Visible light induced photocatalytic degradation of methylene blue and rhodamine B from the catalyst of CdS nanowire

Accepted Manuscript Research paper Visible light induced photocatalytic degradation of Methylene blue and Rhodamine B from the catalyst of CdS nanowire R. Sankar Ganesh, E. Durgadevi, M. Navaneethan, Sanjeev K. Sharma, H.S. Binitha, S. Ponnusamy, C. Muthamizhchelvan, Y. Hayakawa PII: DOI: Reference:

S0009-2614(17)30560-2 http://dx.doi.org/10.1016/j.cplett.2017.06.021 CPLETT 34883

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Chemical Physics Letters

Received Date: Revised Date: Accepted Date:

18 April 2017 9 June 2017 12 June 2017

Please cite this article as: R. Sankar Ganesh, E. Durgadevi, M. Navaneethan, S.K. Sharma, H.S. Binitha, S. Ponnusamy, C. Muthamizhchelvan, Y. Hayakawa, Visible light induced photocatalytic degradation of Methylene blue and Rhodamine B from the catalyst of CdS nanowire, Chemical Physics Letters (2017), doi: http://dx.doi.org/ 10.1016/j.cplett.2017.06.021

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Visible light induced photocatalytic degradation of Methylene blue and Rhodamine B from the catalyst of CdS nanowire R. Sankar Ganesh1, 4, E. Durgadevi1, M. Navaneethan 2, Sanjeev K. Sharma3, *, H. S. Binitha4, S. Ponnusamy4, *, C. Muthamizhchelvan 4, Y. Hayakawa 2 1

Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8011, Japan. 2

Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 4328011, Japan.

3

Department of Semiconductor Science, Dongguk University-Seoul, Jung-gu, Seoul 04620, South Korea 4

Center for Materials Science and Nano Devices, Department of Nanotechnology, SRM University, Kattankulathur, Kancheepuram- 603203, Tamil Nadu, India.

*Corresponding author: [email protected], [email protected] Abstract CdS nanowires and nanorods were successfully synthesized by the simple solvothermal method and tested their photocatalytic degradation of methylene blue (MB) and rhodamine B (RhB). The monodispersed CdS nanowire and nanorods were confirmed from the field emission-scanning electron microscopy (FE-SEM) and high resolution-transmission electron microscopy (HRTEM) analysis. The prepared photocatalyst demonstrated the superior visible light photocatalytic degradation of methylene blue (MB) and rhodamine B (RhB). The highest degradation (97 %) of MB was achieved within 180 min and 90 % towards RhB. Therefore, CdS nanowire has a remarkable towards organic pollutants under the visible light irradiation.

Keywords: PVP-capped CdS nanoflowers, Microstructures, Structural and optical properties, Chemical bonding, Photoluminescence

1. Introduction Nanostructured cadmium sulfide (CdS), such as nanoparticles, nanorods, nanospheres, are widely used in optical, electronic, photocatalytic, solar cell and biological applications. A direct band gap semiconductor or the inorganic compound like cadmium sulfide (CdS, Eg ~ 2.4 eV) has paid the attention for the photocatalytic degradation of organic pollutants due to the excitation of holes and electrons by illumination of visible light [1-5]. The position of the conduction band is sufficiently negative to allow the electron transfer process from their surface

to the adsorbed molecules [6]. Therefore, the CdS has been considered as the excellent photocatalyst to degrade the dyes like Rhodamine B (RhB) and Methylene blue (MB) [6-8]. However, the crystallography and morphologies of CdS powders can be controlled via the alteration of various synthesis parameters such as the type of precursors, the concentration of reactants, types of capping agents, capping concentration, reaction temperature and pH of the reaction media [1, 6, 9-15]. To control the microstructures of CdS, the sol-gel or the chemical method has been preferred to manipulate or the alternation of morphologies [16-19]. Phuruangrat et al. synthesized the hexagonal phase structure of CdS nanowires by the solvothermal and tested the photocatalytic degradation of methyl orange (MO) and rhodamine B (RhB) under the illumination of visible light [20]. Vaquero et al. synthesized CdS nanowire and nanorods by the solvothermal method at low (90 °C) and high temperature (190 °C). The mixed microstructure of nanowire and nanorods of CdS enhanced the photocatalytic activity for the hydrogen production [21]. Lately, Ren et al. synthesized CdS nanowires by a solvothermal method and showed the promising nanomaterial for photonics [22]. Zhidan et al., reported that ternary composite of rGO/CdS/TiO2 sphere showed excellent degradation of 90% of methylene blue in 60 min and the better stability and reproducibility [23]. Qian Mi et al., synthesized nitrogen doped graphene CdS hollow sphere nanocomposite and achieved degradation of 75 % of methylene blue utilizing pure CdS and improved the degradation percentage by N-doped graphene about 86 % [24]. Repo et al., synthesized CdS microsphere by simple hydrothermal method and degraded 100 % methylene blue in 3 h utilizing LED as light source [25]. Therefore, the nanostructured CdS materials highly utilized to study the degradation of organic dyes. To synthesize CdS nanorods and nanowire, the solvothermal method was preferred to consider simple and inexpensive for the mole concentration and by varying the temperature. Moreover, it is very important to reduce the processing time, temperature and the cost, which can be identified as the simplest route. CdS nanorods and nanowires can be synthesized by several methods as already reported. However, mostly monodispersed nanorods and nanowires were synthesized at high temperature. The objective of this work is to synthesize the lateral CdS nanowires by the solvothermal method and test their photocatalytic activity for the degradation of organic pollutants like methylene blue (MB) and rhodamine B (RhB). The microstructures, phase transition of CdS nanowire and nanorods were evaluated from field emission-scanning electron microscopy (FESEM) and high resolution-transmission electron microscopy (HR-TEM) and X-ray diffraction

