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Preparation and characterization of single-handed twisted platinum tubular nanoribbons
Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Preparation and characterization of single-handed twisted platinum tubular nanoribbons Hui Cai a, Chundong Wang b, Baozong Li a, Yi Li a,n, Yonggang Yang a a Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Polymer Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, PR China b Laboratory of Solid-State Physics and Magnetism, Department of Physics and Astronomy, KU Leuven, Belgium
art ic l e i nf o
a b s t r a c t
Article history: Received 15 April 2014 Accepted 22 June 2014
Single-handed twisted tubular Pt nanoribbons were prepared through sol–gel transcription, using selfassemblies of low-molecular weight amphiphiles as templates. The nanoribbons were characterized using field-emission scanning electron microscopy, transmission electron microscopy (TEM) and diffuse reflectance circular dichroism (DRCD). Nanoribbons handedness was controlled by that of the organic self-assembly. Nanoribbons were constructed from nanoparticles and short nanowires with diameters of 1.5–3.0 nm. The TEM results indicated that these nanoparticles and short nanowires were randomly arranged; however, DRCD spectra indicated that the nanoribbons exhibited optical activity. Pt atoms were proposed to arrange in a chiral manner on the surfaces and in the cores. & 2014 Published by Elsevier B.V.
Keywords: Sol–gel preparation Nanoparticles Chiral Pt
1. Introduction Chiral zero- and one-dimensional metal nanoparticles have received much interest since the first report on chiral glutathioneprotected gold nanoparticles [1]. The formation of these chiral particles has been proposed to originate from their chiral core, chiral surfaces or chiral arrangement of nanoparticles [1,2]. Platinum (Pt) is an important metal in catalysis [3], but is very expensive. Much effort has focused on forming nanosized Pt shapes, to increase its surface areas and control its crystal facets for enhancing catalysis [4]. Pt can be used as an asymmetric catalyst, with the adsorption of chiral modifiers [5,6]. While asymmetric catalysis mechanisms are still not well understood, it is clearly beneficial to prepare Pt nanoparticles with angstrom level chirality for practical applications. Chiral low-molecular weight amphiphiles (LMWAs) can selfassemble into chiral nanostructures such as helical nanofibers and twisted/coiled nanoribbons [7]. These chiral nanostructures can then be transcripted to nanomaterials. Single-handed helical silica, polysilsesquioxane, titania, cadmium sulfide and tantalum oxide tubular and mesoporous nanostructures have been prepared by sol–gel transcription [8–13]. Chiral organization can be observed using diffuse reflectance circular dichroism (DRCD), and such materials have potential in asymmetric catalysis [14]. Morphologies of Pt nanostructures have usually been controlled using cationic surfactants, and zero-dimensional nanoparticles and nanowires have been
obtained [3,4]. However, reports on tubular structures are rare. Only straight Pt nanotubes have been prepared using one-dimensional nanocrystals as templates [15,16]. Their formation was due to N and O atoms’ high affinity towards Pt2 þ [17]. Herein, optically active single-handed helical Pt tubular nanoribbons are prepared using organic self-assemblies as templates. To our knowledge, this is the first report of single-handed helical Pt tubular nanoribbons. These Pt tubular nanoribbons are potentially applied for asymmetric catalysis.
2. Experimental section General methods and characterization of the LMWAs LL-12Val8PyBr and DD-12Val8PyBr (Fig. 1) were shown in the Supporting information [18]. K2PtCl4, absolute ethanol and ascorbic acid were purchased from Sinophram Chemical Reagent Co., Ltd. Synthetic procedure for the twisted platinum tubular nanoribbons: LL-(or DD-) 12Val8PyBr was dissolved in 1.2 mL of 10: 1 absolute ethanol: water, at concentrations of 0.2–0.5 mM. 0.4 mL of aqueous K2PtCl4 (10 mM) was added under stirring. 0.4 mL of aqueous ascorbic acid (75 mM) was added 5 min later. Thirty seconds later, stirring was stopped, and the reaction mixture was kept at room temperature for 1 day. Templates were removed by washing three times with ethanol.
3. Results and discussion n
Corresponding author. Tel./fax: þ 86 512 65882052. E-mail address: [email protected] (Y. Li).
