Size control and immobilization of gold nanoparticles stabilized in an ionic liquid on glass substrates for plasmonic applications

Abstract

Gold (Au) nanoparticles were prepared by sputter deposition of Au metal in an ionic liquid (IL) of 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6). The size of Au nanoparticles was increased from 2.6 to 4.8 nm by heat treatment at 373 K. The nanoparticles uniformly dispersed in the IL were densely immobilized on a glass substrate surface modified with a silane coupling agent having an imidazole functional group by spreading the Au particle IL solution on the substrates, followed by heat treatment at 373 K. The optical property of the thus-obtained films was tunable by controlling the size of Au nanoparticles in the IL and the degree of immobilization. An intense localized surface plasmon resonance (LSPR) peak was observed in each Au particle film, and the wavelength of the LSPR peak could be controlled by changing the size of nanoparticles in the IL solution before immobilization. Photoexcitation of the LSPR peak caused enhancement of the photoluminescence of CdTe nanoparticles immobilized on Au nanoparticle films, probably due to the locally enhanced electric field formed around Au nanoparticles.

Nanoparticle Preparation in Room-Temperature Ionic Liquid under Vacuum Condition

“…Future challenge in this field will be how we collect the metal nanoparticles suspended in RTILs and how we develop a metal nanoparticle mass production method. Regarding the former matter, we found a facile way that is adsorption of the suspended nanoparticles on a solid substance (Kameyama et al, 2010;Okazaki et al, 2009;Tsuda et al, 2009b;Tsuda et al, 2010b). Nanoparticles are stably suspended in RTIL by the interaction with ionic species exciting around the nanoparticles.…”

“…Figure 3 shows a schematic illustration of this method that uses a common magnetron sputtering apparatus except for the use of RTIL as a substrate. This method has achieved the preparation of various pure metal nanoparticles, such as Au Hatakeyama et al, 2010;Kameyama et al, 2010;Khatri, et al, 2008;Okazaki et al, 2009;Shishino et al, in press;Torimoto et al, 2006;Wender et al, 2010), Ag Suzuki et al, 2009), Pt (Tsuda et al, 2009b;Tsuda et al, 2010b), In (Suzuki et al, in press) etc., possessing particle sizes less than 10 nm in diameter without any specific stabilizing agent. Small-angle X-ray scattering study revealed initial formation mechanism of the gold nanoparticles during the sputtering process onto several 1,3-dialkylimidazolium tetrafluoroborate ).…”

“…Several reserch groups including us have succeeded in metal nanoparticle prepration by using both RTIL and the vacuum technologies, e.g., physical vapor deposition (PVD) method (Richter et al, 2010;Prondzinski et al, 2010) and plasma depostion method Abedin et al, 2007;Baba et al, 2009;Kaneko et al, 2009;Brettholle et al, 2010). In this chapter, we introduce our created nanoparticle preparation methods in RTIL under vacuum condition including electron beam (Imanishi et al, 2009;Tsuda et al, 2009a;Tsuda et al, 2010a) and γ-ray radiation method (Tsuda et al, 2009a), magnetron sputtering onto IL Hatakeyama et al, 2010;Kameyama et al, 2010;Khatri et al, 2008;Okazaki et al, 2008;Okazaki et al, 2009;Shishino et al, in press;Suzuki et al, 2009;Suzuki et al, in press;Torimoto et al, 2006;Tsuda et al, 2009;Tsuda et al, 2010b;Wender et al, 2010). The contents also include electrochemical applications of Pt nanoparticles produced by the methods established in our group.…”

Ionic Liquids for the Synthesis and Stabilization of Metal Nanoparticles

“…Likewise, Au-NPs were prepared by sputter deposition of Au metal in [BMIm] [PF 6 ]. The size of Au nanoparticles was increased from 2.6 to 4.8 nm by heat treatment at 373 K [175].…”

On the formation of anisotropic gold nanoparticles by sputtering onto a nitrile functionalised ionic liquid

“…[9][10][11][12][13][14] Moreover, in the case of sputtering deposition onto ILs, very stable spherical NPs are easily prepared by simply adjusting the physical parameters during the sputtering process, allowing for control of the NPs size and size distribution without the addition of extra stabilisers. 15 However, the factors that govern NPs growth in the sputtering process are still unclear. In fact, recent reports suggest that NPs nucleate and grow on the IL surfaces, 16 as also observed for sputtering onto castor oil.…”