Ultrathin β-In2S3 Nanobelts: Shape-Controlled Synthesis and Optical and Photocatalytic Properties Weimin Du,†,‡ Jun Zhu,† Shixiong Li,† and Xuefeng Qian*,† School of Chemistry and Chemical Technology, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong UniVersity, Shanghai 200240, P. R. China, and Department of Chemistry, Anyang Normal UniVersity, Anyang 455000, P. R. China
CRYSTAL GROWTH & DESIGN 2008 VOL. 8, NO. 7 2130–2136
ReceiVed September 22, 2007; ReVised Manuscript ReceiVed March 21, 2008
ABSTRACT: Ultrathin β-In2S3 nanobelts have been successfully synthesized via a facile improved solvothermal route. The crystal phase, morphology, crystal lattice and composition of as-prepared products were characterized by XRD, FESEM, TEM, HRTEM and EDS, respectively. Results revealed that the as-synthesized β-In2S3 nanobelts are in cubic structure 50-90 nm in width, 13 ( 2 nm in thickness, and the overall length even up to several microns. A possible shape evolution and crystal growth mechanism was suggested, and the formation of β-In2S3 nanobelts resulted from the preferential growth along the 〈220〉 direction and enclosed by {202} and {022j} crystallographic facets. The strong quantum confinement effect in UV-vis spectra and the blue emission in photoluminescence spectra imply the as-synthesized β-In2S3 nanobelts as a promising candidate for phosphor in display devices. Furthermore, the good photocatalytic effects indicate that these β-In2S3 nanobelts are likely to be applied as a new kind of photocatalyst in the future.
1. Introduction One-dimensional nanostructures (e.g., rods, wires, tubes, belts or ribbons) have attracted much research attention due to their novel physicochemical properties, and potential applications in optics, electronics, catalysis, piezoelectricity and sensor, etc.1–3 Furthermore, these nanostructures represent ideal systems for dimension-dependent optical, electric and mechanical properties, and are expected to play an important role as building blocks in nanodevices, e.g. light emitting diodes, solar cells, lasers and biological labels, etc.4–6 Since the first report of semiconductor oxide nanobelts by Wang et al.,7 planar nanostructures of functional nanobelts or nanoribbons have been intensively studied because of their dimensionally confined electron transport phenomena.8–10 To date, the reported beltlike or ribbonlike functional nanomaterials are mainly in the following several groups, i.e., elemental crystals (Au, Zn and Te, etc),11–13 semiconductor oxides (ZnO, SnO2, In2O3, CdO,7,14 MoO3 and Cr2O3, etc.15,16), binary chalcogenides (ZnS, Sb2S3, Sb2Se3 and CdSe, etc),17–19 polynary compounds (ZnIn2S4, chromate and molybdate, etc),20–22 nitride (AlN etc.)23 and other heteromaterials (ZnO/ZnS, SiGe/Si and SiGe/Si/Cr, etc.).24,25 However, the preparation and property studies of beltlike or ribbonlike indium sulfide have been less reported until now. As one kind of mid band gap semiconductors, indium sulfide has two kinds of compositional forms [i.e., InS (Eg ) 2.44 eV) and In2S3 (Eg ) 2.07 eV)].26,27 Furthermore, In2S3 exists in three different structure forms: i.e., R-In2S3 (defect cubic structure),28 β-In2S3 (defect spinel structure obtained in either the expected cubic or tetragonal form),29 and γ- In2S3 (layered hexagonal structure).28,30 During the past decades, considerable attention has been focused on In2S3 because of its defect structure and corresponding optical, acoustic and electronic properties.31,32 Meanwhile, it has inspired applied research in the preparation of green or red phosphors for color televisions, dry cells and heterojunction in photovoltaic cell, etc.33,34 To date, many efforts * To whom correspondence should be addressed. E-mail:
[email protected]. Phone: +86-21-5474-3262. Fax: +86-21-5474-1297. † Shanghai Jiao Tong University. ‡ Anyang Normal University.
