323.5
cm-1 and 798.1 cm-1, which are attributed to in-plane B-N stretching
vibrations and out of plane bending, respectively. After
recrystallization, the two peaks showed a slight blueshift to 1341.7 cm-
1
and 807.7 cm-1, respectively, owing to the ordered pattern and
connection of the hexagonal structure within the h-BN framework, as
well as perhaps a composition change after treatment by Mg. Further
X-ray photoelectron spectroscopy (XPS) analysis was conducted to
gain more information on the surface structure change of the h-BN
(Figure S2). In the h-BN precursor, the main peaks with a binding
energy (BE) of 190.8 eV in the B1s and 398.5 eV in the N1s
correspond to B-N bonds. In addition, the B-O bond with BE=192.3
eV and N-C bond with BE=400.1 eV are also exhibited within the h-
BN framework, and are in close agreement with the reported data.[13]
Comparatively, the crystalline h-BNNS after treatment by Mg powder
only showed a signal of B-N bonds with BE=190.3 eV in B1s and
BE=397.9 eV in N1s, indicating that most of the residual carbon and
oxygen elements from the starting materials were further removed
during the heating process through combination with Mg, resulting in
high-purity h-BN. The removal of oxygen atoms during the
recrystallization process is also evidenced by the magic angle
o
tubes and treated at 900 C under N2 atmosphere (for details, see
Supporting Information). After removing the Mg by washing,
crystalline h-BN was obtained with a yield of 88 % by weight. The
atomically precise periodic architecture of the obtained h-BN was
investigated by PXRD, and these data match well with a typical
hexagonal structure of h-BN (JCPDS card no. 01-073-2095).[2]
A
strong diffraction (002) peak at 2θ = 26.41 degrees corresponds to the
This article is protected by copyright. All rights reserved.

10.1002/anie.201904996
Angewandte Chemie International Edition
COMMUNICATION
spinning (MAS) 11B solid-state NMR spectroscopy (Figure S3). In the
11B spectra of the h-BN precursor, an obvious signal for BO3 is shown
at -0.72 ppm, which disappears in the crystalline h-BNNS. Both the h-
BN precursor and the crystalline h-BNNS exhibited 11B signals at 10.2
ppm and 26.1 ppm, which is attributed to the BN3 structure.[29]
Although h-BN generally exhibited high thermal stability considering
its fabrication process performing at high temperature under N2,
inevitable residual carbon and oxygen elements within the backbone
will lead to decreased thermal stability under air. Thermogravimetric
analysis (TGA) of the h-BN precursor showed a weight loss beginning
at 260 oC under air (Figure S4), probably caused by the loss of carbon
atoms, with the weight loss reaching ~30 wt% up to 800 oC. A further
increase in temperature led to a slight increase in the sample weight
due to the combination of boron in BN2 or BN units with oxygen atoms
in the air. Comparatively, only a slight weight loss in the crystalline h-
BNNS was observed from 520 oC (<10 wt%), demonstrating its
enhanced thermal stability.
suggesting the coexistence of micro- and mesopores. Based on the
calculated result of the non-local density functional theory method
(NLDFT), it was clear that micropores around 1.06-1.92 nm in size
and mesopores with pore diameters in the range of 2-13.5 nm were
present. The Brunauer–Emmett–Teller (BET) surface area of the
crystalline h-BN was estimated to be 347 m2 g-1, owing to the high
surface area of the amorphous precursor (Figure S5 D~F), with a total
pore volume of 0.41 m3 g-1. Notably, mesopores played a dominant
role in the pore structure, contributing ~99% of the total pore volume
(Vmicro=0.0085 cm3 g-1, calculated using the t-plot method). For
catalytic or adsorptive materials, this high surface area can enhance
their reactivity due to an improved mass transfer effect. The result
further suggested that the method developed in this work is highly
efficient in generating few-layered nanoporous crystalline h-BNNS of
high purity, high surface area and high thermal stability.
