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Preparation of Cu2O Nanoparticles as a Catalyst in Photocatalyst Activity Using a Simple Electrodeposition Route

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Nano Biomed Eng
2018, 10(4): 406-416. doi: 10.5101/nbe.v10i4.p406-416.
Research Article
406 Nano Biomed. Eng., 2018, Vol. 10, Iss. 4
Preparation of Cu2O Nanoparticles as a Catalyst in
Photocatalyst Activity Using a Simple Electrodeposition
Route
Abstract
In order to obtain inexpensive and effective application of catalyst for photodegradation, Cu2O
powder was prepared by the simple and inexpensive electrodeposition method using surfactants
such as glycerin (GLY), polyvinyl alcohol (PVA), poly(N-vinylpyrrolidone) (PVP) that helped the
growth and nucleation of suspended particles. These particles were distinguished by atomic force
microscopy (AFM), X-ray diffraction (XRD), eld-emission scanning electron microscopy (FESEM)
and high-resolution transmission electron microscopy (HRTEM). Diameter size of these obtained
particles was found to reach to about 40 nm. In order to demonstrate the photodegradation efciency
of the copper oxide in the removal of organic malachite green oxalate (MG) dye, the catalyst was
used both in calcination at 300 °C and without calcination. Parameters such as the amount of
catalyst, the concentration of dye, the pH of dye sol, and the temperature were calculated. Pseudo
rst order reactions according to Langmuir-Hinshelwood kinetics could be obtained from the result
of photocatalytic reactions. Parameters such as energy activation (Ea), enthalpy of activation (ΔH0),
entropy of activation (ΔS0) and free energy of activation (ΔG0) were calculated. The activation energy
was equal to 11.719 ± 1 and 11.083 ± 1 kJ/mol for MG dye in the presence of Cu2O nanoparticles in
both two cases of calcination and without calcination respectively.
Keywords: Electrochemical deposition of Cu2O; Photochemical processing; Thermodynamic;
Kinetic; Mechanism
Hayder Khudhair Khattar1, Amer Mousa Jouda1, Fuad Alsaady2
1Department of Chemistry, Faculty of Science, University of Kufa, Najaf, Iraq.
2College of Pharmacy, University of Al-Mustansiriyah, Baghdad, Iraq.
Corresponding authors. E-mail: khydr12@yahoo.com
Received: Jun. 6, 2018; Accepted: Aug. 12, 2018; Published: Dec. 4, 2018.
Citation: Hayder Khudhair Khattar, Amer Mousa Jouda, and Fuad Alsaady, Preparation of Cu2O Nanoparticles as a Catalyst in Photocatalyst Activity
Using a Simple Electrodeposition Route. Nano Biomed. Eng., 2018, 10(4): 406-416.
DOI: 10.5101/nbe.v10i4.p406-416.
Introduction
Nanotechnology is in a fast progress of development
and its products are quite advantageous in all domains.
Nanoparticles (NPs) display a major surface-to-size
proportion when they are matched to macro and micro-
materials [1]. Cuprous oxide is p-type semiconductor
with direct band gap of 2.0 eV, the applications of
which in solar energy transmutation, gas sensors,
electronics, and magnetic storage have attracted
large interests [2-4]. Electrodeposition, a chemical
deposition, is a method to synthesize Cu2O nanocrystal
of various shapes and sizes [5]. Properties of copper
oxides have been studied through experiments and
have been proven a promising photocatalyst in direct
water splitting and organic contamination degradation
under visible-light radiation [6, 7]. Cu2O can adsorb
molecular oxygen effectively [8], which can clean the
407
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photogenerated electrons to inhibit the recombination of
electron-hole pairs, and then develop the photocatalytic
efficiency. Moreover, the essential properties of
Cu2O include low toxicity and inexpensive price
[9]. Octahedral Cu2O with bared {111} facets show
extremely photocatalytic performance compared to
cubes, making it a possible candidate for photocatalytic
applications [10-12]. Advanced oxidation processes
include the production of much interacting radicals,
such as hydroxyl radicals, into least molecules, the
entire mineralization of compounds into CO2 and H2O.
