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Facile synthesis of copper-antimony-sulfide nanostructures on WO3 electrodes: Investigation of electrochemical performance
Materials Letters 245 (2019) 126–129
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Facile synthesis of copper-antimony-sulfide nanostructures on WO3 electrodes: Investigation of electrochemical performance Janthima Sribenjawan a, Duanghatai Raknual b, Veeramol Vailikhit b, Nareerat Kitisripanya c, Auttasit Tubtimtae a,⇑ a b c
Department of Physics, Faculty of Liberal Arts and Science, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand Department of Chemistry, Faculty of Liberal Arts and Science, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand Department of General Science, Faculty of Science and Engineering, Kasetsart University Chalermphrakiat Sakon Nakhon Province Campus, Sakon Nakhon 47000, Thailand
a r t i c l e
i n f o
Article history: Received 31 January 2019 Received in revised form 21 February 2019 Accepted 23 February 2019 Available online 2 March 2019 Keywords: Copper antimony sulfide pH treatment Structural Electrochemical Nanosheet
a b s t r a c t In this study, copper-antimony-sulfide (CAS) nanostructures, including CuSbS2, Cu3SbS3, and Cu3SbS4, were synthesized from a Cu-Sb-S solution via ion deposition. The CAS nanostructures changed to more nanosheet-like structures after pH treatment with an ammonia solution (NH4OH). Additionally, the pH increased from 2.1 to 9.2, with the highest exchange current density, J0, of 0.523 mA/cm2, indicating high charge-storage capacity. The results revealed a faster response time for the de-intercalation/intercalation current, and improved breakdown potential. Furthermore, a morphological change occurred that yielded a larger active material surface; these changes increased electron transport and ion conductivity, and improved the charge-storage capability, demonstrating the high potential for use in electric doublelayer capacitors, batteries, and energy-storage devices. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction Chalcogenide nanomaterials are currently considered to be one of the most promising types of semiconductor compounds for technological applications, with the simplest combinations of metal alloys and sulfur, selenium, and tellurium elements being applied in solid oxide fuel cells [1] and thin-film/hybrid photovoltaic devices [2]. Ternary Cu-based chalcogenide semiconductor nanocrystals are being intensively investigated as a new class of ptype solar absorber layers and electrochemical devices owing to their non-toxic, relatively abundant, inexpensive, and economical [3]. As is known, copper-containing materials can be good absorber materials as the p-type conductivity originates from copper ion decomposition; therefore, these materials (e.g., Cu(In,Ga)Se2 (CIGS) compounds) will serve as efficient p-type absorber layers [4]. Among these materials, copper-antimony-sulfide (CAS) is considered a promising solar-energy absorber material, and its constituent elements are widely available [5]. CAS materials contain four stable ternary compounds: CuSbS2 (chalcostibite) [5], Cu3SbS4 (famatinite) [6,7], Cu12Sb4S13 (tetrahedrite) [7], and Cu3SbS3 (skinnerite and wittichenite) [8]. Furthermore, the phases of CAS materials are complex because of the very narrow thermodynamic ⇑ Corresponding author. E-mail address: [email protected] (A. Tubtimtae). https://doi.org/10.1016/j.matlet.2019.02.120 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
stability windows within the four phases. However, the phases are crucial to the device behavior, as CAS materials are expected to be employed as low-band gap materials for photo-electrochemical applications [9]. Several fabrication methods, such as electrochemical deposition [10], thermal evaporation [11], hot-injection [12], hydrothermal method [13], and solvothermal method [14] have been used to synthesize CuSbS2 thin films for photoelectrochemical devices. Cu3SbS3 is conductive and provides the requisite optical and carrier transport performances [15]. Moreover, famatinite Cu3SbS4 and tetrahedrite Cu12Sb4S13 materials are also promising candidates that possess energy gap (Eg) values of 1.0 and 1.70 eV, respectively, and have high absorption coefficients similar to that of the Cu3SbS3 material [6]. For an electron acceptor, tungsten oxide (WO3) has carrier mobility of 10 cm2/V s with a diffusion coefficient of 0.25 cm2/s in a single crystal [16,17]. The conduction band edge (ECB) of WO3 is 4.60 eV; this lower than that of ZnO (ECB = 4.19 eV) and TiO2 (ECB = 4.21 eV) [18]. These properties allow the injection of more carriers and timely charge transfer from the electrode surface to the electron acceptor surface. Furthermore, a higher number of effective electrons for the attendant redox reactions and enhanced electrocatalytic activity in the devices can be obtained. In this study, CAS nanostructures were fabricated and coated on WO3 electrodes. Further, an ammonia solution (NH4OH) was introduced into the mixed precursor to obtain various pH values
J. Sribenjawan et al. / Materials Letters 245 (2019) 126–129
127
Fig. 1. CV curves for the WO3/CAS condition for various (a) dropping cycles and (b) pH treatments.