(XRD). The optical properties, elemental composition, and chemical bonding of CdS nanowire and nanorods were investigated by UV-VIS absorption spectroscopy, Photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Furthermore, the photocatalytic performance of the CdS nanowire was investigated for the photocatalytic degradation of methylene blue (MB) dye and Rhodamine B (RhB) in aqueous solution under illumination of the visible light. 2. Experimental 2.1 Materials and synthesis of CdS nanowires Cadmium nitrate tetrahydrate [Cd(NO3)2.4H2O], ethylenediamine [C2H8N2], and sulfur powder were purchased from Merck India and used without any further purification. In the typical synthesis of CdS nanostructure at different temperature, 0.25 mol of cadmium nitrate tetrahydrate and 0.05 mol of sulfur in 40 mL of ethylenediamine. The solution was well stirred for 1 h at room temperature. Then, the solution was transferred into the Teflon-lined autoclave and kept at 150 C for 2 h. Finally, the autoclave was cooled down to room temperature. Thereafter, the precipitates were centrifuged, washed with ethanol and deionized (DI) water and dried at 60 °C in an oven. The process was repeated with respect to the growth temperature (150, 200, 250 and 300 C). All the reaction processes were allowed for 2 h. 2.2 Measurement of photocatalytic activities of MB and RhB The photocatalytic activities of the CdS nanowire were investigated for the degradation of Methylene blue (MB) dye at their natural pH (pH = 6.5). The photocatalytic degradation reactions of MB were considered from the model pollutants. The 80 mg of the prepared photocatalyst was mixed with 80 mL of aqueous solution containing the appropriate dye (10 mg/L for MB). Prior to reactions, the dye solution with catalysts was stirred in the dark for 30 min to attain the adsorption, desorption equilibrium. The light source, (150 W tungsten lamp, λ > 420 nm, Heber scientific, India) was used for the degradation of MB. All samples were collected at the regular time interval for the illumination of visible light. The centrifuged and clear solution of 3 mL was transferred into the cuvette for the analysis of UV-visible spectrophotometer (Specord 200 plus, Analytik Jena, Germany) to quantify the concentration of MB. The Same procedure was followed for the degradation of Rhodamine blue. 3. Result and Discussion

3.1. Structural analysis of CdS nanostructures: XRD Fig.1 represents the X-ray diffraction spectra of sample prepared at different temperature (150 °C, 200 °C, 250 °C and 300 °C). All samples have the wurtzite structure which is consistent with the values in standard card (JCPDS file No. 80-0006) with a lattice constants of a= 4.121, c=6.682 and no other byproduct peaks were obtained. The strong peaks at 24.94 and 28.31 indicate that the product is highly crystalline. X-ray diffraction reveals that the (002) plane intensity increases as temperature increase which may be due to the orientation growth along c – axis [26]. 3.2. Morphology analysis of CdS nanostructures: FE-SEM, TEM, HR-TEM. 3.2.1. Effect of temperature In order to identify the grains of CdS nanostructures, FE-SEM and TEM analysis were performed for the samples. Fig. 2 (a-d) shows the FE-SEM image of CdS with different morphology. Fig.2 (a) clearly reveals that the large amount of uniformly shaped nanowire likemorphology. As the temperature increases the thickness of the nanowire increases and length of nanowire decreases as shown in fig.2 b. Fig. 2 (c, d) indicates nanorods like-morphology as the temperature increases and the thickness of nanorods increases. TEM image clearly reveals nanowire like-morphology which is augmenting with FE-SEM image and the length of nanowire about ~ 2.5 µm (Fig. 4 (a-c)). The nanowires have a diameter of 35 nm, which is uniform along the entire length was observed. The HR-TEM image (fig.4 d) give insight analysis of crystal structure of single nanowire. HR-TEM shows clear crystal stripes which indicate that the CdS nanowire are highly crystalline in nature. 3.2.2. Effect of reaction time To analyze the effect of reaction time on the morphology of CdS, the temperature kept constant at 200 °C and the reaction was carried at different reaction time like 1, 2, 3, 4 h. FESEM image clearly indicates that the bunch of nanowires was obtained with a short length (fig.3 a). Fig. 3 (b) shows that the thickness of nanowire increases and the length of nanowire decreased. Fig.3 (c, d) shows nanorods were obtained as the reaction time increases. TEM image clearly indicated nanorod like-morphology and the length of the nanorod about 300-500 nm. The hexagonal structure of nanorod is clearly depicted in fig.5 (c). HR-TEM image clearly shows clear crystal stripes in CdS nanorods which indicated that the CdS nanorods are highly crystalline in nature.

