Biomass Sucrose-Derived Cobalt@Nitrogen-Doped Carbon for Catalytic Transfer Hydrogenation of Nitroarenes with Formic Acid

Article abstract of DOI:10.1002/cssc.201802163

Fabrication of non-noble metal-based heterogeneous catalysts by a facile and cost-effective strategy for ecofriendly catalytic transfer hydrogenation (CTH) is of great significance for organic transformations. A cobalt@nitrogen-doped carbon (Co@NC) catalyst was prepared from renewable biomass-derived sucrose, harmless melamine, and earth-abundant Co(AcO)₂ as the precursor materials by hydrothermal treatment and carbonization. Co nanoparticles (NPs) were coated with NC shells and uniformly embedded in the NC framework. The as-obtained Co@NC-600 (carbonized at 600 °C) catalyst exhibited excellent catalytic efficiency for CTH of various functionalized nitroarenes with formic acid (FA) as hydrogen donor in aqueous solution. The uniformly incorporated N atoms in the C matrix and the encapsulated Co NPs showed synergistic effects in the CTH reactions. A mechanistic analysis indicated that the protons from FA were activated by Co sites after being captured by N atoms, and then reacted with nitroarenes adsorbed on the surface of the catalysts to generate the corresponding aromatic amines. Moreover, the catalyst showed excellent durability and reusability without obvious decrease in activity even after five reaction cycles. Thus, the study reported herein provides a cost-effective, sustainable strategy for fabrication of biomass-derived non-noble metal-based catalysts for green and efficient catalytic transformations.

Full text of DOI:10.1002/cssc.201802163

Accepted Article
Title: Biomass sucrose derived cobalt@nitrogen-doped carbon for
catalytic transfer hydrogenation of nitroarenes with formic acid
Authors: Man Yuan, Yu Long, Jin Yang, Xiwei Hu, Dan Xu, Yangyang
Zhu, and Zhengping Dong
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: ChemSusChem 10.1002/cssc.201802163
Link to VoR: http://dx.doi.org/10.1002/cssc.201802163
A Journal of
www.chemsuschem.org

10.1002/cssc.201802163
ChemSusChem
1
2
Biomass sucrose derived cobalt@nitrogen-doped carbon for
catalytic transfer hydrogenation of nitroarenes with formic acid
3
4
Man Yuan,[a] Yu Long,[a] Jin Yang,[a] Xiwei Hu,[a] Dan Xu,[a] Yangyang Zhu[a] and Zhengping
Dong*[a]
5
6
[a] College of Chemistry and Chemical Engineering, Gansu Provincial Engineering Laboratory
for Chemical Catalysis, Laboratory of Special Function Materials and Structure Design of the
Ministry of Education, Lanzhou University, Lanzhou 730000, PR China
7
8
9
10
11
12
E-mail address: dongzhp@lzu.edu.cn (Zhengping Dong). Tel: 86 931 8912577.
13 Abstract
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Fabrication of non-noble metal based heterogeneous catalysts via a facile and cost-effective
strategy for eco-friendly catalytic transfer hydrogenation (CTH) is of great significance for
organic transformation. In this study, we prepared a cobalt@nitrogen-doped carbon (Co@NC)
catalyst using renewable biomass-derived sucrose, harmless melamine, and earth-abundant
Co(AcO)2 as the precursor materials via hydrothermal treatment and carbonization. Co
nanoparticles (NPs) were coated with N-doped carbon (NC) shell and uniformly embedded in
the NC framework. The as-obtained Co@NC-600 (carbonized at 600 C) catalyst exhibited
excellent catalytic efficiency for CTH of various functionalized nitroarenes with formic acid
(FA) as hydrogen donor in aqueous solution. The uniformly incorporated N atoms in the C
matrix and the encapsulated Co NPs showed synergistic effects for the CTH reactions. The
mechanistic analysis indicated that the protons from the FA were activated by Co sites after
being captured by N atoms, and then reacted with nitroarenes adsorbed on the surface of the
catalysts to generate corresponding aromatic amines. Moreover, the prepared catalyst showed
excellent durability and reusability without obvious decrease in activity even after five
reaction cycles. Thus, the study reported herein provides a cost-effective, sustainable strategy
for fabrication of biomass-derived non-noble metal based catalysts for green and efficient
catalytic transformations.
1
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
Keywords: Biomass; Co nanoparticles; N-doped carbon; Catalytic transfer hydrogenation;
Nitroarenes
3
4
Introduction
5
6
Aromatic amines are valuable organic intermediates in pharmaceuticals, dyes, and
agrochemicals industries. Generally, aromatic amines can be synthesized through catalytic
reduction or hydrogenation of corresponding nitroarenes.[1-3] In particular, the catalytic
hydrogenation of nitroarenes using supported catalysts is a widely accepted strategy, due to
the easy separation of product and recovery and recyclability of catalyst. Till date, supported
catalysts such as noble metal catalysts, non-noble metal catalysts, and metal-free catalysts
have been reported for catalytic hydrogenation of nitroarenes.[4-8] For example, Doherty et al.
reported phosphine-decorated polymer immobilized ionic liquids stabilized palladium
nanoparticles (NPs) for highly efficient hydrogenation of nitroarenes.[9] Wang et al. fabricated
heterogeneous non-noble metal nickel-molybdenum oxide catalysts supported on ordered
mesoporous silica SBA-15 (Ni-MoO3/CN@SBA-15) that exhibited excellent catalytic activity
for catalytic hydrogenation of nitroarenes with hydrazine hydrate as a hydrogen donor.[10] Li
et al. reported boron and nitrogen (B/N) co-doped graphene-like carbon as an efficient
metal-free catalyst for the hydrogenation of nitroarenes.[11] However, most of the reported
noble metal based catalysts are expensive and not suitable for a large-scale application.
Moreover, the non-noble metal catalysts and metal-free catalysts often need complex
preparation procedure and harsh hydrogenation reaction conditions, including high hydrogen
(H2) pressure and high reaction temperatures. Besides, although molecular H2 as the hydrogen
source is atom-economic; it is explosive and requires strict transportation and storage.[12]
Furthermore, in most of the hydrogenation processes involving H2, functionalized nitroarenes
with reducible functional groups such as halogenated groups and aldehyde group exhibit poor
chemoselectivity.[13, 14]
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
Recently, catalytic transfer hydrogenation (CTH) has attracted significant research interest.