and determine the highest exchange current density (J0), response time, and breakdown potential, as well as investigate the device morphology. 2. Experimental 2.1 Preparation of the WO3 electrodes, electrochemical and morphology analysis See the supplementary data. 2.2 Synthesis of CAS nanostructures 0.064 M of Sb2S3 powder was mixed in distilled water and stirred for 60 min at 15 °C. Then, 0.1 M of Cu(NO3)23H2O was prepared in ethanol, poured into the Sb2S3 solution, and stirred again for 90 min until a homogeneous stock solution was formed. Initially, the pH of the solution was 2.1. Subsequently, the Cu-SbS solution, as a precursor for Cu2+, Sb3+, and S2, was dropped onto the WO3 electrode for 60 s (1 drop 15 lL), rinsed with ethanol, and dried at 60–70 °C for a few minutes. This process constitutes one dropping cycle of CAS nanoparticles, which formed on the WO3 electrode. The samples for cycles 1–5 are shown in Fig. S1. For pH treatment, the Cu-Sb-S solution was transferred into four beakers of 5 mL each. NH4OH (25%, AR Grade, QRëCTM) was dropped into the mixed precursor to obtain various pH values (Table S1) as measured via a pH meter (Cyberscan PC 510, Eutech, Singapore) to determine the highest J0. 3. Results and discussion Fig. 1a shows the CV curves for various dropping cycles. J0 was extracted from the intercept of the Tafel plot (Fig. S2), with larger J0 (0.473 mA/cm2) being implemented in cycle 2. The highest J0 (0.523 mA/cm2) was obtained for WO3/CAS(2)/pH 9.2 (Fig. 1b and Fig. S3), indicating the highest charge-storage capacity among the various pH treatments. Chronoamperometry (CA) was performed by applying a forward potential (0 V to 1.0 V) and reverse potential (0 V to + 1.0 V) vs. Ag/AgCl in steps for 10 s. The current resulting from Faradaic processes was induced at the CAS electrode before and after pH treatment, as shown in Fig. 2a and b, respectively. The response times for the de-intercalation/intercalation current are represented by the colored (tc) and bleached (tb) states, respectively. Based on our results, the response times of the bleached and colored states for the WO3/CAS(2)/pH 2.1 condition were 0.84 and 2.72 s, respectively. A lower tb and slightly higher tc of 0.60 and 2.80 s were respectively observed after pH treatment (pH 9.2).
Fig. 2. (a, b) CA measurements and (c) LSV curves for before and after NH4OH dropping.
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J. Sribenjawan et al. / Materials Letters 245 (2019) 126–129
Fig. 3. SEM images for (a) bare WO3, (b) WO3/CAS(2)/pH 2.1, and (c) WO3/CAS(2)/pH 9.2 conditions and (d) XRD patterns for each condition.
