Nickel titanate microtubes constructed by nearly spherical nanoparticles: Preparation, characterization and properties

Article abstract of DOI:10.1016/j.materresbull.2009.03.010

In this paper, we report the successful synthesis of NiTiO₃ microtubes constructed by nearly spherical nanoparticles via a simple solution-combusting method employing a mixture of ethanol and ethyleneglycol (V/V = 60/40) as the solvent, nickel

Full text of DOI:10.1016/j.materresbull.2009.03.010

Materials Research Bulletin 44 (2009) 1797–1801
Contents lists available at ScienceDirect
Materials Research Bulletin
journal homepage: www.elsevier.com/locate/matresbu
Short communication
Nickel titanate microtubes constructed by nearly spherical nanoparticles:
Preparation, characterization and properties
a,
a
b
Yonghong Ni *, Xinghong Wang , Jianming Hong
a
College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, 1 Beijing Eastern Road, Wuhu 241000, PR China
Center of Modern Analysis, Nanjing University, Nanjing 210093, PR China
b
A R T I C L E I N F O
A B S T R A C T
Article history:
In this paper, we report the successful synthesis of NiTiO3 microtubes constructed by nearly spherical
Received 29 October 2008
Received in revised form 15 March 2009
Accepted 17 March 2009
Available online 27 March 2009
nanoparticles via
a simple solution-combusting method employing a mixture of ethanol and
ethyleneglycol (V/V = 60/40) as the solvent, nickel acetate as the nickel source, tetra-n-butyl titanate
as the titanium source and oxygen gas in the atmosphere as the oxygen source. The as-obtained product
was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning
electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDS). The UV–vis absorption
spectrum of the product showed two absorption peaks centered at 258.6 and 350.1 nm, respectively. The
Keywords:
A. Inorganic compounds
A. Nanostructures
B. Chemical synthesis
C. Electron microscopy
2
Brunauer–Emmett–Teller (BET) surface area of the product was 14.06 m /g and the pore size distribution
mainly located from 20 to 30 nm. The photocatalytic degradation property of the product for organic
dyes showed that the as-obtained porous NiTiO
organic dyes including Pyronine B, Safranine T and Fluorescein.
ß 2009 Elsevier Ltd. All rights reserved.
3
microtubes could strongly promote the degradation of
1
. Introduction
without the need of liquid lubricants [15,16]. Solid lubricants that
can minimize friction and abrasion over a wide operating range are
essential to minimizing the replacement cost and logistical
support costs of advanced engines [17,18]. Many methods, such
as sol–gel technique [17,19], the flux method [20], co-precipita-
tions [21], solid state reactions [22], electrospinning [23] and the
Pechini process [24,16], have been reported for synthesis of
Trinary oxides containing titanium and transition metals, such
3
as MTiO (M = Ni, Pb, Fe, Co, Cu and Zn), are universally known as
chemical and electrical materials due to their weak magnetism and
semiconductivity with wide applications in semiconductor indus-
try, nuclear waste technology, refractory systems, metal–air
barrier, high performance catalysts, color mixtures of surface
coating, gas sensing devices, and solid-oxide fuel cells [1–7]. Nickel
3 3
crystalline NiTiO powders. However, NiTiO fabricated by the
above methods usually require complex equipment and compli-
cated operation. At the same time, the traditional preparation
3
titanate (NiTiO ) belongs to the ilmenite structure. Both Ni and Ti
atoms prefer octahedral coordination with alternating cation
layers occupied by Ni and Ti alone [8]. Powder neutron diffraction
studies [9] and susceptibility measurements [10] have shown that
3
methods can produce large NiTiO particles with uncontrolled
morphologies due to their inherent problems such as high reaction
temperature and heterogeneous solid phase reaction. So, it is still a
great challenge to search for a simple and cost-effective route to
2+
3
NiTiO has an antiferromagnetic structure with M spin parallel
within each layer perpendicular to the rhombohedral axis, and
antiparallel between adjacent layers; also, the spins are directed in
the layers and the Neel temperature is 23 K. Magnetization
3
prepare NiTiO with a high yield.