The LMWAs can form viscous solutions in deionized water. To study the chiral organization of the LMWAs in water, CD and UV
http://dx.doi.org/10.1016/j.matlet.2014.06.138 0167-577X/& 2014 Published by Elsevier B.V.
Please cite this article as: Cai H, et al. Preparation and characterization of single-handed twisted platinum tubular nanoribbons. Mater Lett (2014), http://dx.doi.org/10.1016/j.matlet.2014.06.138i
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H. Cai et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
Fig. 1. Molecular structures of the chiral low-molecular-weight amphiphiles.
absorption spectra were measured at a concentration of 15.0 g L 1 with a 0.01 mm cell at 25 1C (Fig. 2). Absorption bands were apparent at o 200 and 258 nm, predominantly originating from carbonyl groups and pyridinium rings, respectively. Peaks in CD spectra were apparent at 197 and 258 nm. CD signs were both negative for LL-12Val8PyBr, indicating that carbonyl groups and pyridinium rings stacked in left-handedness. In contrast, carbonyl groups and pyridinium rings stacked in righthandedness within self-assemblies of DD-12Val8PyBr. Similar CD signals have been reported for LMWAs structurally similar to those in Fig. 1 [18]. Silica and polysilsesquioxane bundles have been previously prepared using similar organic self-assemblies as templates [10]. The Pt nanostructures were controlled using self-assemblies of the LMWAs shown in Fig. 1 as templates, in a mixture of water and ethanol. Field-emission scanning electron microscopy (FE-SEM) and TEM images of the resulting Pt tubular nanoribbons are shown in Fig. 3. Left- and right-handed helical tubular ribbons were prepared using LL- and DD-12Val8PyBr, respectively (Fig. 3a and b). The FT-IR spectra of the left-handed helical Pt tubular nanoribbons and left-handed helical Pt tubular nanoribbons with LL12Val8PyBr inside are shown in Figs. S1b and S1c. The disappearance of the absorption bands of the methyl groups and alkylene chains at 2925 cm 1 and 2850 cm 1 indicated that LL-12Val8PyBr was almost totally removed. The Nanoribbons were 150–600 nm wide, 40–60 nm thick and ca. 1.0–3.0 mm in helical pitch. Their length reached tens of micrometers. TEM images of left-handed twisted nanoribbons are shown in Fig. 3c and d, in which a tubular structure was observed. The nanotubes appeared to be constructed from two layers of nanoribbons. Magnified TEM images indicated that the tubular nanoribbons were constructed from fine nanoparticles and short nanowires of diameter 1.5–3.0 nm. These fine nanoparticles and short nanowires were randomly packed, and voids among them were observed. Such hierarchical porous structures are likely to be suitable for catalysis. The formation of the nanotubes was studied by collecting FESEM images after different reaction times (Fig. 4). FE-SEM samples were prepared as follows. A given time after ascorbic acid was added, one drop of reaction mixture was removed and deposited on a glass flake. The film was dried under a nitrogen flow as quickly as possible. FE-SEM images were collected using the beam deceleration method without depositing a conductive coating. Twisted nanoribbons were observed after the addition of ascorbic acid, indicating that LL-12Val8PyBr self-assembled into nanoribbons under the given reaction conditions (Fig. 4a). The reaction mixture achieved a black appearance after 1 h. Pt nanoparticles are thought to have already formed and adsorbed on the organic nanoribbon surfaces (Fig. 4b). The sample conductivity increased with Pt nanoparticle adsorption, causing the FE-SEM image resolution to increase. The formation of Pt tubular nanoribbons is proposed as follows. LMWAs first self-assembled into twisted nanoribbons. N and O atoms have a high affinity towards Pt2 þ , and
Fig. 2. CD and UV absorption spectra of viscous solutions of LMWAs, at a concentration of 15.0 g L 1.