The higher response time of the colored state obtained for the post-pH-treatment, which resulted in more electrons, increased ion conductivity, and improved charge-storage capability [19]. The faster response time of the bleached state was due to the existence of some vacancies and more active sites in the host lattice; these led to faster de-insertion of S2 and Na+ ions in the large active sites on the interfaces of the working and counter electrodes, respectively [20,21]. Fig. 2c shows the linear sweep voltammetry (LSV) curves for the WO3/CAS(2) condition with and without pH treatment; these demonstrate the electrolytic production and electrocatalytic activity. The point of x-axis interception indicates the breakdown potential, which slightly increased from 0.18 to 0.20 V after the pH treatment. This increased breakdown potential indicates higher ion mobility and conductivity of the sample [22]. Fig. 3a shows the morphology of bare WO3 before depositing CAS nanostructures. Some CAS nanosheets were observed to have two-dimensional morphology before pH treatment (Fig. 3b). Then, after two-NH4OH dropping for pH treatment, the higher number of nanosheet-like structures were occurred and the active surface area increased with a size from hundreds of nanometers to about 0.5–1 lm (Fig. 3c). The size and morphology characteristics of our synthesized material were similar to those reported previously for ZnCo2O4 nanosheets for sodium ion batteries [23]. Fig. 3d shows the XRD patterns for the WO3/CAS/pH (2.1 and 9.2) conditions as compared to that of bare WO3. The CAS diffraction peaks correspond to three phases: orthorhombic CuSbS2 at 2h = 28.04° and 60.76°, with (1 1 1) and (3 2 2) planes, respectively (JCPDS 44-1417), and monoclinic Cu3SbS3 with 2h = 36.00° and a ( 3 1 1) plane (JCPDS 83-0563). Additionally, most diffraction peaks are observed for tetragonal Cu3SbS4 at 2h = 47.80°, 62.92°, and 70.06° with (2 0 4), (1 0 7), and (0 0 8) planes, respectively (JCPDS 35-0581). The formation of CAS nanostructures can be explained by the chemical reaction in the supplementary data.
The EDS result shown in Fig. S4 indicates that tetrahedrite may have most likely formed due to the loss of sulfur in the crystal structure. Regarding charge neutrality, valence changes from Cu (I) to Cu(II) and Sb(V) to Sb(III) occurred, as shown below [24]: ðIÞ
ðVÞ
ðIÞ
ðIIÞ
ðIIIÞ
Cu3 Sb S4 ! Cu10 Cu2 Sb4 S13
ð1Þ
These results indicate that the facile synthesis and modification of CAS nanostructures should provide improved and specific electrochemical properties that can be applied for high-performance electric double-layer capacitors and energy-storage devices [22].
4. Conclusions CAS nanostructures were synthesized via ion deposition from a mixed precursor. Dropping NH4OH induced morphological CAS changes, and the highest J0 was obtained for the WO3/CAS(2)/pH 9.2 condition. The electrochemical performance suggested that a higher number of nanosheet-like structures corresponded to more electrons, higher breakdown potential and ion conductivity, and improved charge-storage capability.
Conflict of interest The authors declare that there are no conflicts of interest to this work.
Acknowledgments We are grateful to acknowledge the Energy Policy and Planning Office (EPPO) of the Ministry of Energy in Thailand for financial support in the fiscal year 2018.
J. Sribenjawan et al. / Materials Letters 245 (2019) 126–129
Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.02.120.
References [1] S. Yilmaz, E. Yildiz, B. Kavici, Int. J. Appl. Ceram. Technol. 14 (2017) 550–561. [2] W. Ma, J.M. Luther, H. Zheng, Y. Wu, A.P. Alivisatos, Nano Lett. 9 (2009) 1699– 1703. [3] A.C. Rastogi, N.R. Janardhana, Thin Solid Films 565 (2014) 285–292. [4] P. Jackson, R. Wuerz, D. Hariskos, E. Lotter, W. Witte, M. Powalla, Phys. Status Solidi RRL 10 (2016) 583–586. [5] B. Yang, L. Wang, J. Han, Y. Zhou, H. Song, S. Chen, J. Zhong, L. Lv, D. Niu, J. Tang, Chem. Mater. 26 (2014) 3135–3143. [6] J. van Embden, K. Latham, N.W. Duffy, Y. Tachibana, J. Am. Chem. Soc. 135 (2013) 11562–11571. [7] G. Chen, W. Wang, J. Zhao, W. Yang, S. Chen, Z. Huang, R. Jian, H. Ruan, J. Alloys Compd. 679 (2016) 218–224. [8] A.B. Kehoe, D.J. Temple, G.W. Watson, D.O. Scanlon, Phys. Chem. Chem. Phys. 15 (2013) 15477–15484. [9] P.K. Sarswat, M.L. Free, Int. J. Photoenergy 154694 (2013), https://doi.org/ 10.1155/2013/154694.