have been focused on it, and β-In2S3 nanomaterials (in tetragonal or cubic form) with various shapes have been fabricated, e.g., urchinlike microspheres,35 dendrites,36 nanofibers,37 halfshells,38 hollow microspheres consisting of nanoflakes,39,40 etc. However, compared with the significant progress in onedimensional II-VI and III-V semiconductor nanomaterials, the morphologies of the reported In2S3 were usually ill-controlled except for some recent work including hexagonal nanoplates synthesized by organic solution pyrolysis route,41 nanorods obtained by single-molecular precursor method27 and nanowires formed via a CVD method using indium metal and hydrogen sulfide as precursors.42 To the best of our knowledge, the preparation and property studies of beltlike or ribbonlike In2S3 nanomaterials were not reported up to now. Therefore, there still remains a big challenge on the shape-controlled synthesis of In2S3 nanomaterials. Moreover, the corresponding performance investigations might provide some novel approaches to the development of In2S3 for nanodevice applications. In this study, ultrathin cubic β-In2S3 nanobelts have been successfully synthesized for the first time via the improved pyridine solvothermal process with hexadecylamine as capping ligand. A possible growth mechanism was proposed, and its optical properties and photocatalytic effects on dye degradation were also investigated.
2. Experimental Section Synthesis of β-In2S3 nanobelts. In a typical procedure to prepare β-In2S3 nanobelts, 0.4 mmol indium chloride tetrahydrate (AR) and 3.2 mmol hexadecylamine (90% mass fraction) were added to 38.5 mL pyridine (AR) in a Teflon-lined stainless steel autoclave with a capacity of 50 mL at room temperature, and stirred for 1 h. Then 0.5 mL double-distilled water and 1 mL carbon disulfide (AR) were added. After the autoclave was sealed and maintained at 160 °C for 24 h in a preheated oven, it was taken out and cooled to room temperature naturally. Yellow products were collected after being repeatedly washed with absolute ethanol and dried in a vacuum oven. In order to explore the influences of reaction parameters on the morphologies of β-In2S3 nanobelts, controlled experiments were designed, e.g., reaction time, temperature, surfactants, and solvent, etc. Detailed reaction conditions and the corresponding results are summarized in Table 1.
10.1021/cg7009258 CCC: $40.75 2008 American Chemical Society Published on Web 06/12/2008
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sample
figure no.
1 2 3c 4 5 6 7 8 9
3b 3c 1a, 1b, 3d 3e 3f S2ad S2bd
precursor solutiona
surfactantb
solvent
T/°C
t/h
morphology
standard standard standard standard standard standard standard standard standard
HDA, HDA HDA HDA HDA ODA OA HDA HDA
pyridine pyridine pyridine pyridine pyridine pyridine pyridine THFb toluene
160 160 160 160 120 160 160 160 160
2 6 24 48 24 24 24 24 24
nanosheets nanosheets + nanobelts nanobelts bulky pieces urchinlike microspheres similar to sample 3 similar to sample 3 urchinlike microspheres nanofibers
a “Standard precursor solution” refers to a 38.5 mL organic solvent which contained 0.4 mmol of InCl3 · 4H2O, 3.2 mmol surfactant, 0.5 mL of H2O and 1 mL of CS2. b HDA: hexadecylamine. OA: olecylamine. ODA: octadecylamine. THF: tetrahydrofuran. c The data in this row refers to the typical experiment parameters. d See Supporting Information.
Characterization Techniques. Crystal phase of the as-prepared products was characterized on a Rigaku D/Max-2200 diffractometer equipped with a rotating anode and a Cu KR radiation source (λ ) 0.15418 nm). The morphology, crystal lattice and composition of the obtained products were characterized by transmission electron microscopy (TEM, JEOL JEM-100CXII, with an accelerating voltage of 100 kV; and JEM-2010, with an accelerating voltage of 200 kV), highresolution transmission electron microscopy (HRTEM, JEOL JEM2100F, with an accelerating voltage of 200 kV), field-emission scanning electron microscopy (FESEM, FEI SIRION-200, with an accelerating voltage of 5 kV), and energy-dispersive X-ray analysis (EDS, JEOL JSM-6460, with an accelerating voltage of 5 kV). Optical Properties and Photocatalytic Performance Measurements. (1) In order to investigate the optical properties of the obtained products, β-In2S3 nanobelts (4 mg) were ultrasonically dispersed in absolute ethanol (20 mL), and then they were carried by UV-vis absorption spectra and photoluminescence spectra measurement. The UV-vis absorption spectra were obtained at room temperature on Perkin-Elmer Lambda 20 UV-vis spectrometer. Room temperature photoluminescence spectra were recorded on Perkin-Elmer LS-50B luminescence spectrometer. (2) The photocatalytic activity experiments of β-In2S3 nanobelts for the decomposition of methylene blue were performed at ambient temperature. β-In2S3 nanobelts used as catalyst (2.5 mg) were ultrasonically dispersed in absolute ethanol (22.5 mL). Then 2.5 mL (1 × 10-4 mol/L) of methylene blue ethanol solution was added into the above β-In2S3 nanobelt suspensions in a 50 mL quartz conical flask. The final concentration of methylene blue was achieved as 1 × 10-5 mol/L. The stoppered flask was placed 20 cm away from a high-pressure mercury lamp with the wavelength concentrated at ∼250 nm and irradiated for different times at room temperature. The irradiated mixed solution was periodically extracted with a pipet from the 50 mL quartz conical flask and immediately tested for UV-vis absorption spectra. As references, pure methylene blue ethanol solution (1 × 10-5 mol/L) was also irradiated under the same experimental condition for different times.