In 2007, our group designed a simple solution-combusting
route for preparation of binary metal oxide nanoparticles such as
ZnO and cobalt oxides [25]. In this paper, we further developed this
method and successfully prepared NiTiO
by nearly spherical nanoparticles in one step, employing a mixture
of ethanol and ethyleneglycol as the solvent, nickel acetate (NiAc )
2
and tetra-n-butyl titanate as the nickel and titanium sources. The
combustion reaction was carried out in air. Compared with the
above-mentioned methods, this method has the following
advantages: (1) it is very cost-effective and convenient because
of not requiring any sophisticated experimental setups and
complicated operations; (2) different from the high-temperature
measurements between 4.2 and 300 K suggested that NiTiO
weak anisotropy in the lower range of temperatures [11,12].
Furthermore, as a solid lubricant, NiTiO has been investigated as a
3
has
3
microtubes constructed
3
tribological coating to reduce friction and abrasion in high-
temperature applications [13,14] and it is found that titanium
oxide coatings containing nickel can provide lubricious surfaces
*
Corresponding author. Tel.: +86 553 3869303; fax: +86 553 3869303.
E-mail address: niyh@mail.ahnu.edu.cn (Y. Ni).
0025-5408/$ – see front matter ß 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.materresbull.2009.03.010

1
798
Y. Ni et al. / Materials Research Bulletin 44 (2009) 1797–1801
treatment over 1273 K in conventional solid state reactions, the
present method does not need any high-temperature annealing;
(
3) the reaction is safe, quick and environmentally friendly since
the byproducts are CO and H O; (4) the experiments can be easily
repeated and the yield is high (>95%). Furthermore, to our best
knowledge, this is the first report on the synthesis of NiTiO
2
2
3
microtubes constructed by nearly spherical nanoparticles in the
literature.
2
. Experimental
2
.1. Synthesis of NiTiO microtubes
3
All chemicals and reagents were purchased from Shanghai
Chemical Corp. Ltd. and used without further purification. In a
typical experiment, 0.01 mol of nickel acetate (NiAc O) was
ꢀ4H
dissolved in 100 mL mixed solvents of ethanol and ethyleneglycol
with the volume ratio of 60/40. Then, 0.01 mol of Ti(OC was
2
2
4
9 4
H )
added under magnetic stirring. After the solution was transferred
into a spirit lamp with an absorbent cotton lampwick, the spirit
lamp was fired with a match. For a moment, some yellow products
appeared. After the reaction finished, the yellow products were
collected and repeatedly washed with distilled water to remove
the impurities, and finally, dried at 323 K in air for 5 h.
2.2. Characterization of the samples
X-ray powder diffraction (XRD) of the product was carried out
on a Shimadzu XRD-6000 X-ray diffractometer equipped with Cu
K
a
radiation (
l
= 0.154060 nm), employing a scanning rate of
ꢁ
1
0
.028 s and 2u ranges from 108 to 808. Transmission electron
microscopy (TEM) images of the product were carried out on a JEOL
JEM-200CX transmission electron microscope, employing an
accelerating voltage of 200 kV. Field-emission scanning electron
microscopy (FESEM) images and energy dispersive spectrometry
(EDS) analysis of the product were obtained on a Hitachi S-4800
field-emission scanning electron microananlyser, employing the
accelerating voltage of 5 or 15 kV. The UV–vis absorption spectra
were obtained on a Hitachi U-4100 spectrophotometer (Tokyo,
Japan). The Brunauer–Emmett–Teller (BET) surface area and pore
size distribution of the product was measured with an accelerated
surface area and porosimetry system (ASAP 2020).
Fig. 1. (a) The XRD pattern and (b) EDS analysis of the product prepared under the
present conditions.
˚
c = 13.78 A, space group: R3[148]). No characteristic peaks of other
impurities such as TiO and NiO are detected, indicating that the
2
2.3. Photocatalytic activity measurements
product is rather pure. The strong and narrow diffraction peaks
reveal the highly crystalline nature of the as-prepared product.