129
[10] W. Septina, S. Ikeda, Y. Iga, T. Harada, M. Matsumura, Thin Solid Films 550 (2014) 700–704. [11] Y. Fadhli, A. Rabhi, M. Kanzari, J. Mater. Sci. 25 (2014) 4767–4773. [12] K. Chen, J. Zhou, W. Chen, Q. Chen, P. Zhou, Y. Liu, Nanoscale 8 (2016) 5146– 5152. [13] S. Dekhil, H. Dahman, S. Rabaoui, N. Yaacoub, L. El Mir, J. Mater. Sci. Mater. Electron. 28 (2017) 11631–11635. [14] M. Han, J. Jia, W. Wang, J. Alloys Compd. 705 (2017) 365–1362. [15] D.J. Temple, A.B. Kehoe, J.P. Allen, G.W. Watson, D.O. Scanlon, J. Phys. Chem. C 116 (2012) 7334–7340. [16] J. Yan, Handbook of Clean Energy Systems, vol. 6, John Willey & Sons Ltd., United Kingdom, 2015. [17] R.S. Crandall, B.W. Faughnan, Appl. Phys. Lett. 26 (1975) 120–121. [18] Y. Xu, M.A.A. Schoonen, Am. Miner. 85 (2000) 543–556. [19] G.L. Xu, R. Amine, Y.F. Xu, J. Liu, J. Gim, T. Ma, Y. Ren, C.J. Sun, Y. Liu, X. Zhang, S. M. Heald, A. Solhy, I. Saadoune, W.L. Mattis, S.G. Sun, Z. Chen, K. Amine, Energy Environ. Sci. 10 (2017) 1677–1693. [20] K.S. Usha, R. Sivakumar, C. Sanjeeviraj, V. Sathe, V. Ganesan, T.Y. Wang, RSC Adv. 6 (2016) 79668–79680. [21] Y.X. Wang, B. Zhang, W. Lai, Y. Xu, S.L. Chou, H.-K. Liu, S.X. Dou, Adv. Energy Mater. (2017) 1602829. [22] V. Selvanathan, M.N.A. Halim, A.D. Azzahari, M. Rizwan, N. Shahabudin, R. Yahya, Ionics 24 (2018) 1955–1964. [23] X. Cao, Y. Yang, A. Li, Nanomaterials 8 (2018), 377(1–9). [24] S. Suehiro, K. Horita, M. Yuasa, T. Tanaka, K. Fujita, Y. Ishiwata, K. Shimanoe, T. Kida, Inorg. Chem. 54 (2015) 7840–7845.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Facile synthesis of copper-antimony-sulfide nanostructures on WO3 electrodes: Investigation of electrochemical performance Janthima Sribenjawan a, Duanghatai Raknual b, Veeramol Vailikhit b, Nareerat Kitisripanya c, Auttasit Tubtimtae a,⇑ a b c
Department of Physics, Faculty of Liberal Arts and Science, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand Department of Chemistry, Faculty of Liberal Arts and Science, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand Department of General Science, Faculty of Science and Engineering, Kasetsart University Chalermphrakiat Sakon Nakhon Province Campus, Sakon Nakhon 47000, Thailand
a r t i c l e
i n f o
Article history: Received 31 January 2019 Received in revised form 21 February 2019 Accepted 23 February 2019 Available online 2 March 2019 Keywords: Copper antimony sulfide pH treatment Structural Electrochemical Nanosheet
a b s t r a c t In this study, copper-antimony-sulfide (CAS) nanostructures, including CuSbS2, Cu3SbS3, and Cu3SbS4, were synthesized from a Cu-Sb-S solution via ion deposition. The CAS nanostructures changed to more nanosheet-like structures after pH treatment with an ammonia solution (NH4OH). Additionally, the pH increased from 2.1 to 9.2, with the highest exchange current density, J0, of 0.523 mA/cm2, indicating high charge-storage capacity. The results revealed a faster response time for the de-intercalation/intercalation current, and improved breakdown potential. Furthermore, a morphological change occurred that yielded a larger active material surface; these changes increased electron transport and ion conductivity, and improved the charge-storage capability, demonstrating the high potential for use in electric doublelayer capacitors, batteries, and energy-storage devices. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction Chalcogenide nanomaterials are currently considered to be one of the most promising types of semiconductor compounds for technological applications, with the simplest combinations of metal alloys and sulfur, selenium, and tellurium elements being applied in solid oxide fuel cells [1] and thin-film/hybrid photovoltaic devices [2]. Ternary Cu-based chalcogenide semiconductor nanocrystals are being intensively investigated as a new class of ptype solar absorber layers and electrochemical devices owing to their non-toxic, relatively abundant, inexpensive, and economical [3]. As is known, copper-containing materials can be good absorber materials as the p-type conductivity originates from copper ion decomposition; therefore, these materials (e.g., Cu(In,Ga)Se2 (CIGS) compounds) will serve as efficient p-type absorber layers [4]. Among these materials, copper-antimony-sulfide (CAS) is considered a promising solar-energy absorber material, and its constituent elements are widely available [5]. CAS materials contain four stable ternary compounds: CuSbS2 (chalcostibite) [5], Cu3SbS4 (famatinite) [6,7], Cu12Sb4S13 (tetrahedrite) [7], and Cu3SbS3 (skinnerite and wittichenite) [8]. Furthermore, the phases of CAS materials are complex because of the very narrow thermodynamic ⇑ Corresponding author. E-mail address: [email protected] (A. Tubtimtae). https://doi.org/10.1016/j.matlet.2019.02.120 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