Encouraged by the above results, we conducted time-dependent
experiments to gain better insight into the transformation of
amorphous h-BN to crystalline h-BN. As shown in Figure 3A, PXRD
results of the materials obtained at different calcination times
indicated that the long-rang ordering of h-BN already occurred when
the reaction time reached 40 min, and the crystallinity of h-BNNS
gradually increased from 20 min to 60 min. Heat treatment
temperatures are also very critical to the recrystallization of the h-BN
precursor. As mentioned above, crystalline h-BNNS can be obtained
at a calcination temperature of 900 oC. Under otherwise identical
treatment conditions, the h-BN samples obtained at calcination
temperatures of 800 oC and 1000 oC led to amorphous materials, as
shown by the PXRD patterns (Figure 3B). The SEM images showed
o
that h-BN obtained at 800 C were still big blocks with thick layers
(Figure S6), somewhat like the h-BN precursor, while h-BN obtained
at 1000 oC became bulky particles. This indicated that the appropriate
temperature is needed for the solubilization of h-BN in molten Mg, but
too high a temperature led to the shrinkage of the h-BN skeleton. The
PXRD results also showed that a short reaction time (20 min) or low
heating temperature led to a small amount of carton nitride (JCPDS
card no. 50-0664) formation within the obtained h-BN samples. As
previously reported, dissolution-precipitation mechanism and
formation-decomposition of carbide intermediate mechanism have
been proposed to explain the graphitization process in the presence
of metal catalysts.[26, 30] Considering the the high thermal stability of h-
BN (up to 2800 oC) under N2,[31] the recrystallization process of h-BN
in this work was estimated to proceed through a dissolution-
precipitation mechanism.
Figure 2. (A) SEM image of the bulk h-BN precursor and (B) crystalline h-BNNS.
(C, E) (HR)-TEM image of h-BN precursor and (D, F) crystalline h-BNNS. (G)
Electron diffraction pattern of h-BN precursor and (H) crystalline h-BNNS. (I)
Hexagonal structure of h-BN. The inset images magnify selected regions. Scale
bar 100 nm for (A~D), 20 nm for (E, F), 5 1/nm for (G) and 10 1/nm for (H).
The permanent porosity of crystalline h-BNNS was measured by N2
adsorption/desorption analysis at 77 K (Figure S5). The N2 sorption
isotherms exhibited combined features of type I and type IV with two
evident steep steps in the regions of P/P0=0-0.01 and 0.80-0.98,
Figure 3. PXRD patterns of h-BN obtained at (A) different calcination time and
(B) different heating temperature.
This article is protected by copyright. All rights reserved.

10.1002/anie.201904996
Angewandte Chemie International Edition
COMMUNICATION
Handling hydrogen in chemically bound form as liquid organic
hydrogen carriers (LOHCs) supports concept that a future hydrogen
economy may work without the need to handle large amounts of
elemental hydrogen.[32-34] But the realization of this future economy
relies on the development of a highly efficient catalytic system for the
reversibility and high selectivity of LOHC,[35] especially the N-
ethylcarbazole (NEC) and dodecahydro-N-ethylcarbazole (12H-NEC)
cycle systems.[36] However, even after decades of research, the
unsatisfactory performance obtained using high doses of precious-
metal dehydrogenation catalysts and the required high reaction
In conclusion, we have developed a novel strategy used to construct
highly crystalline nanoporous h-BNNS through the transformation of
amorphous h-BN precursors in the presence of Mg. The as-prepared
h-BNNS are characterized by high crystallinity, high purity, high
porosity and high thermal stability. These desirable structural patterns
and properties render enhanced catalytic efficiency and potential
application of h-BNNS in the dehydrogenation of LOHC as metal-free
catalyst under mild conditions. This protocol could also dramatically
expand the scope of convenient preparation of crystalline h-BN and
its utilization in energy storage and conversion.
temperatures has proven to be
a
bottleneck (Table S1).[34]
Considering the highly efficient catalytic activity of h-BN in oxidative
dehydrogenation of propane (ODHP) for olefin production,[11, 12, 37, 38]
we envisioned that the crystalline nanoporous h-BNNS obtained in
this study could act as an efficient metal-free catalyst for the
dehydrogenation of 12H-NEC. Indeed, taking NEC-12H as a model
substrate (Figure 4), a 74% yield of NEC was obtained using the as-
prepared crystalline h-BNNS as the catalyst at a low reaction
temperature (120 oC). Notably, this yield is much higher than that
obtained by the bulk amorphous h-BN (NEC yield: 40%),
commercialized h-BN (NEC yield: 10%) as well as Pd/C (NEC yield:
5.2%) under the same conditions. The enhanced catalytic activity of
crystalline h-BNNS is also observed in the dehydrogenation of
Acknowledgements
The research was supported financially by the Division of
Chemical Sciences, Geosciences, and Biosciences, Office of
Basic Energy Sciences, US Department of Energy. J.F. was
supported by the National Natural Science Foundation of China
(No. 21436007, 21706228), the Zhejiang Provincial Natural
Science Foundation of China (No. LR17B060002). The TEM
imaging part of this research was completed at the Center for
Nanophase Materials Sciences, which is a DOE Office of Science
User Facility. This manuscript has been authored by UT-Battelle,
LLC, under contract DE-AC05-00OR22725 with the US
Department of Energy (DOE). The US government retains and
the publisher, by accepting the article for publication,
acknowledges that the US government retains a nonexclusive,
paid-up, irrevocable, worldwide license to publish or reproduce
the published form of this manuscript, or allow others to do so, for
US government purposes. DOE will provide public access to
these results of federally sponsored research in accordance with
the DOE Public Access Plan (http://energy.gov/downloads/doe-
public-access-plan).