The formation of nanowire and nanorods by solvothermal reaction at a different temperature is explained in the following. In this reaction ethylenediamine (en) acts as a solvent as well as a complexing agent. The cadmium ions which dissolve in ethylenediamine (en). Ethylenediamine act as bidentate ligand and form Cd-ethylenediamine complex ([Cd(en)2]2+ which is stabilized in the solution. The sulfur powder was dissolved in the solution, the slow release of S2- ions and Cd2+ ions concentration favor slow reaction and initiate the growth of onedimensional nanowire and nanorods. (1) (2) Usually, the nucleation and growth of CdS nanorods were controlled by the dielectric constant of the solvents by water but in our case, there is no water content in the solvent. The dielectric constant is very low and the ions were easily saturated, resulting in the high CdS monomer concentration,

with a

crucial precondition

for

non-equilibrium of crystal growth.

Ethylenediamine is one of the best solvent to promote the selective anisotropic growth of CdS and provide an appropriate CdS monomer concentration for the preferential growth [27]. 3.2. Chemical bonding and composition of CdS nanostructures: FT-IR, RAMAN. FTIR spectra of CdS nanostructures synthesized with ethylenediamine solvent at different temperatures was shown in fig.6. The two band at located 1045 and 1323 cm-1 can be assigned to C-N stretching vibrations of aromatic amines [28]. The peak at 2921 cm-1 attributed to stretching vibration of C-H. The band vibration at 3436 cm-1 confirmed the presence of water molecules on the surface of the sample [29, 30]. Raman Spectra shown in fig.7 clearly reveals two major peaks corresponding to 1LO and 2 LO mode. CdS nanostructures represent sharp peaks at 294 cm-1 and 595 cm-1 in the Raman spectra analysis [31, 32]. The confinement of phonon, strain, defect and broadening significantly affected the Raman spectra of nanostructure which may be associated with the size distribution. Raman spectra of bulk CdS showed peaks at 300 (1 LO) and 600 cm-1 (2 LO) [33]. 3.3. Optical properties of CdS nanostructures: UV-vis, PL. The optical property of CdS nanostructure prepared at different temperature (150 °C, 200 °C, 250 °C and 300 °C) depicted in fig. 8. The strong absorption edge appeared at 488.7, 487.3, 482.5 and 484.2 nm, respectively. The CdS nanowires showed absorption edge at 488.7

eV which indicate slight blue shift compare to the bulk CdS. CdS nanorods showed an increase in blue shift compare to nanowire which may be due to the length of nanorods [34]. When the temperature increases, the size of the nanorods increases and the sample showed slight red shift compared to lower temperature. PL spectra of CdS nanostructures at different temperature were analyzed (150 °C, 200 °C, 250 °C and 300 °C) under the excitation wavelength of 420 nm. Fig. 9 displays green emission located at 557 nm for all the samples. The green emission attributed to the bandgap emission of CdS nanostructure and the narrow peak indicates the size of CdS nanowire and nanorods will be smaller [35-37]. 3.4. XPS analysis of CdS nanowire X-ray photoelectron spectroscopy (XPS) was used to characterize and to understand the chemical composition and valence state of the core-shell of semiconductors. The XPS survey scan in Fig.10 (a) shows the presence of Cd, S, and C elements only. The C elements at 284.9 eV was the reference to correct the binding energies. Fig. 10 (b) indicated the binding energy of Cd 3d5/2 and Cd 3d3/2 peaks at 411.9 and 405.1 eV which have an energy splitting of 6.8 eV. The binding energy belongs to CdS. The core level of S 2p shown in fig. 10 (c) clearly reveals peak at 161. 6 eV. Gaussian fitting used to fit S 2p peaks and the core level of 160.6, 161.6 and 162.5 eV. The split value is around 0.9 ~ 1.0 eV [38-40]. 3.5 Photocatalytic studies Methylene blue (MB) and Rhodamine B (RhB) was utilized as a model pollutant to demonstrate the performance of the prepared catalyst under visible light irradiation [41].

