Facile Fabrication of Nickel/Heazlewoodite@Carbon Nanosheets and their Superior Catalytic Performance of 4-Nitrophenol Reduction

Article abstract of DOI:10.1002/cctc.201800889

A facile molten salt method was utilized for the synthesis of carbon anchored nickel/heazlewoodite nanoparticles (Ni/Ni₃S₂@C nanosheets) with potassium humate as the carbon and sulfur source and NaCl as template. The morphology, particle size and crystallinity of the products were characterized by various techniques containing TEM, FE-SEM and XRD. Furthermore, the mesoporous Ni/Ni₃S₂@C own easy accessibility of active sites and high surface area (149.04 m² g^?1). Thus, the as-prepared Ni/Ni₃S₂@C exhibited prominent performance for catalytic reduction of 4-nitrophenol (4-NP). Catalytic reduction of other nitrophenols (NPs) were also tested which can prove that the catalyst own selectivity on reduction of NPs. For durability, the property of the catalyst does not decrease obviously after five cycles. More significant correlations concerning effect of activation parameters (E_a=37.21 kJ mol^?1) on 4-NP reduction were scrutinized and discussed. Hence, we provide a facile method for fabrication of metal/metal sulfide@C which own better dispersity, small dimension and excellent catalytic performance for further studies.

Full text of DOI:10.1002/cctc.201800889

Full Papers
DOI: 10.1002/cctc.201800889
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Facile Fabrication of Nickel/Heazlewoodite@Carbon
Nanosheets and their Superior Catalytic Performance of
4-Nitrophenol Reduction
Xinyu Wang,[a, b] Jing Lu,[c] Yunlong Zhao,[b] Xiaopeng Wang,[b] Zhang Lin,[a] Xueming Liu,[a]
Ronglan Wu,[b] Chao Yang,[b] and Xintai Su*[a]
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A facile molten salt method was utilized for the synthesis of
carbon anchored nickel/heazlewoodite nanoparticles (Ni/
Ni3S2@C nanosheets) with potassium humate as the carbon and
sulfur source and NaCl as template. The morphology, particle
size and crystallinity of the products were characterized by
various techniques containing TEM, FE-SEM and XRD. Further-
more, the mesoporous Ni/Ni3S2@C own easy accessibility of
active sites and high surface area (149.04 m2 gꢀ1). Thus, the as-
prepared Ni/Ni3S2@C exhibited prominent performance for
catalytic reduction of 4-nitrophenol (4-NP). Catalytic reduction
of other nitrophenols (NPs) were also tested which can prove
that the catalyst own selectivity on reduction of NPs. For
durability, the property of the catalyst does not decrease
obviously after five cycles. More significant correlations concern-
ing effect of activation parameters (Ea =37.21 kJmolꢀ1) on 4-NP
reduction were scrutinized and discussed. Hence, we provide a
facile method for fabrication of metal/metal sulfide@C which
own better dispersity, small dimension and excellent catalytic
performance for further studies.
25 Introduction
26
ress[1] etc. However, these methods do not make good use of
and deal with 4-NP. Furthermore, 4-NP is also a precursor of 4-
aminophenol (4-AP) which is renewed to be an available
material and related in many ways including antipyretic and
analgesic drug, sulfur dye, corrosion inhibitor, photographic
developer, anticorrosion lubricant and hair-dyeing agent etc.
Based on these advantages, chemical reduction of 4-NP is a
most efficient and potential method. However, the reaction rate
is very slow without catalysts. For this reason, a method of
catalytic chemical reduction[2] comes into researchers eyes.
Thus, correlated works have been done during last few decades
to make effective reduction of 4-NP to 4-AP.
27 Over the last few years, environment pollution and energy
28 shortage have become the most serious issues that human
29 society face. To the best of our knowledge, water is source of
30 life, however, the fresh water is meeting an enormous
31 contamination. What’s more, heavy-metal pollution and organic
32 pollution are the significant segments of water pollution, which
33 have the worst effects on health. Of these pollutants, 4-
34 nitrophenol (4-NP) is a familiar organic pollutant, which is a
35 highly hazardous and carcinogenic material. It is hard to tackle
36 the 4-NP from environment due to its stable chemical proper-
37 ties and better water solubility. Although 4-NP is environmental
38 hazardous and difficult to handle, 4-NP also has wide adhibition
39 in industry, agriculture and pharmacy etc. So how to solve these
40 problems is imminent. Up till now, a lot of technologies have
41 been developed for nitrophenols (NPs) removal, such as
42 biodegradation, adsorption, photodegradation, Fenton prog-
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Usually, the precious metal-based catalysts are still exten-
sively utilized in catalytic reduction of 4-NP, for example
platinum,[3] aurum,[4] argentum[5] nanocatalysts etc. However,
their high cost, rapid deactivation, low reusability and low
earth-abundance limit their widespread application. For the
sake of solving these problems, various transition metal
catalysts, especially copper-based[6] and nickel-based[7] nano-
catalysts, which are cost-effective, own high performance and
stability have aroused great attraction. And the main factors
which effect the catalytic activity of catalysts are the size, shape,
crystallinity, and surface state of catalyst. So, the small nano-
particles are the ideal materials. Nevertheless, small nano-
particles could aggregate irreversibly during catalytic reaction
systems on account of their high surface energies that
dramatically limit catalytic activity.[8] To solve this problem,
many methods have been putting forward, including core-shell
nanocomposites,[9] York-shell nanocomposites,[10] and nanopar-
ticles supported on various type of nanocomposites supports.
In recent years, the supports such as KCC-1,[11] SBA-15,[12]
Al2O3,[13] and other carbon supports[14] have been used which
could effectively avoid aggregation of nanoparticles. However,
[a] X. Wang, Z. Lin, X. Liu, Prof. X. Su
The Key Laboratory of Pollution Control and Ecosystem Restoration in In-
dustry Clusters (Ministry of Education)
School of Environment and Energy
South China University of Technology
Guangzhou 510006 (P.R. China)
E-mail: suxintai827@163.com
[b] X. Wang, Y. Zhao, X. Wang, R. Wu, Prof. C. Yang
Ministry Key Laboratory of Oil and Gas Fine Chemicals
College of Chemistry and Chemical Engineering
Xinjiang University
Urumqi 830046 (P.R. China)
[c] J. Lu
Academy of Instrument Analysis
Xinjiang Uygur Autonomous Region
Urumqi 830011 (P.R. China)
Supporting information for this article is available on the WWW under
https://doi.org/10.1002/cctc.201800889
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the above catalysts are either more expensive or the prepara-
tion process is complicated. Therefore, it is highly desirable to
develop a high efficient and low-cost catalysts for the reduction
of 4-NP.
