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Vol. 8. Issue 3.
Pages 2481-3388 (May - June 2019)
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Vol. 8. Issue 3.
Pages 2481-3388 (May - June 2019)
Short Communication
DOI: 10.1016/j.jmrt.2017.06.013
Open Access
Structural, optical, magnetic and electrochemical properties of pure and cobalt-doped cadmium monosulfide by the hydrothermal process
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Chinnadurai Ramamoorthy
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ramjessy362@gmail.com

Corresponding author.
, Varadharajan Rajendran
Department of Physics, Presidency College, Chennai 600005, India
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Abstract

Effect of pure and cobalt-doped (2% and 3%) cadmium monosulfide nanoparticles were successfully synthesized. The obtained samples were characterized by XRD, SEM-EDX, TEM, UV–visible, PL, VSM and CV analysis. The cubic structure was confirmed from the XRD results. The surface morphology and composition purity of the prepared samples was characterized by the SEM-EDX studies. The spherical morphology of the particle size is found to be 14nm, 12nm and 9nm, which is confirmed from the XRD results. The blue shifted are occurred compared to the bulk value; this was due to quantum size effect (QSE) from the UV–visible analysis and it could be used for optical devices. The PL spectra revealed that the all samples were presented in visible emission at 375nm due to sulfur vacancy defects. The ferromagnetic behavior is observed from the obtained product, which given results indicates of high magnetic moment (3% cobalt doped) for obtaining the hysteresis loop. The above electrochemical reactions shows, the super capacity behavior increased for the (3%) cobalt-doped cadmium monosulfide sample and its used for electrode applications.

Keywords:
ZnS
Co2+ doped
QSE
Magnetic
Electrochemical
Full Text
1Introduction

The synthesis and characterization of II–VI group semiconductor materials is most important in the field of optics due to their size and surface effect, which depends on the optical, electrical, magnetic and chemical properties with various applications in photo electro catalysis, photo electricity devices, electrode and laser light-emitting diodes etc. [1–4]. Hence, it would be utilized to synthesize nanostructured cadmium monosulfide for different technological and industrial applications. The cadmium monosulfide is a yellow solid with more stable cubic zinc blende and hexagonal structure and its like ZnS structure and has used as an important phosphor for PL, EL and CL devices due to its better chemical stability [5–8]. The size of the semiconductor nanomaterials depend on the electronic and optoelectronic properties in the quantum size region [9–11]. It is well known that the quantum confinement effect modify the electronic structure when their radius is smaller than the bulk value. Thus we are focused on the synthesis of cadmium monosulfide nanoparticles with size, shape and surface effect. The size of the nanoparticles decreases by the effect of dopant (different concentration) on the original matrix, which is used toward the LED and low-voltage display [12–15]. The concentration of the dopant plays an important role for changing the luminescence and emission bands of cadmium monosulfide nanoparticles. Therefore, it is very important to study the variation of opticals and electrical properties of cadmium monosulfide nanoparticles by changing the concentration of the doping and it could be used for various applications, such as catalytic activity, optoelectronics, photoconductivity, etc. The cadmium monosulfide nanoparticles have reported by different techniques, such as thermal evaporation, co-precipitation, microemulsions, irradiation, etc. [13–17]. The hydrothermal is very simple method and several advantages compared to other methods, such as easy manipulation low temperature and high purity.

In the present work, pure and cobalt-(2% and 3%) doped cadmium monosulfide nanoparticles synthesized by the hydrothermal method and their optical properties were investigated. In addition, the possible formation mechanism of cadmium monosulfide has also proposed.

2Experimental

All the chemical reagents were commercial with AR purity and used without further purification. In a typical experiment, 0.1M of cadmium acetate and 0.3M of thiourea were separately dissolved in 50ml of distilled water and the small amount of PVP was added in order to control the growth of particles during the above reaction under continuous stirring for 120min. The above solution was transferred into a 100mL teflon-lined stainless autoclave and maintained at 200°C for 1440min at a ramping rate of 5°/min. The obtained product was washed several times with ethanol and dried in a vacuum at 90mmHg for 360min at room temperature. The same procedure was followed for the (2% and 3%) cobalt-doped cadmium monosulfide nanoparticles.