 c  Dyedegradatio n %1  t  100  co 

(4)

(ct/co) was calculated from the initial (co) and absorbance value of MB and RhB at different time interval. Fig. 11 (a) and (b) show the photocatalytic properties of CdS nanowire (150 C). The absorbance value of MB and RhB gradually decreased by the photocatalytic degradation reaction catalyzed by CdS nanowire (150 C) under visible light irradiation. The absorption peak centered at 664 nm for MB and 554 nm for RhB and the different degradation patterns were observed for CdS nanowire. The RhB curve shifted toward the shorter wavelength and the absorption intensity decreased to nearly Zero. But in MB degradation curve decreased to zero without any shift. The CdS nanowire showed better degradation of methylene blue compared to rhodamine B. Fig. 11

(c) shows the degradation of RhB and methylene blue versus irradiation time of CdS nanowire. The electron in the valence band (VB) excited to the conduction band by visible light and the generation of hole (h+) in the valence band. The electron and holes transfer to the surface of the crystals and react with the molecular oxygen (O2) and H2O to generate the superoxide radical anion (O2-) and hydroxyl radical (OH), which act as the active center and strong oxidizing agent for the photocatalytic activity. The possible mechanism of photocatalytic reaction of Rhodamine B dye as follows:

(5)  

(6) (7) (8) (9)



(10)

The degradation of RhB under the irradiation of the stimulated visible light depends on two reactions like de-ethylation and decomposition of chromophore structure of the RhB. These processes can be characterized by the shift of the maximum absorption band (max) and change in the absorption maximum Cmax /

respectively [42]. The degradation of methylene blue under

irradiation of the stimulated visible light depends on chromophore structure of methylene blue. The degradation (%) versus time (Fig. 11 c) of RhB and MB dyes clearly indicated that the irradiation of visible light for 180 min degraded to 97 % and 90 % degradation dyes. The schematic diagram of photocatalytic process shown in the Fig. 11 d. The observed degradation of RhB and MB are significant compared with previously reported CdS nanostructures (table.1) 4. Conclusions CdS nanorods and nanowire were synthesized successfully in a single step by the solvothermal method. CdS nanostructures was controlled by controlling the reaction time and temperature. Morphology analysis clearly revealed that at a low-temperature bunch of nanowire was obtained. XRD pattern showed the hexagonal phase for the samples. The UV-vis spectra showed that the absorption peaks were blue shifted from 488 nm to 484 nm as the temperature

increase. The PL spectrum of CdS nanostructure showed the broad peak at 557 nm due to S vacancies and/or surface defects. The highest degradation (97 %) of MB was achieved by the irradiation of visible light for 180 min compared to RhB. Therefore, CdS nanowires are the most suitable material for the degradation of MB under illumination of visible light. References [1]

D.S. Kim, Y.J. Cho, J. Park, J. Yoon, Y. Jo, M. Jung, ( Mn , Zn ) Co-Doped CdS Nanowires, 10861 (2007) 10861–10868. doi: 10.1021/jp072364k.

[2]

M. Zhang, M. Wille, R. Rder, S. Heedt, L. Huang, Z. Zhu, S. Geburt, D. Grtzmacher, T. Schpers, C. Ronning, J.G. Lu, Amphoteric nature of Sn in CdS nanowires, Nano Lett. 14 (2014) 518–523. doi:10.1021/nl4035169.

[3]

L. Li, Z. Lou, G. Shen, Hierarchical CdS nanowires based rigid and flexible photodetectors with ultrahigh sensitivity, ACS Appl. Mater. Interfaces. 7 (2015) 23507– 23514. doi:10.1021/acsami.5b06070.

[4]

D.S. Bhatkhande, V.G. Pangarkar, A.A.C.M. Beenackers, Photocatalytic degradation for environmental applications - A review, J. Chem. Technol. Biotechnol. 77 (2002) 102–116. doi:10.1002/jctb.532.

[5]

A. Hernandez-Gordillo, A.G. Romero, F. Tzompantzi, R. Gmez, New nanostructured CdS fibers for the photocatalytic reduction of 4-nitrophenol, Powder Technol. 250 (2013) 97– 102. doi:10.1016/j.powtec.2013.10.008.

[6]

B. Kaur, K. Singh, A.K. Malik, Precursor dependent morphological and photo-catalytic behaviour

of

CdS

nanostructures,

Dye.

Pigment.