Moreover, CTH with formic acid (FA) as hydrogen source is considered as an alternative to
replace H2 for nitroarenes hydrogenation.[6, 15, 16] FA, as a byproduct from the acidic hydrolysis
2
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
of biomass, is sustainable and renewable.[17] FA possesses advantages such as non-toxic,
high-energy density, and excellent stability that make it suitable for CTH. With respect to
3
specific reactions, there are two competing processes for the decomposition of FA:[18]
HCOOH → H2 + CO2 ····································································· (1)
HCOOH → H2O + CO ····································································· (2)
The catalytic dehydrogenation of FA is a rate controlling step for the release of hydrogen
stored in it. There are many noble metals based catalysts possessing high efficiency for
catalytic decomposition of FA and CTH reactions through process (1).[19-23] In case of
non-noble metal based catalysts, few applications in CTH with FA have been reported
because of the poor tolerance of non-noble metals in acidic environment. These factors hinder
the large-scale application of CTH with FA. Therefore, fabrication of non-noble metal based
catalysts for CTH of nitro-compounds with FA under eco-friendly conditions is very attractive,
but still remains a major challenge.
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Nitrogen-doped carbon materials (NC) have been considered as fascinating supporting
materials for heterogeneous catalysts due to their enhanced chemical and electrical
properties.[24-26] Doping of nitrogen atoms can lead to a slight distortion in the crystal lattice of
the carbon material, thereby causing defects. Moreover, electronegative N as a basic site can
more effectively enrich protons on the surface of NC materials.[27-29] In the past decade,
non-noble metals incorporated into NC materials have not only become an alternative for
noble metal based catalysts in electrocatalysis,[30-32] but also its excellent properties have been
discovered and reported for catalytic hydrogenation.[4, 33-38] For example, Beller’s group
reported the use of nanoscaled iron(III) oxide (Fe2O3) particles surrounded by N-doped
graphene layers for the selective transfer hydrogenation of nitroarenes with hydrazine hydrate
as hydrogen source.[39] Our group also reported a -Fe2O3-modified NC material for CTH of
nitroarenes.[40] Shen et al. reported metal organic frameworks (MOFs)-derived yolk-shell
cobalt (Co@C-N) as highly efficient and recyclable nanocatalysts for oxidation of alcohols in
aqueous slolution.[41] Li’s group reported N-rich carbon-coated Co NPs for base-free aerobic
oxidation of alcohols to esters.[42] All these reported studies confirmed that the incorporated N
atoms in the carbon matrix possess synergistic effects with the non-noble metal NPs for the
catalytic applications. Nonetheless, drawbacks still exist in these reported catalytic systems,
3
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
such as the use of expensive organic ligands, tedious catalyst fabrication procedure,
uneconomical, and emission of organic wastes in the preparation process. In order to avoid
3
these issues, utilization of naturally renewable biomass accompanying earth-abundant
non-noble metals to fabricate NC materials-supported catalysts is a fascinating strategy.
Inspired by the above mentioned considerations, in this study, the earth abundant renewable
biomass sucrose, low-cost melamine, and earth-abundant Co(AcO)2 as the precursor materials
were used, and a N-doped carbon catalyst with embedded Co NPs (Co@NC) was successfully
fabricated for CTH of nitroarenes. The preparation procedure for Co@NC is depicted in
Scheme 1. First, biomass sucrose, melamine, and Co(AcO)2 were hydrothermally treated by a
one-pot procedure. Second, the hydrothermal product was carbonized to obtain the desired
product Co@NC. The Co NPs were embedded in the porous NC framework; therefore, the
corrosion and leaching of Co NPs were effectively avoided. More importantly, the strong
interaction between the Co core and NC shell affected the electronic structures of the NC
shell, and the synergistic effects further promoted the transfer hydrogenation of functionalized
nitroarenes with FA. Thus, the Co@NC catalyst exhibited excellent catalytic performance for
chemoselective CTH of nitroarenes under green reaction conditions. Furthermore, the
as-obtained Co@NC catalyst also showed superior durability and reusability. Therefore, this
study provides a useful platform for constructing non-noble metal based catalysts with
renewable biomass and earth abundant precursor materials for green and sustainable organic
transformations.
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Scheme 1. The preparation procedure of Co@NC catalyst.
23 Experimental
24
25
Chemicals
Sucrose, melamine, Co(AcO)2·4H2O, CoCl2·6H2O, Co(NO3)2·6H2O, ferric acetylacetonate,
4
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
nickel acetylacetonate, and all the nitroarenes were purchased from Aladdin Industrial
Corporation. FA, EtOH, i-PrOH, and ethyl acetate were provided by Sinopharm Chemical
3
Reagent Co., Ltd., China. Deionized water was used throughout the experiment. All
chemicals were used as received without further treatment.
4
5
Preparation of Co@NC
6
Sucrose, melamine, and Co(AcO)2·4H2O with the mass ratio of 1: 1: 0.5 were added into a
100-mL single-necked flask containing deionized water (60 mL) and sonicated for 30 min.
Then, the mixture was transferred to a 100-mL Teflon-lined stainless steel autoclave and
heated at 150 °C for 12 h. After cooling to room temperature, the product was collected by
filtration, washed several times with deionized water, and dried in a vacuum oven at 60 °C for
6 h. Next, the obtained brown powder was transferred to a tube furnace and heated to 600 °C
at a heating rate of 2.5 °C min1 in N2 atmosphere and held for 4 h. After cooling naturally to
room temperature, a black material was obtained and denoted as Co@NC-600. The brown
powder was also calcined at different temperatures such as 400, 500, 700, and 800 °C , and the
corresponding materials obtained were named as Co@NC-400, Co@NC-500, Co@NC-700,
and Co@NC-800, respectively.
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
The detailed preparation procedures for NC, Co@C, Ni@NC, Fe@NC, and Co/AC, are
described in the Supporting Information. Co@NC-600(Cl) and Co@NC-600(NO3) were also
prepared using CoCl2·6H2O and Co(NO3)2·6H2O as metal precursors, respectively.
Catalytic transfer hydrogenation of nitroarenes
Briefly, nitrobenzene (0.5 mmol), Co@NC-600 (40 mg) catalyst, and solvent system
containing ethanol (1 mL) and water (4 mL) were added into a 25-mL two-necked flask. Then,
FA (500 μL) was added into the above mentioned mixture. The entire reaction was performed
under magnetic stirring at 90 °C . The aliquots of reaction samples were collected using a
syringe every one hour, extracted with ethyl acetate after being filtered, and measured by gas
chromatography mass spectrometry (GC-MS, Agilent 5977E) to determine the reaction
conversion and selectivity. After the completion of the reaction, the Co@NC-600 catalyst was
recovered using an external magnet and washed with water, ethyl acetate, and ethanol for next
cycle.
