Angewandte
Chemie
DOI: 10.1002/anie.201301069
Nanomaterials
Improving Hydrothermal Carbonization by Using Poly(ionic liquid)s**
Pengfei Zhang, Jiayin Yuan,* Tim-Patrick Fellinger, Markus Antonietti, Haoran Li, and
Yong Wang*
Functional carbonaceous materials with high specific surface
areas and controllable structural compositions have been an
appealing topic in recent years, owing to their wide applica-
Herein, we report an improvement of HTC through
template-free poly(ionic liquid)s (PILs) assisted structure
formation, a facile yet efficient process to prepare nano-
[
1]
tions in various fields. So far, a number of well-known
synthetic methods including thermal pyrolysis of organic
structured porous nitrogen-doped carbon materials (S
up
BET
2
À1
to 572 m g ) from inexpensive, harmless, and naturally
available sugars by HTC at 160–2008C, followed by a post-
synthesis heating treatment. PILs are surface-active and
multifunctional polyelectrolytes made up of ionic liquid (IL)
[
2a]
[2b]
[2c]
compounds, high-voltage-arc electricity, laser ablation,
[
2d]
and chemical vapor deposition, have been developed for
the preparation of carbon materials with different sizes,
shapes, and chemical compositions. Nowadays, energy and
sustainability issues are seriously considered when designing
synthetic strategies. The recently rediscovered environmen-
tally friendly and facile hydrothermal carbonization (HTC)
procedure offers new perspectives, as it involves the use of
renewable resources (e.g., cellulose) at low temperatures
[
5]
repeating units joined in a polymer chain. Although the
originally designed role of PILs here was only to effectively
stabilize the primary carbon nanoparticles formed by HTC,
their unexpectedly versatile properties were quickly recog-
nized and enabled the formation of more diverse products.
For example, this approach was successfully coupled with
metal salts to directly produce novel porous nanohybrids
(
130–2508C) in aqueous medium under self-generated pres-
[3]
2
À1
sure. Materials prepared by this straightforward water-
based method are commonly nonporous and have unfavor-
ably low surface areas (< 20 m g ).
(SBET up to 255 m g ) of Au–Pd core-shell nanoparticles
trapped in N-doped carbon materials, which served as active
and highly recyclable (reused forty times) catalysts for the
selective semihydrogenation of phenylacetylene under mild
2
À1 [3a]
To induce pore
formation, both hard- and soft-templating strategies, and
some other efficient techniques (such as the use of metal salts
or protein additives) have been recently introduced into the
reaction conditions (808C, H 1 atm).
2
HTC of d-fructose and d-glucose was performed at 160–
2008C in the presence of different ILs and PILs (Figure 1).
The products are denoted as Fru-PILa-1.2@160, etc., where
[
4]
HTC process. For example, a novel borax-mediated HTC
method was reported to produce aerogel materials that have
similarities to the traditional resorcinol–formaldehyde-based
[4i]
organic aerogels. Considering practical applications, HTC
carbonaceous materials with not only porous nanostructures
but also more specific features (e.g., heteroatom or metal
nanoparticle doping) are highly desirable and of great
potential, in particular for catalysis.
[*] P. F. Zhang, Prof. Dr. H. R. Li, Prof. Dr. Y. Wang
ZJU-NHU United R&D Center
Key Lab of Applied Chemistry of Zhejiang Province
Department of Chemistry
Zhejiang University
Hangzhou 310028 (P. R. China)
E-mail: chemwy@zju.edu.cn
Homepage: http://mypage.zju.edu.cn/chemwy
Figure 1. Synthetic route to porous nitrogen-doped carbon nanostruc-
tures by a HTC-PILs protocol.
Dr. J. Yuan, Dr. T.-P. Fellinger, Prof.Dr. M. Antonietti
Abteilung Kolloidchemie
Max-Planck-Institut fꢀr Kolloid- und Grenzflꢁchenforschung
Golm, Potsdam 14424 (Germany)
E-mail: Jiayin.Yuan@mpikg.mpg.de
PILa-1.2 corresponds to the type and amount (g) of additive
per 9 g of sugar and the last number, in this case 160, denotes
the carbonization temperature. Figure 2, Figure S1, and Fig-
ure S2 show the scanning-electron-microscopy (SEM) micro-
graphs of several HTC carbon materials. The HTC carbon
materials obtained from pure fructose are micrometer sized,
spherical particles (diameter: 2.3 Æ 0.5 mm; Figure 2a). When
0.1–1.2 g of PILb additive is used, the particle size drops
[
**] Financial support from the Joint Petroleum and Petrochemical
Funds of the National Natural Science Foundation of China and
China National Petroleum Corporation (U1162124), Specialized
Research Fund for the Doctoral Program of Higher Education
(
J20130060), the Fundamental Research Funds for the Central
Universities, the Program for Zhejiang Leading Team of S&T
Innovation, and the Partner Group Program of the Zhejiang
University and the Max-Planck Society are greatly appreciated.
Angew. Chem. Int. Ed. 2013, 52, 1 – 6
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
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