3. Results and Discussion Morphological, Crystal Phase and Compositional Characterizations of β-In2S3 Nanobelts. When the reaction was carried out at 160 °C for 24 h, larger amounts of 1D β-In2S3 nanomaterials were obtained (Figure 1a). Careful observations reveal that the obtained 1D β-In2S3 nanomaterials are, in fact, ultrathin nanobelts. The obvious creasing or curling places (highlighted by white arrows) in the larger magnification TEM image (Figure 1b) sufficiently evidence that the as-synthesized products are in beltlike shape rather than in rodlike or wirelike shape. On the other hand, these curling or creasing places also imply that the obtained nanobelts are flexible, and it might lead to the obtained nanobelts in a larger distributed size range. These TEM images clearly reveal that the as-synthesized nanobelts are in 50-90 nm in width and 13 ( 2 nm in thickness, and the overall length up to several microns. The regular hexagonal diffraction spots shown in the SAED pattern of a random nanobelt indicate that these nanobelts are crystalline in nature.
The corresponding XRD pattern (Figure 1c) evidences that all the diffraction peaks can be indexed to the cubic phase of β-In2S3 structure (JCPDS No. 65-0459) with the Fd3jm space group and a primitive cubic unit cell a ) 10.774 Å. No other impurities, e.g., In2O3, InS or In(OH)3, are detected, indicating the pure phase of the obtained products. The lower intensity and broader width of the diffraction peaks in XRD pattern should be related with the smaller sizes of the obtained β-In2S3 nanobelts. Compared with the standard XRD pattern, the intensity of the (440) peak is strengthened, implying the preferential growth orientation of cubic β-In2S3 nanobelts. EDS spectrum (Figure 1d) further demonstrates that the atom content ratio of In and S in products is 2:2.99, agreeing well with its stoichiometric proportion. Similar EDS profiles for other samples prepared at different temperature suggest that reaction temperature does not have great effect on the chemical composition of the final products. HRTEM Analysis of β-In2S3 Nanobelts. To understand the growth direction of β-In2S3 nanobelts, HRTEM analysis (Figure 2) was carried out on a single β-In2S3 nanobelt. The typical HRTEM image of a nanobelt (Figure 2b) was obtained with the incident electron beam perpendicular to its wide surface. The 1.91 Å lattice spacing corresponding to the (440) interplanar distance of cubic β-In2S3 indicates the preferential growth along the [220] direction. The corresponding hexagonal symmetrical diffraction pattern in Figure 2c further demonstrates that the obtained β-In2S3 nanobelt is in single crystalline structure with preferential growth along the 〈220〉 direction and enclosed by {202} and {022j} crystallographic facets.39 By rotating the sample in certain angle, more clearly continuous lattice fringes separated by 3.11 Å in Figure 2d correspond to the (222) plane of cubic β-In2S3, demonstrating its growth direction on other way. In addition, the vacancy defects highlighted by white circles in Figure 2b and Figure 2d also agree well with its defect structure. Influences of Different Reaction Parameters on β-In2S3 Nanobelts. In general, the reaction environment has a great effect on the phase and/or morphology of the final products. Our experimental results indicated that alkyl amines do play an important role on the formation of β-In2S3 nanobelts. Few products were obtained without the existence of hexadecylamine in the pyridine system, while substituting hexadecylamine with octadecylamine or oleylamine allowed the formation of similar β-In2S3 beltlike nanostructures. It is well-known that pyridine is a kind of stronger coordinating solvents and can coordinate with In3+ to form In2Cl4 · 4L (L ) pyridine) complex compound.43 The formed complex compound would severely suppress the combining reaction between In3+ and S2-. Therefore, no In2S3 products could be obtained without the existence of alkyl amines. If alkyl amines, e.g. hexadecylamine,
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Figure 1. (a, b) Typical TEM images, (c) XRD pattern and (d) EDS pattern of β-In2S3 nanobelts synthesized in pyridine solution at 160 °C for 24 h; the inset in (b) shows the selected area electron diffraction (SAED) pattern obtained from a random β-In2S3 nanobelt.