Pt2 þ adsorbed on the organic nanoribbon surfaces [17]. Pt2 þ was reduced to Pt0 upon the addition of ascorbic acid, and further grew into nanoparticles and short nanowires. Pt tubular nanoribbons were obtained after removing the LMWAs. DRCD and diffuse reflectance ultraviolet–visible (DRUV–vis) spectra of single-handed twisted tubular Pt nanoribbons are shown in Fig. 5. They exhibited broad DRUV–vis absorbance at 250–800 nm. They also exhibited broad DRCD signals at 250–800 nm. Left- and right-handed twisted tubular nanoribbons exhibited positive and negative signals, respectively. It was reported that chiral organization of silver particles or rods can exhibit such DRCD signals [2]. TEM results indicated that Pt nanoparticles were randomly arranged (Fig. 3), so DRCD signals were unlikely to have originated from the chiral stacking of Pt nanoparticles. Pt2 þ has a strong affinity with the N and O atoms of the LMWGs, so the LMWG chirality was likely transferred to the Pt nanoparticle surfaces. The interaction between Pt and N atoms could be identified in Figs. S1a and S1c. For LL-12Val8PyBr, the Hbonded N–H absorption bands appeared at 3287 cm 1 and 1553 cm 1 (Fig. S1a). The intensity of them decreased when LL12Val8PyBr was trapped within the Pt tubular nanoribbons, indicating the binding of Pt to N (Fig. S1b) [19]. However, the interaction between Pt atom and carbonyl group was not identified. The absorption bands of the samples kept at 1634 cm 1 (Figs. S1a and S1b). For the FTIR spectra of the Pt tubular nanoribbons with LL-12Val8PyBr inside, the absorption bands at 1796 cm 1 should originate from a mixture of ascorbic acid, oxlic acid and some intermediates. DRCD spectra were recorded after removing the templates, so surface distortion appears to have been memorized. Pt atoms have been reported to organize helically, when nanowires were thinner than 1.0 nm [20]. Therefore, in addition to the surfaces, the cores of Pt nanoparticles and nanowires were also likely to be chiral. Previous results indicated that the chirality of silica nanotubes prepared using chiral low-molecular-weight gelator existed in the inner walls [21]. Herein, the chiral Pt nanotubes were also prepared through this approach. The chirality
Please cite this article as: Cai H, et al. Preparation and characterization of single-handed twisted platinum tubular nanoribbons. Mater Lett (2014), http://dx.doi.org/10.1016/j.matlet.2014.06.138i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
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Fig. 3. (a) and (b) FE-SEM and (c) and (d) TEM images of twisted tubular Pt nanoribbons.
Fig. 4. FE-SEM images of the reaction mixture recorded after (a) 0 and (b) 1 h reaction times.
might be also originated from the nanoparticles or nanowires in the inner walls.
4. Conclusion
Fig. 5. DRCD and DRUV–vis spectra of twisted tubular Pt nanoribbons.
In conclusion, single-handed twisted tubular Pt nanoribbons were prepared through sol–gel transcription, using self-assemblies of LMWAs as templates. Nanotube handedness was controlled by that of the organic self-assembly. Nanoribbons were constructed from nanoparticles and short nanowires with diameters of 1.5–3.0 nm. These nanoparticles and short nanowires were randomly arranged; however, DRCD spectra indicated that the
Please cite this article as: Cai H, et al. Preparation and characterization of single-handed twisted platinum tubular nanoribbons. Mater Lett (2014), http://dx.doi.org/10.1016/j.matlet.2014.06.138i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
H. Cai et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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nanoribbons exhibited optical activity. Pt atoms were proposed to arrange in a chiral manner on the surfaces and in the cores. Chiral Pt tubular nanoribbons have potential in asymmetric catalysis. The other chiral metal nanostructures were proposed to be obtained through this approach. Acknowledgements
[2] [3] [4] [5] [6] [7] [8] [9] [10]
This work was supported by Natural Science Foundation of Jiangsu Province (no. BK2011354), the National Natural Science Foundation of China (no. 21104053), the Priority Academic Program Development of Jiangsu High Education Institutions (PAPD), and the Open Research Project of the Key Laboratory of Lithium Battery Materials of Jiangsu Province. Appendix A. Supporting information Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.matlet.2014.06.138.
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References [1] Noguez C, Garzon IL. Chem Soc Rev 2009;38:757–71.