stability windows within the four phases. However, the phases are crucial to the device behavior, as CAS materials are expected to be employed as low-band gap materials for photo-electrochemical applications [9]. Several fabrication methods, such as electrochemical deposition [10], thermal evaporation [11], hot-injection [12], hydrothermal method [13], and solvothermal method [14] have been used to synthesize CuSbS2 thin films for photoelectrochemical devices. Cu3SbS3 is conductive and provides the requisite optical and carrier transport performances [15]. Moreover, famatinite Cu3SbS4 and tetrahedrite Cu12Sb4S13 materials are also promising candidates that possess energy gap (Eg) values of 1.0 and 1.70 eV, respectively, and have high absorption coefficients similar to that of the Cu3SbS3 material [6]. For an electron acceptor, tungsten oxide (WO3) has carrier mobility of 10 cm2/V s with a diffusion coefficient of 0.25 cm2/s in a single crystal [16,17]. The conduction band edge (ECB) of WO3 is 4.60 eV; this lower than that of ZnO (ECB = 4.19 eV) and TiO2 (ECB = 4.21 eV) [18]. These properties allow the injection of more carriers and timely charge transfer from the electrode surface to the electron acceptor surface. Furthermore, a higher number of effective electrons for the attendant redox reactions and enhanced electrocatalytic activity in the devices can be obtained. In this study, CAS nanostructures were fabricated and coated on WO3 electrodes. Further, an ammonia solution (NH4OH) was introduced into the mixed precursor to obtain various pH values
J. Sribenjawan et al. / Materials Letters 245 (2019) 126–129
127
Fig. 1. CV curves for the WO3/CAS condition for various (a) dropping cycles and (b) pH treatments.
and determine the highest exchange current density (J0), response time, and breakdown potential, as well as investigate the device morphology. 2. Experimental 2.1 Preparation of the WO3 electrodes, electrochemical and morphology analysis See the supplementary data. 2.2 Synthesis of CAS nanostructures 0.064 M of Sb2S3 powder was mixed in distilled water and stirred for 60 min at 15 °C. Then, 0.1 M of Cu(NO3)23H2O was prepared in ethanol, poured into the Sb2S3 solution, and stirred again for 90 min until a homogeneous stock solution was formed. Initially, the pH of the solution was 2.1. Subsequently, the Cu-SbS solution, as a precursor for Cu2+, Sb3+, and S2, was dropped onto the WO3 electrode for 60 s (1 drop 15 lL), rinsed with ethanol, and dried at 60–70 °C for a few minutes. This process constitutes one dropping cycle of CAS nanoparticles, which formed on the WO3 electrode. The samples for cycles 1–5 are shown in Fig. S1. For pH treatment, the Cu-Sb-S solution was transferred into four beakers of 5 mL each. NH4OH (25%, AR Grade, QRëCTM) was dropped into the mixed precursor to obtain various pH values (Table S1) as measured via a pH meter (Cyberscan PC 510, Eutech, Singapore) to determine the highest J0. 3. Results and discussion Fig. 1a shows the CV curves for various dropping cycles. J0 was extracted from the intercept of the Tafel plot (Fig. S2), with larger J0 (0.473 mA/cm2) being implemented in cycle 2. The highest J0 (0.523 mA/cm2) was obtained for WO3/CAS(2)/pH 9.2 (Fig. 1b and Fig. S3), indicating the highest charge-storage capacity among the various pH treatments. Chronoamperometry (CA) was performed by applying a forward potential (0 V to 1.0 V) and reverse potential (0 V to + 1.0 V) vs. Ag/AgCl in steps for 10 s. The current resulting from Faradaic processes was induced at the CAS electrode before and after pH treatment, as shown in Fig. 2a and b, respectively. The response times for the de-intercalation/intercalation current are represented by the colored (tc) and bleached (tb) states, respectively. Based on our results, the response times of the bleached and colored states for the WO3/CAS(2)/pH 2.1 condition were 0.84 and 2.72 s, respectively. A lower tb and slightly higher tc of 0.60 and 2.80 s were respectively observed after pH treatment (pH 9.2).