dodecahydro-N-propylcarbazole (12H-NPC) with
a yield of N-
propylcarbazole (NPC) as 63% (crystalline h-BNNS) and 36%
(amorphous h-BN). Notably, the catalytic efficiency of h-BNNS is
much higher than that of Pd-, Pt-, Ru-loaded heterogeneous catalysts
previously reported (Table S1). According to the previously reported
39]
literatures,[11,
the dehydrogenation process of 12H-NEC is
proposed to include the adsorption of 12H-NEC on the B sites,
cleavage of the C-H bond and formation of H2 gas. We proposed that
the synergistic effect of the nanoporous structure (beneficial to mass
transport) and highly ordered crystalline pattern of h-BNNS (exposure
of more B sites) plays crucial role in achieving this superior
dehydrogenation performance.
Keywords: boron nitride • boron nitride nanosheet • crystallinity
• magnesium • dehydrogenation
[1]
[2]
K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V.
Dubonos, I. V. Grigorieva, A. A. Firsov, Science 2004, 306, 666.
C. Tan, X. Cao, X.-J. Wu, Q. He, J. Yang, X. Zhang, J. Chen, W. Zhao,
S. Han, G.-H. Nam, M. Sindoro, H. Zhang, Chem. Rev. 2017, 117, 6225-
6331.
[3]
[4]
X. Huang, X. Qi, F. Boey, H. Zhang, Chem. Soc. Rev. 2012, 41, 666-686.
F. K. Kessler, Y. Zheng, D. Schwarz, C. Merschjann, W. Schnick, X.
Wang, M. J. Bojdys, Nat. Rev. Mater. 2017, 2, 17030.
A. Savateev, I. Ghosh, B. König, M. Antonietti, Angew. Chem. Int. Ed.
2018, 57, 15936-15947.
[5]
[6]
[7]
[8]
Q. Weng, X. Wang, X. Wang, Y. Bando, D. Golberg, Chem. Soc. Rev.
2016, 45, 3989-4012.
Q. Li, L. Chen, M. R. Gadinski, S. Zhang, G. Zhang, H. U. Li, E. Iagodkine,
A. Haque, L.-Q. Chen, T. N. Jackson, Q. Wang, Nature 2015, 523, 576.
W. Zhu, Z. Wu, G. S. Foo, X. Gao, M. Zhou, B. Liu, G. M. Veith, P. Wu,
K. L. Browning, H. N. Lee, H. Li, S. Dai, H. Zhu, Nat. Commun. 2017, 8,
15291.
[9]
P. Wu, S. Yang, W. Zhu, H. Li, Y. Chao, H. Zhu, H. Li, S. Dai, Small 2017,
13, 1701857.
Figure 4. Comparison of the catalytic efficiency of various catalysts including
the crystalline h-BNNS for the dehydrogenation of 12H-NEC.
[10] Y. Kubota, K. Watanabe, O. Tsuda, T. Taniguchi, Science 2007, 317,
932-934.
[11] J. T. Grant, C. A. Carrero, F. Goeltl, J. Venegas, P. Mueller, S. P. Burt,
S. E. Specht, W. P. McDermott, A. Chieregato, I. Hermans, Science 2016,
354, 1570-1573.
This article is protected by copyright. All rights reserved.

10.1002/anie.201904996
Angewandte Chemie International Edition
COMMUNICATION
[12] A. M. Love, B. Thomas, S. E. Specht, M. P. Hanrahan, J. M. Venegas,
S. P. Burt, J. T. Grant, M. C. Cendejas, W. P. McDermott, A. J. Rossini,
I. Hermans, J. Am. Chem. Soc. 2019, 141, 182-190.
[27] W. Lei, V. N. Mochalin, D. Liu, S. Qin, Y. Gogotsi, Y. Chen, Nat. Commun.
2015, 6, 8849.
[28] L. H. Li, J. Cervenka, K. Watanabe, T. Taniguchi, Y. Chen, ACS Nano
2014, 8, 1457-1462.
[13] S. Chen, R. Xu, J. Liu, X. Zou, L. Qiu, F. Kang, B. Liu, H.-M. Cheng, Adv.
Mater. 2019, 31, 1804810.
[29] C. Gervais, J. Maquet, F. Babonneau, C. Duriez, E. Framery, M. Vaultier,
P. Florian, D. Massiot, Chem. Mater. 2001, 13, 1700-1707.
[30] A. Ōya, H. Marsh, J. Mater. Sci. 1982, 17, 309–322.