The obtained samples were characterized by the powder XRD XPERT PRO with Cu Kα X-ray radiation (λ=0.15496nm). The SEM studies and compositions of elements are confirmed by EDX spectra FEI Quanta FEG 200-HR Scanning Electron Microscope, IIT and Chennai. The magnification images and polycrystalline nature were observed by the TEM-SAED pattern (Philips model CM 20) analysis. The UV–visible studies have been carried out using Varian Cary (5E UV-vis Spectrophotometer IIT Chennai). The PL emission spectra were observed by Jobin Yvan Flourometer IIT Chennai. The magnetic properties of the samples were studied by the vibrating sample magnetometer (Cryogenic Ltd. Model 3639) and magnetic field strength of 3T at room temperature. The electrochemical properties of the obtained products were studied by CV. Three electrode systems were used consisting of glassy carbon electrode (GCE) with geometric surface area 7.1mm2, Ag/AgCl reference electrode [Ag/AgCl 3moll−1 KCl] and Pt counter electrode. The working electrode was prepared by coating a slurry containing a mixture of the active material (80wt%) and Nafion® 117 solutions (20wt%). The coated mesh was dried at 80°C in vaccum cabinet overnight. The Ag/AgCl electrode with obtained product grown on the surface was characterized by electrochemical measurements. The CV measurements were carried out at a scan rate 20mVs−1.

3Results and discussion

The X-ray diffraction patterns of pure and (2% and 3%) cobalt-doped cadmium monosulfide samples are shown in Fig. 1(a)–(c). The intensity of diffraction peaks with 2θ values of 26.7°, 44.5° and, 52.4°, which correspond the indexed reflection planes of 111, 220 and 311, respectively. The lattice constants of cobalt-doped samples were observed and the result is smaller than pure CdS, because the cobalt (Co2+) has been small ionic radii [0.74Å] compared than cadmium (Cd2+) [0.96Å]. It is identified cubic structure of the samples, which is well agreed with the reported value [18,19]. There is no other phase peaks observed in the diffracted patterns, which indicate the high purity of the obtained products. The average particle size is calculated to 14nm, 12nm and 9nm using Debye–Scherer's equation (D=/βcosθ (nm)). Where, the wavelength of X-rays (λ), full width at half maximum in radian (β) and Bragg angle (θ) values.

Fig. 1.

(a–c) The XRD pattern of CdS nanoparticles.

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The SEM image of the pure and (2% and 3%) cobalt-doped cadmium monosulfide samples is shown in Fig. 2(a)–(c). The spherical like morphologies are depicted in all the samples; it could be seen SEM images. The EDX image of the pure and (2% and 3%) cobalt-doped cadmium monosulfide samples is shown in Fig. 2(d)–(f). The presence of the elements, such as cadmium, sulfur and cobalt was identified. The cobalt peak indicates that the no impurity and the elemental composition of the as prepared samples were verified. The particle size of the pure and (2% and 3%) cobalt-doped cadmium monosulfide samples is shown in Fig. 3(a)–(c). The spherical morphology of the particle size is found to be 14nm, 12nm and 9nm for pure and (2% and 3%) cobalt-doped cadmium monosulfide, which is confirmed from the XRD results. The size of the particles is comparable to Bohr radius and it resembles with the values are calculated from Scherer's formula, which was due to formation of QSE. The SAED pattern clearly indicates the broad rings with dots and it also confirms that the samples are crystallized in cubic structure. The diffraction ring patterns and dots show the polycrystalline nature of the obtained product samples.

Fig. 2.

(a–c) The SEM-EDX image of CdS nanoparticles.

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Fig. 3.

(a–c) The TEM-SAED pattern of CdS nanoparticles.