137

(2017)

352–359.

doi:10.1016/j.dyepig.2016.10.043. [7]

X. Yang, Z. Wang, X. Lv, Y. Wang, H. Jia, Enhanced photocatalytic activity of Zn-doped dendritic-like CdS structures synthesized by hydrothermal synthesis, J. Photochem. Photobiol. A Chem. 329 (2016) 175–181. doi:10.1016/j.jphotochem.2016.07.005.

[8]

S. Sankar, S.K. Sharma, N. An, H. Lee, D.Y. Kim, Y.B. Im, Y.D. Cho, R.S. Ganesh, S. Ponnusamy, P. Raji, L.P. Purohit, Photocatalytic properties of Mn-doped NiO spherical

nanoparticles synthesized from sol-gel method, Optik. 127 (2016) 10727-10734. doi:10.1016/j.ijleo.2016.08.126. [9]

M. Molaei, M.H.M. Ara, Z. Dehghani, R.A. Ravari, Investigation of the effect of capping agent molecule type on the nonlinear optical responses of CdS nanocrystals, Synth. React. Inorg. Met. Nano-Metal Chem. 44 (2014) 247–250. doi:10.1080/15533174.2013.770024.

[10] L.F.F.F. Gonçalves, C.J.R. Silva, F.K. Kanodarwala, J.A. Stride, M.R. Pereira, Effect of acid or alkaline catalyst and of different capping agents on the optical properties of CdS nanoparticles incorporated within a diureasil hybrid matrix, Opt. Mater. 49 (2015) 171– 181. doi:10.1016/j.optmat.2015.09.007. [11] L.F.F.F. Gonçalves, C.J.R. Silva, F.K. Kanodarwala, J.A. Stride, M.R. Pereira, M.J.M. Gomes, Influence of Cd2+/S2- molar ratio and of different capping environments in the optical properties of CdS nanoparticles incorporated within a hybrid diureasil matrix, Appl. Surf. Sci. 314 (2014) 877–887. doi:10.1016/j.apsusc.2014.06.181. [12] D.C. Onwudiwe, T. Arfin, C.A. Strydom, Synthesis, characterization, and dielectric properties of N-butyl aniline capped CdS nanoparticles, Electrochim. Acta. 116 (2014) 217–223. doi:10.1016/j.electacta.2013.11.046. [13] N. Qutub, B.M. Pirzada, K. Umar, S. Sabir, Synthesis of CdS nanoparticles using different sulfide ion precursors: Formation mechanism and photocatalytic degradation of Acid Blue-29, J. Environ. Chem. Eng. 4 (2016) 808–817. doi:10.1016/j.jece.2015.10.031. [14] J.S. Roy, T. Pal Majumder, C. Schick, Optical characterization of CdS nanorods capped with starch, J. Mol. Struct. 1088 (2015) 95–100. doi:10.1016/j.molstruc.2015.02.027. [15] W. Qingqing, X. Gang, H. Gaorong, Solvothermal synthesis and characterization of uniform CdS nanowires in high yield, J. Solid State Chem. 178 (2005) 2680–2685. doi:10.1016/j.jssc.2005.06.005. [16] L.F.F.F. Gonçalves, F.K. Kanodarwala, J.A. Stride, C.J.R. Silva, M.J.M. Gomes, One-pot synthesis of CdS nanoparticles exhibiting quantum size effect prepared within a sol-gel

derived

ureasilicate

matrix,

Opt.

Mater.

(Amst).

36

(2013)

186–190.

doi:10.1016/j.optmat.2013.08.026. [17] C. Zhang, H. Huo, Y. Li, B. Li, Y. Yang, Preparation of helical CdS nanotubes using a sol-gel

transcription

approach,

Mater.

Lett.

102–103

(2013)

50–52.

doi:10.1016/j.matlet.2013.03.105. [18] A. Abdolahzadeh Ziabari, F.E. Ghodsi, Growth, characterization and studying of sol-gel derived CdS nanoscrystalline thin films incorporated in polyethyleneglycol: Effects of post-heat

treatment,

Sol.

Energy

Mater.

Sol.

Cells.

105

(2012)

249–262.

doi:10.1016/j.solmat.2012.05.014. [19] D. Mo, J. Liu, H.J. Yao, J.L. Duan, M.D. Hou, Y.M. Sun, Y.F. Chen, Z.H. Xue, L. Zhang, Preparation and characterization of CdS nanotubes and nanowires by electrochemical synthesis

in

ion-track

templates,

J.

Cryst.

Growth.

310

(2008)

612–616.

doi:10.1016/j.jcrysgro.2007.11.034. [20] A. Phuruangrat, P. Dumrongrojthanath, O. Yayapao, T. Thongtem, S. Thongtem, Solvothermal synthesis and photocatalytic properties of CdS nanowires under UV and visible

irradiation,

Mater.

Sci.

Semicond.

Process.

