Facile synthesis and photocatalytic activity of bi-phase dispersible Cu-ZnO hybrid nanoparticles
Liu et al. Nanoscale Research Letters
Facile synthesis and photocatalytic activity of bi-phase dispersible Cu-ZnO hybrid nanoparticles
Xiao Liu 1
HongLing Liu 1
WenXing Zhang 2
XueMei Li 1
Ning Fang 1
XianHong Wang 1
JunHua Wu 0 3
0 Department of Materials Science and Engineering, South University of Science and Technology of China , Shenzhen 518055 , China
1 Key Lab of Polyoxometalate Chemistry of Henan Province, Institute of Molecular and Crystal Engineering, School of Chemistry and Chemical Engineering, Henan University , Kaifeng 475001 , China
2 Shangqiu Normal University , Shangqiu, HeNan Province 476000 , China
3 Pioneer Research Center for Biomedical Nanocrystals, Korea University , Seoul 136-713 , South Korea
Bi-phase dispersible Cu-ZnO hybrid nanoparticles were synthesized by one-pot non-aqueous nanoemulsion with the use of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) as the surfactant. The transmission electron microscopy (TEM) and X-ray diffraction (XRD) show high crystallinity of the Cu-ZnO hybrid nanoparticles and an average particle size of ~19.4 nm. The ultraviolet-visible light absorbance spectrometry (UV-vis) and photoluminescence spectrophotometry (PL) demonstrate well dispersibility and excellent optical performance of Cu-ZnO hybrid nanoparticles both in organic and aqueous solvent. The X-ray photoelectron spectroscopy (XPS) confirms Cu1+ and Cu2+ in ZnO. The observation using Sudan red (III) as probe molecule reveals that the Cu-ZnO hybrid nanoparticles possess enhanced photocatalytic activity and stability which are promising for potential applications in photocatalysis.
Nanoemulsion; Bi-phase dispersible; Cu-ZnO nanoparticles; Photocatalytic performance
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Background
Multi-constituent nanomaterials with different
compositions and tailorable morphology display multiple
functionalities and novel properties, showing prospective
potentials in drug delivery, biological detection and
sensing, imaging, separation, strong catalysis, magnetic data
storage, chemotherapy agent, and many other areas [1-7].
Syntheses of such nanoparticles and investigating their
various properties are hence of general interest. ZnO is a
widely studied n-type semiconductor, with direct band gap
(3.37 eV) and large exciton binding energy of 60 meV, and
has promising applications in catalysis, solar cells, gas
sensor, and miniaturized sensor [8-11]. However, its
applications are somewhat restricted [12]. Doping ZnO with
transition metal elements has been confirmed as an
effective method to improve its functionality including electrical
and optical properties. Among the transition metal
elements, Cu is the best choice as impurity for realization of
p-type ZnO due to the minimum size mismatch between
Zn and Cu which leads to the lowest formation energy
[13,14]. After nano-engineering Zn and Cu into a single
entity, the nanostructure would not only possess the
unique properties of the copper and the semiconductor
but also generate collective new property based on the
interaction between Cu and ZnO. The photocatalytic
performance, magnetic, electrical, and gas-sensing properties
of Cu-ZnO have been studied for their potential
applications in photocatalysis, spintronics, and gas sensor
[15-17]. Up to now, Cu-ZnO has been synthesized by a
variety of methods such as electrochemical synthesis,
coprecipitation, vapor phase transport method, and
hydrothermal method [18-21].
In our research, excellent nanoparticles could be
synthesized via one-pot non-aqueous nanoemulsion process
aided by poly(ethylene glycol)-block-poly(propylene
glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO). The
triblock copolymer PEO-PPO-PEO possesses many
distinctive merits, such as non-charging, aqueous solubility,
nontoxicity, and biocompatibility, and is widely used in various
fields [22-26]. In nanoemulsion process, the
PEO-PPOPEO molecules predominantly participate in the reaction
as a surfactant, even playing a role in stabilizing the
nanoparticles formed and acting as the role of a reducing agent.
We have previously generated long-term stable,
monosized, highly crystalline Fe3O4-ZnO, Au-ZnO, Ag-ZnO,
and hybrid-phase iron oxide nanoparticles [27-30]. In this
paper, we report the preparation of polymer-capped
Cu-ZnO hybrid nanoparticles using non-toxicity and
biocompatible triblock copolymer PEO-PPO-PEO as
the surfactant. The characterization demonstrates that
the nanoparticles are monosized and of high crystallinity,
showing excellent dispersibility and optical performance
both in organic and aqueous medium. The photocatalytic
behavior of the nanoparticles is evaluated using Sudan red
(III) as a probe molecule. The results reveal that the
nanostructured Cu-ZnO moieties unveil enhanced
photocatalytic performance and stability. Therefore, the
assynthesized Cu-ZnO hybrid nanoparticles could be acted
as a promising photocatalyst candidate in the degradation
of organic pollutants.
Methods
Cu-ZnO hy (...truncated)