Figure 2. (a) Local amplified area of typical cubic β-In2S3 nanobelts; (b, d) the HRTEM images and (c) the SAED pattern of the circled zone in panel a, respectively.
existed in the system, it would react with CS2 and produce dithiocarbamate anion. Subsequently, In3+ would preferentially combine with the bidentate ligand, dithiocarbamate anion, to form In(S2CNHR)3 rather than with monodentate ligand (pyridine) to form In2Cl4 · 4L (L ) pyridine) complex compound.44,45 The whole reaction can be expressed as the following equation:
In3+ + 6C16H33NH2 + 3CS2 f In(S2CNHC16H33)3 + 3C16H33NH3+ In succession, β-In2S3 would be formed by decomposing the new-formed In(S2CNHC16H33)3 under the high-temperature and high-pressure solvothermal conditions. In some ways, this decomposing process of In(S2CNHR)3 is similar to the orga-
nometallic single source precursor approach: e.g., β-In2S3 nanorods obtained using [Et2In(S2CNMenBu)] as a single-source precursor27 or group 12 sulfides formed by thermolysis of [M(S2CNR2)2] precursors in high-boiling solvent.46–48 In order to further demonstrate the formation process of 1D β-In2S3 nanobelts, XRD patterns and FESEM images of the products synthesized at 160 °C for different reaction time are presented in Figure 3. It could be found from XRD patterns (Figure 3a) that the intensity of the (440) peak relative to other peaks gradually increase along with the reaction time prolonging, and the intensity ratio of I(440)/I(311) is increased from 0.96 to 1.19 and 1.52 corresponding to β-In2S3 obtained for 2, 6 and 24 h, respectively. This observation implied that the crystal growth of β-In2S3 along the 〈440〉 direction is gradually strengthened. The corresponding FESEM images further evidence the shape evolution process of β-In2S3 nanobelts. From Figure 3b to Figure 3e, we could find that β-In2S3 nanosheets 500-800 nm in diameter and 13 ( 2 nm in thickness were the exclusive products when the reaction was carried out for 2 h (Figure 3b), and then beltlike nanostructures similar to those in Figure 1a gradually appeared besides nanosheets with the reaction time prolonging to 6 h (Figure 3c). Finally, large amounts of beltlike products 50-90 nm in width, 13 ( 2 nm in thickness, and the overall length even up to several microns were obtained when the reaction time was up to 24 h. This result (Figure 3d) is also consistent with the observation in Figure 1. However, if the reaction solution was solvothermally treated for 48 h, bulky β-In2S3 pieces were the exclusive products (Figure 3e). Additionally, if the reaction solution was treated at 120 °C, β-In2S3 microspheres built by nanosheets were the exclusive products with few beltlike products (Figure 3f) which was similar to the products obtained in ref 39. This phenomenon
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Figure 3. (a) XRD patterns of β-In2S3 synthesized at 160 °C for different times; (b-e) FESEM images of β-In2S3 synthesized at 160 °C for (b) 2 h, (c) 6 h, (d) 24 h and (e) 48 h, respectively; (f) FESEM images of β-In2S3 synthesized at 120 °C for 24 h.