26

(2014)

329–335.

doi:10.1016/j.mssp.2014.04.026. [21] F. Vaquero, R.M. Navarro, J.L.G. Fierro, Evolution of the nanostructure of CdS using solvothermal synthesis at different temperature and its influence on the photoactivity for hydrogen

production,

Int.

J.

Hydrogen

Energy.

41

(2016)

11558–11567.

doi:10.1016/j.ijhydene.2015.12.039. [22] B. Ren, M. Cao, Q. Zhang, J. Huang, Z. Zhao, X. Jin, C. Li, Y. Shen, L. Wang, Controllable synthesis of CdS nanowire by a facile solvothermal method and its temperature dependent photoluminescent property, J. Alloys Compd. 659 (2016) 74–81. doi:10.1016/j.jallcom.2015.11.030. [23] Z. Tian, N. Yu, Y. Cheng, Z. Wang, Z. Chen, L. Zhang, Hydrothermal synthesis of graphene/TiO 2 /CdS nanocomposites as efficient visible-light-driven photocatalysts, Mater. Lett. 194 (2017) 172–175. doi:10.1016/j.matlet.2017.02.048.

[24] Q. Mi, D. Chen, J. Hu, Z. Huang, J. Li, Nitrogen-doped graphene/CdS hollow spheres nanocomposite with enhanced photocatalytic performance, Cuihua Xuebao/Chinese J. Catal. 34 (2013) 2138–2145. doi:10.1016/S1872-2067(12)60641-X [25] E. Repo, S. Rengaraj, S. Pulkka, E. Castangnoli, S. Suihkonen, M. Sopanen, M. Sillanpää, Photocatalytic degradation of dyes by CdS microspheres under near UV and blue LED radiation, Sep. Purif. Technol. 120 (2013) 206–214. doi:10.1016/j.seppur.2013.10.008. [26] R. Sankar Ganesh, E. Durgadevi, M. Navaneethan, P. Raji, S. Ponnusamy, C. Muthamizhchelvan, Y. Hayakawa, Fabrication of bistable switching device using CdS nanorods embedded in PMMA (polymethylmethacrylate) nanocomposite, J. Mater. Sci. Mater. Electron. 26 (2015) 9010-9015. doi:10.1007/s10854-015-3584-0. [27] T. Thongtem, A. Phuruangrat, S. Thongtem, Solvothermal synthesis of CdS nanowires templated

by

polyethylene

glycol,

Ceram.

Int.

35

(2009)

2817–2822.

doi:10.1016/j.ceramint.2009.03.024. [28] V. Bala, M. Sharma, S.K. Tripathi, R. Kumar, Investigations of Al:CdS/PVA nanocomposites: A joint theoretical and experimental approach, Mater. Chem. Phys. 146 (2014) 523–530. doi:10.1016/j.matchemphys.2014.04.003. [29] Seoudi R. El- Bailly A. B. Eisa W. Shabaka A. A. Soliman S.I. Abd E Hamid R. K. Ramadan R. A., Synthesis , optical and dielectric properties of ( PVA / CdS ) nanocomposites, J. Appl. Sci. Res. 8 (2016) 658–667. [30] I.S. Elashmawi, N.A. Hakeem, M.S. Selim, Optimization and spectroscopic studies of CdS/poly(vinyl alcohol) nanocomposites, Mater. Chem. Phys. 115 (2009) 132–135. doi:10.1016/j.matchemphys.2008.11.034. [31] F. Vaquero, R.M. Navarro, J.L.G. Fierro, Influence of the solvent on the structure, morphology and performance for H2 evolution of CdS photocatalysts prepared by solvothermal

method,

Appl.

doi:10.1016/j.apcatb.2016.10.073.

Catal.

B

Environ.

203

(2016)

753–767.

[32] L. Zeiri, I. Patla, S. Acharya, Y. Golan, S. Efrima, Raman spectroscopy of ultranarrow CdS nanostructures, J. Phys. Chem. C. 111 (2007) 11843–11848. doi:10.1021/jp072015q. [33] M.A. Mahdi, J.J. Hassan, S.J. Kasim, S.S. Ng, Z. Hassan, Solvothermal growth of singlecrystal CdS nanowires, Bull. Mater. Sci. 37 (2014) 337–345. doi: 10.1007/s12034-0140655-4 [34] S. Yan, L. Sun, P. Qu, N. Huang, Y. Song, Z. Xiao, Synthesis of uniform CdS nanowires in high yield and its single nanowire electrical property, J. Solid State Chem. 182 (2009) 2941–2945. doi:10.1016/j.jssc.2009.07.016. [35] J.G. Zhao, Z.H. Hua, Y. Yao, Solvothermal synthesis and characterization of onedimensional

CdS

nanowires,

Superlattices

Microstruct.