The application of homogeneous photodegradation
(single-phase system) to treat contaminated waters
concerns the use of ultraviolet (UV)/ozone and UV/
H2O2 [13]. Nanopwoder was characterized using atomic
force microscopy (AFM), X-ray diffraction (XRD),
eld emission scanning electron microscope (FESEM),
energy-dispersive X-ray spectroscopy (EDS), and
transmission electron microscope (TEM).
Experimental
The method was simple and useful for generating
NPs, which included using two electrodes, i.e. anode
and cathode plates made of copper with high purity
reaching to 99.99% with the scale of 2 cm, width
of 2 cm and length of 1.5 mm. The two electrodes
were placed facing each other in a vertical way with
a distance of 6 cm between each other. The electrical
cell that contained 100 mL deionized water (DW)
was obtained from Faculty of Pharmacy, University
of Kufa, Iraq. The electrolysis was employed at the
temperature of 60 °C with continuous various voltages.
The current passing in the circuit was monitored with
a voltmeter. Additionally, the NPs were produced in
a way of electrochemical reduction in changing the
polarity of the direct current between the electrodes
during electrolysis process, in order to obtain the
better precipitation [14]. Electrolyte was used to
prepare copper (I) oxide, with 25 g/100 mL NaCl
(99% Thomas, Indi) at pH 8, and the distance for tow
electrodes was 6 cm. A power supply under study
(current DC 5 amp, maximum voltage 30 V, China)
was utilized to supply and measure with more precision
the current. Additives included glycerin (GLY),
polyvinyl alcohol (PVA) and poly(N-vinylpyrrolidone)
(PVP) (CDH-India). All the materials are listed in
Table 1. Afterwards, the orange or red color of copper
oxide powder was washed repeatedly with deionized
water numerous times by using centrifugal; then
washed twice with 99% ethanol and dried in an oven at
60 °C for 1h. Later, the deposited Cu2O was stored in
tightly blocked vials, in a vacuum container containing
silica gel powder [15].
Result and Discussion
Characterization of Cu2O
Atomic force microscopy (AFM) measure-
ments of Cu2O powder electrodeposition
AFM (CSPM-4000 Hitachi, Japan) of the Cu2O
powder was prepared by electrical method using
glycerin, PVA and PVP (20 mL) as stabilizer (Fig. 1,
Table 2). Fig. 1(a) shows distance among the metal
Table 1 Chemicals and working conditions applied in the experiment of Cu2O powder electrodeposition of NaCl solutions
Chemicals PVP PVA Glycerin
NaCl 25 g / 100 mL 25 g / 100 mL 25 g / 100 mL 25 g / 100 mL
NaOH 5 g / 100 mL 1.5 mL 1.5 mL 1.5 mL
K2Cr2O71 g / 100 mL 1 mL 1 mL 1 mL
Citric acid 5 g / 100 mL 1 mL 1 mL 1 mL
Deionized water 0.7 μs/cm 0.7 μs/cm 0.7 μs/cm 0.7 μs/cm
Glycerin 1 g/100 mL -- -- 20 mL
PVA 1 g/100 mL -- 20 mL --
PVP 1 g/100 mL 20 mL -- --
pH 8-9 8-9 8-9 8-9
Temperature 50-60 50-60 50-60 50-60
General current density 500 A/m2500 A/m2500 A/m2500 A/m2
(Copper) Anode area 8 cm28 cm28 cm28 cm2
Current density 0.4 A 0.4 A 0.4 A 0.4 A
Voltage / Time -- 3.4 V / 60 min 3.5 V / 60 min 3.8 V / 60 min
Note: PVP = Poly(N-vinylpyrrolidone); PVA = Polyvinyl alcohol.
408 Nano Biomed. Eng., 2018, Vol. 10, Iss. 4
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oxide NPs was equal to 18 nm; Fig. 2(b) shows
distribution of the metal oxide NPs was in three
dimensions: X, Y and Z [16]. X and Y represent
measurement of the area, and Z = 19.17 nm represents
the height within nanoscale 0-100 nm. It could be
observed that distribution of the copper oxide particles
ranged from 60 to 140 nm (Fig. 1(c)). Average
Granulite cubulation distribution of diameter for
NPs Cu2O, when using 20 mL PVP, was 82.10 nm.
Similarly, we noted the distribution of grain formed
in PVA was 77.42 nm (Fig. 2), and was 56.64 nm in
glycerin (Fig. 3).