indicated that β-In2S3 nanosheets did not evolve into beltlike products but aggregated into microspheres at lower temperature. Formation Mechanism of β-In2S3 Nanobelts. Generally, the final shapes of nanocrystals were dominated by the inherent crystal structure during the initial nucleation stage, and the external factors on the subsequent growth stage, e.g., temperature, time, surfactants, and solvent, etc.49 Therefore, the final crystal shape is the cooperative result of internal crystal factor and external reaction factors. According to Gibbs-Wulff’s theorem,50 higher surface tension faces tend to grow along its normal direction and eventually disappear from the final appearance, and a sequence of γ{111} < γ{100} < γ{110} can be easily obtained for the cubic phase in light of this theorem.51 Therefore, when newly formed In(S2CNHC16H33)3 complex compounds took place thermolysis reaction in present synthetic system with hexadecylamine as the capping regent, a kind of platelike nuclei bounded by alternant {100} and {111} facets and a (111) base was formed for cubic β-In2S3. Similar platelike nuclei also appeared in the formation process of cubic gold
tetrapods52 or cubic silver nanoplatelets53 (see Supporting Information Figure S1). During the subsequent growth process, larger β-In2S3 nanosheets were rapidly formed in less than 2 h because of its platelike nuclei (Figure 3b). However, rapid growth would lead to more defects and lower crystallinity for the obtained products, and also lead to the insufficient cap of hexadecylamine on the surfaces of β-In2S3. Therefore, the dissolution and surfactant/solvent-directed recrystallization happened along with the reaction time. Meanwhile, more hexadecylamine molecules might further cap on the surfaces of β-In2S3 and increase the difference of surface energy among different crystal facets. As a result, the undissolved or new-born β-In2S3 nanosheets served as the seeds and preferentially grew along 〈110〉 under the direction of surfactant and solvent due to the higher surface tension of {110} faces, and finally formed β-In2S3 nanobelts. The existence of smaller amount of nanosheets in the resulting product (Figure 3d) and the obtained microspheres built by nanosheets at 120 °C (Figure 3e) also support this growth process. To some extent, this dissolution and surfactant/
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Figure 4. Schematic depiction of the proposed growth mechanism for β-In2S3 nanobelts (a), microspheres built by nanosheets (b) and bulky pieces (c).
solvent-directed recrystallization process is similar to the selfseeding growth of LiMn2O4 nanobelts,54 or seed-mediated, surfactant-directed growth of gold nanorods.55 The corresponding growth process was illustrated in Figure 4; whereas longer reaction time would lead to the ill-controlled growth of β-In2S3 and result in the formation of bulky pieces. In addition, solvent also had important influences on the morphology of β-In2S3 nanobelts. Aggregated nanofibers were the exclusive products and no beltlike or ribbonlike nanostructures could be obtained in other reaction medium, e.g., THF or toluene, which is similar to the reported products in ref 37 (see Supporting Information Figure S2). Optical Properties of β-In2S3 Nanobelts. It is well-known that the optical and electronic properties of semiconductor would be obviously changed when the size of a particle approaches its exciton Bohr diameter.56 The excitonic radius of In2S3 is calculated to be 33.8 nm.57 So the obtained β-In2S3 nanobelts would be expected to exhibit pronounced size quantization effects. It could be found from Figure 5a that β-In2S3 nanobelts have the steplike absorption band between 260-430 nm which is very consistent with the characteristic UV-vis absorption shape of bulk In2S3 because of the valence-to-conduction-band transition.36,41,57 In addition, this steplike absorption is also possibly relative with its beltlike morphology, simultaneously possessing the properties of 1D and 2D nanomaterials in which the two-dimensional crystals confined along a specific direction and 1D crystals confined along two directions have the staircase and sawtoothlike density of states (DOS), respectively.58 On the other hand, the band gap (Eg) for bulk In2S3 is reported as 2.07 eV with the corresponding UV-vis band around 598 nm.27 Considering the onset position in the UV-visible spectra (∼430 nm) of β-In2S3 nanobelts (with band gap 2.89 eV), the larger blue shift implies the existence of the strong quantum confinement of the excitonic transition in the obtained products. Bulk In2S3 does not present any luminescence properties because of its virtually nonluminescent character. However, if the as-prepared β-In2S3 nanobelts in this study were excited by ultraviolet light (270 nm wavelength) at room temperature, blue light at ∼380 nm wavelength was obtained (line 1 in Figure 5b). It means that stronger electronic transition at particular wavelength exists in our samples. This result further demonstrated the strong quantum confinement effects existing in the obtained In2S3 because of the special size and morphology. Similar luminescent character of In2S3 in nanoscale is also reported by Xiong et al.59 and Zhu et al.37 Meanwhile, the ethanol solution of pyridine was excited by the same wavelength
Figure 5. (a) Room-temperature UV-vis absorption spectra of β-In2S3 nanobelts synthesized at 160 °C. (b) Room-temperature photoluminescence spectra of (1) β -In2S3 nanobelts (sample 3) and (2) pyridine in absolute ethanol excited at 270 nm.