61

(2013)

146–151.

doi:10.1016/j.spmi.2013.06.019. [36] C. Hu, X. Zeng, J. Cui, H. Chen, J. Lu, Size Effects of Raman and Photoluminescence Spectra of CdS Nanobelts, (2013). doi:10.1021/jp407272u. [37] J. Yang, H. Yan, X. Zong, F. Wen, M. Liu, C. Li, Roles of cocatalysts in semiconductorbased photocatalytic hydrogen production, Philos. Trans. R. Soc. A. 371 (2013) 1–6. doi:10.1098/rsta.2011.0430. [38] B. Han, S. Liu, N. Zhang, Y.J. Xu, Z.R. Tang, One-dimensional CdS@MoS2 core-shell nanowires for boosted photocatalytic hydrogen evolution under visible light, Appl. Catal. B Environ. 202 (2017) 298–304. doi:10.1016/j.apcatb.2016.09.023. [39] D. Wang, C. Bao, Q. Luo, R. Yin, X. Li, J. An, Z. Xu, Improved visible-light photocatalytic activity and anti-photocorrosion of CdS nanoparticles surface-modified by conjugated derivatives from polyvinyl chloride, J. Environ. Chem. Eng. 3 (2015) 1578– 1585. doi:10.1016/j.jece.2015.05.013. [40] J. Yu, C. Gong, Z. Wu, Y. Wu, W. Xiao, Y. Su, L. Sun, C. Lin, Efficient visible lightinduced photoelectrocatalytic hydrogen production using CdS sensitized TiO 2 nanorods on

TiO2

nanotube

arrays,

doi:10.1039/C5TA04107D.

J.

Mater.

Chem.

A.

3

(2015)

22218–22226.

[41] R.S. Ganesh, S.K. Sharma, E. Durgadevi, M. Navaneethan, H.S. Binitha, S. Ponnusamy, C. Muthamizhchelvan, Y. Hayakawa, D.Y. Kim, Surfactant free synthesis of CdS nanospheres, microstructural analysis, chemical bonding, optical properties and photocatalytic

activities,

Superlattices

Microstruct.

104

(2017)

247–257.

doi:10.1016/j.spmi.2017.02.029. [42] Y. Ao, L. Xu, P. Wang, C. Wang, J. Hou, J. Qian, Preparation of CdS nanoparticle loaded flower-like Bi2O2CO3 heterojunction photocatalysts with enhanced visible light photocatalytic activity, Dalt. Trans. 44 (2015) 11321–11330. doi:10.1039/C5DT01168J. [43]

N. Soltani, E. Saion, W. Mahmood Mat Yunus, M. Navasery, G. Bahmanrokh, M. Erfani, M.R. Zare, E. Gharibshahi, Photocatalytic degradation of methylene blue under visible light using PVP-capped ZnS and CdS nanoparticles, Sol. Energy. 97 (2013) 147–154. doi:10.1016/j.solener.2013.08.023.

[44] Y. Huang, F. Sun, T. Wu, Q. Wu, Z. Huang, H. Su, Z. Zhang, Photochemical preparation of CdS hollow microspheres at room temperature and their use in visible-light photocatalysis, J. Solid State Chem. 184 (2011) 644–648. doi:10.1016/j.jssc.2011.01.012. [45] C. Deng, X. Tian, Facile microwave-assisted aqueous synthesis of CdS nanocrystals with their photocatalytic activities under visible lighting, Mater. Res. Bull. 48 (2013) 4344– 4350. doi:10.1016/j.materresbull.2013.07.019. [46] Z. Yu, B. Yin, F. Qu, X. Wu, Synthesis of self-assembled CdS nanospheres and their photocatalytic activities by photodegradation of organic dye molecules, Chem. Eng. J. 258 (2014) 203–209. doi:10.1016/j.cej.2014.07.041. [47] E. Repo, S. Rengaraj, S. Pulkka, E. Castangnoli, S. Suihkonen, M. Sopanen, M. Sillanpää, Photocatalytic degradation of dyes by CdS microspheres under near UV and blue LED radiation, Sep. Purif. Technol. 120 (2013) 206–214. doi:10.1016/j.seppur.2013.10.008. [48] Q. Hao, J. Xu, X. Zhuang, Q. Zhang, Q. Wan, H. Pan, X. Zhu, A. Pan, Template-free synthesis and photocatalytic activity of CdS nanorings, Mater. Lett. 100 (2013) 141–144. doi:10.1016/j.matlet.2013.02.091.