X-ray diffraction (XRD) measurements of Cu2O
powder electrodeposition
The purity and crystal phases of Cu2O powder was
tested by XRD. The XRD data came from employing
a Shimadzu 6000 diffractometer equipped with Cu
Fig. 1 AFM images of Cu2O powder electrodeposition in NaCl solutions with PVP (20 mL), avg. diameter = 82.10 nm: (a)
2-Dimensional image; (b) 3-Dimensinal image; (c) Granulite cubulation distribution chart.
2000
1500
1000
500
0
nm
nm
nm
0 500 1000 1500 2000
18
16
14
12
10
8
6
4
2
0
....208.csm
CSPM Title
Topography
Pixels = (388, 388)
Size = (2047 nm,
2047 nm)
19.17
1535
1024
512
00
511.79
1023.57
1535.36
0.37
nm
nm
nm
Percentage (%)
16
12
8
4
0 20 40 60 80 100
Diameter (nm)
Granularity cumulation distribution chart
120 140
(a) (b) (c)
Fig. 2 AFM images of Cu2O powder electrodeposition in NaCl solutions with PVA (20 mL), avg. diameter = 77.42 nm: (a)
2-Dimensional image; (b) 3-Dimensinal image; (c) Granulite cubulation distribution chart.
2000
1500
1000
500
0
nm
nm
nm
nm
nm
0 500 1000 1500 2000
16
14
12
10
8
6
4
2
0
....210.csm
CSPM Title
Topography
Pixels = (416, 421)
Size = (2024 nm,
2049 nm)
0.12
17.85
1518.22
1012.14
506.07
00
512.15
1024.31
1536.46
nm
Percentage (%)
16
12
8
4
0 20 40 60 80 100
Diameter (nm)
Granularity cumulation distribution chart
120 140
(a) (b) (c)
17.85
Fig. 3 AFM images of Cu2O powder electrodeposition in NaCl solutions with glycerin (20 mL), avg. diameter = 56.64 nm: (a)
2-Dimensional image; (b) 3-Dimensinal image; (c) Granulite cubulation distribution chart.
2000
1500
1000
500
0
nm
nm
nm
0 500 1000 1500 2000
10
8
6
4
2
0
....207.csm
CSPM Title
Topography
Pixels = (424, 424)
Size = (2041 nm,
2041 nm)
0.24
10.11
1531
1021
510
00
510
1021
1531
nm
nm
nm
Percentage (%)
8
6
4
2
0 20 40 60 80 100
Diameter (nm)
Granularity cumulation distribution chart
120
(a) (c)(b)
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Kα ray = 1.5406 Å) (at 40 mA and 50 KV) in zone
from 20° to 80°. XRD patterns of the as-prepared
samples were revealed in different conditions. In Fig.
4, diffraction peaks showed at 29.61°, 36.48°, 42.38°,
61.46°, 73.56° and 77.52°, identical to 110, 111,
200, 220, 311 and 222 planes of Cu2O, respectively,
which indicated the formation of Cu2O nanocrystals
according to JCPDS Card No. 05-0667 [17, 18]. The
average crystalline size of Cu2O NPs was determined
by taking the full width at half maximum (FWHM) of
the most intense peak at 36.50° using Debye-Scherrer’s
formula, which was of about 46.50 nm. The crystalline
size calculated from XRD patterns was usually bigger
than that from TEM images, which also occurred in
our previous study [19].
Scanning electron microscope (SEM) measure-
ments of Cu2O (NPs) electrodeposition with
Gly, PVA, PVP
Field emission scanning electron microscopy
(FESEM) (TESCAN, MIRA3, Czech) images (Fig. 5-7)
show that range of the particle size of Cu2O NPs was
40-80 nm. The TEM form revealed that the prepared
Cu2O NPs were particularly single crystals with twin
boundaries (amorphous), as shown in Fig. 5. With the
stabilizing agent GLY, it was found that the content of
Cu in the Cu2O NPs was 86.72 w%, and with PVA it
was 83.19 w%, and with PVP it was 71.44 w%.
When the concentration of sample in glycerin
(20 mL) was 1 g/100 mL, octahedral Cu2O crystals
were formed, SEM image showing the structure of
Cu2O octahedron revealed the typical morphology of
octahedral Cu2O (eight {111} faces) with about 40 nm
in size (Fig. 5) [20].
