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Role of Temperature in the Growth of Silver Nanoparticles Through a Synergetic Reduction Approach

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ABSTRACT

This study presents the role of reaction temperature in the formation and growth of silver nanoparticles through a synergetic reduction approach using two or three reducing agents simultaneously. By this approach, the shape-/size-controlled silver nanoparticles (plates and spheres) can be generated under mild conditions. It was found that the reaction temperature could play a key role in particle growth and shape/size control, especially for silver nanoplates. These nanoplates could exhibit an intensive surface plasmon resonance in the wavelength range of 700–1,400 nm in the UV–vis spectrum depending upon their shapes and sizes, which make them useful for optical applications, such as optical probes, ionic sensing, and biochemical sensors. A detailed analysis conducted in this study clearly shows that the reaction temperature can greatly influence reaction rate, and hence the particle characteristics. The findings would be useful for optimization of experimental parameters for shape-controlled synthesis of other metallic nanoparticles (e.g., Au, Cu, Pt, and Pd) with desirable functional properties.

No MeSH data available.


The average size of silver nanoplates (curve a) and nanospheres (curve b) obtained at different temperatures from 17 to 55°C.
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Figure 3: The average size of silver nanoplates (curve a) and nanospheres (curve b) obtained at different temperatures from 17 to 55°C.

Mentions: To compare the particle size and growth trend, Figure 3 shows the average size of silver plates (curve a) and spheres (curve b) obtained at different temperatures from 17 to 55°C. With temperature increasing, the triangular silver nanoplates grow larger from 90 nm (17–28°C) to 180 nm (>32°C), according to the curve a (Figure 3). There is a significant jump in plate size growth. This is also confirmed by TEM image shown in Figure 1. This phenomenon is consistent with previous study on the bimodal growth of silver nanoprisms reported by Mirkin et al. [28,29]. The authors demonstrated that the observed bimodal growth process occurs through an edge-selective particle fusion mechanism, with four 'small' nanoprisms coming together in step-wise fusion to form a 'big' one. The fusion mechanism was confirmed by a few experimental observations in the photoinduced approach: (1) the cumulative edge length of triangular nanoprism increases nearly twice; (2) edge-selective growth occurs with no apparent change in nanostructure thickness; (3) detailed time-dependent UV–vis–NIR measurements show that the onset of the growth of the band at 1,065 nm (assigned to 'big') is significantly delayed in comparison with the growth of the band at 640 nm (assigned to 'small'). This indicates that the fusion of nanoprisms occurs only after 'small' nanoprisms have accumulated; and (4) a small population of dimer 2 and trimer 3 intermediates is observed during the early stages of 'small' particle growth. This means that the similar fusion growth of triangular particles could occur under an appropriate heating process (30–35°C). A detailed mechanism for these types of conversions remains to be determined.


Role of Temperature in the Growth of Silver Nanoparticles Through a Synergetic Reduction Approach
The average size of silver nanoplates (curve a) and nanospheres (curve b) obtained at different temperatures from 17 to 55°C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211407&req=5

Figure 3: The average size of silver nanoplates (curve a) and nanospheres (curve b) obtained at different temperatures from 17 to 55°C.
Mentions: To compare the particle size and growth trend, Figure 3 shows the average size of silver plates (curve a) and spheres (curve b) obtained at different temperatures from 17 to 55°C. With temperature increasing, the triangular silver nanoplates grow larger from 90 nm (17–28°C) to 180 nm (>32°C), according to the curve a (Figure 3). There is a significant jump in plate size growth. This is also confirmed by TEM image shown in Figure 1. This phenomenon is consistent with previous study on the bimodal growth of silver nanoprisms reported by Mirkin et al. [28,29]. The authors demonstrated that the observed bimodal growth process occurs through an edge-selective particle fusion mechanism, with four 'small' nanoprisms coming together in step-wise fusion to form a 'big' one. The fusion mechanism was confirmed by a few experimental observations in the photoinduced approach: (1) the cumulative edge length of triangular nanoprism increases nearly twice; (2) edge-selective growth occurs with no apparent change in nanostructure thickness; (3) detailed time-dependent UV–vis–NIR measurements show that the onset of the growth of the band at 1,065 nm (assigned to 'big') is significantly delayed in comparison with the growth of the band at 640 nm (assigned to 'small'). This indicates that the fusion of nanoprisms occurs only after 'small' nanoprisms have accumulated; and (4) a small population of dimer 2 and trimer 3 intermediates is observed during the early stages of 'small' particle growth. This means that the similar fusion growth of triangular particles could occur under an appropriate heating process (30–35°C). A detailed mechanism for these types of conversions remains to be determined.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

This study presents the role of reaction temperature in the formation and growth of silver nanoparticles through a synergetic reduction approach using two or three reducing agents simultaneously. By this approach, the shape-/size-controlled silver nanoparticles (plates and spheres) can be generated under mild conditions. It was found that the reaction temperature could play a key role in particle growth and shape/size control, especially for silver nanoplates. These nanoplates could exhibit an intensive surface plasmon resonance in the wavelength range of 700–1,400 nm in the UV–vis spectrum depending upon their shapes and sizes, which make them useful for optical applications, such as optical probes, ionic sensing, and biochemical sensors. A detailed analysis conducted in this study clearly shows that the reaction temperature can greatly influence reaction rate, and hence the particle characteristics. The findings would be useful for optimization of experimental parameters for shape-controlled synthesis of other metallic nanoparticles (e.g., Au, Cu, Pt, and Pd) with desirable functional properties.

No MeSH data available.