Eco-Friendly Synthesis of Cuprous Oxide (Cu2O) Nanoparticles and Improvement of Their Solar Photocatalytic
Eco-Friendly Synthesis of Cuprous Oxide (Cu2O) Nanoparticles and Improvement of Their Solar Photocatalytic
Eco-Friendly Synthesis of Cuprous Oxide (Cu2O) Nanoparticles and Improvement of Their Solar Photocatalytic
A R T I C L E I N F O A BS T RAC T
Keywords: In this work, we have synthesized cuprous oxide (Cu2O) nanoparticles with octahedral and spherical like shapes
Nanoparticles by an ecofriendly, simple and coast effective method, by using the aqueous extract of Aloe vera and copper
Green synthesis sulfate as solvent and precursor respectively. The effect of Aloe vera aqueous extract concentration on the
Cuprous oxide morphological, structural and optical properties of as synthesized nanoparticles was studied by Scanning
Aloe vera extract
electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform (FT-IR) spectroscopy and UV–visible
Solar photocatalysis
diffuse reflectance. The SEM images showing octahedral and spherical agglomeration of nanoparticles. The
cubic structure of Cu2O was confirmed by XRD analysis, the crystallites size depends to the concentration of
Aloe vera aqueous extract with an average size ranged between 24 and 61 nm. The FT-IR vibration
measurements valid the presence of pure Cu2O in the samples. The UV–visible spectra show that the prepared
cuprous oxide (Cu2O) has a gap energy estimated from 2.5 to 2.62 eV. The photocatalytic activities of the as-
prepared material were highly improvement by the fast degradation of methylene blue in aqueous solution at
room temperature under solar simulator irradiation.
⁎
Corresponding author.
E-mail address: kerour.a@gmail.com (A. Kerour).
https://doi.org/10.1016/j.jssc.2018.04.010
Received 15 February 2018; Received in revised form 12 April 2018; Accepted 13 April 2018
Available online 14 April 2018
0022-4596/ © 2018 Elsevier Inc. All rights reserved.
A. Kerour et al. Journal of Solid State Chemistry 263 (2018) 79–83
nanoparticles are terpenoids, flavonoids, alkaloids and phenolic com- kαradiation. The chemical composition of the synthesized powder was
pounds [23]. characterized, by Fourier transform infrared (FT-IR) (JASCO 7800) in
To the best of our knowledge, the use of Aloe vera leaf aqueous the range (400 – 4000 cm−1). The optical properties of nanoparticles
extract for the green synthesis of cuprous oxide Cu2O nanoparticles, were measured by UV–visible spectrophotometer (JASCO 670-V) on
has not been reported. Herein, in the present work, we report the effect diffuse reflectance in the wavelength range from 250 nm to 800 nm.
of Aloe vera aqueous extract concentration on the morphological,
structural and optical properties of cuprous oxide. The solar photo- 2.3. Photocatalytic study
catalytic activity of the as synthesized photocatalyst was evaluated by
photo degradation of methylene blue (MB) under simulated sunlight The photocatalytic activity of the photocatalyst was carried out
irradiations. under solar simulator light irradiation (100 mW/cm2, model 16S-300-
002, with AM1.5 filter). As-prepared Cu2O nanoparticles were evalu-
2. Experimental ated by the degradation of methylene blue (MB) dye solution at room
temperature. The distance between the source and samples was
2.1. Synthesis fixedat17 cm. The initial concentration of MB solution is C0 = 10 mg/
L, 0.4 mg of the photocatalyst (Cu2O) was added to the MB solution in
2.1.1. Preparation of Aloe vera leaves extract order to activate the degradation process. The variation in concentra-
Aloe vera leaves were collected from Constantine University garden tion of irradiated MB solution was measured after 3 min for every
in month of October. Leaves were washed thoroughly with distilled 1 min by the absorbance of the solution at 662 nm using UV–visible
water, then cut into small pieces. These fine pieces were boiled in spectrophotometer (JASCO 670-V).
distilled water for 10 min on medium flame, and finally were purified
and stored under 5 °C for used in biosynthesis of cuprous oxide 3. Results and discussion