In the past few years, carbon supported nanocomposites
which have versatile applications in the domains of catalysis,[15]
energy storage/conversion,[16] gas sensing,[17] environmental
remediation[18] etc., have attracted increasing interests on
account of their unique physicochemical properties. Further-
10 more, based on the good conductivity, thermal/mechanical
11 stability and durability, carbon materials are utilized in versatile
12 catalytic reactions because the electrons transfer can be
13 accelerated. Hence, many carbon supports are synthesized to
14 meet the huge demands, such as graphene,[19] carbon nano-
15 tube,[20] amorphous carbon[21] etc. In this work, the amorphous
16 carbon is employed as the supports. It can not only be a good
17 two-dimensional (2D) support, but also can encapsulate the
18 nanoparticles to form core-shell structure by using molten salt
19 process.[22] Hyeon T et al. applied this method for successful
20 synthesis of carbon-encapsulated ferrite.[23] By utilizing this
21 method, sodium oleate and other organic materials can also be
22 used as the carbon source to prepare 2D carbon loaded
23 nanomaterials.[24] However, these sources of carbon are still
24 more expensive.
25
In this work, potassium humate, a chemical raw material
26 from weathered coal, is used for the first time in the synthesis
27 of carbon loaded nanomaterials. Because potassium humate
28 comes from coal, it contains a certain amount of sulfur, which
29 may contribute to the generation of sulfides. In accordance
30 with the aforementioned, we envision that the fabrication of
31 carbon anchored nickel/heazlewoodite nanoparticles 2-dimen-
32 sional (2D) material via facile pyrolysis of solid precursor at
33 6008C, 7008C and 8008C, respectively under argon atmosphere.
34 For debating overall formation process for Ni/Ni3S2@C nano-
35 composites, we systematically investigated synthesis process
36 via one-step pyrolysis with the temperature range from 4008C
37 to 8008C. Hereon, we found that throughout the pyrolysis,
38 when the temperature was low, the sulfidation of NiO by the
39 sulfide source from potassium humate. While the temperature
40 increase, the carbon as the reductant to reduce the Ni2+ which
41 was complexation with humic acid. In addition, these 2D
42 nanocomposites with open structure, rapid electron transfer
43 and accessible active sites exhibit superior catalytic reduction of
44 4-NP, and showed better performance (K/m=166.8 sꢀ1gꢀ1).
45 Therefore, this work provides a novel method for the synthesis
46 of Ni/Ni3S2@C nanocomposites without the need for additional
47 sulfur source, which is also of great reference for the synthesis
48 of other sulfides.
Figure 1. (a) FT-IR spectra of the potassium humate. (b) TGA (red curve) and
DTA (left) measurements of precursor under Ar atmosphere.
out to verify the potassium humate in fabrication of the Ni2+
/precursor. As shown in Figure 1(a), a large amount of peaks
appears in the spectrum. Peaks at 3695 cmꢀ1 could be ascribed
to the NꢀH bond. And peaks at 3378 cmꢀ1 is attributed to OꢀH
which is combined by hydrogen bond. The adsorption bands at
the 1870 cmꢀ1 and 1375 cmꢀ1 could be due to carbonyl
vibrations of carboxyl and ketone groups. Similarly, the
conjugation of C=C in the aromatic structure, the frame
vibration in aromatic ring, and the telescopic shock in CꢀC
bond peaked at 1578 cmꢀ1,1876 cmꢀ1 and 1102 cmꢀ1, respec-
tively. And peaks at 617 cmꢀ1, 534 cmꢀ1 and 469 cmꢀ1 could be
attributed to sulfhydryl and disulfide bond. Because of these
organic groups, the potassium humate is also acted as the
sulfur source. And the element analysis of the potassium
humate in the Table S1 also illustrates that the sulfide content is
around 0.88%.
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As illustrated in Scheme 1, the synthetic strategy of 2D Ni/
Ni3S2@C nanosheets principally consist of the following proc-
esses:
51 Results and Discussion
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(1) synthesis of precursor;
53 Process for Fabrication of Ni/Ni3S2@C
(2) carbonization;
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(3) sulfuration;
55 Potassium humate as chemical raw material from weathered
56 coal and natural organic matters are used as the carbon and
57 sulfur source in this work. The FT-IR analysis is further carried
(4) carbon-thermal reduction.
The process of fabricating samples is followed by these
steps. First of all, in synthesis of precursor, the potassium
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acid, was reduced by carbon that act as reductant at high
temperature as illustrated by Equation (6). After that, 2D carbon
anchored Ni/Ni3S2 nanoparticles structure is fabricated. At
length, with the increase of temperature, the crystallinity of the
nanoparticles was better, as exhibited in Figure 4. Finally, the
catalysts were separated by dissolved sodium chloride particles
in deionized water.
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potassium humate þ H2O ! humic acid þ OHꢀ
ð1Þ
ð2Þ
ð3Þ
ð4Þ
ð5Þ
ð6Þ
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Ni2þ þ H2O ! NiðOHÞ2 þ Hþ
D; Ar
Scheme 1. Synthetic scheme of nickel/heazlewoodite nanoparticles sup-
ported on amorphous carbon sheet.
humic acid
C þ CO þ CO2 þ H2O
ƒƒƒ!
D; Ar
NiðOHÞ2
NiO þ H2O
ƒƒ!
D; Ar
NiO þ sulfide
Ni2þ þ C
ƒƒƒ!
Ni S
ƒƒƒ!
3
2
16 humate was dispersed in the deionized water and stirring at
17 708C, which the potassium humate can be sufficient hydro-
18 genation to obtain humic acid with the pH value between 8 to
19 9, and this can be expressed as Equation (1). Moreover, nickel
20 chlorite concentration was transferred into the above suspen-
21 sion, and with stirring at the same temperature so that the ions
22 could interact with humic acid by complexation and chelation.
23 After the reaction, the suspension was cooled to room temper-
24 ature, with the pH value of 4.2 [Eq. (2)]. The Ni(OH)2 obtained
25 by hydrolysis was also adsorbed by humic acid. Hence, humic
26 acid played a significant role in this work. The second step is
27 synthesis of the samples. For the fabrication of Ni/Ni3S2 nano-
28 particles homogeneously disperse on carbon nanosheets, the
29 precursor was mixed with sodium chlorite which utilized as the
30 template to prevent the aggregation of the carbon sheet, and
31 make the carbon sheet uniform. whereupon, in-site the
32 precursor was uniformly coated on the outside surface of
33 sodium chlorite which possess the face-centered cubic struc-
34 ture. This mixture was calcined under inert gas (argon)
35 atmosphere and successfully annealing at argon. To optimize
36 the calcination temperature, the TGA analysis was used.