29
30
Characterization
5
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
The morphologies of the as-obtained catalysts, and the size and dispersity of Co NPs in the
samples were characterized by transmission electron microscopy (TEM, Tecnai G20 F30).
3
Over 200 monodispersed Co NPs were investigated to determine the average particle size.
Elemental composition of Co@NC-600 was determined by energy dispersive X-ray
spectroscopy (EDS). Fourier transform infrared (FTIR) spectra were recorded using a Nicolet
FT-170SX instrument. X-ray photoelectron spectroscopy (XPS, Perkin-Elmer PHI-5702) was
used to measure the electronic states of Co, N, and C in the as-obtained catalysts. Powder
X-ray diffraction (XRD) was recorded using a Rigaku D/max-2400 diffractometer with
Cu-Kα radiation, which was used for investigating the crystalline phase structures of the
as-obtained catalysts. A Raman spectrometer (Jobin Yvon Lab Ram HR evolution) was also
employed to analyze the prepared catalyst at room temperature. The surface area, pore
volume, and pore size distribution of Co@NC-600 were measured by Brunauer–Emmett–
Teller (BET, Micromeritics ASAP 2010) analysis. Thermogravimetric analysis (TGA) of the
precursor obtained by hydrothermal treatment was performed using a TA-Q50 equipment
under N2 atmosphere, in which the material was heated from 20 °C to 900 °C at a heating rate
of 10 °C min1. The content of Co in Co@NC samples was determined by inductively
coupled plasma optical emission spectroscopy (ICP-OES, PQ 9000). The magnetic property
of the Co@NC-600 catalyst was measured at room temperature by varying the applied
magnetic field from 20 to 20 kOe by vibrating sample magnetometry (VSM, MicroSense).
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20 Results and discussion
21
22
23
Fig. 1. (a) FTIR spectra of the raw materials, Co@NC precursor and Co@NC-600 (inset:
partial enlargement for FTIR of Co@NC-600); (b) TGA curve of the Co@NC precursor.
6
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
The FTIR spectra of Co@NC-600, the mixture of sucrose/melamine/Co(AcO)2, and
Co@NC precursor obtained by hydrothermal treatment are displayed in Fig. 1a. The band of
3
1651.1 cm-1 in the mixture of sucrose/melamine/Co(AcO)2 is caused by the C=O vibration
present only in Co(AcO)2. It is red shifted to 1721.4 cm1, indicating successful binding of the
Co(AcO)2 to the hydrolysate of sucrose during the hydrothermal treatment. The appearance of
the band at 1616.7 cm1 demonstrates the aromatization of sucrose during hydrothermal
treatment.[43] Furthermore, the stretching vibration peak of -OH at 3567.7 cm1 disappeared
after hydrothermal treatment, which indicated the occurrence of chemical changes in sucrose.
Unlike these changes, many important groups still remained in Co@NC precursor, including
aromatic C=N (1543.8 cm1 and 1436.9 cm1), O–H and N–H (3477.9 cm1 and 3336.8 cm1,
respectively). The IR spectrum of Co@NC-600 indicates that most of the groups of sucrose
and melamine have been pyrolyzed at a carbonization temperature of 600 °C. Moreover, C=C
bond was constructed in NC material, and the characteristic peak emerges at about 1000 cm1.
Noteworthy, the peak at 3405.2 cm1 might be caused by the stretching vibration of O–H
group in water adsorbed on the catalyst. Fig. 1b shows the TGA results of Co@NC precursor,
which is performed to test the thermal pyrolysis and thermal stability. The loss of weight
below 238.4 °C is mainly attributed to the escape of water bound to Co@NC precursor. When
the pyrolysis temperature is further increased, some of the melamine that has not chemically
changed during the hydrothermal process begins to sublimate, and the sublimation continues
from 238.4 °C to 279.2 °C. With the further increase in the pyrolysis temperature, the
decrease in weight of the precursor materials gradually approaches an approximate linear
stage (from 380 °C to 900 °C ). In the linear stage, the decrease in mass is due to the pyrolysis
of Co@NC precursor material and further pyrolysis of NC nanosheets. Accordingly, the
investigation of the different carbonization temperatures for Co@NC was also based on the
linear range.
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
7
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
3
4
5
6
7
Fig. 2. TEM images of NC-600 (a), Co@NC-400 (b), Co@NC-500 (c), Co@NC-600 (d),
Co@NC-700 (e) and Co@NC-800 (f) (insets: the Co NPs size distribution histograms); (g)
HRTEM images of Co@NC-500, Co@NC-600, Co@NC-700 and Co@NC-800; (h)
elemental mapping images of the Co@NC-600.
8
9
The morphologies of the as-obtained samples were characterized by TEM (Fig. 2). Fig. 2a
shows that the NC-600 is a thin pleated nanosheet material. The morphology of Co@NC-600
is almost the same as that of NC-600, which illustrates that the doping of Co does not affect
the morphology of the NC material (Fig. 2d). Fig. 2b displays the TEM image of
Co@NC-400; and Co NPs are hardly observed. It may be attributed that Co2+ is difficult to be
reduced to form Co NPs at a carbonization temperature of 400 °C . As the temperature rises to
500 °C , Co NPs begin to form. A small amount of Co NPs with average diameter of 8.2 nm
can be seen from the TEM image of Co@NC-500 (Fig. 2c). Co NPs are formed in large
amounts and uniformly dispersed in the NC sheets at 600 °C (Fig. 2d). And the average
10
11
12
13
14
15
16
17
18
particle diameter of Co NPs in Co@NC-600 is 10.3 nm. When the catalyst precursor was
8
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
calcined at 700 °C, Co NPs still maintained high dispersion while the particle size became
larger to about 12.9 nm (Fig. 2e). Fig. 2f shows the TEM image of Co@NC-800. Due to the
3
higher carbonization temperature, Co NPs display significant agglomeration with average
particle size of 17.6 nm. Thus, the carbonization temperature affects the morphology of
Co@NC samples and should further affect the CTH of nitroarenes. From the HRTEM images,
it can be observed that Co NPs are wrapped by NC shell in Co@NC-500, Co@NC-600,
Co@NC-700 and Co@NC-800 (Fig. 2g). In addition to Co@NC-500, the lattice fringes of
Co(111) in Co@NC obtained at other carbonization temperatures can be clearly observed.