nanoparticles. Different concentrations of Aloe vera aqueous extracts
were prepared from 0.25 to3.5 g/ml. 3.1. MEB analysis
2.1.2. Synthesis of cuprous oxide (Cu2O) The particles morphology was studied by means of FE-SEM. Fig.
In this “bottom-up” biological procedure, the nanoparticles are .2(a,c,e) shows images of as-obtained samples S1, S2, S3 and S4 at
built from atoms and molecules to form the first nanostructures. different magnifications. As can be seen, Particles have irregular shapes
Cuprous oxide nanoparticles were synthesized by an eco-friendly and size. For the low concentration of ALE (S1), the Cu2O nanocrystals
synthesis method. Fig. 1 shows a schematic synthesis of Cu2O have the truncated octahedral structure with small square facets and
nanoparticles, in typical procedures, different solutions with several the size of these particles is in the range of 1252 ± 12 nm, while ALE
concentrations of Aloe vera aqueous extract(0.25–3.5 g/ml) and fixed extract concentration increasing up to 1.5 g/ml (S2), leads to particles
amount of copper sulfate were prepared (0.5 g of CuSO4-5H2O + with octahedral shape. Sphere-like Cu2O particle was observed with
100 ml of Aloe vera aqueous extract), then 40 ml of 2 M of NaOH rough surface and an average size range of 500 nm at 3.5 g/ml of ALE
solution was added drop by drop to the solutions. The reactional (S4). However, the spherical form was conserved with the increasing of
mixtures were kept under magnetic vigorous steering at 130 °C, after ALE (S4).
25 min, brick red precipitates appear, indicating the formation of Cu2O. It is well-known that the nanoparticles contact each other to
The precipitates were collected and washed by water and ethanol minimize the surface energy of the planes and grow along different
several times, then dried at 90 °C for 7 h. According to the concentra- directions with different growth rate. This will drive the grain
tion of Aloe vera extract, the as-obtained samples were labeled S1, S2, morphology evolution [24,25]. The morphological transformation
S3 and S4 respectively. among the polyhedron, octahedron, and truncated octahedron depend
on the ratio, R(R is the ratio of growth rate along the 〈100〉 versus
2.2. Characterizations 〈111〉 direction) [26]. It is reported that a perfect octahedron is
achieved when the ratio (Roct) is 1.73. While, when R is within the
The shape and size of the nanoparticles were characterized by range 0.8–1.73, the truncated octahedron is formed. If the amount of
scanning electron microscopy (SEM) (Quanta 200 F). The crystalline additive (ALE) increases, nanocrystals of Cu2O nucleated in all crystal-
phase and crystallite orientation of the as-prepared Cu2O were lographic directions to form spherical structure [27]. Actually, nano-
investigated by X-ray diffractometer (D8 Focus, Bruker) using Cu particles aggregate together to form particles, this may explain the
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A. Kerour et al. Journal of Solid State Chemistry 263 (2018) 79–83
Fig. 2. SEM images and magnified images of truncated octahedral Cu2O prepared with 0.25 g/ml of ALE (a, b), octahedral Cu2O prepared with1.5 g/ml of ALE (c, d), spherical like Cu2O
prepared with 3.5 g/ml of ALE (e, f, g).
measured large particles diameter between 200, 500 and 1000 nm. The average crystallite sizes were estimated using Scherrer'sEq. (1).
The obtained values are varied between 24 and 61 nm for different
3.2. DRX analysis samples.
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A. Kerour et al. Journal of Solid State Chemistry 263 (2018) 79–83
Fig. 6. UV–Vis spectra of Cu2O nanoparticles with different concentration of ALE (a)
and variation of band gap with the grain size (b).
Fig. 4. Variation of grain size with concentration of Aloe vera extract. existence of organic bands is attributed to the adsorption of Aloe vera
molecules on the cuprous oxide.
3.3. FT-IR analysis
3.4. UV–Vis analysis
The FT-IR patterns of all samples are shown in Fig. 5, all spectra
exhibit characteristic band at 616 cm−1 which corresponds to the Fig. 6a shows the UV–Vis spectra of the as-obtained nanoparticles.
stretching vibration of pure Cu2O [29]. The bands in 2915, 2852 due Cu2O band gap energies were calculated using the Eq. (2) [31]:
to C-H stretching vibration [8]. The band at 1596 cm−1 is assigned to
C˭O stretching vibration while bands of C–O and C–C stretching 1240
Eg(eV) =
vibrations are observed in the region 1413 and 1051 cm−1. The bands λ max(nm) (2)
at 878 cm−1 represent C–O out of plane bending vibrations [30]. The
The variation of gap energy with grain size is shown in Fig. 6b. The
estimated band gap energies of Cu2O nanoparticles increases from
2.50 eV to 2.62 eV with decrease in particle size. The relative large band
gap values, by comparison to Cu2O bulk (2.17 eV), is attributed to the
quantum confinement effects due to the crystallite small sizes [32].
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A. Kerour et al. Journal of Solid State Chemistry 263 (2018) 79–83
Fig. 7. Photo degradation of MB in the presence of the photocatalyst (Cu2O) (a), without photocatalyst (b), degradation rate of MB with and without Cu2O (c).
4. Conclusion [7] Tianjie Hong, Feifei Tao, Jiudong Lin, Wei Ding, Mingxuan Lan, J. Solid State
Chem. 228 (2015) 174–182.
[8] Asar Ahmed, Namdeo, S. Gajbhiye, Amish, G. Joshi, J. Solid State Chem. 184
In summary, cuprous oxide (Cu2O) nanoparticles were successfully (2011) 2209–2214.