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The field magnetization curves of the pure and cobalt-doped (3%) cadmium monosulfide samples are shown in Fig. 4(a) and (b). The magnetic saturation (Ms) values are found to be 0.013emu/g (3%-Co2+ doped) and 0.01emu/g (pure), respectively. The saturation magnetization of 3%-Co2+ doped CdS slightly greater than that of pure CdS due the adding of cobalt dopant. Moreover, the increase in saturation magnetization (Ms) was probably caused by the increase in electrons, which induced more efficient ferromagnetic coupling between 3% cobalt doped ions. The above result shows that the 3%-Co2+ doped CdS leads to an enhancement in magnetic moment compared to pure CdS. If is because that the 3%-Co2+ ions substitute the Cd2+ ions, with the local hole concentration at the anion increasing. The local density of states at Fermi level increases and exchange interaction is enhanced leading to enhance ferromagnetism. The ferromagnetic behavior is observed from the obtained products, which given results indicates of high magnetic moment (3% cobalt doped) for obtaining the hysteresis loop due to the creation of a spin-split impurity band and hybridization between the charge careers of cobalt and cadmium at the Fermi-level [20,21]. Here, the ferromagnetic behavior is indicated, when substitution of cobalt ions are does not change the cubic structure. Moreover, tiny hysteresis loop curve was observed 3% Co-doped CdS sample from M–H curve. Generally, tiny hysteresis loop curve (ferromagnetic behavior), which indicates the smaller crystallite size. Moreover, 3% Co-doped CdS sample exhibits soft magnetic nature and it can be used for temporary magnet.

Fig. 4.

(a and b) The hysteresis loop of CdS nanoparticles.

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The UV–visible absorption spectrum of the pure and (2% and 3%) cobalt-doped cadmium monosulfide samples is shown in Fig. 5(a)–(c). In the present work, the calculated band gap values are 2.26, 2.45 and 2.62eV, respectively. The optical direct band gap was calculated using following relation for photon energy vs (αhv)2 [(αhv)2=A(hvEg)]. Where, α is an absorption coefficient, A is a constant, Eg is the band gap and the absorption peaks were observed at 494, 489 and 484nm in visible region correspond to the transition of tetrahedral coordination [4A2 (F) to 4T1 (P)] and the absorption values of the obtained samples are blue shifted from bulk cadmium monosulfide (520nm). The blue shifts indicate the formation of obtained particles in the nanometer region; this was due to quantum size effect associated with smaller particle size [22,23]. The spectral changes dominate in shift with size, because spatial location of the wave functions revealed that the binding energy of the exciton increases with decreasing size due to the columbic overlap enhanced. Hence, the quantum size effect was well presented for the pure and Co-doped cadmium monosulfide samples. The photoluminescence of the pure and (2% and 3%) cobalt-doped cadmium monosulfide samples is shown in Fig. 6(a)–(c). The PL spectra were observed at 372nm and the emission peak position of all the obtained samples is same. However, intensity is significantly changed and maximum PL intensity has been observed for 3% cobalt doped sample cadmium monosulfide. The increase of dopant concentration increases the intensity of PL emission which indicates the optimum concentration for enhanced PL properties. The strong emission band was observed due to the increased recombination of electrons trapped (sulfur vacancy) with a hole in the valance band [24,25]. The present study indicates the luminescence properties having minimized surface defects and enhances electron–hole recombination and it might be used for photo thermal applications.

Fig. 5.

(a–c) The UV–visible spectra of CdS nanoparticles.

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Fig. 6.

(a–c) The PL emission spectra of CdS nanoparticles.

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The oxidations and reductions peak of the pure and (3%) cobalt-doped cadmium monosulfide samples are shown in Fig. 7(a) and (b). The anodic and cathodic peaks show that the detailed information of charge and discharge process and the obtained curves exhibit mirror symmetry (shape), reversible reaction and excellent capacitive behavior. The reduction and oxidation peaks occurred at 1.0760(C1) and −0.1016(A1) and the additional peaks (C2, C3 and A2) are appearing due to redox reaction. The anodic peak A1 was involved in the oxidation of OOH produced by dissolved oxygen and the additional anodic peak A2 (0.53V), due to the oxidation of the C1 reduction product and in this peaks are indicate that the obtained nanoparticles have strong light interactions. The observed peaks were shifted (positive and negative), this was due to kinetic limitation of the electrochemical reactions and the above result show, the super capacity behavior increased for the (3%) cobalt-doped sample than the pure cadmium monosulfide sample.