Please cite this article as: Cai H, et al. Preparation and characterization of single-handed twisted platinum tubular nanoribbons. Mater Lett (2014), http://dx.doi.org/10.1016/j.matlet.2014.06.138i
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Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Preparation and characterization of single-handed twisted platinum tubular nanoribbons Hui Cai a, Chundong Wang b, Baozong Li a, Yi Li a,n, Yonggang Yang a a Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Polymer Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, PR China b Laboratory of Solid-State Physics and Magnetism, Department of Physics and Astronomy, KU Leuven, Belgium
art ic l e i nf o
a b s t r a c t
Article history: Received 15 April 2014 Accepted 22 June 2014
Single-handed twisted tubular Pt nanoribbons were prepared through sol–gel transcription, using selfassemblies of low-molecular weight amphiphiles as templates. The nanoribbons were characterized using field-emission scanning electron microscopy, transmission electron microscopy (TEM) and diffuse reflectance circular dichroism (DRCD). Nanoribbons handedness was controlled by that of the organic self-assembly. Nanoribbons were constructed from nanoparticles and short nanowires with diameters of 1.5–3.0 nm. The TEM results indicated that these nanoparticles and short nanowires were randomly arranged; however, DRCD spectra indicated that the nanoribbons exhibited optical activity. Pt atoms were proposed to arrange in a chiral manner on the surfaces and in the cores. & 2014 Published by Elsevier B.V.
Keywords: Sol–gel preparation Nanoparticles Chiral Pt
1. Introduction Chiral zero- and one-dimensional metal nanoparticles have received much interest since the first report on chiral glutathioneprotected gold nanoparticles [1]. The formation of these chiral particles has been proposed to originate from their chiral core, chiral surfaces or chiral arrangement of nanoparticles [1,2]. Platinum (Pt) is an important metal in catalysis [3], but is very expensive. Much effort has focused on forming nanosized Pt shapes, to increase its surface areas and control its crystal facets for enhancing catalysis [4]. Pt can be used as an asymmetric catalyst, with the adsorption of chiral modifiers [5,6]. While asymmetric catalysis mechanisms are still not well understood, it is clearly beneficial to prepare Pt nanoparticles with angstrom level chirality for practical applications. Chiral low-molecular weight amphiphiles (LMWAs) can selfassemble into chiral nanostructures such as helical nanofibers and twisted/coiled nanoribbons [7]. These chiral nanostructures can then be transcripted to nanomaterials. Single-handed helical silica, polysilsesquioxane, titania, cadmium sulfide and tantalum oxide tubular and mesoporous nanostructures have been prepared by sol–gel transcription [8–13]. Chiral organization can be observed using diffuse reflectance circular dichroism (DRCD), and such materials have potential in asymmetric catalysis [14]. Morphologies of Pt nanostructures have usually been controlled using cationic surfactants, and zero-dimensional nanoparticles and nanowires have been
obtained [3,4]. However, reports on tubular structures are rare. Only straight Pt nanotubes have been prepared using one-dimensional nanocrystals as templates [15,16]. Their formation was due to N and O atoms’ high affinity towards Pt2 þ [17]. Herein, optically active single-handed helical Pt tubular nanoribbons are prepared using organic self-assemblies as templates. To our knowledge, this is the first report of single-handed helical Pt tubular nanoribbons. These Pt tubular nanoribbons are potentially applied for asymmetric catalysis.
2. Experimental section General methods and characterization of the LMWAs LL-12Val8PyBr and DD-12Val8PyBr (Fig. 1) were shown in the Supporting information [18]. K2PtCl4, absolute ethanol and ascorbic acid were purchased from Sinophram Chemical Reagent Co., Ltd. Synthetic procedure for the twisted platinum tubular nanoribbons: LL-(or DD-) 12Val8PyBr was dissolved in 1.2 mL of 10: 1 absolute ethanol: water, at concentrations of 0.2–0.5 mM. 0.4 mL of aqueous K2PtCl4 (10 mM) was added under stirring. 0.4 mL of aqueous ascorbic acid (75 mM) was added 5 min later. Thirty seconds later, stirring was stopped, and the reaction mixture was kept at room temperature for 1 day. Templates were removed by washing three times with ethanol.
3. Results and discussion n
Corresponding author. Tel./fax: þ 86 512 65882052. E-mail address: [email protected] (Y. Li).
