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Ultrasonic-aided fabrication of gold nanofluids.

Chen HJ, Wen D - Nanoscale Res Lett (2011)

Bottom Line: The ultrasonication technique is found to be a very powerful tool in engineering the size and shape of GNPs.Subsequent property measurement shows that both particle size and particle shape play significant roles in determining the effective thermal conductivity.A large increase in effective thermal conductivity can be achieved (approximately 65%) for gold nanofluids using plate-shaped particles under low particle concentrations (i.e.764 μM/L).

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Engineering and Materials Science, Queen Mary University of London, London, UK. d.wen@qmul.ac.uk.

ABSTRACT
A novel ultrasonic-aided one-step method for the fabrication of gold nanofluids is proposed in this study. Both spherical- and plate-shaped gold nanoparticles (GNPs) in the size range of 10-300 nm are synthesized. Subsequent purification produces well-controlled nanofluids with known solid and liquid contents. The morphology and properties of the nanoparticle and nanofluids are characterized by transmission electron microscopy, scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffraction spectroscopy, and dynamic light scattering, as well as effective thermal conductivities. The ultrasonication technique is found to be a very powerful tool in engineering the size and shape of GNPs. Subsequent property measurement shows that both particle size and particle shape play significant roles in determining the effective thermal conductivity. A large increase in effective thermal conductivity can be achieved (approximately 65%) for gold nanofluids using plate-shaped particles under low particle concentrations (i.e.764 μM/L).

No MeSH data available.


SEM images of gold nanoplates fabricated by CR with ultrasonication of 0 min. (a), 10 min (b), 20 min (c), and 30 min (d).
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Figure 4: SEM images of gold nanoplates fabricated by CR with ultrasonication of 0 min. (a), 10 min (b), 20 min (c), and 30 min (d).

Mentions: The resulting dispersion of CR produced gold nanoplates appears cloudy brown in color (Group C samples). SEM image illustrates that the main products are in plate-like shape. Figure 4a shows that these gold nanoplates are around 220-280 nm in size along their longest edge, having triangular and truncated triangular shapes with uniform edges. The particle size is not uniform, with some small gold nanoplates of about 60-70 nm appearing. The formation mechanism of CR gold nanoplates can be related to the kinetically preferred development of the redundant Au ions in the lateral direction of the small gold nuclei. The temperature has been found to have an important effect on the CR reduction rate. At 25°C, the reduction process is substantially slow and the formation changes to a kinetic-controlled mechanism that is appropriate for the production of highly anisotropic structures, which is the reason why gold nanoplates can be fabricated without additional stabilizers. Furthermore, the existence of natural light is another important feature for the formation of gold nanoplates. It is difficult to process the reaction without the exposure to natural light even if all other conditions are the same.


Ultrasonic-aided fabrication of gold nanofluids.

Chen HJ, Wen D - Nanoscale Res Lett (2011)

SEM images of gold nanoplates fabricated by CR with ultrasonication of 0 min. (a), 10 min (b), 20 min (c), and 30 min (d).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211254&req=5

Figure 4: SEM images of gold nanoplates fabricated by CR with ultrasonication of 0 min. (a), 10 min (b), 20 min (c), and 30 min (d).
Mentions: The resulting dispersion of CR produced gold nanoplates appears cloudy brown in color (Group C samples). SEM image illustrates that the main products are in plate-like shape. Figure 4a shows that these gold nanoplates are around 220-280 nm in size along their longest edge, having triangular and truncated triangular shapes with uniform edges. The particle size is not uniform, with some small gold nanoplates of about 60-70 nm appearing. The formation mechanism of CR gold nanoplates can be related to the kinetically preferred development of the redundant Au ions in the lateral direction of the small gold nuclei. The temperature has been found to have an important effect on the CR reduction rate. At 25°C, the reduction process is substantially slow and the formation changes to a kinetic-controlled mechanism that is appropriate for the production of highly anisotropic structures, which is the reason why gold nanoplates can be fabricated without additional stabilizers. Furthermore, the existence of natural light is another important feature for the formation of gold nanoplates. It is difficult to process the reaction without the exposure to natural light even if all other conditions are the same.

Bottom Line: The ultrasonication technique is found to be a very powerful tool in engineering the size and shape of GNPs.Subsequent property measurement shows that both particle size and particle shape play significant roles in determining the effective thermal conductivity.A large increase in effective thermal conductivity can be achieved (approximately 65%) for gold nanofluids using plate-shaped particles under low particle concentrations (i.e.764 μM/L).

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Engineering and Materials Science, Queen Mary University of London, London, UK. d.wen@qmul.ac.uk.

ABSTRACT
A novel ultrasonic-aided one-step method for the fabrication of gold nanofluids is proposed in this study. Both spherical- and plate-shaped gold nanoparticles (GNPs) in the size range of 10-300 nm are synthesized. Subsequent purification produces well-controlled nanofluids with known solid and liquid contents. The morphology and properties of the nanoparticle and nanofluids are characterized by transmission electron microscopy, scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffraction spectroscopy, and dynamic light scattering, as well as effective thermal conductivities. The ultrasonication technique is found to be a very powerful tool in engineering the size and shape of GNPs. Subsequent property measurement shows that both particle size and particle shape play significant roles in determining the effective thermal conductivity. A large increase in effective thermal conductivity can be achieved (approximately 65%) for gold nanofluids using plate-shaped particles under low particle concentrations (i.e.764 μM/L).

No MeSH data available.