in the present study and no luminescence peaks further eliminated the possible influence of reaction solvent (line 2 in Figure 5b). The peak at 540 nm could be attributed to the second order peak of the excitation frequency at 270 nm. This blue emission enables theses nanobelts as a promising candidate for phosphor in display devices. Photocatalytic Performance of β-In2S3 Nanobelts. Methylene blue is one kind of organic dye, and often used as model pollutant to study the photocatalytic activity or performance of nanomaterials.62 The maximal absorptive energy of methylene blue is at 655 nm (see Supporting Information Figure S3). In this study, methylene blue was chosen as object for the first time to investigate the photocatalytic degradation properties of the as-prepared β-In2S3 nanobelts with the help of UV-vis absorption spectra. From Figure 6a, it is found that the
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preferentially grown along the 〈220〉 direction and enclosed by {202} and {022j} crystallographic facets. Room-temperature UV-vis absorption spectra reveal that β-In2S3 nanobelts have strong quantum confinement effect and the blue emission in photoluminescence spectra enables it as a promising candidate for phosphor in display devices. The good photocatalytic performance on methylene blue shows that these β-In2S3 nanobelts are likely to be a new kind of photocatalyst in the future. Acknowledgment. The work described here was financially supported by the National Science Foundation of China (No. 20671061), National Basic Research Program of China (2007CB209705) and the Program for New Century Excellent Talents of Education Ministry of China. Supporting Information Available: The schematic illustration of the platelike nuclei of β-In2S3, TEM images of In2S3 synthesized in different solvents and the absorption spectrum of methylene blue at room temperature. This material is available free of charge via the Internet at http://pubs.acs.org.
References
Figure 6. (a) Room-temperature UV-vis absorption spectra of methylene blue in β-In2S3 nanobelt suspensions irradiated for different times. (b) Photocatalytic degradation curve of methylene blue under different conditions: (1) no catalyst; (2) with β-In2S3 nanobelts as photocatalyst (sample 3).
absorptive intensity of methylene blue at 655 nm gradually decreases with prolonging the irradiation time when the mixed solution of methylene blue and β-In2S3 nanobelts was exposed to UV irradiation from high-pressure mercury lamp at room temperature. This result indicated that methylene blue underwent obvious degradation behavior under the catalysis of β-In2S3 nanobelts. If the degradation ratio is defined as the ratio between the decreased absorptive intensity and that of the initial methylene blue solution, the degradation ratio of methylene blue is about 62.1% when the mixed solution was irradiated for 8 h (line 2 in Figure 6b). However, if there are no β-In2S3 nanobelts as the photocatalyst and the other conditions are kept unchanged, the degradation ratio of methylene blue is only 3.41% with the same irradiating time (line 1 in Figure 6b), indicating that methylene blue is stable in ethanol solution even with the strong irradiation of a high-pressure mercury lamp. These results revealed that the as-synthesized β-In2S3 nanobelts have good photocatalytic activity for methylene blue and are likely to be a kind of good photocatalyst in the applied field. As to the photocatalytic mechanism of β-In2S3 nanobelts on methylene blue, we are apt to that the electron injection from photoexcited methylene blue molecules to β-In2S3 leads to reduction of molecular oxygen and oxidative decomposition of the electrondeficient methylene blue.61,62 However, because the research of β-In2S3 photocatalytic performances was not reported in previous works, the catalytic mechanism of β-In2S3 was not fully clear until now. Our further work will deeply investigate the detailed catalytic mechanism of β-In2S3 nanobelts.