TEM images from Philips CM300 300 kV High-
Resolution Transmission Electron Microscope revealed
the formation of octahedral Cu2O crystals, which was
compatible with the results of XRD and SEM showing
particles of eight {111} faces [21] (Fig. 5).
When the sample with PVA (20 mL) was at the
concentration of 1 g/100 mL, hexapods Cu2O particles
were formed with about 60 nm in size. It had eight and
twenty-four {111} faces (Fig. 6).
When 20 mL PVP from 1 g / 100 mL concentration
was used as stabilizer, it can yield the cubic shape of
Cu2O particles (having all six {110} faces) with formed
uniform surface, and regular shape with particle size
of about 80 nm according to the TEM size and SEM
shape in nano scale (Fig. 7).
Photodegradation of malachite green (MG)
oxalate dye by Cu2O as catalyst
In order to prove in an electrical way the potential
of copper oxide as a catalyst in the destruction of
organic pollutants from pigments, wastewater or
textile plants, and to satisfy the increasing demand
for highly efficient and inexpensive catalysts, MG
Table 2 AFM measurements of Cu2O powder electrodeposition
in NaCl solutions by using glycerin, PVP and PVA
CSPM Imager surface roughness analysis
Amplitude parameters
Cu2O PVP PVA GLY
Roughness average (sa) (nm) 4.0100 4.5300 2.5900
Root mean square (sq) (nm) 4.7600 5.2100 2.9900
Surface skewness (Ssk) (nm) 0.1050 0.0672 0.0001
Surface kurtosis (sku) (nm) 2.1000 1.7900 1.8000
Sku = (3) mesokurtic, < (3)
liptokurtic, > (3) platykurtic 2.1000 > 1.8000 > 1.7900
Peak-peak (sy) (nm) 19.5000 18.000 10.300
Ten point height (sz) (nm) 19.5000 18.000 10.300
Hybrid parameters
Mean summit curvature (Ssc) (1/nm) -0.01730 -0.0135 -0.0105
Root mean square slope (sdq) (1/nm) 0.2950 0.2670 0.2370
Surface area ratio (sdr) 3.9200 3.4400 2.6600
Functional parameters
Surface bearing index (sbi) 2.1300 5.3000 5.5800
Core uid retention index (sci) 1.5600 1.5100 1.4900
valley uid retention index (svi) 0.0836 0.0700 0.0692
Reduced summit height (spk) (nm) 2.3600 2.7100 1.1000
Core roughness depth (sk) (nm) 14.3000 14.700 9.0000
Reduced valley depth (svk) (nm) 2.7800 0.5910 0.2630
Spatial parameters
Density of summits (Sds) (1/um2) 250.00 363.00 308.00
Fractal dimension 2.4400 2.1100 2.5200
Avg. diameter (nm) 82.10 77.42 56.64
Voltaic (V) 3.4 3.5 3.8
Fig. 4 X-ray images of Cu2O powder electrodeposition in NaCl
solutions.
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
Counts
110
200 220 311
222
111
20 30 40 50 60 70 80
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dye was studied with absorption of about 617 nm and
good stability with visible light [22]. MG which is
specific as a basic dye and a great water soluble dye
related to the triphenylmethane family, M.wt 927.01 g/
mol [34-36], was used to improve the photocatalytic
properties. The cuprous oxide under study was used in
tow phase calcined to 300 °C, termed A, and without
calcination was termed B. The homely photoreactor
equipment mercury lamp-Philips-Holland (250W)
without cover glass as a source for UV irradiation
(Shimadzu UV 1650 PC Japan) was used to determine
the declination degree of the MG dye solutions (LAB
Tech, Hotplate. Korea). The space of lamp and solution
glass was 15 cm. The test was carried out at 25 °C,
and the compartment was closed to block escape of
harmful radiation. The suspension pH values were
adjusted at desired level using 0.01 N NaOH or 0.01 N
HCl solutions, measured via pH meter (Hanna Tool).
The water mixture was stirred magnetically during the
amount of dye adsorbed and reduced was determined
by change in the absorbance of MG dye using Equation
(1).
D% = [(Co Ca)/Co]×100%, (1)
where D% is the degradation ratio, Co is the
initial concentration of dye solution, and Ca is the
Fig. 5 SEM, EDS and TEM images of Cu2O NPs electrodeposition in NaCl with glycerin (20 mL), size = 40 nm, under vigorous
stirring. Cu = 86.72 w%, O = 13.28 w%.
