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Size-controlled synthesis of monodispersed gold nanoparticles via carbon monoxide gas reduction.

Young JK, Lewinski NA, Langsner RJ, Kennedy LC, Satyanarayan A, Nammalvar V, Lin AY, Drezek RA - Nanoscale Res Lett (2011)

Bottom Line: It is also found that speciation of aqueous HAuCl4, prior to reduction, influences the size, morphology, and properties of AuNPs when reduced with CO gas.Ensemble extinction spectra and TEM images provide clear evidence that CO reduction offers a high level of monodispersity with standard deviations as low as 3%.Upon synthesis, no excess reducing agent remains in solution eliminating the need for purification.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Electrical and Computer Engineering, Rice University, MS-366, 6100 Main St,, Houston, TX 77005, USA. drezek@rice.edu.

ABSTRACT
An in depth analysis of gold nanoparticle (AuNP) synthesis and size tuning, utilizing carbon monoxide (CO) gas as a reducing agent, is presented for the first time. The sizes of the AuNPs are tunable from ~4 to 100 nm by altering the concentration of HAuCl4 and inlet CO gas-injection flow rate. It is also found that speciation of aqueous HAuCl4, prior to reduction, influences the size, morphology, and properties of AuNPs when reduced with CO gas. Ensemble extinction spectra and TEM images provide clear evidence that CO reduction offers a high level of monodispersity with standard deviations as low as 3%. Upon synthesis, no excess reducing agent remains in solution eliminating the need for purification. The time necessary to synthesize AuNPs, using CO, is less than 2 min.

No MeSH data available.


Nanoparticle spectra as a function of K2CO3 concentration and aging. UV-visible spectra of AuNPs produced from a mixture of 0.38 mM HAuCl4 aqueous solution with 2.71 mM or 3.62 mM K2CO3. A and B are 2.71 mM K2CO3 aged at 30 and 40 min, respectively, at an aeration volume of 40 mL. C, D, and E are 3.62 mM K2CO3 aged for 30 min each at aeration volumes of 20, 40, and 50 mL, respectively. All samples were aerated at a gas flow rate of 25.5 mL/min.
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Figure 7: Nanoparticle spectra as a function of K2CO3 concentration and aging. UV-visible spectra of AuNPs produced from a mixture of 0.38 mM HAuCl4 aqueous solution with 2.71 mM or 3.62 mM K2CO3. A and B are 2.71 mM K2CO3 aged at 30 and 40 min, respectively, at an aeration volume of 40 mL. C, D, and E are 3.62 mM K2CO3 aged for 30 min each at aeration volumes of 20, 40, and 50 mL, respectively. All samples were aerated at a gas flow rate of 25.5 mL/min.

Mentions: By controlling the development of the [AuClx(OH)4-x]- species, colloids of various sizes can be synthesized using CO as a reducing agent. When the pH is sufficiently high, the resultant aging process can generate coalescence of Au(OH)4 initiating a limited nucleation process absent of a reducing agent. This nucleation process is out of favor with the requirements necessary for generating monodispersed nanoparticles. Thus proper aging times must be determined to synthesize monodispersed nanoparticles of a particular size from a given K2CO3 and HAuCl4 concentration. Exploiting the control of [AuClx(OH)4-x]- species development, by addition of K2CO3 and aging of the solution, Au colloid in the ranges of 15 to 100 nm in diameter were produced. Spectra A and B in Figure 7 show the UV-visible spectra of Au colloid produced from a mixture of 200 mL 0.38 mM HAuCl4 aqueous solution and K2CO3 (2.71 mM) aged at 30 and 40 min, respectively, in solution reduction volumes of 40 mL. Both SPR peaks were well ordered with a SPR peak at 536 nm for the 30-min aged solution and 546 nm for the 40-min aged solution. Both solutions were aerated with CO gas at an inlet gas flow rate of 25.5 mL/min. The red-shift and dampening of the SPR peak indicated an increase in particle size. The effect of the solution volume being aerated was explored to determine if the amount of solution being aerated had an effect on nanoparticle size and monodispersity. Spectra C, D, and E in Figure 7 were produced from AuNPs synthesized from a 200 mL 0.38 mM HAuCl4 aqueous solution with K2CO3 (3.62 mM) aged for 30 min. The aeration volumes were 20, 40, and 50 mL, respectively. The amount of solution aerated had a small but noticeable effect on SPR peak position. The resulting SPR peak positions were 550, 553, and 554 nm for aeration volumes of 20, 40, and 50 mL, respectively. Increasing the amount of K2CO3, in a HAuCl4 aqueous solution of known concentration, while decreasing the aging time, produced larger AuNPs while still maintaining monodispersity. Aqueous solutions of 200 mL 0.38 mM HAuCl4 with 2.71 and 3.62 mM of K2CO3 aged for 30 min each produced AuNPs with SPR peak positions at 536 and 553 nm, respectively.