4. Conclusions In summary, ultrathin β-In2S3 nanobelts in cubic structure have been synthesized via a facile pyridine solvothermal process with simple inorganic compounds as precursors. HRTEM analysis and the formation process indicate these nanobelts are
(1) Xia, Y. N.; Yang, P. D.; Sun, Y. G.; Wu, Y. Y.; Mayers, B.; Gates, B.; Yin, Y. D.; Kim, F.; Yan, Y. Q. AdV. Mater. 2003, 15, 353. (2) Hu, J. T.; Li, L. S.; Yang, W. D.; Manna, L.; Wang, L. W.; Alivisatos, A. P. Science 2001, 292, 2060. (3) Agarwal, R.; Barrelet, C. J.; Lieber, C. M. Nano Lett. 2005, 5, 917. (4) Friedman, R. S.; McAlpine, M. C.; Ricketts, D. S.; Ham, D.; Lieber, C. M. Nature 2005, 434, 1085. (5) Hong, B. H.; Bae, S. C.; Lee, C. W.; Jeong, S.; Kim, K. S. Science 2001, 294, 348. (6) Huynh, W. U.; Dittmer, J. J.; Alivisatos, A. P. Science 2002, 295, 2425. (7) Pan, Z. W.; Dai, Z. R.; Wang, Z. L. Science 2001, 291, 1947. (8) Wang, Z. L. Nanowires and Nanobelts, Vol. I: Metal and Semiconductor, Nanowires; Kluwer Academic Publisher: New York, 2003. (9) Wang, Z. L. Nanowires and Nanobelts, Vol. II: Nanowires and Nanobelts of Functional Materials; Kluwer Academic Publisher: New York, 2003. (10) Shi, W. S.; Peng, H. Y.; Wang, N.; Li, C. P.; Xu, L.; Lee, C. S.; Kalish, R.; Lee, S. T. J. Am. Chem. Soc. 2001, 123, 11095. (11) Zhang, J. L.; Du, J. M.; Han, B. X.; Liu, Z. M.; Jiang, T.; Zhang, Z. F. Angew. Chem., Int. Ed. 2006, 45, 1116. (12) Wang, Y.; Zhang, L.; Meng, G.; Liang, C.; Wang, G.; Sun, S. Chem. Commun. 2001, 2632. (13) He, Z. B.; Yu, S. H. J. Phys. Chem. B 2005, 109, 22740. (14) Duan, J. H.; Yang, S. G.; Liu, H. W.; Gong, J. F.; Huang, H. B.; Zhao, X. N.; Zhang, R.; Du, Y. W. J. Am. Chem. Soc. 2005, 127, 6180. (15) Li, X. L.; Li, Y. D. Chem. Eur. J. 2003, 9, 2726. (16) Han, W. Q.; Wu, L. J.; Stein, A.; Zhu, Y. M.; Misewich, J.; Warren, J. Angew. Chem., Int. Ed. 2006, 45, 6554. (17) Hao, Y. F.; Meng, G. W.; Wang, Z. L.; Ye, C. H.; Zhang, L. D. Nano Lett. 2006, 6, 1650. (18) Yu, Y.; Wang, R. H.; Chen, Q.; Peng, L. M. J. Phys.Chem. B 2006, 110, 13415. (19) Joo, J.; Son, J. S.; Kwon, S. G.; Yu, J. H.; Hyeon, T. J. Am. Chem. Soc. 2006, 128, 5632. (20) Gou, X. L.; Cheng, F. Y.; Shi, Y. H.; Zhang, L.; Peng, S. J.; Chen, J.; Shen, P. W. J. Am. Chem. Soc. 2006, 128, 7222. (21) Liang, J. H.; Peng, C.; Wang, X.; Zheng, X.; Wang, R. J.; Qiu, X. P. P.; Nan, C. W.; Li, Y. D. Inorg. Chem. 2005, 44, 9405. (22) Shi, H. T.; Qi, L. M.; Ma, J. M.; Cheng, H. M.; Zhu, B. Y. AdV. Mater. 2003, 15, 1647. (23) Wu, Q.; Hu, Z.; Wang, X. Z.; Chen, Y.; Lu, Y. N. J. Phys. Chem. B 2003, 107, 9726. (24) Shen, G. Z.; Chen, D.; Lee, C. J. J. Phys. Chem. B 2006, 110, 15689. (25) Zhang, L.; Ruh, E.; Grutzmacher, D.; Dong, L. X.; Bell, D. J.; Nelson, B. J.; Schonenberger, C. Nano Lett. 2006, 6, 1311. (26) Nishino, T.; Hamakawa, Y. Jpn. J. Appl. Phys. 1977, 16, 1291. (27) Afzaal, M.; Malik, M. A.; O’Brien, P. Chem. Comm. 2004, 334. (28) Diehl, R.; Nitsche, R. J. Cryst. Growth 1975, 28, 306. (29) Herrasti, P.; Fatas, E. J. Mater. Sci. 1990, 25, 3535.