More importantly, the lattice fringes of graphite carbon surround the periphery of Co NPs,
which suggest that Co NPs are successfully embedded in the NC layer.[44, 45] Elemental
mapping images of Co@NC-600 obviously confirm that Co NPs are uniformly dispersed in
the NC shell (Fig. 2h). Besides, the EDS analysis also demonstrates the existence of Co, C,
and N elements in Co@NC-600 (Fig. S1).
4
5
6
7
8
9
10
11
12
13
14
15
Fig. 3. Wide-range XPS spectra of NC-600 and different Co@NC samples.
9
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
3
Fig. 4. (a) C 1s spectra of NC-600 and different Co@NC samples; (b) N 1s spectra of NC-600
and different Co@NC samples; (c) Co 2p spectra of different Co@NC samples.
4
5
Fig. 3 shows the wide-range XPS spectra of NC-600 and different Co@NC samples. It also
reveals the elemental composition of the prepared materials, which is in accordance with the
EDS results (Fig. S1). The signal of Co 2p is very weak, probably due to the Co NPs were
covered by NC shell. And as the carbonization temperature increases, the signal of N 1s
gradually weakens, which is consistent with the results of elemental analysis (Table S1). Fig.
4a displays the high-resolution C 1s spectra of NC-600 and Co@NC samples calcined at
different temperatures. It can be observed that the appearance of the characteristic signals of
C mainly at 284.6 eV, which indicates that C in all samples mainly exists as C=C bond. And
the weak signals corresponding to C=O and O–C=O bonds confirm the significant pyrolysis
of the oxygen-containing functional groups of the catalyst precursor in the carbonization
process. Notably, the characteristic signals of C=N in NC-600 and different Co@NC samples
can be clearly observed. The high-resolution N 1s spectra of NC-600 and Co@NC samples
are shown in Fig. 4b. It can be clearly observed that three peaks located at 398.1, 399.5 and
400.6 eV, corresponding to pyridinic N, pyrrolic N and graphitic N, respectively. Comparing
6
7
8
9
10
11
12
13
14
15
16
17
18
the spectra of Co@NC-600 and NC-600, the type of N does not change, and the intensity of
10
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
each signal is similar. Interestingly, the intensity of pyrrolic N in different Co@NC is
gradually weakened with the increase of carbonization temperature; and it even disappears at
3
800 °C . In Co@NC-400, the degree of graphitization of the NC layer is very low at the low
carbonization temperature; and there is no graphitic N in Co@NC-400 sample. When the
carbonization temperature rises to 500 °C , graphitization begins to occur and a small amount
of graphitic N is formed. The intensity of graphitic N increases as the carbonization
temperature increases, indicating the N atoms can be easily doped in the carbon frameworks
to form NC nanosheets at high carbonization temperatures. The high-resolution Co 2p spectra
of Co@NC samples are presented in Fig. 4c. Careful analysis of the Co 2p spectrum indicates
the existence of Co0 (778.2 eV), CoxOy or CoCxNy (780.3 eV), and Co–N (781.6eV).[46] At the
carbonization temperature of 400 °C, Co NPs are not formed as also shown in the TEM (Fig.
2b), and metallic Co cannot be detected correspondingly in Co@NC-400. Co@NC-500 with a
small quantity of Co NPs also exhibits weak XPS peak at 778.2 eV. At higher carbonization
temperatures of 600, 700 and 800 °C , more Co2+ is reduced to Co0 or formed the CoxOy or
CoCxNy NPs. Therefore, from the above XPS results, the Co NPs were successfully covered
with NC layer and formed the Co-N species that can be used for CTH of nitroarenes.
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Fig. 5. (a) XRD spectra of NC-600 and different Co@NC samples; (b) Raman spectra of
different Co@NC samples.
21
22
23
24
Fig. 5a shows the XRD patterns of NC-600 and Co@NC samples that calcined at different
temperatures. All samples show characteristic diffraction peaks of carbon at around 26°;
especially for the high carbonization temperature of Co@NC-800, the peak around 26° is
stronger. And in the curve of Co@NC-800, three peaks at 2 = 44.1°, 51.2° and 75.8° can be
11
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
seen, corresponding to the (111), (200), and (220) planes of metallic Co NPs.[47, 48] Comparing
the XRD spectra of different Co@NC samples, the peak at 44.1° has a significant relationship
3
with the carbonization temperature; as the temperature increases, the peak intensity gradually
becomes stronger. Additionally, the peaks of Co(111) plane in Co@NC-400 and Co@NC-500
are very weak. This is because Co NPs have not formed at 400 °C and only a small amount of
NPs are formed at 500 °C as also can be confirmed in TEM images (Figs. 2b and c).
Fig. 5b shows the Raman spectra, which displays that both D (1350 cm1) and G (1587
cm1) peaks change with the calcination temperatures. The values of ID/IG at different
temperatures occur in the following sequence: Co@NC-600 (1.07) > Co@NC-700 (1.06) >
Co@NC-800 (1.00) = Co@NC-500 (1.00) > Co@NC-400 (0.98). The regularity of ID/IG and
carbonization temperature indicates that the defect density increases with increasing
carbonization temperature (Fig. S2). After reaching a maximum value of ID/IG, further
increase of carbonization temperature leads to the increase in the degree of graphitization,
resulting in decrease of ID/IG. Herein, the Co@NC-600 catalyst exhibited a relatively high
value of ID/IG, which implies more defects in the Co@NC-600 that could mostly affect the
catalytic performance. The elemental analysis results of the Co@NC samples obtained under
different calcination temperatures are listed in Table S1. As the calcination temperature
increased from 400 °C to 800 °C, the N content decreased from 15.34% to 2.77%. The
content of N in the Co@NC-600 catalyst was 11.76%. In addition, Co contents measured by
ICP-OES in Co@NC-400, Co@NC-500, Co@NC-600, Co@NC-700, and Co@NC-800 are
7.1%, 8.3%, 9.3%, 10.3% and 11.5%, respectively.
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Nitrogen adsorption–desorption isotherm of Co@NC-600 was measured to study the
surface area, pore size, and pore volume. Fig. 6a exhibits typical type IV isotherm for
Co@NC-600. A hysteresis loop occurs in the medium and high pressure region, and it closes
at relative pressure of P/P0 = 0.4. These characteristics indicate that Co@NC-600 is mainly a
mesoporous structure. The surface area of Co@NC-600 is 342.1 m2 g1. The large surface
area plays a positive role in the catalytic reactions. The pore width distribution of
Co@NC-600 is mainly at 4–5 nm with an average pore width of 4.1 nm (inset of Fig. 6a).