37 Figure 1(b) showed the TGA and DTG curves of the precursor
38 which was treated from room temperature to 8008C under
39 argon atmosphere. The first loss (~8.7%) below about 1008C
40 could be ascribed to the removal of the physically adsorbed
41 water of the precursor. The subsequent loss (~6.9%) ranged
42 from 1008C to 1508C was attributed to water of hydration in
43 the precursor. And then the humic acid was carbonized from
44 1508C to 3608C [Eq. (3)]. When the temperature was range
45 from 3608C to 4508C, Ni(OH)2 transferred to NiO. And at the
46 same time, the obtained NiO nucleus was spread, and it quickly
47 combined with sulfide to generate Ni3S2, as expressed by
48 Equation (4) and (5). The sample calcinated at 4008C also
49 demonstrated this procedure. As shown in Figure S1(b), the
50 XRD pattern illustrates that the sample contents NiOOH, NiO
51 and Ni3S2. Because of the intricate reaction, the nanoparticles
52 were aggregated, obviously showed in Figure S1(a). While the
53 temperature raised to 5008C, the NiO was all transferred to
54 Ni3S2, as displayed in the Figure S2(b). The TEM image Fig-
55 ure S2(a), also showed the nanoparticles uniformly disperse on
56 the carbon nanosheets. Then, when the temperature raised to
57 6008C, Ni2+, which was complexation and chelation with humic
D; Ar
Nið6Þ
Characterized of Ni/Ni3S2@C Nanosheets
The morphology of carbon anchored nickel/heazlewoodite
nanosheets were characterized by transmission electron micro-
scopy (TEM), and Field-emission scanning electron microscopy
(FE-SEM). TEM analysis found that the nickel/heazlewoodite
nanoparticles in the Ni/Ni3S2@C samples are anchored with
uniformly dispersion, as shown in Figure 2(a), (d), (g). As can be
seen from Figure 2(a) and (c), the Ni/Ni3S2 nanoparticles in S1-
600 were not uniform in size which were in range from 5 to
18 nm. In more details, the TEM image in Figure 2(f) and (i)
shown that the Ni/Ni3S2 nanoparticles in S1-700 and S1-800 are
about 6 nm and 20 nm, respectively. Field-emission SEM
exhibits the morphology of the carbon sheets. Figure 2(b), (e),
(h) shown FE-SEM images of S1-600, S1-700 and S1-800,
respectively. And the carbon sheets like a flower experienced
flower bud, bursting into bloom and withering throughout this
process. This is because when the temperature increased, the
carbon sheet becomes thinner and thinner so that it tends to
aggregate. When it coated on the sodium chloride, this can
avoid aggregation, but while the sodium chloride is molten, the
carbon sheet tends aggregation. Meanwhile, the elemental
mapping images illustrate that amorphous carbon, Ni, S, and O
were homogeneously dispersed in the whole product S1-700
[Figure S5(a~e)], whereas the results also indicated that Ni/
Ni3S2 nanoparticles were anchored on the carbon sheets. EDS
spectra shows that the weight percentage of different
elements, as given in Figure S4.
The crystal phase of carbon anchored nickel/heazlewoodite
nanosheets were further confirmed by X-ray diffraction (XRD).
The XRD pattern in the Figure 3 showed the Ni/Ni3S2@C
structural information. The pattern for Ni has three prominent
peaks that could be well-indexed to nickel which was face-
centered cubic structure (JCPDS no. 04-0850). And the
diffraction pattern exhibits three peaks at 44.58, 51.88, and
76.48, corresponding to (111), (200), and (220) crystal face,
respectively. Furthermore, other peaks appearing in the pattern
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Figure 2. TEM image of Ni/Ni3S2@C nanosheets: (a) S1-600; (d) S1-700; (g) S1-800, and their relative particles size distribution of Ni/Ni3S2@C nanosheets: (c) S1-
600; (f) S1-700; (i) S1-800. FE-SEM image of Ni/Ni3S2@C nanosheets: (b) S1-600; (e) S1-700; (h) S1-800.
as shown in Figure S3. In addition, by using Scherer equation,[25]
the results of Ni/Ni3S2 nanoparticles are shown in Table 1. This
compare with the above TEM consequence in Table 1, the
nanoparticles were aggregated to the larger agglomerates on
the carbon sheet.
The graphite sheets in the S1-600, S1-700 and S1-800 were
also confirmed with Raman spectrum as shown in Figure 4. Two
apparent peaks corresponding to the D peak and G peak were
observed clearly at 1340 cmꢀ1 and 1590 cmꢀ1, respectively.
Herein, the ID/IG ratio from the Raman spectrum was used to
further characterize the average size of sp2 domains.[26] Hence,
the higher ratio of ID/IG means the smaller size sp2 domains.[15a]
From Figure 5, the ratio of ID/IG for S1-600, S1-700 and S1-800
Figure 3. XRD patterns of the as-prepared S1-600, S1-700 and S1-800.
were 0.806, 0.922 and 0.933, respectively. It is reasonable that
the ID/IG ratio of S1-700 is higher than the ID/IG ratio of S1-600. It
can be seen from TEM image the size of nanoparticles is smaller
52 could be indexed to heazlewoodite (JCPDS no. 44-1418).
in size of S1-700, and the amount of Ni/Ni3S2 nanoparticles are
more adequate on the carbon sheet. And the smaller particles
might decorate the surface of the carbon sheet. The reason for
ID/IG ratio of S1-800 is higher than S1-700 is that the aggregation
of the carbon sheet.
53 Similarly, the X-ray diffraction showed the 2q=21.78, 31.18,
54 37.88, 44.38, 49.78, 50.18, 54.68, and 55.18 which were character-
55 istic of the crystal face (101), (110), (003), (202), (113), (211),
56 (104), and (122) respectively, of heazlewoodite. And the
57 characteristic peak of carbon was observed at about 2q=238,
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856.28 eV and 873.88 eV that corresponded to Ni 2p3/2 and 2p1/
2, respectively with the spin-orbit splitting of 17.6 eV, which
revealed that the stronger NiꢀS bonding. And this also confirm
Table 1. BET surface area, pore volume, pore diameter, crystallite size[a] and
TEM crystallite size of Ni/Ni3S2@C and the corresponding catalysts of S1-600,
S1-700 and S1-800, respectively.