Fig. 2. (a, b) CA measurements and (c) LSV curves for before and after NH4OH dropping.
128
J. Sribenjawan et al. / Materials Letters 245 (2019) 126–129
Fig. 3. SEM images for (a) bare WO3, (b) WO3/CAS(2)/pH 2.1, and (c) WO3/CAS(2)/pH 9.2 conditions and (d) XRD patterns for each condition.
The higher response time of the colored state obtained for the post-pH-treatment, which resulted in more electrons, increased ion conductivity, and improved charge-storage capability [19]. The faster response time of the bleached state was due to the existence of some vacancies and more active sites in the host lattice; these led to faster de-insertion of S2 and Na+ ions in the large active sites on the interfaces of the working and counter electrodes, respectively [20,21]. Fig. 2c shows the linear sweep voltammetry (LSV) curves for the WO3/CAS(2) condition with and without pH treatment; these demonstrate the electrolytic production and electrocatalytic activity. The point of x-axis interception indicates the breakdown potential, which slightly increased from 0.18 to 0.20 V after the pH treatment. This increased breakdown potential indicates higher ion mobility and conductivity of the sample [22]. Fig. 3a shows the morphology of bare WO3 before depositing CAS nanostructures. Some CAS nanosheets were observed to have two-dimensional morphology before pH treatment (Fig. 3b). Then, after two-NH4OH dropping for pH treatment, the higher number of nanosheet-like structures were occurred and the active surface area increased with a size from hundreds of nanometers to about 0.5–1 lm (Fig. 3c). The size and morphology characteristics of our synthesized material were similar to those reported previously for ZnCo2O4 nanosheets for sodium ion batteries [23]. Fig. 3d shows the XRD patterns for the WO3/CAS/pH (2.1 and 9.2) conditions as compared to that of bare WO3. The CAS diffraction peaks correspond to three phases: orthorhombic CuSbS2 at 2h = 28.04° and 60.76°, with (1 1 1) and (3 2 2) planes, respectively (JCPDS 44-1417), and monoclinic Cu3SbS3 with 2h = 36.00° and a ( 3 1 1) plane (JCPDS 83-0563). Additionally, most diffraction peaks are observed for tetragonal Cu3SbS4 at 2h = 47.80°, 62.92°, and 70.06° with (2 0 4), (1 0 7), and (0 0 8) planes, respectively (JCPDS 35-0581). The formation of CAS nanostructures can be explained by the chemical reaction in the supplementary data.
The EDS result shown in Fig. S4 indicates that tetrahedrite may have most likely formed due to the loss of sulfur in the crystal structure. Regarding charge neutrality, valence changes from Cu (I) to Cu(II) and Sb(V) to Sb(III) occurred, as shown below [24]: ðIÞ
ðVÞ
ðIÞ
ðIIÞ
ðIIIÞ
Cu3 Sb S4 ! Cu10 Cu2 Sb4 S13
ð1Þ
These results indicate that the facile synthesis and modification of CAS nanostructures should provide improved and specific electrochemical properties that can be applied for high-performance electric double-layer capacitors and energy-storage devices [22].
4. Conclusions CAS nanostructures were synthesized via ion deposition from a mixed precursor. Dropping NH4OH induced morphological CAS changes, and the highest J0 was obtained for the WO3/CAS(2)/pH 9.2 condition. The electrochemical performance suggested that a higher number of nanosheet-like structures corresponded to more electrons, higher breakdown potential and ion conductivity, and improved charge-storage capability.
Conflict of interest The authors declare that there are no conflicts of interest to this work.