There are also a few larger mesopores with size of 6 to 15 nm, which embody the richness of
the pore size and promote the diffusion of the substrate in Co@NC-600. Magnetism is one of
12
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
3
4
the important properties of Fe, Co, and Ni-based catalysts due to their easy magnetic
recycling. The magnetization of Co@NC-600 is 14.09 emu g1 (Fig. 6b). Fig. 6b inset
demonstrates the magnetic separation of Co@NC-600, exhibiting magnetic recovery
operation.
5
6
7
8
Fig. 6. (a) Nitrogen adsorption/desorption isotherm of Co@NC-600, inset: pore-width
distribution curve of Co@NC-600. (b) Magnetization curve of Co@NC-600, inset: the
magnetic separation of catalyst.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
The catalytic performance of the prepared Co@NC catalysts was investigated by the CTH
of nitrobenzene with FA as a model reaction. The CTH reaction conditions were screened and
listed in Table 1. The Co@NC catalysts obtained at different carbonization temperatures were
tested under same reaction condition (Table 1, entries 1 to 5, and Fig. S3), and showed an
activity order of Co@NC-600 > Co@NC-700 > Co@NC-800 > Co@NC-500 > Co@NC-400,
which is substantially in accordance with the TEM results of the Co@NC samples (Fig. 2);
and also related with the values of ID/IG from Raman analysis (Fig. S2). Aniline cannot be
generated in absence of catalyst (Table 1, entry 6). NC-600 and Co@C-600 exhibited little
catalytic activity for CTH of nitrobenzene with FA (Table 1, entries 7 and 8). The activity
comparison between the Co@NC-600 (Table 1, entry 3) and Co@C-600 (Table 1, entry 8)
confirms that, nitrogen species in the Co@NC-600 catalysts exhibit synergistic catalysis
effect in the CTH of nitrobenzene. Furthermore, the conversion of nitrobenzene decreased
sharply when Co in Co@NC-600 was replaced with Fe and Ni (Table 1, entries 9 and 10, and
Fig. S4). This indicates that Co as active sites in the prepared catalysts played an important
role in catalytic activity for CTH of nitrobenzene with FA. Therefore, the above mentioned
results reveal that both Co and N are important for excellent catalytic activity towards CTH of
13
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
3
4
5
6
7
8
9
nitrobenzene with FA over Co@NC-600.
Entries 11 and 12 in Table 1 indicate that the conversion of nitrobenzene over
Co@NC-600 is better than that over Co@NC-600(Cl) and Co@NC-600(NO3) catalysts. This
might be attributed to the fact that Co(AcO)2 was bound well to the aromatized product of
sucrose in the hydrothermal process, which is also reflected by FTIR (Fig. 1a) spectroscopy
results. Therefore, Co NPs could be immobilized in the NC material with excellent dispersity
during carbonization. However, Co(NO3)2 and CoCl2 could not be well incorporated into the
hydrothermal mixture. Therefore, the catalytic activities of Co@NC-600(Cl) and
Co@NC-600(NO3) were lower than that of Co@NC-600 (Fig. S5).
10
11
Table 1. The optimal reaction conditions screening for CTH of nitrobenzene.
Catalyst, hydrogen source
NO2
NH2
Solvent
12
Hydrogen
donor
FA
Water :
EtOH
2:3
2:3
2:3
2:3
2:3
2:3
2:3
2:3
2:3
2:3
2:3
2:3
4:1
4:1
5:0
4:1
3:2
2:3
1:4
0:5
4:1
4:1
4:1
4:1
Reaction
Reaction
Yieldb
(%)
Entry
Catalysta
temperature (°C )
time (h)
1
2
Co@NC-400
Co@NC-500
Co@NC-600
Co@NC-700
Co@NC-800
-
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
6
6
6
6
6
6
6
6
6
6
6
6
6
6
2
2
2
2
2
2
2
4
4
4
1.7
FA
13.3
99.9
32.4
24.6
trace
0.5
3
FA
4
FA
5
FA
6
FA
7
NC-600
FA
8
Co@C-600
Fe@NC-600
Ni@NC-600
Co@NC-600(Cl)
Co@NC-600(NO3)
Co/AC
FA
0.3
9
FA
7.8
10
11
12
13
14c
15
16
17
18
19
20
21
22
23
24
FA
3.6
FA
18.0
68.9
93.4
trace
87.2
94.4
75.3
26.2
13.5
7.3
FA
FA
Co/AC
FA
Co@NC-600
Co@NC-600
Co@NC-600
Co@NC-600
Co@NC-600
Co@NC-600
Co@NC-600
Co@NC-600
Co@NC-600
Co@NC-600
FA
FA
FA
FA
FA
FA
-
trace
2.73
49.5
99.9
i-PrOH
1atm H2
FA
14
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
25
26
Co@NC-600
Co@NC-600
FA
FA
4:1
4:1
70
50
4
4
42.0
12.2
1
2
3
a 40 mg of catalyst; b Detected by GC-MS; c After one run, recovered by centrifugation since no
magnetism.
4
5
Co/AC did not remain stable when used to catalyze the transfer hydrogenation of
nitrobenzene (Table 1, entries 13 and 14). When Co/AC underwent one reaction cycle, it lost
its activity. It was no longer paramagnetic and could not be magnetically separated (Fig. S6),
which is attributed to the severe loss of bare Co NPs due to acid corrosion of the reaction
system. Different ratios of EtOH and water as solvent system were also tested in CTH of
nitrobenzene with FA (Table 1, entries 15 to 20, and Fig. S7). After the start of the reaction,
the conversion of nitrobenzene in the solvent system (EtOH: water = 1: 4) was the highest at 2
h. However, when only EtOH was used as a solvent, a small amount of nitrobenzene was
converted to aniline. Aniline was not generated without hydrogen donor (Table 1, entry 21).
Entry 22 of Table 1 reveals that the hydrogen donor i-PrOH, which is difficult to decompose
to generate hydrogen, hardly provided H for CTH of nitrobenzene. When H2 was used as the
hydrogen source, the yield of aniline was only 49.5% (Table 1, entry 23). Compared to FA
(Table 2, entry 24), i-PrOH and H2 showed a poor hydrogenation ability for nitrobenzene
hydrogenation under mild reaction conditions (Fig. S8). As expected, higher reaction
temperatures favor the CTH of nitrobenzene over Co@NC-600 (Table 1, entries 24–26, and
Fig. S9). According to these control experiments, the biomass-derived FA could effectively
transfer hydrogenate nitrobenzene to aniline by using the Co@NC-600 catalyst in inexpensive,
nontoxic, and environmentally benign solvent system (EtOH: water = 1: 4).