Catalysts SBET
[m2 gꢀ1
Pore volume Pore
Crystallite
TEM
crystallite
size
that Ni3S2 is formed. The satellite peaks at around 879.78 eV and
]
[cm3 gꢀ1
]
diameter size
[27]
861.98 eV could be attributed to Ni 2p1/2 and 2p3/2,
[nm]
[nm]
Ni
respectively. Additionally, Figure 5(c) displays the HRXPS spectra
of the S-2p binding energy of Ni3S2. The obvious peaks at
163.48 eV and 164.58 eV were due to the S 2p3/2 and 2p1/2
binding energies, respectively. And the peaks at around
168.3 eV and 169.6 eV would be attributed to the other
inconsequential NixSy.[28] Figure 5(d) shows HR-XPS of C in the
S1-600, S1-700 and S1-800, respectively. The XPS spectrum
illustrated the characteristic peaks of carbon at CꢀC (at
284.78 eV), CꢀOꢀ-C (at 286.68 eV), C=O (at 288.78 eV) and O=
CꢀO (at 290.48 eV). These peaks could be ascribed to the
functional groups in humic acid.
[nm]
Ni3S2
S1-600
S1-700
S1-800
116.05
149.04
68.88
0.3425
0.3225
0.3989
3.85
3.93
3.98
2.45
2.39
2.85
1.56
1.11
6.21
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[a] Crystallite size calculate from XRD using the Scherer equation.
For further investigate the surface property, the N2
adsorption/desorption isotherm of Brunauer-Emmett-Teller
(BET) surface area and Barrett-Joyner-Halenda (BJH) pore size
were utilized to characterize the catalysts. And the result of
surface area and pore diameter are shown in Table 1. Each
isotherm could be corresponded to a type-IV isotherm with a
small hysteresis loop which indicate the presence of mesopores
in the catalysts, (Figure 6). Compared with these three catalysts,
S1-700 possesses the largest BET surface area about
149.04 m2 gꢀ1, and the smaller pore diameter about 3.93 nm.
This indicate that it could adsorb more molecules. Furthermore,
the pore volume of S1-700 was 0.3225 m3 gꢀ1, the smallest pore
volume in three catalysts, which could be attributed to the
decoration of the nanoparticles. And it may also suggest that it
can accommodate fewer molecules, and the product could
easily desorb on the surface.
Figure 4. Raman spectra of S1-600, S1-700 and S1-800.
Catalytic Reaction of 4-NP to 4-AP
For detecting the catalytic performance of the carbon anchored
nickel/heazlewoodite nanoparticles\, the catalytic reduction of
4-NP to 4-AP with an excessive amount of sodium borohydride
was selected as a model reaction. And all the reactions which
were determined by UV-vis spectrophotometry were performed
in aqueous solution with no magnetic string. As is known, the
reduction of 4-NP to 4-AP at ambient condition is favorable
thermodynamically with borohydride which is a strong reduc-
tant, because the difference of their standard electrode
potentials
(DE0 =E0(4-NP/4-AP)ꢀE0(H3BO3/BH4ꢀ)=
Figure 5. XPS spectra of Ni/Ni3S2@C: (a) full survey spectrum of S1-600, S1-700
and S1-800; high resolution (b) Ni 2p peaks of S1-600, S1-700 and S1-800; (c) S
2p peaks; (d) C 1s peaks.
ꢀ0.76ꢀ(ꢀ1.33)=0.67 V) is higher than zero.[29] But the chal-
lenge of this reaction is kinetic barrier. With kinetic barrier, the
process of this reaction is very slow. Significantly, the UV-vis
spectrum indicates that 4-NP aqueous solution shows a strong
peak at 317 nm before addition of NaBH4, and after adding the
excessive sodium borohydride, the solution is changed to
alkaline condition which suggest that the absorption peak of 4-
NP red-shifts from 317 nm to 400 nm immediately as shown in
Figure 7 (a), and accompanied with the color of the solution
change from light yellow to bright yellow as illustrated in
Scheme 2, because of the formation of 4-nitrophenolate anions.
For further acknowledged the catalysts, X-ray photoelectron
52 spectroscopy (XPS) was utilized to analyze the surface compo-
53 sition and bonding state of the Ni/Ni3S2@C as shown in the
54 Figure 5. And the XPS survey spectrum of Ni/Ni3S2@C illustrated
55 that Ni, S, C, O were present in the composition as shown in
56 the Figure 5(a). Two distinct peaks shown in the Figure 5(b) that
57 were obtained in the core level spectrum are Ni 2p at about
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Figure 6. N2 adsorption-desorption isotherms of (a) S1-600), (b) S1-700 and (c) S1-800; the corresponding BJH desorption pore size distributions curve (inset)
and the magnified pore size distributions range from 0–20 nm.
Figure 7. (a) UV-vis spectra of 4-NP before, 1 s after and 24 h after addition of NaBH4 solution. (b)–(d) UV- vis spectra of 4-NP ions at different time; (b) S1-600,
(c) S1-700, (d) S1-800. The plots of (e) Ct/C0 and (f) ln Ct/C0 versus reaction time.
Before detecting the catalytic reduction of 4-NP to 4-AP of
the catalyst it must be check: (1) the effect of self-hydrolysis of
sodium borohydride reduce the 4-NP; (2) whether the support
can be used as the catalyst. Hence, without addition of the
catalyst, the adsorption peak at 400 nm have not very
noticeable change last for 24 h in the Figure 8(a). Accordingly,
there isn’t any apparent adsorption peak related to the product
of 4-AP after adding S1-700 (C) as Figure S7 shows, this might
indicate that the 4-nitrophenolate anions were just adsorbed
on carbon sheets, and carbon sheets were inactive for the
reaction. After addition of Ni/Ni3S2@C to bright solution, the
color of the solution fades up which resulted in the decrease in
the adsorption peaks of 4-nitrophnolate anions with a new
peak appeared at 300 nm [Figure 8(b)] of 4-AP. Moreover, the
Scheme 2. Schematic diagram for 4-NP reduction.
isosbestic point demonstrates that single product is forma-
tion.[30] Kinetic traces [Figure 8(b), (c),and (d)] show the UV-vis
absorption spectra of 4-NP with the reaction time in the
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The kinetic studies of this reaction were carried out by
using Langmuir-Hinshelwood equation. With the excess sodium
borohydride, this reaction is a pseudo-first-order reaction. So, a
plot of the experimental data according to Equation (7) for the
different catalysts could give a linear relationship [Figure 8(f)],
which can correspond to pseudo-first-order kinetics. In the
Equation (7) where C0 and Ct are the initial concentrations of 4-
NP and concentrations of 4-NP at time t, respectively. And Kapp
can represent the apparent rate constant. For comparing the
performance of different catalyst, we choose K/m as the
standard.
