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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.


UV–vis spectra of silver nanoparticles for the growth process obtained at different temperatures: a 17; b 23; (c) 28; d 32; e 43; and f 55°C.
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Figure 2: UV–vis spectra of silver nanoparticles for the growth process obtained at different temperatures: a 17; b 23; (c) 28; d 32; e 43; and f 55°C.

Mentions: The formation and growth of the silver nanostructures was further identified by UV–vis spectroscopy. Surface plasmon resonances are typically studied as physical properties of metal nanostructures rather than chemical tools that can provide control over growth and ultimate particle dimensions. Figure 2 shows the UV–vis spectra recorded at different times, corresponding to the different temperatures of 17–55°C (a–f). In general, with temperature increasing, the strongest absorption band gradually shift to a longer wavelength, e.g., from λ = 1,115 nm at 17°C (Figure 2a) to λ = 1,157 nm at 23°C (Figure 2b) and to λ = 1,342 nm at 28°C (Figure 2c). While it is heated over 32°C, the strongest absorption band is beyond 1400 nm. This means that the size of silver nanoplates increases with temperature, which is in a good agreement with the TEM observations shown in Figure 1. In addition, the profile and growth trend of UV–vis spectra of silver particles at 32°C are apparently different from those happened at other temperatures (e.g., 17, 23, 28, 43, and 55°C). In the range of 350–600 nm, only a very weak absorption emerges centred at around 425 nm, while the strongest absorption band is beyond the detection wavelength range (300–1,400 nm). This suggests that the silver nanoplates are the main product, and the plates could be larger than those obtained at other temperatures (e.g., 17, 23, and 28°C). This is further confirmed by TEM observations (Figure 1). Moreover, the crystal structure and composition of silver nanoparticles has been investigated by high-resolution TEM (HRTEM), electron diffraction, and X-ray diffraction techniques (XRD) (the images/patterns are not shown here). The nanoplates are of single crystal structure, similar as those reported in our recent work [49-55].


Role of Temperature in the Growth of Silver Nanoparticles Through a Synergetic Reduction Approach
UV–vis spectra of silver nanoparticles for the growth process obtained at different temperatures: a 17; b 23; (c) 28; d 32; e 43; and f 55°C.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: UV–vis spectra of silver nanoparticles for the growth process obtained at different temperatures: a 17; b 23; (c) 28; d 32; e 43; and f 55°C.
Mentions: The formation and growth of the silver nanostructures was further identified by UV–vis spectroscopy. Surface plasmon resonances are typically studied as physical properties of metal nanostructures rather than chemical tools that can provide control over growth and ultimate particle dimensions. Figure 2 shows the UV–vis spectra recorded at different times, corresponding to the different temperatures of 17–55°C (a–f). In general, with temperature increasing, the strongest absorption band gradually shift to a longer wavelength, e.g., from λ = 1,115 nm at 17°C (Figure 2a) to λ = 1,157 nm at 23°C (Figure 2b) and to λ = 1,342 nm at 28°C (Figure 2c). While it is heated over 32°C, the strongest absorption band is beyond 1400 nm. This means that the size of silver nanoplates increases with temperature, which is in a good agreement with the TEM observations shown in Figure 1. In addition, the profile and growth trend of UV–vis spectra of silver particles at 32°C are apparently different from those happened at other temperatures (e.g., 17, 23, 28, 43, and 55°C). In the range of 350–600 nm, only a very weak absorption emerges centred at around 425 nm, while the strongest absorption band is beyond the detection wavelength range (300–1,400 nm). This suggests that the silver nanoplates are the main product, and the plates could be larger than those obtained at other temperatures (e.g., 17, 23, and 28°C). This is further confirmed by TEM observations (Figure 1). Moreover, the crystal structure and composition of silver nanoparticles has been investigated by high-resolution TEM (HRTEM), electron diffraction, and X-ray diffraction techniques (XRD) (the images/patterns are not shown here). The nanoplates are of single crystal structure, similar as those reported in our recent work [49-55].

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.