Issue 26, 2009
From the journal:

Physical Chemistry Chemical Physics

Formation of gold and gold sulfide nanoparticles and mesoscale intermediate structures in the reactions of aqueous HAuCl4 with sulfide and citrate ions

Yuri Mikhlin,*a   Maxim Likhatski,a   Anton Karacharov,a   Vladimir Zaikovskib  and  Alexander Krylovc  

* Corresponding authors

a Institute of Chemistry and Chemical Technology of the Siberian Branch of the Russian Academy of Sciences, K. Marx Street, 42, Krasnoyarsk, Russia
E-mail: yumikh@icct.ru
Fax: +7 391 2238658
Tel: +7 391 2494885

b Boreskov Institute of Catalysis of Siberian Branch of Russian Academy of Sciences, Pr. Lavrent’eva, 5, Novosibirsk, Russia

c Kirensky Institute of Physics of the Siberian Branch of the Russian Academy of Sciences, Akademgorodok, Krasnoyarsk, Russia

Abstract

The effects of the molar ratio of sodium sulfide to chloroauric acid in the range of 0.5 to 5 and the time factor on the formation of the nanoparticles (NPs) of metallic Au, Au2S or their mixtures have been studied applying in situ and ex situ techniques (UV-Vis absorption spectroscopy, potentiometry, TEM, SPM, SERS, XPS). The products and intermediates have been compared with those for the reduction of chloroaurate with citrate ions and combinations of citrate and sulfide ions. An increase in the concentration of sulfide ions accelerates the reduction of Au(III) complexes but hinders the nucleation and growth of Au NPs, resulting in a prolonged period before the appearance of plasmon peaks. The electrochemical potential is not directly associated with the plasmon intensities, although the potential sharply decreases simultaneously with a blue shift of the near-IR peak emerging with the Na2S/HAuCl4 ratios of 0.5 to 1.5. It was concluded that the peak is due to longitudinal plasmon resonance of gold nanoplates. Au2S NPs, the nucleation of which is effectively inhibited, and probably some structures and fragments visible in TEM and AFM, including 2–5 nm Au NPs, crystallize in part outside the solutions. The evidence of partially liquid mesoscale structures comprising intermediate gold species as precursors of nanoparticles is presented, and their origin, ex situ transformation and role in the reaction mechanisms are discussed.

Graphical abstract: Formation of gold and gold sulfide nanoparticles and mesoscale intermediate structures in the reactions of aqueous HAuCl4 with sulfide and citrate ions

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Article information

DOI
https://doi.org/10.1039/B823539B
Article type
Paper
Submitted
08 Jan 2009
Accepted
23 Mar 2009
First published
20 Apr 2009

Phys. Chem. Chem. Phys., 2009,11, 5445-5454

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Formation of gold and gold sulfide nanoparticles and mesoscale intermediate structures in the reactions of aqueous HAuCl4 with sulfide and citrate ions

Y. Mikhlin, M. Likhatski, A. Karacharov, V. Zaikovski and A. Krylov, Phys. Chem. Chem. Phys., 2009, 11, 5445 DOI: 10.1039/B823539B

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