Facile one-pot synthesis of polytypic CuGaS2 nanoplates
© Liu et al.; licensee Springer. 2013
Received: 31 October 2013
Accepted: 3 December 2013
Published: 13 December 2013
CuGaS2 (CGS) nanoplates were successfully synthesized by one-pot thermolysis of a mixture solution of CuCl, GaCl3, and 1-dodecanethiol in noncoordinating solvent 1-octadecene. Their morphology, crystalline phase, and composition were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. Crystalline structure analysis showed that the as-prepared CGS nanoplates were polytypic, in which the wurtzite phase was interfaced with zincblende domains. The growth process of CGS nanoplates was investigated. It was found that copper sulfide nanoplates were firstly formed and then the as-formed copper sulfide nanoplates gradually transformed to CGS nanoplates with proceeding of the reaction. The optical absorption of the as-synthesized CGS nanoplates was also measured and the direct optical bandgap was determined to be 2.24 eV.
I-III-VI2 semiconductor nanocrystals have received much research interest in recent years because they have low toxicity, high absorption coefficient, narrow bandgap, and tunable emission wavelength in the red to near-infrared region and have shown great potential in many fields such as low-cost solar cells, bio-imaging, light-emitting diodes, and visible-light photocatalyst [1–6]. These compounds have two different metal ions, complex structures, and flexible compositions, so it is a formidable challenge to synthesize their nanomaterials in a controlled manner [7–11].
As a member of the I-III-VI2 compounds, CuGaS2 (CGS) has a direct bandgap of approximately 2.49 eV for the bulk, and can be applied in green-light emission as well as in visible-light-induced photocatalysis [12, 13]. Generally, CGS crystallizes in tetragonal chalcopyrite phase at room temperature, and corresponding nanocrystals were previously synthesized by hydrothermal and solvothermal methods [14–16]. However, the products obtained using these methods are mostly in the form of large crystallites with a board size distribution. Recently, CGS nanocrystals with well-defined sizes and shapes, including quantum dots, tadpole-like nanocrystals, nanorods, and nanoplates, were prepared by several research groups [17–21]. For instance, Tung et al. synthesized chalcopyrite CGS nanorods by irradiating the precursor solution with intense X-rays . In particular, several research groups have synthesized CGS nanocrystals with metastable wurtzite structure which is a cation-disordered phase [18–21]. Wang et al. reported tadpole-like CGS nanocrystals with wurtzite phase by a hot-injection approach . Xiao et al. prepared wurtzite CGS nanorods by the reaction of copper(I) acetate, gallium(III) acetylacetonate, and 1-dodecanethiol (DT) in the solvent 1-octadecene at elevated temperature . However, two-dimensional CGS nanocrystals such as nanoplates are less reported up to now, despite the fact that Kluge et al. obtained CGS nanoplates by bulk thermolysis of complex single-source precursors .
In this work, we present a facile one-pot method to synthesize CGS nanoplates, wherein the mixed solution of CuCl, GaCl3, and 1-dodecanethiol was thermally decomposed in non-coordinating solvent 1-octadecene at elevated temperature. The crystal phase of the as-prepared CGS nanoplates was revealed to be wurtzite-zincblende polytypism. Their growth process and optical absorption were also investigated.
CuCl, DT, toluene, and anhydrous ethanol were of analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China); GaCl3 (99.999%) was purchased from Alfa Aesar (Wardhill, MA, USA); 1-octadecene (ODE, 90%) was purchased from Aldrich (St. Louis, MO, USA). All the reagents were used as received without any further purification.
Synthesis of CuGaS2 nanoplates
In a typical synthesis, 0.25 mmol CuCl, 0.25 mmol GaCl3, 0.5 mL DT, and 5 mL ODE were loaded into a 50-mL three-neck flask in a glovebox. The flask was then attached to a Schlenk line. Prior to heating, the mixture system was cycled between vacuum and nitrogen three times, heated to 90°C and then was vacuumed for 10 min. The flask was then filled with nitrogen and heated to 270°C at a rate of 12°C · min-1 with magnetic stirring. After the reaction was allowed to proceed for 40 min, the reaction flask was naturally cooled to room temperature. The resulting CuGaS2 nanocrystals were collected by centrifugation and were washed thoroughly with toluene and ethanol. Finally, the purified nanocrystals were dried under vacuum for characterization.