[31] J. Yin, J. Li, Y. Hang, J. Yu, G. Tai, X. Li, Z. Zhang, W. Guo, Small 2016,
12, 2942-2968.
[14] A. Pakdel, Y. Bando, D. Golberg, Chem. Soc. Rev. 2014, 43, 934-959.
[15] J. Yin, J. Li, Y. Hang, J. Yu, G. Tai, X. Li, Z. Zhang, W. Guo, Small 2016,
12, 2942-2968.
[16] W. Zhu, X. Gao, Q. Li, H. Li, Y. Chao, M. Li, S. M. Mahurin, H. Li, H. Zhu,
S. Dai, Angew. Chem. Int. Ed. 2016, 55, 10766-10770.
[17] P. Wu, W. Zhu, Y. Chao, J. Zhang, P. Zhang, H. Zhu, C. Li, Z. Chen, H.
Li, S. Dai, Chem. Commun. 2016, 52, 144-147.
[32] E. Gianotti, M. Taillades-Jacquin, J. Rozière, D. J. Jones, ACS Catal.
2018, 8, 4660-4680.
[33] U. Eberle, M. Felderhoff, F. Schüth, Angew. Chem. Int. Ed. 2009, 48,
6608-6630.
[18] M. Liu, K. Jiang, X. Ding, S. Wang, C. Zhang, J. Liu, Z. Zhan, G. Cheng,
B. Li, H. Chen, S. Jin, B. Tan, Adv. Mater. 2019, e1807865.
[19] M. Zhao, Y. Huang, Y. Peng, Z. Huang, Q. Ma, H. Zhang, Chem. Soc.
Rev. 2018, 47, 6267-6295.
[34] P. Preuster, C. Papp, P. Wasserscheid, Acc. Chem. Res. 2017, 50, 74-
85.
[35] D. Teichmann, K. Stark, K. Müller, G. Zöttl, P. Wasserscheid, W. Arlt,
Energy Environ. Sci. 2012, 5, 9044-9054.
[20] C. S. Diercks, O. M. Yaghi, Science 2017, 355, eaal1585.
[21] Z. Miao, G. Liu, Y. Cui, Z. Liu, J. Li, F. Han, Y. Liu, X. Sun, X. Gong, Y.
Zhai, Y. Zhao, Y. Zeng, Angew. Chem. Int. Ed. 2019, DOI:
10.1002/anie.201813999.
[36] M. C. Williams, J. P. Strakey, W. A. Surdoval, J. Power Sources 2005,
143, 191-196.
[37] J. Tian, J. Tan, M. Xu, Z. Zhang, S. Wan, S. Wang, J. Lin, Y. Wang, Sci.
Adv. 2019, 5, eaav8063.
[22] J. Xiong, W. Zhu, H. Li, W. Ding, Y. Chao, P. Wu, S. Xun, M. Zhang, H.
Li, Green Chem. 2015, 17, 1647-1656.
[38] Y. Wang, W.-C. Li, Y.-X. Zhou, R. Lu, A.-H. Lu, Catal. Today 2018,
https://doi.org/10.1016/j.cattod.2018.1012.1028.
[39] F. Sotoodeh, K. J. Smith, J. Catal. 2011, 279, 36-47.
[23] A. Ōya, S. Ōtani, Carbon 1979, 17, 131-137.
[24] A. Oberlin, Carbon 1984, 22, 521-541.
[25] J. Peng, N. Chen, R. He, Z. Wang, S. Dai, X. Jin, Angew. Chem. Int. Ed.
2017, 129, 1777-1781.
[26] L. Zhao, X. Zhao, L. T. Burke, J. C. Bennett, R. A. Dunlap, M. N. Obrovac,
ChemSusChem 2017, 10, 3409-3418.
This article is protected by copyright. All rights reserved.

10.1002/anie.201904996
Angewandte Chemie International Edition
COMMUNICATION
Entry for the Table of Contents
COMMUNICATION
Hao Chen, Zhenzhen Yang*, Zihao
Zhang, Zitao Chen, Miaofang Chi, Song
Wang, Jie Fu* and Sheng Dai*
Page No. – Page No.
A Strategy for Construction of a
Nanoporous Highly Crystalline
Hexagonal Boron Nitride from an
Amorphous Precursor
Highly crystalline nanoporous hexagonal boron nitride nanosheets (h-BNNS) were
fabricated using amorphous h-BN precursors through a successive dissolution-
precipitation/crystallization process in the presence of magnesium.
This article is protected by copyright. All rights reserved.