Fig. 7.

(a and b) The electrochemical properties of CdS nanoparticles.

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4Conclusions

The XRD patterns confirm the cubic structure of pure and (2% and 3%) cobalt-doped cadmium monosulfide. The spherical morphology and particle size of the obtained samples have been studied by SEM and TEM analysis. The presence of elements (cadmium, sulfur and cobalt) in the pure and doped materials was confirmed, from the EDX spectrum. The UV–visible spectra were occurred as blue shifted due to quantum size effect. The PL emission spectra can attribute sulfur vacancies in the surface, which would be used to optoelectronic devices. The ferromagnetic behavior is observed from the field magnetization curve of the obtained products revealed that the VSM analysis. From the CV study shows that the electrochemical properties were obtained using electrode applications.

Conflicts of interest

The authors declare no conflicts of interest..

Acknowledgements

The authors would like to acknowledge “Department of Science and Technology” (DST) and “Tamilnadu Council for Science and Technology” (TNSC) in India for their financial support.

References
[1]
M.A. Gondala, A.M. Ilyasa, T.A. Fasasia, M.A. Dastageera, Z.S. Seddigib, T.F. Qahtana, et al.
Synthesis of green TiO2/ZnO/CdS hybrid nano-catalyst for efficient light harvesting using an elegant pulsed laser ablation in liquids method.
Appl Surf Sci, 357 (2015), pp. 2217-2222
[2]
H. Zhaoa, M. Wua, J. Liua, Z. Denga, Y. Lia, B.-L. Sua.
Synergistic promotion of solar-driven H2 generation by three-dimensionally ordered macroporous structured TiO2–Au–CdS ternary photocatalyst.
Appl Catal B: Environ, 184 (2016), pp. 182-190
[3]
S. Fang, M. Sun, Y. Zhou, Q. Liang, Z. Li, S. Xu.
Solvothermal synthesis of CdS QDs/MWCNTs nanocomposites with high efficient photocatalytic activity under visible light irradiation.
J Alloys Compd, 656 (2016), pp. 771-776
[4]
J. Park, S. Kim, Y. Sim, O.J. Yoon, M.-S. Han, H.S. Yang, et al.
Simple synthesis of high-quality CdS nanowires using Au nanoparticles as catalyst.
J Alloys Compd, 659 (2016), pp. 38-43
[5]
Y. Li, Y.L. Song, F.Q. Zhou, P.F. Ji, M.-L. Tian, M.-L. Wan, et al.
Photovoltaic properties of CdS/Si multi-interface nano heterojunction with incorporation of Cd nanocrystals into the interface.
Mater Lett, 164 (2016), pp. 539-542
[6]
A. Raouf, S. Maybodi, M. Rasool, S. Maleki.
In-situ synthesis of high stable CdS quantum dots and their application for photocatalytic degradation of dyes.
Spectrochim Acta Part A: Mole Biomol Spectrosc, 152 (2016), pp. 156-164
[7]
Y.G. Ana, Y.W. Changa, H.R. Kima, G. Leeb, M.J. Kangb, J.K. Parkb, et al.
Highly sensitive photosensor based on in situ synthesized CdS nanowires.
Sens Actuators B, 221 (2015), pp. 884-890
[8]
J. Chen, F. Zhang, Y.L. Zhao, Y.-C. Guo, P. Gong, Z.Q. Li, et al.
Facile synthesis of CdS/C core–shell nanospheres with ultrathin carbon layer for enhanced photocatalytic properties and stability.
Appl Surf Sci, 362 (2016), pp. 126-131
[9]
G.A. Martínez-Castañón, M.G. Sánchez-Loredo, J.R. Martínez-Mendoza, F. Ru.
Synthesis of CdS nanoparticles: a simple method in aqueous media.
Mater Lett, 1 (2005), pp. 1-7
