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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.


a UV–vis spectra showing the growth of silver nanoparticles at ~0°C and b the size evolution of these particles with time.
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Figure 7: a UV–vis spectra showing the growth of silver nanoparticles at ~0°C and b the size evolution of these particles with time.

Mentions: The corresponding UV–vis spectra recorded at ~0°C were shown in Figure 7a. It was found that the absorption intensity increases with time. The absorption band centred at 450 nm also increases significantly. The shift in the strongest absorption peak to longer wavelengths means the plate size increases, as shown in Figure 7b. Noting that the reaction took a long time (over tens of hours) to reach the end at such a low temperature. On the contrary, a high temperature over 60°C was not considered in this work because the higher the temperature the faster the reaction, hence the data are difficult to collect for TEM or UV–vis analysis. Generally speaking, the effect of temperature on the formation and growth of silver nanoparticles is significant under the reported conditions. Some components related to temperature still need to investigate in the future, such as the reducing ability of citric acid and ascorbic acid, the complex ability of citric acid or AOT surfactant molecules with silver ions. The thermodynamical parameters in this system, including Gibbs free energy (ΔG), enthalpy (ΔH), entropy (ΔS), and heat capacity (Cp), will be estimated quantitatively according to the TEM observations and UV–vis spectrum analysis. The results will be reported in our upcoming work.


Role of Temperature in the Growth of Silver Nanoparticles Through a Synergetic Reduction Approach
a UV–vis spectra showing the growth of silver nanoparticles at ~0°C and b the size evolution of these particles with time.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: a UV–vis spectra showing the growth of silver nanoparticles at ~0°C and b the size evolution of these particles with time.
Mentions: The corresponding UV–vis spectra recorded at ~0°C were shown in Figure 7a. It was found that the absorption intensity increases with time. The absorption band centred at 450 nm also increases significantly. The shift in the strongest absorption peak to longer wavelengths means the plate size increases, as shown in Figure 7b. Noting that the reaction took a long time (over tens of hours) to reach the end at such a low temperature. On the contrary, a high temperature over 60°C was not considered in this work because the higher the temperature the faster the reaction, hence the data are difficult to collect for TEM or UV–vis analysis. Generally speaking, the effect of temperature on the formation and growth of silver nanoparticles is significant under the reported conditions. Some components related to temperature still need to investigate in the future, such as the reducing ability of citric acid and ascorbic acid, the complex ability of citric acid or AOT surfactant molecules with silver ions. The thermodynamical parameters in this system, including Gibbs free energy (ΔG), enthalpy (ΔH), entropy (ΔS), and heat capacity (Cp), will be estimated quantitatively according to the TEM observations and UV–vis spectrum analysis. The results will be reported in our upcoming work.

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.