Fig. 6 SEM, EDS and TEM images of Cu2O NPs electrodeposition in NaCl with PVA (20 mL), size = 60 nm, under vigorous stirring.
Cu = 83.19 w%, O = 16.81 w%.
2000
1500
1000
500
0
CuLα
CuKα
0 Kα
CuKβ
2 µm
0 5 10 15
keV
40 nm
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
CuLα
CuKα
0 Kα
CuKβ
2 µm
0 5 10 15
keV
60 nm
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concentration of dyes after adsorption by the catalyst.
Copper oxide obtained by electrostatic deposition
method can be used in two cases in the process of
photodegradation. Cu2O calcination at 300 °C was
termed A and Cu2O without calcination was termed B.
Dark reaction of Cu2O catalyst in the absence
of ultraviolet (UV) radiation
In dark reaction tests in the lack of UV beam, Cu2O
was employed as a catalyst, as shows in Fig. 3. The
results showed no deterioration in the loss of UV,
where adding stimulation generated a slight change
in the dye concentration. In an incubation time, the
pigment concentration decreased slightly; after a
limited period of time, it became fixed, where the
monolayer configured on the surface of the catalyst,
because of no active sites useful for extra adsorption.
Hence, no additional lessening in dye concentrations
was observed. Thus, the yield obtained from the tested
absorption conrmed the low concentration of solutions
(MG) which was due to the absorption of dyes over
catalysts, and then no degradation of dyes was found.
The conclusion showed that the balance occurred after
120 min. The percentage of decomposition efciency
was calculated at 76.825% and 78.185% for the Cu2O
(A and B), respectively.
Photodegradation of malachite green (MG)
oxalate dye solution by ultraviolet (UV)
irradiation in the absence of catalyst
Results of the photodegradation of MG dye
solution, by UV irradiation in catalyst absence (Fig.
9) could be determined after 90 min of UV treating.
The photodegradation efficiency (PDE%) could be
observed as of 49.75% with ultraviolet radiation in
catalyst absence.
Inuence of the amount of catalyst
Fig. 7 SEM, EDS and TEM images of Cu2O NPs electrodeposition in NaCl with PVP (20 mL), size = 80 nm, under vigorous stirring.
Cu = 71.44 w%, O = 28.56 w%.
4000
3500
3000
2500
2000
1500
1000
500
0
CuLα
CuKα
0 Kα
CuKβ
5 µm
0 5 10 15
keV
80 nm
Fig. 8 The degradation efciency of MG with A and B catalysts,
in the absence of UV radiation.
90
80
70
60
50
40
30
20
10
0
PDE
0 50 100
Time (min) 150
Fig. 9 The photodegradation efciency of MG dyes without the
catalyst.
60
50
40
30
20
10
0
PDE
0 50
MG dye
100
Time (min)
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Influence of the amount of catalyst onto
photocatalytic degradation for MG dyes was studied.
The solution was examined under the exam provision
with dye concentration of 4 ppm, light power 250 W,
at 25 °C and variable of the mass of Cu2O NPs for both
A and B in the range of 0.01-0.07 g in 100 mL. From
4 ppm of MG dye, if concentration of the photocatalyst
crossed certain optimum value in the suspension, the
penetration of light through the suspension reduced,
causing decrease in the rate of decolourization of dye.
Some studies explained that the rate of disintegration
of the pollutant when increasing the amount of optical
catalyst to the loss of a semiconductor molecule
excited the state when it collided with other molecules
that were not excited according to Equation (2) [23].
Thus, for executing any continuous research, the
catalyst dose optimization is required before starting
any photolysis process. In Fig. 10, for both copper
oxides A and B, the best weight of Cu2O was 0.03,
and 0.07 g for A and B respectively. PDE for Cu2O
NPs both A and B was equal to 95.55% and 98.02%
respectively.
TiO2 + TiO2 * + TiO2 # TiO2. (2)
The inuence of pH solution
By studying the changes in pH solution in the range
of 2-10 while maintaining other test conditions xed:
dye concentration of 4 ppm, light power of 250 W,
Fig. 10 (a) Effect of weight of Cu2O (A) on photodegradation efciency of MG; (b) Effect of weight Cu2O (B) on photodegradation
efciency of MG.