Size-controlled synthesis of monodispersed gold nanoparticles via carbon monoxide gas reduction.

Young JK, Lewinski NA, Langsner RJ, Kennedy LC, Satyanarayan A, Nammalvar V, Lin AY, Drezek RA - Nanoscale Res Lett (2011)

Nanoparticle spectra as a function of K2CO3 concentration and aging. UV-visible spectra of AuNPs produced from a mixture of 0.38 mM HAuCl4 aqueous solution with 2.71 mM or 3.62 mM K2CO3. A and B are 2.71 mM K2CO3 aged at 30 and 40 min, respectively, at an aeration volume of 40 mL. C, D, and E are 3.62 mM K2CO3 aged for 30 min each at aeration volumes of 20, 40, and 50 mL, respectively. All samples were aerated at a gas flow rate of 25.5 mL/min.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211845&req=5

Figure 7: Nanoparticle spectra as a function of K2CO3 concentration and aging. UV-visible spectra of AuNPs produced from a mixture of 0.38 mM HAuCl4 aqueous solution with 2.71 mM or 3.62 mM K2CO3. A and B are 2.71 mM K2CO3 aged at 30 and 40 min, respectively, at an aeration volume of 40 mL. C, D, and E are 3.62 mM K2CO3 aged for 30 min each at aeration volumes of 20, 40, and 50 mL, respectively. All samples were aerated at a gas flow rate of 25.5 mL/min.
Mentions: By controlling the development of the [AuClx(OH)4-x]- species, colloids of various sizes can be synthesized using CO as a reducing agent. When the pH is sufficiently high, the resultant aging process can generate coalescence of Au(OH)4 initiating a limited nucleation process absent of a reducing agent. This nucleation process is out of favor with the requirements necessary for generating monodispersed nanoparticles. Thus proper aging times must be determined to synthesize monodispersed nanoparticles of a particular size from a given K2CO3 and HAuCl4 concentration. Exploiting the control of [AuClx(OH)4-x]- species development, by addition of K2CO3 and aging of the solution, Au colloid in the ranges of 15 to 100 nm in diameter were produced. Spectra A and B in Figure 7 show the UV-visible spectra of Au colloid produced from a mixture of 200 mL 0.38 mM HAuCl4 aqueous solution and K2CO3 (2.71 mM) aged at 30 and 40 min, respectively, in solution reduction volumes of 40 mL. Both SPR peaks were well ordered with a SPR peak at 536 nm for the 30-min aged solution and 546 nm for the 40-min aged solution. Both solutions were aerated with CO gas at an inlet gas flow rate of 25.5 mL/min. The red-shift and dampening of the SPR peak indicated an increase in particle size. The effect of the solution volume being aerated was explored to determine if the amount of solution being aerated had an effect on nanoparticle size and monodispersity. Spectra C, D, and E in Figure 7 were produced from AuNPs synthesized from a 200 mL 0.38 mM HAuCl4 aqueous solution with K2CO3 (3.62 mM) aged for 30 min. The aeration volumes were 20, 40, and 50 mL, respectively. The amount of solution aerated had a small but noticeable effect on SPR peak position. The resulting SPR peak positions were 550, 553, and 554 nm for aeration volumes of 20, 40, and 50 mL, respectively. Increasing the amount of K2CO3, in a HAuCl4 aqueous solution of known concentration, while decreasing the aging time, produced larger AuNPs while still maintaining monodispersity. Aqueous solutions of 200 mL 0.38 mM HAuCl4 with 2.71 and 3.62 mM of K2CO3 aged for 30 min each produced AuNPs with SPR peak positions at 536 and 553 nm, respectively.

Bottom Line: It is also found that speciation of aqueous HAuCl4, prior to reduction, influences the size, morphology, and properties of AuNPs when reduced with CO gas.Ensemble extinction spectra and TEM images provide clear evidence that CO reduction offers a high level of monodispersity with standard deviations as low as 3%.Upon synthesis, no excess reducing agent remains in solution eliminating the need for purification.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Electrical and Computer Engineering, Rice University, MS-366, 6100 Main St,, Houston, TX 77005, USA. drezek@rice.edu.

ABSTRACT
An in depth analysis of gold nanoparticle (AuNP) synthesis and size tuning, utilizing carbon monoxide (CO) gas as a reducing agent, is presented for the first time. The sizes of the AuNPs are tunable from ~4 to 100 nm by altering the concentration of HAuCl4 and inlet CO gas-injection flow rate. It is also found that speciation of aqueous HAuCl4, prior to reduction, influences the size, morphology, and properties of AuNPs when reduced with CO gas. Ensemble extinction spectra and TEM images provide clear evidence that CO reduction offers a high level of monodispersity with standard deviations as low as 3%. Upon synthesis, no excess reducing agent remains in solution eliminating the need for purification. The time necessary to synthesize AuNPs, using CO, is less than 2 min.

No MeSH data available.