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ꢀ
ꢁ
Ct
ln
¼ Kapp ꢁ t
ð7Þ
C0
Catalytic Performance of S1-700 Catalyst with Different
Amount of Sodium Borohydride
For investigating the effect for the amount of sodium
borohydride on the catalytic reaction, we do some experiments
with different amount of sodium borohydride under other
conditions unchanged. It could be seen that the apparent rate
constant tends to increase with amount of sodium borohydride
increase as shown in Figure S8. In addition, from our work, the
synergistic effect about nickel sulfide and metallic nickel
nanoparticles is also discussed. Table 3 is summary of Kapp and
Table 3. Catalytic reduction of 4-NP.
Catalysts
Amount
of
catalyst
[mg]
NaBH4 Kapp
K/m
R2
Ref.
Figure 8. The plots of Ct/C0 (a) and ln (Ct/C0) (b) versus reaction time using
S1-700 catalyst.
[mmol] [sꢀ1]ꢁ10ꢀ3 [sꢀ1 gꢀ1
]
[a]
S1-700
S1-700
S1-700
S1-500
0.05
0.05
0.05
0.05
1.00
7.00
0.10
0.05
0.05
0.05
0.14
0.21
0.28
0.28
2.64
0.30
3.00
0.50
0.50
0.25
3.69
7.43
8.34
4.14
9.95
2.82
5.42
0.70
6.18
4.50
73.8
0.94
0.97
0.99
0.98
0.99
–
–
–
–
–
#
#
#
[a]
35 presence of S1-600, S1-700, and S1-800, respectively. After
36 addition of catalysts, the suspension become colorless, gradu-
37 ally within 360 s. The equilibrium conversion rate of 4-NP was
38 calculated to be 99.9% as summarized in Table 2 when S1-700 is
39
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43
44
45
46
47
48
49
50
51
148.6
166.8
82.8
9.95
0.41
54.2
15.0
123.6
257.0
[a]
[a]
#
[31]
Ni0.22/CB
NCMSS-4
CNFs@Au
Pt black
Au NCs/rGO
Ni@PtNi NCs-
rGO
Ni3S2@C
Ni@Pd/KCC-1
Ag/C-0.05
[7]
[4]
[32]
[33]
[34]
Table 2. Reduction of 4-NP by using different catalysts.[a]
Catalysts
Amount of
catalyst
[mg]
Kapp
K/m
Conversion
[%]
[35]
[11]
[36]
[sꢀ1
]
[sꢀ1 gꢀ1
]
0.15
0.40
2.00
0.05
0.25
0.35
0.90
20.4
5.32
6.00
51.0
2.66
–
0.99
–
S1-500
S1-600
S1-700
S1-800
50
50
50
50
4.14ꢁ10ꢀ3
6.12ꢁ10ꢀ3
8.34ꢁ10ꢀ3
3.20ꢁ10ꢀ3
82.8
75.6
89.0
99.9
65.2
122.4
166.8
64.0
[a] #: This work.
[a] Reduction conditions: temperature (298.15 K), 4-NP (2.95 mL, 0.12 mM),
catalysts (50 mL, 1 mgmLꢀ1), NaBH4 (0.28 mmol), and reaction time (360 s).
K/m values about different catalysts and amount of NaBH4. With
the listed datum, the performance of Ni/Ni3S2@C was better
than single nickel sulfide and metallic nickel nanoparticles
supported on carbon sheets. What’s more, our catalytic
performance is better than that of many noble nanoparticles
catalyst.
52 utilized as a catalyst. And while the catalyst was present in the
53 reaction system, there was a rapid decrease with the order of
54 S1-700>S1-600>S1-500>S1-800. In all these cases, S1-700
55 proves to be the most efficient among the other catalysts
56 tested.
57
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Catalytic Performance of S1-700 Catalyst for the Reduction of
Various Nitrophenols
nitrophenols could be selectively reduced under these opti-
mized conditions in the presence of S1-700 catalyst, and the
results are listed on it.
In this work, we choose catalytic reduction of 4-NP as the
reaction model, to optimized reaction conditions. The results
revealed that with the same condition, the catalytic reduction
of 4-NP (360 s) was faster than 4-nitroaniline (480 s) shown in
Figure S9(b). Because when ꢀOH connected with benzene ring,
the benzene ring could be activated. The consideration of the
The Activation Parameters for S1-700 Catalyzed Reduction of
4-NP
The effect of temperature on the catalytic reaction of 4-NP was
investigated via preparing a series of experiments for 4-NP
under same condition with the temperature range from
298.15 K to 323.15 K [Figure 9(a)]. The apparent rate constants
of catalytic reaction at different temperature are summarized in
the Table 5. The activation parameters contain activation
10 consumption graphs given in Figure 8 revealed that the initial
11 rate of S1-700 catalytic reduction of nitrophenols[37] at same
12 condition followed the sequence of 2,4,6-trinitrophenol >2,4-
13 dinitrophenol >4-nitrophenol >2,6-dinitrophenol>2-nitrophe-
14 nol. The results indicate that the catalyst has better selectivity.
15 And the UV-vis spectrum of these nitrophenols are given in the
16 Figure S9 (a), (c), (d), (e). As shown in Table 4, a variety of
17
Table 5. [a] Reduction conditions: nitrophenols (2.95 mL, 0.12 mM), S1-700
catalyst (50 mL, 1 mgmLꢀ1), NaBH4 (0.28 mmol), temperature (298.15 K) and
reaction time (360 s).Table 5
18
19
Table 4. Reduction of nitrophenols by using S1-700.[a]
Reduction of 4-NP by using S1-700 at different temperature.[a]
Amount of
catalysts
[mg]
Substrates
Kapp
K/m
Conversion
[%]
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
Amount of
catalysts [mg]
Temperature [K]
Kapp [sꢀ1
]
R2
[sꢀ1
]
[sꢀ1 gꢀ1
]
50
50
50
50
50
50
298.15
303.15
308.15
313.15
318.15
323.15
8.34ꢁ10ꢀ3
13.10ꢁ10ꢀ3
18.54ꢁ10ꢀ3
23.18ꢁ10ꢀ3
25.25ꢁ10ꢀ3
30.00ꢁ10ꢀ3
0.9921
0.9840
0.9912
0.9857
0.9907
0.9884
50
50
8.34ꢁ10ꢀ3
166.8
67.4
99.9
70.0
[a] 4-NP (2.95 mL, 0.12 mM), S1-700 catalyst (50 mL, 1 mgmLꢀ1), NaBH4
(0.28 mmol).