The LMWAs can form viscous solutions in deionized water. To study the chiral organization of the LMWAs in water, CD and UV
http://dx.doi.org/10.1016/j.matlet.2014.06.138 0167-577X/& 2014 Published by Elsevier B.V.
Please cite this article as: Cai H, et al. Preparation and characterization of single-handed twisted platinum tubular nanoribbons. Mater Lett (2014), http://dx.doi.org/10.1016/j.matlet.2014.06.138i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
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H. Cai et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
Fig. 1. Molecular structures of the chiral low-molecular-weight amphiphiles.
absorption spectra were measured at a concentration of 15.0 g L 1 with a 0.01 mm cell at 25 1C (Fig. 2). Absorption bands were apparent at o 200 and 258 nm, predominantly originating from carbonyl groups and pyridinium rings, respectively. Peaks in CD spectra were apparent at 197 and 258 nm. CD signs were both negative for LL-12Val8PyBr, indicating that carbonyl groups and pyridinium rings stacked in left-handedness. In contrast, carbonyl groups and pyridinium rings stacked in righthandedness within self-assemblies of DD-12Val8PyBr. Similar CD signals have been reported for LMWAs structurally similar to those in Fig. 1 [18]. Silica and polysilsesquioxane bundles have been previously prepared using similar organic self-assemblies as templates [10]. The Pt nanostructures were controlled using self-assemblies of the LMWAs shown in Fig. 1 as templates, in a mixture of water and ethanol. Field-emission scanning electron microscopy (FE-SEM) and TEM images of the resulting Pt tubular nanoribbons are shown in Fig. 3. Left- and right-handed helical tubular ribbons were prepared using LL- and DD-12Val8PyBr, respectively (Fig. 3a and b). The FT-IR spectra of the left-handed helical Pt tubular nanoribbons and left-handed helical Pt tubular nanoribbons with LL12Val8PyBr inside are shown in Figs. S1b and S1c. The disappearance of the absorption bands of the methyl groups and alkylene chains at 2925 cm 1 and 2850 cm 1 indicated that LL-12Val8PyBr was almost totally removed. The Nanoribbons were 150–600 nm wide, 40–60 nm thick and ca. 1.0–3.0 mm in helical pitch. Their length reached tens of micrometers. TEM images of left-handed twisted nanoribbons are shown in Fig. 3c and d, in which a tubular structure was observed. The nanotubes appeared to be constructed from two layers of nanoribbons. Magnified TEM images indicated that the tubular nanoribbons were constructed from fine nanoparticles and short nanowires of diameter 1.5–3.0 nm. These fine nanoparticles and short nanowires were randomly packed, and voids among them were observed. Such hierarchical porous structures are likely to be suitable for catalysis. The formation of the nanotubes was studied by collecting FESEM images after different reaction times (Fig. 4). FE-SEM samples were prepared as follows. A given time after ascorbic acid was added, one drop of reaction mixture was removed and deposited on a glass flake. The film was dried under a nitrogen flow as quickly as possible. FE-SEM images were collected using the beam deceleration method without depositing a conductive coating. Twisted nanoribbons were observed after the addition of ascorbic acid, indicating that LL-12Val8PyBr self-assembled into nanoribbons under the given reaction conditions (Fig. 4a). The reaction mixture achieved a black appearance after 1 h. Pt nanoparticles are thought to have already formed and adsorbed on the organic nanoribbon surfaces (Fig. 4b). The sample conductivity increased with Pt nanoparticle adsorption, causing the FE-SEM image resolution to increase. The formation of Pt tubular nanoribbons is proposed as follows. LMWAs first self-assembled into twisted nanoribbons. N and O atoms have a high affinity towards Pt2 þ , and
Fig. 2. CD and UV absorption spectra of viscous solutions of LMWAs, at a concentration of 15.0 g L 1.