In order to investigate the photocatalytic property of NiTiO
microtubes for the degradation of organic dyes, 15 mg of NiTiO
3
3
3
Further evidence of the formation of NiTiO came from energy
dispersive X-ray spectrum (EDS) analysis of the product (see
Fig. 1b). The peaks of Ti, Ni and O can be easily found. Based on the
calculation of the peak areas, the atomic ratio of Ni/Ti/O equals
was dispersed into 40 mL aqueous solutions containing Pyronine B,
ꢁ1
Safranine T, or Fluorescein with a concentration of 10 mg L and
irradiated by the 254 nm UV light for the given time, respectively.
The suspension was dispersed by ultrasonic wave for 15 min and
then stirred in the dark for 30 min to ensure an adsorption/
desorption equilibrium prior to UV irradiation. The suspension was
then irradiated using the 254 nm UV light under continuous
stirring for given time. Finally, the suspensions after irradiating
various time were centrifuged at 10,000 rpm for 5 min to remove
1:1:3.1, which is very close to the stoichiometry of NiTiO
3
. The
weak C and Cu peaks should be attributed to CO
sample and the support, respectively.
2
adsorbed by the
The morphology of the product was characterized by FESEM
and TEM. Fig. 2a gives a representative FESEM image of the
product. Abundant tubular products with outer diameters of 500–
600 nm, inner diameters of 400–500 nm and lengths ranging from
the NiTiO
3
catalysts and the UV–vis absorption spectra of the as-
2 to 4 mm can be found. A magnified FESEM image shown in Fig. 2b
obtained solutions were measured.
clearly showed that all tubes was composed of many nearly
spherical nanoparticles with a mean diameter of ꢂ50 nm. There
3
. Results and discussion
3
are many pores among the nanoparticles. The NiTiO nanoparticles
are significantly faceted in the SEM and TEM images. Fig. 2c depicts
a typical TEM image, from which the tube constructed by nearly
spherical nanoparticles can be clearly seen. This further confirmed
the result of FESEM observations.
Fig. 1a shows the XRD pattern of the product prepared under
the present conditions. All of the diffraction peaks can be indexed
as hexagonal NiTiO form with measured lattices parameters
3
˚
˚
a = 5.033 A and c = 13.82 A, which is in good agreement with the
Fig. 3a is the UV–vis absorption spectrum of the as-prepared
˚
literature values (JCPDS Card files No. 89-3743, a = 5.031 A and
3
NiTiO microtubes, which was obtained on a Hitachi U-4100

Y. Ni et al. / Materials Research Bulletin 44 (2009) 1797–1801
1799
3
Fig. 2. (a) A low magnification SEM image, (b) a magnified SEM image and (c) a typical TEM image of the as-prepared NiTiO particles.
spectrophotometer by dispersing NiTiO
3
powders in distilled
Pyronine B, Safranine T, and Fluorescein in the absence/presence
of porous NiTiO microtubes under the irradiation of 254 nm UV
light. Fig. 4 depicts the UV–vis absorption spectra of three dyes
irradiated by the UV light of 254 nm for 0–90 min in the presence/
water and using distilled water as the reference. One shoulder peak
centered at 258.6 nm and one strong peak centered at 350.9 nm
can be found. Since no report is found on the optical property study
3
of NiTiO
needs further studying. Fig. 3b shows the N
isotherm and the corresponding pore size distribution of NiTiO
3
in the literature, the application of its optical property
absence of porous NiTiO
change trend can also be found: under the absence of porous
NiTiO microtubes, the intensities of all absorption peaks slightly
reduced after irradiation for 60 min; while the peak intensities
obviously decreased when the systems contained porous NiTiO
3
microtubes, respectively. A similar
2
adsorption/desorption
3
3
microtubes constructed by nanoparticles. The measurement
2
showed that the BET surface area was 14.06 m /g and the pore
3
size distribution mainly located from 20 to 30 nm (inset in Fig. 3b).
According to the SEM observations, the product should have a
bigger BET surface area. The present low BET value should be
microtubes and were irradiated only for 30 min. After 90 min, the
absorption peaks nearly disappeared in all spectra. The above
3
facts clearly imply that the as-prepared porous NiTiO microtubes
caused by the sintering/coalescence of NiTiO
the measurement.