3.37
50
50
5.62
9.61
112.4
192.2
88.0
99.9
energy, activation enthalpy, activation entropy, etc. And the
activation energy which is a critical kinetic parameter for
heterogeneous catalytic reaction is calculated by using the
Arrhenius equation [Eq. (8)]. From the Equation (8), the Ea is
activation energy, and where A is pre-exponential factor. Hence,
we could calculate the activation energy (Ea) is 39.79 kJmolꢀ1,
which is between 8.368 and 41.84 kJmolꢀ1 for the surface
catalytic reaction.[38] What’s more, the activation parameters,
activation enthalpy (DH#) and activation entropy (DS#) are
calculated via the Eyring equation [Eq. (9)]. From the equation,
where kB and h are Boltzmann constant and Planck constant,
respectively. And we also calculated the DH# is 37.21 kJmolꢀ1,
and DS# is ꢀ158.73 Jmolꢀ1Kꢀ1). With obtained DH# and DS#
50
50
5.80
116.0
338.8
88.1
99.9
16.94
Figure 9. The plots of (a) ln (Ct/C0) versus reaction time, (b) ln K versus 1/T and (c) ln (Kapp/T) versus 1/T using S1-700 catalyst.
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values, the calculated DG#(298.15
is 84.54 kJmolꢀ1 which
K)
demonstrates that the reaction requires energy. It states that
the reaction is feasible in the presence of the S1-700 in this
experiment.
4
5
6
7
8
À
Á
Ea
ln Kapp ¼ ꢀ þ lnAð8Þ
ð8Þ
ð9Þ
RT
ꢀ
ꢁ
DH#
DS#
Kapp
kB
h
ln
¼ ꢀ
þ ln
þ
9
T
RT
R
10
11
12
13 Mechanism for the Reaction of 4-NP
14
15 On the basis of our experimental results and related litera-
16 ture,[31,39] the mechanism for the catalytic reaction of 4-NP by
17 means of Ni/Ni3S2@C is proposed on account of Langmuir-
18 Hinshelwood mechanism. To start with, the borohydride anion
Figure 10. Reusability of S1-700 for reduction of 4-NP.
ꢀ
19 (BH4 ) react with H2O which root in the concentration, to
ꢀ
20 fabricate metaborate (BO2 ) and hydrogen on the surface of
Conclusions
21 nickel/heazlewoodite nanoparticles, as shown by Equation (10)
22 and a large proportion of hydrogen is adsorbed on the surface
23 of the nanoparticles, inducing a nanoparticles hydride complex
24 to be the active reductant. At the same time, 4-nitrophenolate
25 anions are adsorbed onto the amorphous carbon sheets via
26 electrostatic interaction, for example hydrogen bond with
27 ꢀCOOH which exist in the amorphous carbon. This can put the
28 substrate close approximately to the active reductant. And
29 then, the active reductant is oxidized with the charge lost. The
30 lost electron is quickly transferred through the carbon sheet to
31 4-nitrophelate anions. Stepwise reduction of the nitro groups
32 to amino products is accomplished as soon as possible.
33 Ultimately, 4-AP desorbed from carbon sheets. The hydroxyl-
34 amine intermediates are abscission from carbon sheets, quickly,
35 which can make more nitroso close to the carbon sheets to
36 accelerate the reaction.
In summary, a novel catalyst nickel/heazlewoodite nanoparticles
which were anchored onto amorphous carbon (Ni/Ni3S2@C
nanosheets) were successfully fabricated by a facile molten salt
method. And potassium humate, a raw material from weath-
ered coal could be served as carbon source and sulfur source.
The particle size of as-prepared catalysts could be adjusted by
pyrolysis the power at different temperature. The obtained
products with large surface area and accessible active sites
exhibited excellent performance on catalytic reduction of 4-NP
via excess sodium borohydride. In addition, other nitrophenols
were also tested to indicate the selectivity of the catalyst.
What’s more, it’s indicated that amorphous carbon sheets play
an important role in catalytic activity. And the as-prepared
products also have other applications to be a promising
material.
37
BHꢀ4 þ 2H2O ! BOꢀ2 þ 4H2
ð10Þ
38
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42
43
Experimental Section
The Catalytic Durability of S1-700 in Reduction of 4-NP in the
Presence of NaBH4
Reagents: The chemical reagents were used without purification
after purchase. The Nickle chloride tetrahydrate (NiCl2 ·4H2O) and
sodium borohydride (NaBH4) were purchased from Tianjin Hongyan
Chemical Reagent Company; potassium humate, an industrial raw
material, was obtained from Xinjiang Double Dragon Humic Acid
Company; 4-nitrophenol (4-NP) was purchased from Aladdin; 2-
nitrophenol (2-NP), 4-nitroaniline, 2,6-dinitrophenol, 2,4-dinitrophe-
nol and 2,4,6-trinitrophenolwere from Shanghai Shanpu Chemical
Co. LTD. The water that was used throughout this work was
purified using a Millipore system. All other reagents were of
analytical grade except potassium humate.
44 The reusability as a crucial measure of catalytic durability is also
45 tested for S1-700 catalyst in catalytic reduction of 4-NP at
46 298.15 K. For this purpose, after every complete catalytic
47 reaction, S1-700 catalyst was washed with water and ethanol,
48 dried in vacuum at 708C. And after 5 cycles as given in
49 Figure 10, the durable performance of S1-700 catalyst had not
50 very decreased apparently. The conversion of 4-NP was over
51 97% for every cycle. After the reaction, the S1-700 catalyst was
52 characterized by XRD, and from XRD result, the phase of this
53 catalyst was not changed (Figure S10). This proved that our
54 catalyst has better stability for catalytic applications.
55
Synthesis of Ni/HA Precursor: In the typical synthesis of precursor,
first of all, potassium humate (5 g) was dissolved into 200 mL of
deionized water, and then the brown suspension was ultra-
sonicated to obtain the homogeneous solution. Next, the homoge-
neous solution was stirred at 708C for 12 h. At the same time,
50 mmol of NiCl2 ·4H2O was dissolved in another 100 mL of
deionized water. After stirring for 12 h, the green solution was
56
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quickly added in the brown solution. Subsequently, the mixture
was stirred at the same temperature for 24 h. And after the
dispersion was cooled to the room temperature, the mixture was
freeze-dried. Finally, the precursor was obtained.
1
2
3
and Technology Bureau (2017E0116 and 2017E01005) and the
Project of Xinjiang Education Office (XJEDU2017I004).
4
Fabrication of Ni/Ni3S2@C Catalyst: In a typical procedure for
preparation of the catalyst, the precursor was uniformly mixed with
sodium chloride, with the weight ratio of precursor and NaCl (1:
15). And after that, the mixed powder was calcined at 6008C,
7008C and 8008C, respectively, with the heating rate of 58Cminꢀ1
in an airtight tube furnace under flowing argon atmosphere for 4 h.
