On the Effects of Diluted and Mixed Ionic Liquids as Liquid Substrates for the Sputter Synthesis of Nanoparticles

Abstract

The synthesis of nanoparticles by combinatorial sputtering in ionic liquids is a versatile approach for discovering new materials. Whereas the influence on nanoparticle formation of different pure ionic liquids has been addressed, the influence of (I) dilution of ionic liquid with solvents and (II) different mixtures of ionic liquids is less known. Therefore, mixtures of the ionic liquid [Bmim][(Tf)2N] with the organic solvent anisole and other ionic liquids ([Bmim][(Pf)2N], [BmPyr][(Tf)2N]) were used as liquid substrates for the sputter synthesis of nanoparticles, in order to investigate the influence of these mixtures on the size of the nanoparticles. First, mixtures of anisole with a suspension of sputtered Ag nanoparticles in [Bmim][(Tf)2N] were prepared in different volumetric steps to investigate if the stabilization of the NPs by the ionic liquid could be reduced by the solvent. However, a continuous reduction in nanoparticle size and amount with increasing anisole volume was observed. Second, Ag, Au and Cu were sputtered on ionic liquid mixtures. Ag nanoparticles in [Bmim][(Tf)2N]/[Bmim][(Pf)2N] mixtures showed a decrease in size with the increasing volumetric fraction of [Bmim][(Tf)2N], whereas all nanoparticles obtained from [Bmim][(Tf)2N]/[BmPyr][(Tf)2N] mixtures showed increasing size and broadening of the size distribution. Maximum sizes of sputtered Ag and Au NPs were reached in mixtures of [Bmim][(Tf)2N] with 20 vol.% and 40 vol.% [BmPyr][(Tf)2N]. The results indicate that ionic liquid mixtures with different portions of cations and anions have the capability of influencing the ionic liquid stabilization characteristics with respect to, e.g., nanoparticle size and size distribution.

Sputtering onto liquids: a critical review

“…A wide range of elements has been successfully sputtered onto liquids to create monometallic NPs, including Au [12, 114, 115, 118, 120, 122, 125, 126, 129, 132, 134, 138, 139, 142, 143, 145 -149, 153, 167, 174 -176, 180 -183, 188, 189, 203,204,207,208,210,211,214,216,218,229-238], Ag [11,118,119,123,131,164,175,179,184,185,188,196,205,206, 217, 218, 231-233, 239], Cu [150,155,164,188,189,198,210,230,240,241], Pt [121,133,163,168,169,186,[242][243][244][245], Pd [116,212,231,242,246,247], Fe [11,161,162], In [187], Ni [135] and Mo [20...…”

Controlling the oxidation state of molybdenum oxide nanoparticles prepared by ionic liquid/metal sputtering to enhance plasmon-induced charge separation

“…4,[25][26][27][28][29] On the other hand, room-temperature ionic liquids (RTILs) have been fascinating media to prepare nanostructured materials because the obtained structures were quite stable without the addition of any stabilizing agents. [30][31][32][33][34][35][36][37][38][39] We have reported strategies to prepare metal and alloy NPs by sputtering a metal onto RTILs under a reduced pressure, the RTIL/metal sputtering technique, with the use of unique features of RTILs such as extremely low vapor pressure and high thermal stability. [40][41][42] This technique enabled clean preparation of plasmonic NPs such as Au, 43 Ag, 44 Cu, 45 AgAu, 46 and AuCu.…”

Enhancing composition control of alloy nanoparticles from gas aggregation source by in operando optical emission spectroscopy

“…A broad variety of PVD‐based strategies to produce alloy NPs with control over NP composition has already been employed successfully. These PVD strategies include surface energy‐related self‐organization of NPs on solid substrates [ 25,33–35 ] and in liquids (i.e., “Sputter into liquids”) [ 36–38 ] as well as gas‐phase synthesis. In this study, alloy AgAu NPs are fabricated using a PVD approach known as gas aggregation cluster source (GAS), which was first realized by Haberland in 1992.…”