Lignin-assisted solid-phase synthesis of nano-CuO
for a photocatalyst with excellent catalytic activity
and high performance supercapacitor electrodes†
Xiaohong Wang,
*
a
Fangsheng Wu,
a
Yawei Duan,
a
Yingying Wang,
a
Chen Hao
*
a
and Cunwang Ge
b
CuO nanostructures were successfully synthesized using NaOH and Cu(NO
3
)
2
as starting materials by an
aminated lignin (AL)-assisted solid-phase method. The results of X-ray diffraction (XRD) analyses indicate
that the prepared CuO nanoparticles have a monoclinic crystal structure with an abundance of
mesopores. The emission scanning electron microscopy (SEM) images exhibit noticeable changes in
morphology and size of the CuO samples with different content of AL. The CuO nanostructures were
applied into the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) under UV
light irradiation. Meanwhile, the best photocatalytic activity with an AL dosage of 0.5 g and the
calcination temperature at 400
C shows almost complete degradation (97.83%) for MB and 66.76% for
MO under UV light irradiation for 1.5 h, respectively. The supercapacitor behavior was characterized by
cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy
techniques. The maximum specific capacitances of CA3.0-400 are found to be 644.8 F g
1
, much
higher than other samples. However, it exhibits slightly worse cyclic stability compared with CA0.5-400.
Introduction
In recent years, the fabrication of high-efficiency photocatalysts
and energy storage devices has received increased attention in
the eld of environmental remediation and renewable energy
resources. Photocatalysts with well-dened morphologies, have
great potential in the applications of degradation of harmful
pollutants from industrial wastewater. In particular, the col-
oured dye emissions of textile and paper industries such as MB,
acid red 14, remazol red RR, reactive blue 19 and MO, can easily
lead to severe environmental contamination because of their
toxicity and non-biodegradation.
1,2
However, conventional bio-
logical treatment methods cannot be used efficiently for the
degradation of dyes and organic pollutants.
3
Hence, photo-
catalytic treatment of organic pollutants from water and air
using semiconductors as photocatalysts has increased more
and more extensive research due to their excellent decoloriza-
tion and degradation efficiency.
4–8
Additionally, supercapacitors
(SCs), known as electrochemical capacitors, are recognized as
promising energy storage devices because of its high power
density, long cycle life, rapid charge/discharge rate and low
maintenance cost than batteries.
9,10
Copper oxide (CuO) as an p-type important semiconductor
with a narrow band-gap,
11–13
has been studied extensively over
recent decades due to its unique physicochemistry properties,
which include excellent chemical stability, low toxicity, low cost,
desirable optical and environmentally friendly.
14,15
The
morphology and size of CuO nanoparticles have a signicant
effect on their chemical and physical properties.
16,17
Thus CuO
has received widespread attention and has potential applica-
tions in magnetic storage media,
18
photocatalysts,
19
electro-
optical devices,
20
gas sensors,
21
electrode materials,
22
and
nanodevices.
23
A novel and simple solid-state reaction in the presence of AL
has been developed to synthesize mesoporous CuO nano-
particles because of the following reasons: good homogeneity,
ease of composition control, low processing temperature, large
area coatings, low equipment cost, low pollution and good
optical properties.
24
Particularly, the solid-phase processes are
efficient in preparing mesoporous copper oxide in accordance
with the process route of our proposal.
Lignin is the third most abundant biopolymer on earth,
exceeded only by cellulose and hemicelluloses.
25–28
It can be
acquired from wood during wood pulping and paper-making
and has been used primarily as a bioresources for the raw
material of the synthesis of environmentally compatible poly-
mers.
29
The comprehensive utilization of lignin not only econ-
omizes natural resources, but also helps preserve the ecological
a
School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang, Jiangsu
212013, China. E-mail: chhao@ujs.edu.cn; xhwang@ujs.edu.cn; Fax: +86 511
88791800; Tel: +86 511 88791800
b
School of Chemistry and Chemical Engineering, Nantong University, Nantong, Jiangsu
226019, China
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c6ra11911e
Cite this: RSC Adv.,2016,6, 65644
Received 8th May 2016
Accepted 4th July 2016
DOI: 10.1039/c6ra11911e
www.rsc.org/advances
65644 | RSC Adv.,2016,6, 65644–65653 This journal is © The Royal Society of Chemistry 2016
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