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Scheme 2. Possible reaction mechanism for CTH of nitrobenzene with FA over Co@NC-600.
15
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
In general, three equivalents of FA are required for CTH of one equivalent nitrobenzene
(Fig. S10a). Moreover, in the above mentioned reaction system, FA as weak acid can
3
dissociate in water to produce H+. Therefore, a possible reaction mechanism for CTH of
nitrobenzene with FA over Co@NC-600 was proposed as shown in Scheme 2.[47, 49, 50]
Noteworthy, base is not required in this reaction system. The proton capture throughout the
catalytic process was performed with N atoms on the surface of Co@NC-600. The
electronegativity of N atom makes it serve as a basic site on the surface of catalyst, thereby
capturing H+ from FA to generate NH+. Moreover, the HCOO is coordinated with Co atoms
to form Co-formate intermediate. Herein, the possible hydrogenation of nitrobenzene is
simplified into four steps. First, when nitrobenzene diffuses and adsorbs onto the H-enriched
surface of Co@NC-600, one of O atoms in nitro group combines with H+ to form O–H, while
electropositive N of nitrobenzene reacts with Co-formate intermediate to form N–H. The
reaction intermediate should be Ph–N+(OH)H–O with the release of one molecule of carbon
dioxide (CO2) (Fig. S10b). The intermediate Ph–N+(OH)H–O is unstable; therefore, it is
easily quenched by the surrounding H+. Thus the second step is a momentary reaction step. H+
attacks O (generates an extremely unstable structure Ph–N+(OH)2H followed by dehydration
to generate N=O) or OH (the excess electrons of the retained O form N=O bond with N after
dehydration) with removal of a portion of water, which generates intermediate Ph–N+HO (Fig.
S10c). The third step is similar to the first step. N=O reacts with the activated H+ on the
catalyst surface to generate N–O–H. On the other hand, the negative Co-formate intermediate
attacks the electropositive N to generate N–H and releases CO2 (Fig. S10d). Finally, the
intermediate Ph–N+H2OH from the third step reacts with HCOO on the surface of
Co@NC-600 to produce the target product aniline (Fig. S10e).
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
The as-prepared Co@NC-600 was compared with other reported non-noble metals based
catalysts used for CTH of nitrobenzene and the Co-based catalyst for reduction of
nitrobenzene (Table S2). Compared to the most non-noble metal catalysts used in CTH of
49, 51-53]
nitrobenzene,[15,
Co@NC-600 exhibits excellent catalytic efficiency without the
addition of a base, and the reaction in this study was carried out in a more environmentally
friendly solvent. Moreover, it is difficult to avoid high pressure when a Co-based catalyst uses
H2 as a hydrogen source for catalytic hydrogenation of nitrobenzene.[26] Besides, toxic and
16
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
3
4
unsustainable reducing agents (N2H4·H2O or NaBH4) are harmful to the environment,
although they tend to have a faster reaction rate.[54, 55] Thus, CTH of nitroaromatics with FA
over Co@NC-600 in this study combines the advantages of cost-effectiveness and
environmental benignancy and green development.
5
6
Table 2. CTH of nitroarenes to corresponding aromatic amines over Co@NC-600 catalyst.a
7
Entry
1
Substrate
Product
Reaction time (h) Conv. (%)b
Sel. (%)b
>99
4
4
>99
>99
2
3
>99
>99
98.0
>99
>99
>99
94.5
>99
>99
>99
>99
>99
>99
4
4
95.7
>99
>99
>99
94.2
>99
>99
>99
>99
>99
56
4
5
4
6
4
7
4
8
4
9
8
10
11
12
13
14
5
5
5
23
23
92.1
15
16
17
6
6
4
>99
>99
>99
>99
>99
>99
17
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
18
19
8
8
>99
>99
>99
92.8
7.2
1
2
3
4
a Reaction condition: substrate (0.5 mmol), Co@NC-600 (40 mg), FA (500 μL), EtOH (1 mL), water (4
mL), 90 °C .
b Detected by GC-MS.
5
6
In order to further prove the general applicability of the catalyst, various nitroarenes were
subjected to CTH with FA over Co@NC-600 catalyst. First, for halogenated-nitrobenzenes
(Table 2, entries 1 to 8), Co@NC-600 CTH with FA exhibited excellent catalytic activity and
selectivity. The reaction results indicated that there was almost no dehalogenation of
halogenated-nitrobenzenes during the CTH process. Noteworthy, dehalogenation did not
occur even when the number of halogenated groups was increased (Table 2, entry 9). In
particular, among the halogenated-nitrobenzenes tested, o-chloronitrobenzene and
p-iodonitrobenzene exhibited slight dehalogenation; however, the selectivity was still good
(98.0 and 94.5%, respectively). Alkyl-substituted nitrobenzenes could also be efficiently
subjected to CTH to corresponding anilines (Table 2, entries 10 to 12). However, in the CTH
of p-nitrophenol and p-nitroaniline, the conversions were not satisfactory despite excellent
selectivity (Table 2, entries 13 and 14). Considering the chemical properties, both the
substrates easily produce protons. Therefore, these nitro compounds containing relatively
active hydrogen are not easily reduced by transfer hydrogenation. In the CTH of substrates
bearing with aldehyde and carbonyl, such as o-nitrobenzaldehyde (Table 2, entry 15),
p-nitrobenzaldehyde (Table 2, entry 16), p-nitroacetophenone (Table 3, entry 17),
Co@NC-600 still shows excellent catalytic performance. In contrast, the time required for
complete conversion of m-dinitrobenzene to m-nitroaniline was longer than the standard time
(Table 2, entry 18). In the CTH of m-dinitrobenzene, m-phenylenediamine would not be
formed until complete conversion of m-dinitrobenzene to m-nitroaniline occurred.
Interestingly, 2,4-dinitrochlorobenzene could maintain good position selectivity in this
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
catalytic system (Table 2, entry 19). The nitro group ortho to chlorine showed a higher
18
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
priority in the CTH with FA using Co@NC-600. Overall, Co@NC-600 has excellent catalytic
activity and chemical selectivity for CTH of most nitroarenes under green and mild reaction
3
conditions.