3
nanoparticles during
possess good photocatalytic property for the degradation of
Pyronine B, Safranine T and Fluorescein, which has potential
application in wastewater treatment and environmental protec-
tion. In general, the solution containing organic dyes can produce
hydroxide radicals ( OH) under UV irradiation, which cause the
degradation of dyes. However, when no catalyst is used, the above
As for various materials, one of the challenging and intriguing
problems is to investigate their potential properties and thus to
achieve application in life-relating fields. At present, water
pollution control and rapid detection of biomolecules are
considered to be two of the most troublesome embarrassments.
Applications of nano/micromaterials in these fields may be a
direction of materials research. Generally, catalytic process is
mainly related to the adsorption and desorption of molecules on
the surface of the catalyst. Porous micro/nanostructures usually
possess the higher specific surface area and more unsaturated
surface coordination sites, which are favorable to the adsorption
of molecules. As a result, the catalytic performance will be
enhanced. In order to investigate the photocatalytic degradation
ꢃ
photochemical reaction is slow due to the production of a small
ꢃ
amount of OH. Since NiTiO
3
is a semiconductor [1], it can
generate electron–hole pairs under UV irradiation, which rapidly
combine with water molecules in the presence of oxygen to
ꢃ
fabricate a great deal of OH. As a result, organic dyes can be
rapidly degraded.
Usually, the flame of a spirit lamp contains flame-heart, inner-
flame and outer-flame; and the flame temperature ranges from
673 to 773 K, the highest to 1073 K. This provides necessary
property of the as-obtained porous NiTiO
the optical property changes of several organic dyes such as
3
microtubes, we studied
temperature condition for synthesis of NiTiO
3
. In order to ascertain
4 9 4
or Ti(OC H )
the formation process of NiTiO , we employed NiAc
3
2

1
800
Y. Ni et al. / Materials Research Bulletin 44 (2009) 1797–1801
Fig. 3. (a) The UV–vis absorption spectrum and (b) N
isotherm and the corresponding pore size distribution (inset) of the as-prepared
NiTiO microtubes constructed by nanoparticles.
2
adsorption/desorption
3
as the initial reagent and successfully obtained NiO and TiO
nanoparticles, respectively. Thus, a possible formation process of
NiTiO nanoparticles can be suggested below: when the solution
containing equal molar ratio of NiAc and Ti(OC was ignited,
the mixed solvents of ethanol and ethyleneglycol firstly combusted
to produce CO , H O and to released lots of heat; then, NiAc and
Ti(OC reacted with in air to form NiO and TiO
nanoparticles, respectively. The fresh-prepared NiO and TiO
2
3
2
4 9 4
H )
2
2
2
4
H
9
)
4
O
2
2
2
nanoparticles rapidly reacted to produce composite trinary metal
oxide NiTiO nanoparticles. All byproducts are CO and H O, so the
3
2
2
present approach is environment-friendly. The relative reactions
can be described as follows:
C
2
H
5
OHðC
2
H
6
O
2
Þ þ 3O
2
ð2:5O
! NiO þ 4CO
! TiO þ 16CO þ 18H
! NiTiO
However, it is still unclear why the as-prepared NiTiO
2
Þ ! 2CO
2
þ 3H
2
O
(1)
(2)
(3)
Ni2 þ 2CH
þ
COO þ 4O
ꢁ
þ 3H
O
Fig. 4. UV–vis spectra of various dyes under the irradiation of 254 nm UV light for
3
2
2
2
various time in the absence/presence of NiTiO
Safranine T, and (c) Fluorescein.
3
microtubes: (a) Pyronine B, (b)
TiðOC
4
H
9
Þ
4
þ 24O
2
2
2
2
O
NiO þ TiO
2
3
(4)
4. Conclusion
3
nanopar-
3
In summary, porous NiTiO microtubes constructed by abundant
ticles can self-assemble into porous microtubes and needs to be
further studied.
nearly spherical nanoparticles with the mean size of ꢂ50 nm have
been successfully prepared via a simple solution-combusting

Y. Ni et al. / Materials Research Bulletin 44 (2009) 1797–1801
1801
[
[
3] N. Dharmaraj, H.C. Park, C.K. Kim, H.Y. Kim, D.R. Lee, Mater. Chem. Phys. 5 (2004)
7.