The samples were characterized by powder X-ray diffraction (XRD) on a Philips X'pert X-ray diffractometer (Amsterdam, The Netherlands) equipped with Cu Kα radiation (λ =1.5418 Å). Transmission electron microscope (TEM) images were taken with a Hitachi H-7650 microscope at an acceleration voltage of 100 kV. High-resolution transmission electron microscope (HRTEM) images were performed on a JEOL-2010 microscope (Akishima-shi, Japan). The scanning electron microscopy (SEM) images were taken using a Zeiss Supra 40 field emission scanning electron microscope (Oberkochen, Germany) operated at 5 kV. X-ray photoelectron spectra (XPS) were recorded on an ESCALab MKII X-ray photoelectron spectrometer (VG Scienta, Newburyport, MA, USA). The UV–vis absorption spectra were recorded on a Solid Spec-3700 spectrophotometer.
Results and discussion
In summary, we have developed a facile one-pot method to synthesize CuGaS2 nanoplates, wherein the mixed solution of CuCl, GaCl3, and n-dodecanethiol was thermally decomposed in non-coordinating solvent 1-octadecene at elevated temperature. The as-synthesized CuGaS2 nanoplates adopt a unique crystal structure of wurtzite-zincblende polytypism. In the growth process of CuGaS2 nanoplates, copper sulfides firstly formed, and then the as-formed copper sulfides were gradually phase-transformed to CGS nanoplates with proceeding of the reaction. The optical bandgap energy of the nanoplates is estimated to be approximately 2.24 eV. Our results will aid in the application of two-dimensional CuGaS2 nanoplates and the synthesis of other multicomponent sulfide nanomaterials.
This work was supported by the National Natural Science Foundation of China (No. 91022033, No. 21171158), and National Basic Research Program of China (2010CB934700).
- Zhong H, Bai Z, Zou B: Tuning the luminescence properties of colloidal I–III–VI semiconductor nanocrystals for optoelectronics and biotechnology applications. J Phys Chem Lett 2012, 3: 3167–3175. 10.1021/jz301345xView ArticleGoogle Scholar
- Aldakov D, Lefrancois A, Reiss P: Ternary and quaternary metal chalcogenide nanocrystals: synthesis, properties and applications. J Mater Chem C 2013, 1: 3756–3776. 10.1039/c3tc30273cView ArticleGoogle Scholar
- Panthani MG, Akhavan V, Goodfellow B, Schmidtke JP, Dunn L, Dodabalapur A, Barbara PF, Korgel BA: Synthesis of CuInS2, CuInSe2, and Cu(In x Ga1-x)Se2 (CIGS) nanocrystal “inks” for printable photovoltaics. J Am Chem Soc 2008, 130: 16770–16777. 10.1021/ja805845qView ArticleGoogle Scholar
- Tsuji I, Kato H, Kudo A: Photocatalytic hydrogen evolution on ZnS-CuInS2-AgInS2 solid solution photocatalysts with wide visible light absorption bands. Chem Mater 2006, 18: 1969–1975. 10.1021/cm0527017View ArticleGoogle Scholar
- Song WS, Yang H: Efficient white-light-emitting diodes fabricated from highly fluorescent copper indium sulfide core/shell quantum dots. Chem Mater 2012, 24: 1961–1967. 10.1021/cm300837zView ArticleGoogle Scholar
- Pons T, Pic E, Lequeux N, Cassette E, Bezdetnaya L, Guillemin F, Marchal F, Dubertret B: Cadmium-free CuInS2/ZnS quantum dots for sentinel lymph node imaging with reduced toxicity. ACS Nano 2010, 4: 2531–2538. 10.1021/nn901421vView ArticleGoogle Scholar
- Xie RG, Rutherford M, Peng XG: Formation of high-quality I-III-VI semiconductor nanocrystals by tuning relative reactivity of cationic precursors. J Am Chem Soc 2009, 131: 5691–5697. 10.1021/ja9005767View ArticleGoogle Scholar
- Pan DC, An LJ, Sun ZM, Hou W, Yang Y, Yang ZZ, Lu YF: Synthesis of Cu-In-S ternary nanocrystals with tunable structure and composition. J Am Chem Soc 2008, 130: 5620–5621. 10.1021/ja711027jView ArticleGoogle Scholar