Pt2 þ adsorbed on the organic nanoribbon surfaces [17]. Pt2 þ was reduced to Pt0 upon the addition of ascorbic acid, and further grew into nanoparticles and short nanowires. Pt tubular nanoribbons were obtained after removing the LMWAs. DRCD and diffuse reflectance ultraviolet–visible (DRUV–vis) spectra of single-handed twisted tubular Pt nanoribbons are shown in Fig. 5. They exhibited broad DRUV–vis absorbance at 250–800 nm. They also exhibited broad DRCD signals at 250–800 nm. Left- and right-handed twisted tubular nanoribbons exhibited positive and negative signals, respectively. It was reported that chiral organization of silver particles or rods can exhibit such DRCD signals [2]. TEM results indicated that Pt nanoparticles were randomly arranged (Fig. 3), so DRCD signals were unlikely to have originated from the chiral stacking of Pt nanoparticles. Pt2 þ has a strong affinity with the N and O atoms of the LMWGs, so the LMWG chirality was likely transferred to the Pt nanoparticle surfaces. The interaction between Pt and N atoms could be identified in Figs. S1a and S1c. For LL-12Val8PyBr, the Hbonded N–H absorption bands appeared at 3287 cm 1 and 1553 cm 1 (Fig. S1a). The intensity of them decreased when LL12Val8PyBr was trapped within the Pt tubular nanoribbons, indicating the binding of Pt to N (Fig. S1b) [19]. However, the interaction between Pt atom and carbonyl group was not identified. The absorption bands of the samples kept at 1634 cm 1 (Figs. S1a and S1b). For the FTIR spectra of the Pt tubular nanoribbons with LL-12Val8PyBr inside, the absorption bands at 1796 cm 1 should originate from a mixture of ascorbic acid, oxlic acid and some intermediates. DRCD spectra were recorded after removing the templates, so surface distortion appears to have been memorized. Pt atoms have been reported to organize helically, when nanowires were thinner than 1.0 nm [20]. Therefore, in addition to the surfaces, the cores of Pt nanoparticles and nanowires were also likely to be chiral. Previous results indicated that the chirality of silica nanotubes prepared using chiral low-molecular-weight gelator existed in the inner walls [21]. Herein, the chiral Pt nanotubes were also prepared through this approach. The chirality
Please cite this article as: Cai H, et al. Preparation and characterization of single-handed twisted platinum tubular nanoribbons. Mater Lett (2014), http://dx.doi.org/10.1016/j.matlet.2014.06.138i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
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Fig. 3. (a) and (b) FE-SEM and (c) and (d) TEM images of twisted tubular Pt nanoribbons.
Fig. 4. FE-SEM images of the reaction mixture recorded after (a) 0 and (b) 1 h reaction times.
might be also originated from the nanoparticles or nanowires in the inner walls.
4. Conclusion
Fig. 5. DRCD and DRUV–vis spectra of twisted tubular Pt nanoribbons.
In conclusion, single-handed twisted tubular Pt nanoribbons were prepared through sol–gel transcription, using self-assemblies of LMWAs as templates. Nanotube handedness was controlled by that of the organic self-assembly. Nanoribbons were constructed from nanoparticles and short nanowires with diameters of 1.5–3.0 nm. These nanoparticles and short nanowires were randomly arranged; however, DRCD spectra indicated that the
Please cite this article as: Cai H, et al. Preparation and characterization of single-handed twisted platinum tubular nanoribbons. Mater Lett (2014), http://dx.doi.org/10.1016/j.matlet.2014.06.138i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
H. Cai et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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nanoribbons exhibited optical activity. Pt atoms were proposed to arrange in a chiral manner on the surfaces and in the cores. Chiral Pt tubular nanoribbons have potential in asymmetric catalysis. The other chiral metal nanostructures were proposed to be obtained through this approach. Acknowledgements
[2] [3] [4] [5] [6] [7] [8] [9] [10]
This work was supported by Natural Science Foundation of Jiangsu Province (no. BK2011354), the National Natural Science Foundation of China (no. 21104053), the Priority Academic Program Development of Jiangsu High Education Institutions (PAPD), and the Open Research Project of the Key Laboratory of Lithium Battery Materials of Jiangsu Province. Appendix A. Supporting information Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.matlet.2014.06.138.
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Please cite this article as: Cai H, et al. Preparation and characterization of single-handed twisted platinum tubular nanoribbons. Mater Lett (2014), http://dx.doi.org/10.1016/j.matlet.2014.06.138i
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