[9] A.A. Ogwu, T.H. Darma, E. Bouquerel, J. Achiev. Mater. Manuf. Eng. 24 (2007)
synthesized through eco-friendly method using Aloe vera leaves plants 172–177.
extract with different concentrations. The average size of these [10] C.H.B. Ng, W.Y. Fan, J. Phys. Chem. B 110 (2006) 20801.
nanoparticles ranged between 24 and 61 nm proved by XRD analysis. [11] A. Lamberti, M. Destro, S. Bianco, M. Quaglio, A. Chiodoni, C.F. Pirri, C. Gerbaldi,
Electrochim. Acta 70 (2012) 62–68.
The solvent (ALE) concentrations have a significant effect on the [12] Y. Abboud, T. Saffaj, A. Chagraoui, A. El Bouari, K. Brouzi, O. Tanane, Appl.
particles size and shape of as prepared material. The high photocata- Nanosci. 4 (2014) 571–576.
[13] M.M. Rahman, aJ.Saleh Ahammad, J.-.H. Jin, S.J. Ahn, J.-.J. Lee, Switzerland
lytic activity of the obtained Cu2O nanoparticles has demonstrated by
4855–4886, 2010.
degradation of MB with cuprous oxide. The MB pollutant has been [14] Jing Ouyang, Huaming Yang, Aidong Tang, Mater. Des. 92 (2016) 261–267.
completed degraded after 10 min exposure under visible light irradia- [15] Binjie Li, Yuanyuan Li, Yanbao Zhao, Lei Sun, J. Phys. Chem. Solids 74 (2013)
1842–1847.
tion. [16] W. Zhao, W. Fu, H. Yang, C. Tian, R. Ge, C. Wang, et al., Appl. Surf. Sci. 256 (2010)
2269–2275.
Acknowledgments [17] R.V. Kumar, Y. Diamant, A. Gedanken, Chem. Mater. 12 (2000) 2301–2305.
[18] P. He, X. Shen, H. Gao, Colloid Interf. Sci. 284 (2005) 510–515.
[19] C. Ramesh, M. HariPrasad, Ragunathan, Curr. Nanosci. 7 (2011) 995–999.
The authors would like to thank Pr. Mohammed Salah Aida of the [20] Sangeetha Gunalan, Rajeshwari Sivaraj, Rajendran Venckatesh, Spectrochim. Acta
Part A 97 (2012) 1140–1144.
Department of Physics, King Abdulaziz University,Jeddah, Saudi [21] S.P. Chandran, M. Chaudhary, Biotechnol. Prog. 2 (2006) 577–583.
Arabia for his cooperation, that led us to improve the work. [22] J.Y. Song, B.S. Kim, Bioprocess Biosyst. 32 (2009) 79–84.
[23] K.S. Kavitha, Syed Baker, D. Rakshith, H.U. Kavitha, H.C. Yashwantha Rao,
B.P. Harini, S. Satish, Int. Res. J. Biol. Sci. 2 (6) (2013) 66–76.
References [24] Haolan Xu, Wenzhong Wang, Wei Zhu, Phys. Chem. 110 (2006) 13830.
[25] Deli Jiang, Chaosheng Xing, Ximeng Liang, Leqiang Shao, Min Chen, Colloid
[1] K. Govindaraju, S. KhaleelBasha, V. Ganesh Kumar, G. Singaravelu, Mater. Sci. 43 Interface Sci. 461 (2016) 25–31.
(2008) 5115–5122. [26] Hui Yang, Zhi-Hong Liu, Am. Chem. Soc. 10 (2010) 2064–2065.
[2] M.F. Lengke, M.E. Fleet, G. Southam, Langmuir 23 (2007) 2694–2699. [27] Yongming Sui, Wuyou Fu, Haibin Yang, Yi Zeng, Yanyan Zhang, Qiang Zhao, Am.
[3] D. Rautaray, A. Ahmad, M. Sastry, Am. Chem. Soc. 125 (2003) 14656–14657. Chem. Soc. 10 (2009) 99–108.
[4] A. Saxena, R.M. Tripathi, R.P. Singh, Digest J. Nanomater. Biostruct. 5 (2010) [28] R.T. Downs, M. Hall-Wallace, Am. Mineral. 88 (2003) 247–250.
427–432. [29] J.A. Gadsden, Betterworths (1975) 44.
[5] Amit Kumar Mittal, Yusuf Chisti, Uttam Chand Banerjee, Biotechnol. Adv. 31 [30] Madiha A. Shoeib, Omar E. Abdelsalam, Monazah G. Khafagi, Rania E. Hammam,
(2013) 346–356. Adv. Powder Technol. 23 (2012) 298–304.
[6] Iravani Siavash, Green Chem. 13 (2011) 2638. [31] Z. Yang, C.-K. Chiang, H.-T. Chang, Nanotechnology 19 (2008) 025604.
[32] C.H. Kuo, M.H. Huang, Phys. Chem. 12 (2008) 18355.
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