Once cooled to room temperature, the black power was harvested
by centrifugation at 12000 rpm for 10 minutes, and washed several
times with deionized water to remove the NaCl. And then the two-
dimensional Ni/Ni3S2@C nanosheets were obtained. Ultimately, the
as prepared samples were marked as S1-600, S1-700, S1-800,
respectively.
5
6
7
8
Conflict of Interest
The authors declare no conflict of interest.
9
Keywords: activation parameters · catalytic reduction · Ni/
Ni3S2@C · nitro compounds · potassium humate
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[1] a) A. Babuponnusami, K. Muthukumar, J. Environ. Chem. Eng. 2014, 2,
557–572; b) F. Quan, Y. Hu, X. Liu, C. Wei, Phys. Chem. Chem. Phys. 2015,
17, 19401–19409; c) K. Zhang, Y. Liu, J. Deng, S. Xie, H. Lin, X. Zhao, J.
Yang, Z. Han, H. Dai, Appl. Catal. B 2017, 202, 569–579.
[2] P. Zhao, X. Feng, D. Huang, G. Yang, D. Astruc, Coord. Chem. Rev. 2015,
287, 114–136.
[3] W. Ye, J. Yu, Y. Zhou, D. Gao, D. Wang, C. Wang, D. Xue, Appl. Catal. B
2016, 181, 371–378.
[4] P. Zhang, C. Shao, X. Li, M. Zhang, X. Zhang, C. Su, N. Lu, K. Wang, Y. Liu,
Phys. Chem. Chem. Phys. 2013, 15, 10453–10458.
[5] Z. Dong, X. Le, X. Li, W. Zhang, C. Dong, J. Ma, Appl. Catal. B 2014, 158–
159, 129–135.
[6] W.-J. Liu, K. Tian, H. Jiang, H.-Q. Yu, Green Chem. 2014, 16, 4198–4205.
[7] Z. Jiang, J. Xie, D. Jiang, J. Jing, H. Qin, CrystEngComm 2012, 14, 4601–
4611.
[8] a) P. Lu, B. Qiao, N. Lu, D. C. Hyun, J. Wang, M. J. Kim, J. Liu, Y. Xia, Adv.
Funct. Mater. 2015, 25, 4153–4162; b) L. Shang, Y. Liang, M. Li, G. I. N.
Waterhouse, P. Tang, D. Ma, L.-Z. Wu, C.-H. Tung, T. Zhang, Adv. Funct.
Mater. 2017, 27, 16062151–16062157.
[9] Y. Guo, L. Zhang, X. Liu, B. Li, D. Tang, W. Liu, W. Qin, J. Mater. Chem. A
2016, 4, 4044–4055.
Catalytic Property towards Reduction of 4-NP: To the best of our
knowledge, 4-NP is poisonous, but the products (4-AP) is practical
ingredients. Thus, the catalytic reduction of nitro-compounds via
NaBH4 are chosen to be the catalytic model. In the typical
procedure, 2.95 mL of aqueous 4-NP (0.12 mM) was transferred into
a standard quartz cell with the path length of 1 cm. Subsequently,
the sodium borohydride was added to the 4-NP solution. And then,
the color of the solution changed from pale yellow to bright yellow.
After that, 50 mL of the catalyst (concentration 1 mgmLꢀ1) was
added into the above bright yellow concentration, and the
reduction reaction was winded up until it became colorless. At the
same time, the progress of 4-NP reduction reaction was monitored
from 250 nm to 500 nm by the UV-vis adsorption spectra. The
conversion (%) of 4-NP could be calculated by the Equation (1). In
order to test the durability of the S1-700 catalyst, the reduction
reaction model was amplified 20 times which compare with the
origin system. While the bright color was changed to colorless, the
suspension was monitored by the UV-vis adsorption spectra. And
after every cycle, the catalyst was washed with deionized water
and ethanol. Then, it was dried in vacuum at 708C. The same
procedure was repeated for 5 cycles.
[10] T. Yao, T. Cui, X. Fang, F. Cui, J. Wu, Nanoscale 2013, 5, 5896–5904.
[11] Z. Dong, X. Le, C. Dong, W. Zhang, X. Li, J. Ma, Appl. Catal. B 2015, 162,
372–380.
ˇ
[12] G. Kucerovꢂ, J. Strunk, M. Muhler, R. J. Behm, J. Catal. 2017, 356, 214–
228.
[13] M. J. Kale, P. Christopher, ACS Catal. 2016, 6, 5599–5609.
[14] X. Gu, W. Qi, X. Xu, Z. Sun, L. Zhang, W. Liu, X. Pan, D. Su, Nanoscale
2014, 6, 6609–6616.
[15] a) C.-C. Yeh, D.-H. Chen, Appl. Catal. B 2014, 150–151, 298–304 b) X. Y.
Zhu, Z. S. Lv, J. J. Feng, P. X. Yuan, L. Zhang, J. R. Chen, A. J. Wang, J.
Colloid Interface Sci. 2018, 516, 355–363.
[16] C. Kim, K. Kim, J. H. Moon, Sci. Rep. 2017, 7, 14400.
[17] A. S. M. Iftekhar Uddin, D.-T. Phan, G.-S. Chung, Sens. Actuators B 2015,
207, 362–369.
[18] Y. Jiang, S. Chowdhury, R. Balasubramanian, Chem. Eng. J. 2017, 327,
751–763.
[19] a) X. Ou, L. Gan, Z. Luo, J. Mater. Chem. A 2014, 2, 19214–19220; b) Y.
Tan, M. Liang, P. Lou, Z. Cui, X. Guo, W. Sun, X. Yu, ACS Appl. Mater.
Interfaces 2016, 8, 14488–14493.
[20] T. Zhu, H. B. Wu, Y. Wang, R. Xu, X. W. D. Lou, Adv. Energy Mater. 2012, 2,
1497–1502.
[21] X. Zhao, H. Zhu, X. Yang, Nanoscale 2014, 6, 10680–10685.
[22] M. Al-Mamun, H. Yin, P. Liu, X. Su, H. Zhang, H. Yang, D. Wang, Z. Tang,
Y. Wang, H. Zhao, Nano Res. 2017, 10, 3522–3533.
[23] B. Jang, M. Park, O. B. Chae, S. Park, Y. Kim, S. M. Oh, Y. Piao, T. Hyeon, J.
Am. Chem. Soc. 2012, 134, 15010–15015.