[49] J.D. Patel, F. Mighri, A. Ajji, T.K. Chaudhuri, Fatty acid-assisted synthesis of CdS microspheres: Physicochemical properties and photocatalytic activity, Mater. Lett. 110 (2013) 94–97. doi:10.1016/j.matlet.2013.08.007. [50] R.S. Ganesh, S.K. Sharma, E. Durgadevi, M. Navaneethan, S. Ponnusamy, C. Muthamizhchelvan, Y. Hayakawa, D.Y. Kim, Growth, microstructure, structural and optical properties of PVP-capped CdS nanoflowers for efficient photocatalytic activity of Rhodamine B, Mater. Res. Bull. (2017). doi:10.1016/j.materresbull.2017.05.059.

Figures Caption Fig. 1 XRD pattern of CdS nanowires grown in the autoclave with respect to the growth temperatures of 150 C, 200 C, 250 C, and 300 C. Fig. 2 FE-SEM images of CdS nanowires with different growth temperatures, (a) 150 C, (b) 200 C, (c) 250 C, and (d) 300 C, respectively. Fig. 3 FE-SEM image of CdS nanostructure at different reaction time (a).1 h, (b). 2 h, (c). 3 h, (d). 4 h respectively. Fig. 4 (a, b, c) TEM, (d). HRTEM image of CdS nanowire (150 C). Fig. 5 (a, b, c) TEM, (d). HRTEM image of CdS nanorods (250 C). Fig. 6 Raman spectra of CdS nanowires, (a) growth at 150 C, and (b) growth at 250 C. Fig. 7 FTIR spectra of CdS nanowires with respect to the growth temperatures of 150 C, 200 C, 250 C, and 300 C. Fig. 8 UV-vis absorption spectra of CdS nanowires with respect to the growth temperatures of 150 C, 200 C, 250 C, and 300 C. Fig. 9 PL spectra of CdS nanowires with respect to the growth temperatures of 150 C, 200 C, 250 C, and 300 C. Fig. 10 Typical XPS spectra measured for CdS nanowires grown at 150 C, (a) XPS survey spectrum (b). core level XPS spectrum of Cd 3d, and (c) core level XPS spectrum of S 2p. (d). core level XPS spectrum of C 1s.

Fig. 11 Absorbance spectra of dye degradation by CdS nanowire (150 C), (a) Methylene blue, (b) Rhodamine B, (c) Variation of photo-degradation of methylene blue and rhodamine B. (d). Schematic diagram of photocatalytic process.

Table.1 Comparison table of MB and RhB dye degradation utilizing CdS nanostructures previously reported with current work

Figure 1: XRD

Figure 2: FE-SEM

Figure 3

Figure 4

Figure 5

Figure 6: FTIR

Transmittance (%)

CdS nanowires

o

150 C o

556

200 C

o

1636

300 C 2921

3436

1323

o

250 C

4000 3500 3000 2500 2000 1500 1000

500

-1

Wavenumber (cm ) Figure 7: Raman

590.4

Raman Intensity (a.u)

294.1

CdS nanowires

o

250 C

o

150 C

200 250 300 350 400 450 500 550 600 650 -1

Raman shift (cm )

Figure 8: UV-Vis o

CdS nanowires

300 C o

250 C

Absorbance (a.u)

484.2 nm 482.5 nm

o

200 C

487.3 nm 488.7 nm

o

150 C

300

400

500

600

700

800

Wavelength (nm)

PL at RT

557 nm

Figure 9: PL at room temperature (RT)

CdS nanowires o

Intensity (a.u)

300 C

o

250 C o

200 C

o

150 C

450

500

550

600

Wavelength (nm)

650

700

Figure 10 (a). XPS survey spectrum of CdS, (b, c) core level XPS of Cd and S (d). core level of carbon

Figure 11

Table 1

S. NO.

Materials

Dye

(CdS microstructures)

Time

Percentage References

(min)

(%)

1.

CdS nanosphere

Methylene Blue

180

96

[41]

2.

CdS Nanoparticle

Methylene Blue

120

65

[43]

3.

CdS hollow

Methylene Blue

180

38

[44]

microsphere 4.

CdS nanosphere

Methylene Blue

180

70

[45]

6.

CdS nanosphere

Methylene Blue

180

85

[46]

7.

CdS sphere

Methylene blue

180

55

[47]

8.

CdS nanoring

Rhodamine B

300

70

[48]

9.

CdS sphere

Rhodamine B

180

90

[49]

10.

PVP-capped CdS Flower

Rhodamine B

120

95

[50]

11.

CdS nanowire

Rhodamine B

180

97

Reporting

Methylene blue

180

90

Graphical abstract

Highlights

1.

CdS nanowire and nanorods were synthesized at low temperature by simply varying the temperature and reaction time.

2.

CdS nanowire showed enhanced degradation towards methylene blue compared to Rhodamine B.

3.

96 % of methylene blue was degraded within 180 min.

4.

TEM image showed perfect nanowire with nanometer in size and high in length.