[10]
C. Cheng, G. Xu, H. Zhang, H. Wang, J. Cao, H. Ji.
Solvothermal synthesis and photoluminescence properties of single-crystal Mn2+ doped CdS nanowires.
Mater Chem Phys, 97 (2006), pp. 448-451
[11]
Y. Li, F. Huang, Q. Zhang, Z. Gu.
Solvothermal synthesis of nanocrystalline cadmium sulfide.
J Mater Sci, 35 (2000), pp. 5933-5937
[12]
M. Maleki, S. Mirdamadi, R. Ghasemzadeh, M. Sasani Ghamsari.
Effect of sulfur precursor on dimensions of one-dimensional CdS nanocrystals.
J Mater Sci Technol, 25 (2009), pp. 1-4
[13]
Q. Zhang, F. Huang, L. Yan.
Cadmium sulfide nanorods formed in microemulsions.
Colloids Surf A: Phys Eng Aspects, 257 (2005), pp. 497-501
[14]
A. Paula, L. Lopes, M.B. Santos, A. José, S. Mascarenhas, L.A. Silva.
Synthesis of CdS nano-spheres by a simple and fast sonochemical method at room temperature.
Mater Lett, 136 (2014), pp. 111-113
[15]
R.S. Darianin, Z. Emami.
Structural and optical studies of CdS and CdS:Ag nano needles prepared by a SILAR method.
Ceram Int, 41 (2015), pp. 8820-8827
[16]
M.A. Baghchesara, R. Yousefi, M. Cheraghizade, F. Jamali-Sheini, A. Saáedi.
Photocurrent application of Zn-doped CdS nanostructures grown by thermal evaporation method.
Ceram Int, 42 (2016), pp. 1891-1896
[17]
M. Majumder, A.K. Chakraborty, B. Mallik.
Photoluminescence studies on nanostructured cadmium sulfide thin films prepared by chemical bath deposition method and annealed at different temperatures.
J Lumin, 130 (2010), pp. 1497-1503
[18]
K. Kaviyarasu, E. Manikandan, M. Maaza.
Synthesis of CdS flower-like hierarchical microspheres as electrode material for electrochemical performance.
J Alloys Compd, 648 (2015), pp. 559-563
[19]
H.L. Lee, A.M. Issam, M. Belmahi, M.B. Assouar, H. Rinnert, M. Alnot.
Synthesis and characterizations of bare CdS nanocrystals using chemical precipitation method for photoluminescence application.
J Nanomater, 914501 (2009), pp. 1-9
[20]
P. Elavarthi, A. Anil Kumar, G. Murali, D. Amaranatha Reddy, K.R. Gunasekhar.
Room temperature ferromagnetism and white light emissive CdS:Cr nanoparticles synthesized by chemical co-precipitation method.
J Alloys Compd, 656 (2016), pp. 510-517
[21]
L. Saravanan, A. Pandurangan, R. Jayavel.
Synthesis of cobalt-doped cadmium sulphide nanocrystals and their optical and magnetic properties.
J Nanopart Res, 13 (2011), pp. 1621-1628
[22]
H. Du, G.Q. Xu, W.S. Chin, L. Huang, W. Ji.
Synthesis characterization, and nonlinear optical properties of hybridized CdS–polystyrene nanocomposites.
Chem Mater, 14 (2002), pp. 4473-4479
[23]
N.M. Shah.
Structural and Optical Properties of Cadmium Sulphide Thin Films Grown Using Chemical Bath deposition.
Int J Chem Tech Res, 6 (2014), pp. 1959-1961
[24]
S.K. Mishra, R.K. Srivastava, S.G. Prakash, R.S. Yadav, A.C. Panday.
Structural photoconductivity and photoluminescence characterization of cadmium sulfide quantum dots prepared by a co-precipitation method.
Electr Mater Lett, 7 (2011), pp. 31-38
[25]
I. Iorgu, D. Berger, L. Alexandrescu, S. Vasile, C. Matei.
Synthesis of photoluminescent pure and doped cadmium sulfide by reverse microemulsion method.
Chalcog Lett, 10 (2013), pp. 525-531
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