4] O. Yamamoto, Y. Takeda, R. Kanno, M. Noda, Solid State Ions 22 (1987) 241.
method without any requirement of calcination step under a mild
condition. The as-prepared product possessed good UV–vis absorp-
tion property and strong photocatalytic degradation property for
some organic dyes such as Pyronine B, Safranine T and Fluorescein.
8
[5] Y. Shimizu, K. Uemura, N. Miura, N. Yamzoe, Chem. Lett. 67 (1988) 1979.
[
[
[
6] H. Obayashi, Y. Sakurai, T. Gejo, J. Solid State Chem. 17 (1976) 299.
7] A.R. Phani, S. Santucci, Mater. Lett. 50 (2001) 240.
8] Y.M. Chiang, D. Birnie III, W.D. Kingery, Physical Ceramics, John Wiley & Sons Inc.,
New York, 1996, p. 34.
3
This implies the porous NiTiO microtubes prepared via the present
method have potential applications in wastewater treatment and
environmental protection. The present synthesis strategy provides a
simple, mild and practical method for the synthesis of highly
[
9] R.E. Newnhan, J.H. Fang, R.P. Santoro, Acta Crystallogr. 17 (1964) 240.
[
[
10] J.J. Stickler, S. Kern, A. Wold, G.S. Heller, Phys. Rev. 164 (1967) 765.
11] H. Watanabe, H. Yamauchi, H. Takei, J. Magn. Magn. Mater. 15 (1980) 549.
crystalline NiTiO
further developed for syntheses of other trinary metallic oxides.
3
microstructures on a large scale and can also be
[12] R.S. Singh, T.H. Ansari, R.A. Singh, B.M. Wanklyn, Mater. Chem. Phys. 40 (1995)
173.
[13] T. Harikawa, N. Mikami, T. Markita, J. Tanimura, M. Kataoka, K. Sato, N. Nurshita, J.
Appl. Phys. 32 (1993) 4126.
Acknowledgements
[14] D.J. Taylor, P.F. Fleig, S.T. Schwab, R.A. Page, Surf. Coat. Technol. 120 (1999) 465.
[
[
15] R.A. Page, C.R. Blanchard-Ardid, W. Wei, J. Mater. Sci. 23 (1988) 946.
16] H. Taguchi, D. Matsuda, M. Nagao, K. Tanihara, Y. Miyamoto, J. Am. Ceram. Soc. 75
The authors thank the National Natural Science Foundation of
China (20771005 and 20571002), Science and Technological Fund
of Anhui Province for Outstanding Youth (08040106834), the
Education Department of Anhui Province (No. 2006KJ006TD) for
the fund support.
(
1992) 201.
[17] D.J. Taylor, P.F. Fleig, R.A. Page, Thin Solid Films 408 (2002) 104.
[
[
[
18] X.F. Chu, X.Q. Liu, G.Z. Wang, G.Y. Meng, Mater. Res. Bull. 34 (1999) 1789.
19] A.R. Phani, S. Santucci, Thin Solid Films 396 (2001) 1.
20] V. Gupta, K.K. Bamzai, P.N. Kotru, B.M. Wanklyn, Mater. Chem. Phys. 89 (2005) 64.
[21] A.V. Murugan, V. Samuel, S.C. Navale, V. Ravi, Mater. Lett. 60 (2006) 1791.
22] K. Sreedhar, A. Mitra, J. Am. Ceram. Soc. 83 (2000) 418.
[
[
23] N. Dharmaraj, H.C. Park, C.K. Kim, H.Y. Kim, D.R. Lee, Mater. Chem. Phys. 87 (2004)
References
5
.
[24] Y.J. Lin, Y.H. Chang, W.D. Yang, B.S. Tsai, J. Non-Cryst. Solids 352 (2006) 789.
[
[
1] Q.J. Harris, Q. Feng, Y.S. Lee, R.J. Birgeneau, Phys. Rev. Lett. 78 (1997) 346.
2] R. Fisch, Phys. Rev. B 51 (1995) 11507.
[25] Y.H. Ni, X.F. Cao, G. Wu, G. Hu, Z. Yang, X.W. Wei, Nanotechnology 18 (2007)
155603.