2136 Crystal Growth & Design, Vol. 8, No. 7, 2008 (30) Yu, S. H.; Shu, L.; Wu, Y. S.; Yang, J.; Xie, Y.; Qian, Y. T. J. Am. Ceram. Soc. 1999, 82, 457. (31) Kim, W. T.; Kim, C. D. J. Appl. Phys. 1986, 60, 2631. (32) Amlouk, M.; Ben Said, M. A.; Kamoun, N.; Belgacem, S.; Brunet, N.; Barjon, D. Jpn. J. Appl. Phys., Part 1 1999, 38, 26. (33) Dalas, E.; Kobotiatis, L. J. Mater. Sci. 1993, 28, 6595. (34) Dalas, E.; Sakkopoulos, S. J. Mater. Sci. 1993, 28, 5456. (35) Chen, X. Y.; Zhang, Z. J.; Zhang, X. F.; Liu, J. W.; Qian, Y. T. Chem. Phys. Lett. 2005, 407, 482. (36) Xiong, Y. J.; Xie, Y.; Du, G.; Tian, X. B.; Qian, Y. T. J. Solid State Chem. 2002, 166, 336. (37) Zhu, X. Y.; Ma, J. F.; Wang, Y. G.; Tao, J. T.; Zhou, J.; Zhao, Z. Q.; Xie, L. J.; Tian, H. Mater. Res. Bull. 2006, 41, 1584. (38) Gao, P.; Xie, Y.; Chen, S. W.; Zhou, M. Z. Nanotechnology 2006, 17, 320. (39) Liu, Y.; Xu, H. Y.; Qian, Y. T. Cryst. Growth Des. 2006, 6, 1304. (40) Liu, Y.; Zhang, M.; Gao, Y. Q.; Zhang, R.; Qian, Y. T. Mater. Chem. Phys. 2007, 101, 362. (41) Park, K. H.; Jang, K.; Son, S. U. Angew. Chem., Int. Ed. 2006, 45, 4608. (42) Rao, R.; Chandrasekaran, H.; Gubbala, S.; Sunkara, M.; Daraio, C.; Jin, S.; Rao, A. J. Electron. Mater. 2006, 35, 941. (43) Sinclair, I.; Worrall, I. J. Can. J. Chem. 1982, 60, 695. (44) O’Brien, P.; Otway, D. J.; Walsh, J. R. Thin Solid Films 1998, 315, 57. (45) van Poppel, L. H.; Groy, T. L.; Caudle, M. T. Inorg. Chem. 2004, 43, 3180.
Du et al. (46) Malik, M. A.; Revaprasadu, N.; O’Brien, P. Chem. Mater. 2001, 13, 913. (47) Trindade, T.; O’Brien, P.; Zhang, X. m. Chem. Mater. 1997, 9, 523. (48) Nair, P. S.; Revaprasadu, N.; Radhakrishnan, T.; Kolawole, G. A. J. Mater. Chem. 2001, 11, 1555. (49) Lee, S. M.; Cho, S. N.; Cheon, J. AdV. Mater. 2003, 15, 441. (50) Wulff, G.; Zeitschrift, F. Kristallografiya 1901, 34, 449. (51) Wang, Z. L. J. Phys. Chem. B 2000, 104, 1153. (52) Chen, S.; Wang, Z. L.; Ballato, J.; Foulger, S. H.; Carroll, D. L. J. Am. Chem. Soc. 2003, 125, 16186. (53) Chen, S.; Carroll, D. L. Nano Lett. 2002, 2, 1003. (54) Zhang, L. Z.; Yu, J. C.; Xu, A. W.; Li, Q.; Kwong, K. W.; Wu, L. Chem. Commun. 2003, 2910. (55) Murphy, C. J.; Jana, N. R. AdV. Mater. 2002, 14, 80. (56) Ekimov, A. I.; Efros, A. L.; Onushcenko, A. A. Solid State Commun. 1985, 56, 921. (57) Chen, W.; Bovin, J. O.; Joly, A. G.; Wang, S. P.; Su, F. H.; Li, G. H. J. Phys. Chem. B 2004, 108, 11927. (58) Alivisatos, A. P. J. Phys. Chem. 1996, 100, 13226. (59) Xiong, Y. J.; Xie, Y.; Du, G. A.; Tian, X. B. J. Mater. Chem. 2002, 12, 98. (60) Tang, J. W.; Zou, Z. G.; Yin, J.; Ye, J. Chem. Phys. Lett. 2003, 382, 175. (61) Mills, A.; Wang, J. S. J. Photochem. Photobiol., A 1999, 127, 123. (62) Chatterjee, D.; Mahata, A. J. Photochem. Photobiol., A 2002, 153, 199.
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