- Zhong HZ, Zhou Y, Ye MF, He YJ, Ye JP, He C, Yang CH, Li YF: Controlled synthesis and optical properties of colloidal ternary chalcogenide CuInS2 nanocrystals. Chem Mater 2008, 20: 6434–6443. 10.1021/cm8006827View ArticleGoogle Scholar
- Wasim SM, Rincon C, Marin G, Delgado JM: On the band gap anomaly in I-III-VI2, I-III3-VI5, and I-III5-VI8 families of Cu ternaries. Appl Phys Lett 2000, 77: 94–96. 10.1063/1.126888View ArticleGoogle Scholar
- Liu ZP, Tang KB, Wang DK, Wang LL, Hao QY: Facile synthesis of AgInS2 hierarchical flowerlike nanoarchitectures composed of ultrathin nanowires. Nanoscale 2013, 5: 1570–1575. 10.1039/c2nr33219aView ArticleGoogle Scholar
- Prabukanthan P, Dhanasekaran R: Growth of CuGaS2 single crystals by chemical vapor transport and characterization. Cryst Growth Des 2007, 7: 618–623. 10.1021/cg060450oView ArticleGoogle Scholar
- Tabata M, Maeda K, Ishihara T, Minegishi T, Takata T, Domen K: Photocatalytic hydrogen evolution from water using copper gallium sulfide under visible-light irradiation. J Phys Chem C 2010, 114: 11215–11220. 10.1021/jp103158fView ArticleGoogle Scholar
- Lu QY, Hu JQ, Tang KB, Qian YT, Zhou GE, Liu XM: Synthesis of nanocrystalline CuMS2 (M = In or Ga) through a solvothermal process. Inorg Chem 2000, 39: 1606–1607. 10.1021/ic9911365View ArticleGoogle Scholar
- Hu JQ, Deng B, Wang CR, Tang KB, Qian YT: Hydrothermal preparation of CuGaS2 crystallites with different morphologies. Solid State Commun 2002, 121: 493–496. 10.1016/S0038-1098(01)00516-6View ArticleGoogle Scholar
- Zhong J, Zhao Y, Yang H, Wang J, Liang X, Xiang W: Sphere-like CuGaS2 nanoparticles synthesized by a simple biomolecule-assisted solvothermal route. Appl Surf Sci 2011, 257: 10188–10194. 10.1016/j.apsusc.2011.07.016View ArticleGoogle Scholar
- Tung HT, Hwu Y, Chen IG, Tsai MG, Song JM, Kempson IM, Margaritondo G: Fabrication of single crystal CuGaS2 nanorods by X-ray irradiation. Chem Commun 2011, 47: 9152–9154. 10.1039/c1cc12031jView ArticleGoogle Scholar
- Wang Y, Zhang X, Bao N, Lin B, Gupta A: Synthesis of shape-controlled monodisperse wurtzite CuIn x Ga1–xS2 semiconductor nanocrystals with tunable band gap. J Am Chem Soc 2011, 133: 11072–11075. 10.1021/ja203933eView ArticleGoogle Scholar
- Xiao N, Zhu L, Wang K, Dai Q, Wang Y, Li S, Sui Y, Ma Y, Liu J, Liu B, Zou G, Zou B: Synthesis and high-pressure transformation of metastable wurtzite-structured CuGaS2 nanocrystals. Nanoscale 2012, 4: 7443–7447. 10.1039/c2nr31629cView ArticleGoogle Scholar
- Regulacio MD, Ye C, Lim SH, Zheng Y, Xu QH, Han MY: Facile noninjection synthesis and photocatalytic properties of wurtzite-phase CuGaS2 nanocrystals with elongated morphologies. CrystEngComm 2013, 15: 5214–5217. 10.1039/c3ce40352aView ArticleGoogle Scholar
- Kluge O, Friedrich D, Wagner G, Krautscheid H: New organometallic single-source precursors for CuGaS2 - polytypism in gallite nanocrystals obtained by thermolysis. Dalton Trans 2012, 41: 8635–8642. 10.1039/c2dt30904aView ArticleGoogle Scholar
- Lutterotti L, Chateigner D, Ferrari S, Ricote J: Texture, residual stress and structural analysis of thin films using a combined X-ray analysis. Thin Solid Films 2004, 450: 34–41. 10.1016/j.tsf.2003.10.150View ArticleGoogle Scholar
- Liu ZP, Wang LL, Hao QY, Wang DK, Tang KB, Zuo M, Yang Q: Facile synthesis and characterization of CuInS2 nanocrystals with different structures and shapes. CrystEngComm 2013, 15: 7192–7198. 10.1039/c3ce40631hView ArticleGoogle Scholar
- Li Q, Zou C, Zhai L, Zhang L, Yang Y, Chen X, Huang S: Synthesis of wurtzite CuInS2 nanowires by Ag2S-catalyzed growth. CrystEngComm 2013, 15: 1806–1813. 10.1039/c2ce26944aView ArticleGoogle Scholar
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