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
ln (C
0
/C)
ln (C0/C)
0 50 Time (min)
(A)
100 150
0.01 (g)
0.02 (g)
0.03 (g)
0.04 (g)
0.05 (g)
0.06 (g)
0.07 (g)
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0.5 0 50 Time (min)
(B) Weight of (B)Weight of (A )
100 150
0.01 (g)
0.02 (g)
0.03 (g)
0.04 (g)
0.05 (g)
0.06 (g)
0.07 (g)
Fig. 11 Influence of pH on photocatalytic declination efficiency of MG (a) in the presence of 0.03 g Cu2O (A), and (b) in the
presence of 0.07 g Cu2O (B).
0.16
0.12
0.08
0.04
0
K (min−1)
0 5 10 15
pH of (A) (a)
(b)
pH of (A)
pH of (B) pH of (B)
100
80
60
40
20
0
PDE
0 5 10 15
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
K (min−1)
0 5 10 15
120
100
80
60
40
20
00 5 10 15
PDE
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catalyst dose of 0.03 g for sample A, and 0.07 g for
sample B, at 25 °C, the chamber had a variable pH
initial solution for dye solutiоns. The results were
observed in Fig. 3 and 11; the inuence of the initial
solution pH on the removal of MG by Cu2O NPs were
shown. It can be seen that the adsorption percentage
maintained very high, as of 99.97 and 97.53% for both
cuprous oxides A and B respectively, in the pH range
of 2-8. And then, the adsorption of MG decreased
gradually from 94.85 and 89.71% to 87.09 and 84.34%
for both cuprous oxides A and B respectively.
Inuence of primary dye concentration
The influence of primary dye concentration on the
photocatalytic degradation rate could be calculated by
maintaining all other test conditions stable: light power
= 250 W, рH = 2 at 25 °C, 0.03 g for Cu2O (A) and
0.07 g for Cu2O (B), while changing the primary dye
concentration in the domain of 1-7 pрm. Fig. 12 shows
that the photocatalytic degradation rate was elevated
Fig. 12 The variable in photocatalytic degradation efciency for MG dye with concentration (a) in the presence of 0.03 g Cu2O (A),
and (b) in the presence of 0.07 g Cu2O (B).
3.5
3.0
2.5
2.0
1.5
1.0
0.5
00 50
Time (min) (A) ppm (A)
(a)
(b)
PDE
100 0
120
100
80
60
40
20
02 4 6 8
1 ppm
2 ppm
3 ppm
4 ppm
5 ppm
6 ppm
7 ppm
3.0
2.5
2.0
1.5
1.0
0.5
0
ln (C
0
/C) ln (C
0
/C)
0 50
Time (min) (B) ppm (B)
PDE
100 0
120
100
80
60
40
20
02 4 6 8
1 ppm
2 ppm
3 ppm
4 ppm
5 ppm
6 ppm
7 ppm
Table 3 Values of rate constant, kinetics and thermodynamic parameters for the photocatalytic degradation of MG dye at 303-318 K,
with 0.03 g Cu2O (A) and 0.07 g Cu2O (B)
T(ko)1/T
K(sec-1) ×10-5 ln K Ea
(kJ mol-1)ΔH#
(kJ mol-1)ΔS#
(kJ mol-1 k-1)ΔG#
(kJ mol-1)
Cu2O
(B)
Cu2O
(A) Cu2O
(B)
Cu2O
(A) Cu2O
(B)
Cu2O
(A) Cu2O
(B)
Cu2O
(A) Cu2O
(B)
Cu2O
(A) Cu2O
(B)
Cu2O
(A)
303 0.00330 4.166 5.833 -10.085 -9.749
11.083 11.719
8.564 9.200
-0.250 -0.286
84.495 95.850
308 0.00324 4.660 6.698 -9.973 -9.611 8.522 9.158 85.706 97.246
313 0.00319 5.166 7.329 -9.870 -9.521 8.481 9.117 86.918 98.635
318 0.00314 5.500 7.833 -9.808 -9.454 8.439 9.075 88.129 100.023
414 Nano Biomed. Eng., 2018, Vol. 10, Iss. 4
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with lowering of the initial dye concentration. This
might be due to the length of the path of photon entering
the dye solution that decreased with the increased
concentration of the dye solution, which resulted in
a fewer number of photons attached to the surface
of the catalyst, Thus, the hydroxyl root (OH) and the
superoxide (O2-) were lowering, leading to a reduction
in the percentage of photolysis due to the lack of
surface area exposed to excitement [24, 25].