Material characterization: The morphology and microstructure of
the samples were characterized by transmission electron micro-
scopy (TEM, HitachiH-600) and Field-emission scanning electron
microscope (FE-SEM) equipped with Energy Dispersive Spectrom-
eter (EDS) by using silicon wafer as basement on a Hitachi SU8010
microscope operated at 5 kV. The crystal structure of the samples
was determined by a Rigaku D/max-ga X-ray diffractometer (XRD)
at a scanning rate of 68minꢀ1 with Cu Ka radiation (l=1.54178 A).
˚
X-ray photoelectron spectroscopy (XPS) measurements were
performed on a Thermo XPS ESCALAB 250Xi instrument with an Al
Ka (1486.8 eV) X-ray source. Thermogravimetric analysis (TGA) was
taken on a thermogravimetric analyzer (Netzsch TGA 409) from
ambient to 8008C with a heating rate of 108C minꢀ1 under Ar
atmosphere. The surface area and porosity analyzer were obtained
on
a Micromeritics ASAP 2020 physisorption instrument by
Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH)
method. Fourier transform infrared spectroscopy (FTIR) spectra
were recorded on a BRUKER VERTEX 70 with a spectral range from
400 to 4000 cmꢀ1. The UV-visible absorption spectra were recorded
using a Hitachi UV-2550 spectrophotometer equipped with an
integral sphere assembly.
[24] X. Liu, N. Fechler, M. Antonietti, Chem. Soc. Rev. 2013, 42, 8237–8265.
[25] B. M. Mogudi, P. Ncube, R. Meijboom, Appl. Catal. B 2016, 198, 74–82.
[26] a) A. C. Ferrari, J. C. Meyer, V. Scardaci, C. Casiraghi, M. Lazzeri, F. Mauri,
S. Piscanec, D. Jiang, K. S. Novoselov, S. Roth, A. K. Geim, Phys. Rev. Lett.
2006, 97, 1874011–1874014; b) D. H. Shin, J. S. Lee, J. Jun, J. Jang, J.
Mater. Chem. A 2014, 2, 3364–3371; c) F. Tuinstra, J. L. Koenig, J. Chem.
Phys. 1970, 53, 1126–1130.
54 Acknowledgements
[27] a) J. S. Chen, C. Guan, Y. Gui, D. J. Blackwood, ACS Appl. Mater. Interfaces
2016, 9, 496–504; b) W. Zhou, X.-J. Wu, X. Cao, X. Huang, C. Tan, J. Tian,
H. Liu, J. Wang, H. Zhang, Energy Environ. Sci. 2013, 6, 2921–2924.
[28] J. Yang, C. Fang, C. Bao, W. Yang, T. Yu, W. Zhu, F. Li, J. Liu, Z. Zou, RSC
Adv. 2016, 6, 75186–75193.
55
56 We appreciate the financial support of the NSFC (U1503391 and
57 51564045), International Cooperation Project of Xinjiang Science
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[29] Z. Yan, L. Fu, X. Zuo, H. Yang, Appl. Catal. B 2018, 226, 23–30.
[30] B. M. Mogudi, P. Ncube, N. Bingwa, N. Mawila, S. Mathebula, R.
Meijboom, Appl. Catal. B 2017, 218, 240–248.
[31] J. Xia, G. He, L. Zhang, X. Sun, X. Wang, Appl. Catal. B 2016, 180, 408–
415.
[32] J.-J. Lv, A.-J. Wang, X. Ma, R.-Y. Xiang, J.-R. Chen, J.-J. Feng, J. Mater.
Chem. A 2015, 3, 290–296.
[33] P. Song, L.-L. He, A.-J. Wang, L.-P. Mei, S.-X. Zhong, J.-R. Chen, J.-J. Feng,
J. Mater. Chem. A 2015, 3, 5321–5327.
[34] L.-P. Mei, R. Wang, P. Song, J.-J. Feng, Z.-G. Wang, J.-R. Chen, A.-J. Wang,
New J. Chem. 2016, 40, 2315–2320.
[35] L. Gao, R. Li, X. Sui, R. Li, C. Chen, Q. Chen, Environ. Sci. Technol. 2014,
48, 10191–10197.
[37] B. Li, L. Shao, B. Zhang, R. Wang, M. Zhu, X. Gu, J. Colloid Interface Sci.
2017, 505, 653–663.
[38] a) M. Kohantorabi, M. R. Gholami, Ind. Eng. Chem. Res. 2017, 56, 1159–
1167; b) S. Saha, A. Pal, S. Kundu, S. Basu, T. Pal, Langmuir 2010, 26,
2885–2893.
[39] a) X. Z. Li, K. L. Wu, Y. Ye, X. W. Wei, Nanoscale 2013, 5, 3648–3653; b) L.
Liu, R. Chen, W. Liu, J. Wu, D. Gao, J. Hazard. Mater. 2016, 320, 96–104;
c) C. Wen, A. Yin, W.-L. Dai, Appl. Catal. B 2014, 160–161, 730–741.
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[36] Y. Chi, J. Tu, M. Wang, X. Li, Z. Zhao, J. Colloid Interface Sci. 2014, 423,
54–59.
Manuscript received: June 2, 2018
Version of record online: &&&, &&&&
ChemCatChem 2018, 10, 1–12
www.chemcatchem.org
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ꢀ 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÞÞ
These are not the final page numbers!

Full Papers
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SuperHUMATE performance: A
novel catalyst, carbon anchored
nickel/heazlewoodite nanoparticles
(Ni/Ni3S2@C nanosheets), was fabri-
cated by facile pyrolysis of solid
precursor with potassium humate as
carbon source and sulfur source. The
Ni/Ni3S2@C nanocatalyst exhibited
superior catalytic performance
towards 4-nitrophenol reduction
with excessed sodium borohydride
as reactant, which the K/m value up
to 166 sꢀ1 gꢀ1.
X. Wang, J. Lu, Y. Zhao, X. Wang, Z.
Lin, X. Liu, R. Wu, Prof. C. Yang, Prof. X.
Su*
1 – 12
Facile Fabrication of Nickel/Heazle-
woodite@Carbon Nanosheets and
their Superior Catalytic Perform-
ance of 4-Nitrophenol Reduction
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Facile fabrication of nickel/heazlewoodite@carbon #nanosheets and their superior catalytic
performance of 4-nitrophenol #reduction from South China University of Technology, Xinjiang
University and Academy of Instrument Analysis #catalyst
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Xinyu Wang
Jing Lu
Yunlong Zhao
Xiaopeng Wang
Zhang Lin
Xueming Liu
Ronglan Wu
Prof. Chao Yang
Prof. Xintai Su http://orcid.org/0000-0001-6310-8957