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

Joseph K Young,Robert J Langsner,Rebekah A Drezek,Laura C Kennedy,Vengadesan Nammalvar,Nastassja A Lewinski,Adam Y Lin,Arthi Satyanarayan

doi:10.1186/1556-276x-6-428

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.

Highlights

Metallic nanoparticles have attracted substantial attention due to their distinctive properties and various applications
Each sample was aerated at different flow rates controlled by a control valve
The five solutions were exposed to carbon monoxide (CO) gas at flow rates of 16.9, 25.45, 31.59, 37.0, and 42.9 mL/min, respectively

Summary

Background

Metallic nanoparticles have attracted substantial attention due to their distinctive properties and various applications. By adjusting the size of the gold nanoparticles, this optical resonance can be positioned over hundreds of nanometers in wavelength across the visible into the near infrared spectrum [1,2] Since these oscillations are located on the boundary of the metal and the external medium, these waves are very sensitive to changes in this boundary, such as the absorption of molecules to the metal surface [3]. The time necessary to produce AuNPs using CO is less than 2 min compared to 20 min for comparable particle sizes using citrate reduction and 45 min for discharge plasma synthesis. CO reduction offers a cheap and flexible alternative to femtosecond laser-based AuNP synthesis processes while eliminating the need for surfactants and polymers to tune the nanoparticle sizes. Ensemble extinction spectra and TEM images provide clear evidence that CO reduction offers excellent AuNP tunability and is a viable alternative to other synthesis methods

Results and discussion

Conclusions

Methods

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