Acknowledgments We are grateful to acknowledge the Energy Policy and Planning Office (EPPO) of the Ministry of Energy in Thailand for financial support in the fiscal year 2018.
J. Sribenjawan et al. / Materials Letters 245 (2019) 126–129
Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.02.120.
References [1] S. Yilmaz, E. Yildiz, B. Kavici, Int. J. Appl. Ceram. Technol. 14 (2017) 550–561. [2] W. Ma, J.M. Luther, H. Zheng, Y. Wu, A.P. Alivisatos, Nano Lett. 9 (2009) 1699– 1703. [3] A.C. Rastogi, N.R. Janardhana, Thin Solid Films 565 (2014) 285–292. [4] P. Jackson, R. Wuerz, D. Hariskos, E. Lotter, W. Witte, M. Powalla, Phys. Status Solidi RRL 10 (2016) 583–586. [5] B. Yang, L. Wang, J. Han, Y. Zhou, H. Song, S. Chen, J. Zhong, L. Lv, D. Niu, J. Tang, Chem. Mater. 26 (2014) 3135–3143. [6] J. van Embden, K. Latham, N.W. Duffy, Y. Tachibana, J. Am. Chem. Soc. 135 (2013) 11562–11571. [7] G. Chen, W. Wang, J. Zhao, W. Yang, S. Chen, Z. Huang, R. Jian, H. Ruan, J. Alloys Compd. 679 (2016) 218–224. [8] A.B. Kehoe, D.J. Temple, G.W. Watson, D.O. Scanlon, Phys. Chem. Chem. Phys. 15 (2013) 15477–15484. [9] P.K. Sarswat, M.L. Free, Int. J. Photoenergy 154694 (2013), https://doi.org/ 10.1155/2013/154694.
129
[10] W. Septina, S. Ikeda, Y. Iga, T. Harada, M. Matsumura, Thin Solid Films 550 (2014) 700–704. [11] Y. Fadhli, A. Rabhi, M. Kanzari, J. Mater. Sci. 25 (2014) 4767–4773. [12] K. Chen, J. Zhou, W. Chen, Q. Chen, P. Zhou, Y. Liu, Nanoscale 8 (2016) 5146– 5152. [13] S. Dekhil, H. Dahman, S. Rabaoui, N. Yaacoub, L. El Mir, J. Mater. Sci. Mater. Electron. 28 (2017) 11631–11635. [14] M. Han, J. Jia, W. Wang, J. Alloys Compd. 705 (2017) 365–1362. [15] D.J. Temple, A.B. Kehoe, J.P. Allen, G.W. Watson, D.O. Scanlon, J. Phys. Chem. C 116 (2012) 7334–7340. [16] J. Yan, Handbook of Clean Energy Systems, vol. 6, John Willey & Sons Ltd., United Kingdom, 2015. [17] R.S. Crandall, B.W. Faughnan, Appl. Phys. Lett. 26 (1975) 120–121. [18] Y. Xu, M.A.A. Schoonen, Am. Miner. 85 (2000) 543–556. [19] G.L. Xu, R. Amine, Y.F. Xu, J. Liu, J. Gim, T. Ma, Y. Ren, C.J. Sun, Y. Liu, X. Zhang, S. M. Heald, A. Solhy, I. Saadoune, W.L. Mattis, S.G. Sun, Z. Chen, K. Amine, Energy Environ. Sci. 10 (2017) 1677–1693. [20] K.S. Usha, R. Sivakumar, C. Sanjeeviraj, V. Sathe, V. Ganesan, T.Y. Wang, RSC Adv. 6 (2016) 79668–79680. [21] Y.X. Wang, B. Zhang, W. Lai, Y. Xu, S.L. Chou, H.-K. Liu, S.X. Dou, Adv. Energy Mater. (2017) 1602829. [22] V. Selvanathan, M.N.A. Halim, A.D. Azzahari, M. Rizwan, N. Shahabudin, R. Yahya, Ionics 24 (2018) 1955–1964. [23] X. Cao, Y. Yang, A. Li, Nanomaterials 8 (2018), 377(1–9). [24] S. Suehiro, K. Horita, M. Yuasa, T. Tanaka, K. Fujita, Y. Ishiwata, K. Shimanoe, T. Kida, Inorg. Chem. 54 (2015) 7840–7845.