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Shape and phase control of CdS nanocrystals using cationic surfactant in noninjection synthesis.

Zou Y, Li D, Yang D - Nanoscale Res Lett (2011)

Bottom Line: Monodispersed CdS nanocrystals with controllable shape and phase have been successfully synthesized in this study by adding cationic surfactant in noninjection synthesis system.With the increase of the amount of cetyltrimethylammonium chloride (CTAC) added, the shape of the CdS nanocrystals changed from spherical to multi-armed, and the phase changed from zinc-blende to wurtzite.In addition, it was found that the multi-armed CdS nanocrystals lost quantum confinement effect because of the increase of the size with the increase of the concentration of CTAC.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China. mselds@zju.edu.cn.

ABSTRACT
Monodispersed CdS nanocrystals with controllable shape and phase have been successfully synthesized in this study by adding cationic surfactant in noninjection synthesis system. With the increase of the amount of cetyltrimethylammonium chloride (CTAC) added, the shape of the CdS nanocrystals changed from spherical to multi-armed, and the phase changed from zinc-blende to wurtzite. It was found that halide ion Cl- plays a key role in the transformation, and other halide ions such as Br- can also induce similar transformation. We proposed that the strong binding between Cd2+ and halide ions reduced the reactivity of the precursors, decreased the nuclei formed in the nucleation stage, and led to the high concentration of precursor in the growth stage, resulting in the increase of size and phase transformation of CdS nanocrystals. In addition, it was found that the multi-armed CdS nanocrystals lost quantum confinement effect because of the increase of the size with the increase of the concentration of CTAC.

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TEM images of the CdS nanocrystals obtained with different amounts of CTAC added: (a) 0 mmol, (b) 0.25 mmol, (c) 0.5 mmol, and (d) 1 mmol. A shape transformation from spherical to multi-armed was observed with the increase of the amount of CTAC.
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Figure 1: TEM images of the CdS nanocrystals obtained with different amounts of CTAC added: (a) 0 mmol, (b) 0.25 mmol, (c) 0.5 mmol, and (d) 1 mmol. A shape transformation from spherical to multi-armed was observed with the increase of the amount of CTAC.

Mentions: Selecting proper surfactants has been found to be the key to control the shape and phase of colloidal nanocrystals [20,21]. In our experiments, we chose cationic surfactant CTAC as an additive in the noninjection synthesis of CdS nanocrystals. Figure 1 shows the TEM images of the CdS nanocrystals obtained by adding different amounts of CTAC. As can be seen, the spherical CdS nanocrystals with an average diameter of 3.6 nm were obtained when CTAC was absent. With the increase of the amount of CTAC added, the size of the nanocrystals increased, and the morphology varied from spherical to multi-armed. When 0.5 mmol CTAC was used, a mixture of CdS nanorods, bipods, tripods, and tetrapods with an average diameter of about 7 nm was obtained, which is similar to the products synthesized in oleylamine [14,15]. The average diameter of the multi-armed nanorods further increased to 13 nm when 1 mmol CTAC was added.


Shape and phase control of CdS nanocrystals using cationic surfactant in noninjection synthesis.

Zou Y, Li D, Yang D - Nanoscale Res Lett (2011)

TEM images of the CdS nanocrystals obtained with different amounts of CTAC added: (a) 0 mmol, (b) 0.25 mmol, (c) 0.5 mmol, and (d) 1 mmol. A shape transformation from spherical to multi-armed was observed with the increase of the amount of CTAC.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211467&req=5

Figure 1: TEM images of the CdS nanocrystals obtained with different amounts of CTAC added: (a) 0 mmol, (b) 0.25 mmol, (c) 0.5 mmol, and (d) 1 mmol. A shape transformation from spherical to multi-armed was observed with the increase of the amount of CTAC.
Mentions: Selecting proper surfactants has been found to be the key to control the shape and phase of colloidal nanocrystals [20,21]. In our experiments, we chose cationic surfactant CTAC as an additive in the noninjection synthesis of CdS nanocrystals. Figure 1 shows the TEM images of the CdS nanocrystals obtained by adding different amounts of CTAC. As can be seen, the spherical CdS nanocrystals with an average diameter of 3.6 nm were obtained when CTAC was absent. With the increase of the amount of CTAC added, the size of the nanocrystals increased, and the morphology varied from spherical to multi-armed. When 0.5 mmol CTAC was used, a mixture of CdS nanorods, bipods, tripods, and tetrapods with an average diameter of about 7 nm was obtained, which is similar to the products synthesized in oleylamine [14,15]. The average diameter of the multi-armed nanorods further increased to 13 nm when 1 mmol CTAC was added.

Bottom Line: Monodispersed CdS nanocrystals with controllable shape and phase have been successfully synthesized in this study by adding cationic surfactant in noninjection synthesis system.With the increase of the amount of cetyltrimethylammonium chloride (CTAC) added, the shape of the CdS nanocrystals changed from spherical to multi-armed, and the phase changed from zinc-blende to wurtzite.In addition, it was found that the multi-armed CdS nanocrystals lost quantum confinement effect because of the increase of the size with the increase of the concentration of CTAC.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China. mselds@zju.edu.cn.

ABSTRACT
Monodispersed CdS nanocrystals with controllable shape and phase have been successfully synthesized in this study by adding cationic surfactant in noninjection synthesis system. With the increase of the amount of cetyltrimethylammonium chloride (CTAC) added, the shape of the CdS nanocrystals changed from spherical to multi-armed, and the phase changed from zinc-blende to wurtzite. It was found that halide ion Cl- plays a key role in the transformation, and other halide ions such as Br- can also induce similar transformation. We proposed that the strong binding between Cd2+ and halide ions reduced the reactivity of the precursors, decreased the nuclei formed in the nucleation stage, and led to the high concentration of precursor in the growth stage, resulting in the increase of size and phase transformation of CdS nanocrystals. In addition, it was found that the multi-armed CdS nanocrystals lost quantum confinement effect because of the increase of the size with the increase of the concentration of CTAC.

No MeSH data available.


Related in: MedlinePlus