Inuence of varied temperature
Table 3 shows the activation energy for
photocatalytic degradation in MG solution using the
cuprous oxide: 0.03 g Cu2O (A) and 0.07 g Cu2O (B).
The catalyst in the temperature range of 303-318 K
equaled 11.719 ± 1 and 11.083 ± 1 kJ/M, respectively.
Fig. 13 Inuence of photocatalytic degradation efciency of MG at varied temperature (a) in the presence 0.03 g Cu2O (A), and (b)
in the presence of 0.07 Cu2O (B).
(a)
(b)
3.0
2.5
2.0
1.5
1.0
0.5
0
ln (C0/C)ln (C0/C)
0 40 6020 Time (min) (A) 80
Temp.=303
Temp.=308
Temp.=313
Temp.=318
95
94
93
92
91
90
89
88
PDE
300 310 320
Temp. (A)
2.5
2.0
1.5
1.0
0.5
00 40 6020 Time (min) (B) 80
Temp.=303
Temp.=308
Temp.=313
Temp.=318
88
86
84
82
80
78
PDE
300 310 320315305 Temp. (B)
Fig. 14 Arrhenius plot of MG dye with (a) 0.03 g Cu2O (A) and (b) 0.07 g Cu2O (B).
9.4
9.5
9.6
9.7
9.8
ln K
0.0031 0.0032 0.0033
1/T Cu2O (A) 0.0034
y =
1409.6x
5.0242
R2 = 0.9963
9.75
9.85
9.95
10.05
10.15
ln K
0.0031
(a) (b)
0.0032 0.0033
1/T Cu2O (B) 0.0034
y =
1333.1x
5.6216
R2 = 0.9824
415
Nano Biomed. Eng., 2018, Vol. 10, Iss. 4
http://www.nanobe.org
Conclusions
The preparation of cuprous oxide NPs was carried
out successfully by electrochemical rout, in an easy,
inexpensive and highly precise manner to control the
size and shape within nanometer scale. The prepared
NPs were characterized by XRD, FESEM, EDX,
TEM and AFM. To improve the catalytic performance
of photodegradation and to enhance crystallization,
the powder was calcined to 300 °C (A), To test
the catalytic performance, Cu2O calcination was
compared with Cu2O without calcination (B). For
degradation of the sol malachite green dye, the product
photocatalytic reactions suggested that the model
was pseudo-first order reaction represented by the
Langmuir-Hinshelwood model. The thermodynamic
parameters referred to that positive ΔH0 was certain on
endothermic reaction. The positive ΔG0 result indicated
that the non-spontaneous reaction was of clear high
positive ΔG0, which was because the activated case
was solvated structure established between the dye
molecules and the reaction mediate that was hydroxyl
radicals. This was also confirmed by the negative
entropy of activation ΔS0 which was negative and more
ordered to the reactant. The reactive species such as
hydroxyl radical and superoxide anion were produced
from the heterogeneous photocatalytic reaction.
The products of the fragmentation of the dye by the
catalyst were CO2 and H2O. Future work should be
the production of low-cost semiconductors capable of
eliminating organic pollutants in an easy, simple and
controlled electrochemical way.
Conict of Interests
The authors declare that no competing interest
exists.
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Copyright© Hayder Khudhair Khattar, Amer Mousa Jouda, and
Fuad Alsaady. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which
permits unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are credited.
... Removal of these organic dyes from polluted water bodies is a matter of serious environmental concern, and the development of new advanced photocatalytic materials capable of effectively decomposing those dyes can be an amicable solution [5,6]. Various metal oxides such as TiO 2 [7], ZnO [8], Cu 2 O [9], MnO 2 [10], Fe 2 O 3 [11], WO 3 [12] and CeO 2 [13] are used as photocatalysts for the degradation of organic dyes as well as in photoelectrochemical water splitting [14]. Among these, TiO 2 nanoparticles (NPs) have known photocatalytic effectiveness for such applications. ...
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