4
The reusability of Co@NC-600 was tested using CTH of nitrobenzene with FA as a model
reaction. Fig. 7a shows that all the catalytic cycle reactions could maintain about 95%
conversion of nitrobenzene in 4 h. These experimental results confirmed that Co@NC-600
exhibited good chemical stability in CTH. The TEM image of Co@NC-600 after five cycles
indicates that Co NPs in the catalyst did not agglomerate after five cycles and still maintained
their excellent dispersity (Fig. 7b). Fig. S11a shows that the graphite lattice fringes of C still
surround Co NPs. Fig. S11b exhibits that the morphology of Co@NC-600 after five cycles is
consistent with that of the fresh sample. Moreover, the XRD pattern of Co@NC-600 after five
cycles shows characteristic diffraction peaks of C(002) and Co(111), which is in agreement
with those of Co@NC-600 (Fig. S12). The Co@NC-600 catalyst after five cycles almost
retained its original magnetism (12.7 emu g1), which was only reduced by 10%, indicating
that Co remained almost intact during corrosion in the acidic reaction environment in which
FA was present (Fig. S13). Therefore, the as-prepared Co@NC-600 catalyst has excellent
durability and recyclability.
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Fig. 7. (a) Reuse test of Co@NC-600. Reaction conditions: nitrobenzene (0.5 mmol), FA (500
μL), Co@NC-600 (40 mg), 1 mL of EtOH and 4 mL of water, 90 °C , 4 h. (b) TEM image of
Co@NC-600 reused after 5 cycles, inset: the Co NPs size distribution histogram.
23
24 Summary
25
26
Non-noble metal catalyst Co@NC-600 obtained from renewable biomass-derived sucrose,
eco-friendly melamine, and abundant Co(AcO)2 was successfully prepared via a facile
19
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
3
4
5
6
7
8
9
strategy. The Co NPs in the Co@NC-600 catalyst were highly dispersed in the NC matrix and
covered by the NC shell. The abundant N atoms in the NC matrix and the encapsulated Co
NPs exhibited synergistic effects for the transfer hydrogenation reaction. Thus, Co@NC-600
catalyst exhibited excellent catalytic activity and selectivity for CTH of functionalized
nitrobenzenes with FA, and could be magnetically recovered for reusing with excellent
reusability and recyclability. The study reported herein provides an effective strategy for
producing non-noble metal-modified N-doped porous carbon catalysts with high catalytic
efficiency for geeen and sustainable catalysis.
10
11
Conflicts of interest
There are no conflicts to declare.
12
13
14
Acknowledgements
This work was supported by the Fundamental Research Funds for the Central Universities
(lzujbky-2017-112).
15
16
17
References
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
[1]
[2]
S. K. Movahed, N. F. Lehi and M. Dabiri, J. Catal., 2018, 364, 69-79.
O. Metin, A. Mendoza-Garcia, D. Dalmzrak, M. S. Gultekin and S. Sun, Catal. Sci. Technol.,
2016, 6, 6137-6143.
[3]
[4]
B. Sahoo, D. Formenti, C. Topf, S. Bachmann, M. Scalone, K. Junge and M. Beller,
ChemSusChem, 2017, 10, 3035-3039.
X. Sun, A. I. Olivos-Suarez, D. Osadchii, M. J. V. Romero, F. Kapteijn and J. Gascon, J.
Catal., 2018, 357, 20-28.
[5]
[6]
X. Shi, X. Wang, X. Shang, X. Zou, W. Ding and X. Lu, ChemCatChem, 2017, 9, 3743-3751.
X. Cui, Y. Long, X. Zhou, G. Yu, J. Yang, M. Yuan, J. Ma and Z. Dong, Green Chem., 2018,
20, 1121-1130.
[7]
[8]
[9]
P. Zhang, X. Song, C. Yu, J. Gui and J. Qiu, ACS Sustain. Chem. Eng., 2017, 5, 7481-7485.
L. Liuyi, L. Lu, C. Caiyan, F. Hongjun and W. Ruihu, ChemSusChem, 2017, 10, 4921-4926.
S. Doherty, J. G. Knight, T. Backhouse, A. Bradford, F. Saunders, R. A. Bourne, T. W.
Chamberlain, R. Stones, A. Clayton and K. Lovelock, Catal. Sci. Technol., 2018, 8,
1454-1467.
[10]
H. Huang, X. Wang, X. Li, C. Chen, X. Zou, W. Ding and X. Lu, Green Chem., 2017, 19,
809-815.
20
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2
[11]
[12]
F. Yang, Y. Cao, Z. Chen, X. He, L. Hou and Y. Li, New J. Chem., 2018, 42, 2718-2725.
Z. Liu, W. Dong, S. Cheng, S. Guo, N. Shang, S. Gao, C. Feng, C. Wang and Z. Wang, Catal.
Commun., 2017, 95, 50-53.
3
4
[13]
[14]
[15]
[16]
A. Corma, P. Serna, P. Concepción and J. J. Calvino, J. Am. Chem. Soc., 2008, 130,
8748-8753.
5
6
F. Leng, I. C. Gerber, P. Lecante, S. Moldovan, M. Girleanu, M. R. Axet and P. Serp, ACS
Catal., 2016, 6, 6018-6024.
7
8
R. V. Jagadeesh, D. Banerjee, P. B. Arockiam, H. Junge, K. Junge, M.-M. Pohl, J. Radnik, A.
Brueckner and M. Beller, Green Chem., 2015, 17, 898-902.
L. Yu, Q. Zhang, S.-S. Li, J. Huang, Y.-M. Liu, H.-Y. He and Y. Cao, Chemsuschem, 2015, 8,
3029-3035.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
[17]
[18]
[19]
Z. Li and Q. Xu, Acc. Chem. Res., 2017, 50, 1449-1458.
X. Li, S. Wang, Y. Zhu, C. Lv and G. Yang, Energy & Fuels, 2017, 31, 1866-1873.
Z. Li, X. Yang, N. Tsumori, Z. Liu, Y. Himeda, T. Autrey and Q. Xu, Acs Catal., 2017, 7,
2720-2724.
[20]
[21]
S. Akbayrak, Y. Tonbul and S. Ozkar, Appl. Catal. B-Environ., 2017, 206, 384-392.
J.-M. Yan, S.-J. Li, S.-S. Yi, B.-R. Wulan, W.-T. Zheng and Q. Jiang, Adv. Mater., 2018, 30,
1703038.
[22]
[23]
T. Dinesh, L. H. Yin, D. Emma and X. Jianliang, Chem. – A Eur. J., 2015, 21, 5370-5379.
S. Cheng, X. Meng, N. Shang, S. Gao, C. Feng, C. Wang and Z. Wang, New J. Chem., 2018,
42, 1771-1778.
[24]
[25]
[26]
[27]
[28]
[29]
A. Arshad, M. Justus, R. Christoph, X. Wei, W. Philipp, B. A. J. R., F. R. A., S. Wolfgang and
M. Martin, Angew. Chem. Int. Ed., 2016, 55, 4087-4091.
X. Cui, Y. Li, S. Bachmann, M. Scalone, A.-E. Surkus, K. Junge, C. Topf and M. Beller, J. Am.
Chem. Soc., 2015, 137, 10652-10658.
X. Cui, K. Liang, M. Tian, Y. Zhu, J. Ma and Z. Dong, J. Coll. Interf. Sci., 2017, 501,
231-240.
G. Lan, Y. Wang, Y. Qiu, X. Wang, J. Liang, W. Han, H. Tang, H. Liu, J. Liu and Y. Li, Chem.
Commun., 2018, 54, 623-626.
R. Nie, X. Peng, H. Zhang, X. Yu, X. Lu, D. Zhou and Q. Xia, Catal. Sci. Technol., 2017, 7,
627-634.
W. Li, Y. Gao, W. Chen, P. Tang, W. Li, Z. Shi, D. Su, J. Wang and D. Ma, Acs Catal., 2014, 4,
1261-1266.
[30]
[31]
[32]
[33]
[34]
[35]
S. Feng, C. Liu, Z. Chai, Q. Li and D. Xu, Nano Research, 2018, 11, 1482-1489.
B. Y. Guan, Y. Lu, Y. Wang, M. Wu and X. W. Lou, Adv. Funct. Mater. 2018, 28, 1706738.
X. Zhu, X. Shi, A. M. Asiri, Y. Luo and X. Sun, Inorg. Chem. Front., 2018, 5, 1188-1192.
X. Cui, Q. Zhang, M. Tian and Z. Dong, New J. Chem., 2017, 41, 10165-10173.
R. Gao, L. Pan, Z. Li, X. Zhang, L. Wang and T.-J. Zou, Chin. J. Catal., 2018, 39, 664-672.
Y. Li, X. Cai, S. Chen, H. Zhang, K. H. L. Zhang, J. Hong, B. Chen, D.-H. Kuo and W. Wang,
21
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
Chemsuschem, 2018, 11, 1040-1047.
2
3
[36]
[37]
[38]
C. M. Mani, M. Braun, V. Molinari, M. Antonietti and N. Fechler, Chemcatchem, 2017, 9,
3388-3394.
4
W. Xiong, L. Wang, G. Cai, Y. Yang, F. Hao, P. Liu and H. Luo, Chemistryselect, 2017, 2,
11244-11249.
5
6
T. Song, P. Ren, Y. Duan, Z. Wang, X. Chen and Y. Yang, Green Chem., 2018, DOI:
10.1039/C8GC01374H.
7
8
[39]
[40]
R. V. Jagadeesh, K. Natte, H. Junge and M. Beller, Acs Catal., 2015, 5, 1526-1529.
M. Tian, X. L. Cui, M. Yuan, J. Yang, J. T. Ma and Z. P. Dong, Green Chem., 2017, 19,
1548-1554.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
[41]
[42]
H. Chen, K. Shen, Q. Mao, J. Chen and Y. Li, Acs Catal., 2018, 8, 1417-1426.
H. Su, K.-X. Zhang, B. Zhang, H.-H. Wang, Q.-Y. Yu, X.-H. Li, M. Antonietti and J.-S. Chen,
J. Am. Chem. Soc., 2017, 139, 811-818.
[43]
[44]
W. Wang, G. Ding, T. Jiang, P. Zhang, T. Wu and B. Han, Green Chem., 2013, 15, 1150-1154.
Z. Wei, J. Wang, S. Mao, D. Su, H. Jin, Y. Wang, F. Xu, H. Li and Y. Wang, Acs Catal., 2015,
5, 4783-4789.
[45]
[46]
X. Zou, X. Huang, A. Goswami, R. Silva, B. R. Sathe, E. Mikmekova and T. Asefa, Angew.
Chem. Int. Ed., 2014, 53, 4372-4376.
A. Morozan, P. Jegou, B. Jousselme and S. Palacin, Phys. Chem. Chem. Phys., 2011, 13,
21600-21607.
[47]
[48]
[49]
[50]
[51]
Y. Duan, T. Song, X. Dong and Y. Yang, Green Chem., 2018, 20, 2821-2828.
Y. Hou, Z. Wen, S. Cui, S. Ci, S. Mao and J. Chen, Adv. Funct. Mater., 2015, 25, 872-882.
P. Zhou, L. Jiang, F. Wang, K. Deng, K. Lv and Z. Zhang, Sci. Adv., 2017, 3: e1601945.
S. Yamabe and S. Yamazaki, J. Phys. Org. Chem., 2016, 29, 361-367.
I. Sorribes, G. Wienhoefer, C. Vicent, K. Junge, R. Llusar and M. Beller, Angew. Chem. Int.
Ed., 2012, 51, 7794-7798.
[52]
[53]
[54]
[55]
K. J. Datta, A. K. Rathi, M. B. Gawande, V. Ranc, G. Zoppellaro, R. S. Varma and R. Zboril,
Chemcatchem, 2016, 8, 2351-2355.
S. K. Mohapatra, S. U. Sonavane, R. V. Jayaram and P. Selvam, Tetrahedron Lett., 2002, 43,
8527-8529.
H. Huang, X. Liang, X. Wang, Y. Sheng, C. Chen, X. Zou and X. Lu, Appl. Catal. a-Gen.,
2018, 559, 127-137.
Z. Zhujun, W. Xiangru, Y. Yan, C. Zhi, Z. Aijian, L. Wei, W. W. Duo, W. Zhangxiong, C. X.
Dong and D. Y. Zhao, Small, 2017, 13, 1702243.
22
This article is protected by copyright. All rights reserved.

10.1002/cssc.201802163
ChemSusChem
1
2 Entry for the Table of Contents
3
4
5
Biomass sucrose derived cobalt@nitrogen-doped carbon for catalytic
transfer hydrogenation of nitroarenes with formic acid
6
7
8
Man Yuan,[a] Yu Long,[a] Jin Yang,[a] Xiwei Hu,[a] Dan Xu,[a] Yangyang Zhu[a] and Zhengping Dong*[a]
9
10
23
This article is protected by copyright. All rights reserved.