Investigations into Sulfobetaine-Stabilized Cu Nanoparticle Formation:  Toward Development of a Microfluidic Synthesis

Abstract

The mechanistic aspects of the formation of sulfobetaine-stabilized copper nanoparticles were investigated by using in situ XANES (X-ray absorption near edge structure), UV-vis spectroscopy, and reaction calorimetry. The tetracoordinated sulfobetaine-Cu(II) complex was reduced to a stable sulfobetaine-Cu(I) complex prior to the formation of sulfobetaine-stabilized copper nanoparticles. The stability of the Cu(I) complex was found to be sensitive to the concentration of the sulfobetaine stabilizer and the addition rate of the reducing agent. It appears to exist primarily as a linear complex. A tetracoordinated Cu(I) complex as an intermediate has also been postulated. Based on the understanding from these investigations, a microfluidic process for copper nanoparticle synthesis was designed by using sulfobetaine-Cu(I) complex as the starting material. When compared with the copper nanoparticles synthesized by a conventional batch process, the microfluidic reactor process provided particles with a smaller size and narrower size distribution. The copper nanoparticles from the microreactor process could also be more easily purified and the particles were relatively stable in air. Both XRD and SAED indicated that the Cu nanoparticles synthesized have fcc structure.

Copper and copper oxide nanoparticles in a cellulose support studied using anomalous small-angle X-ray scattering

“…[35]). Shim et al [36] incorporated copper complexes into cellulose acetate and observed formation of copper and Cu 2 O nanoparticles.…”

Shell-driven Fine Structure Transition of Core Materials in Co@Au Core-shell Nanoparticles

“…neither significant chemical shift of the absorption edge to higher energy nor a systematically higher white line intensity, or a lower pre-edge intensity is observed [31]. Similar to the standard hcp Co foil, the clear pre-edge feature (the first inflection point at 7712.4 eV) and the presence of a shape resonance at about 7759.7 eV indicate that one is dealing with the metallic Co phase [31,35,38]. Little magnetic bias observed in their hysteresis loops further confirms that these Co NPs and Co@Au NPs are free of oxidative impurities or the oxidative layers are too thin to be detected [36,47].…”

“…Cobalt nanoparticles were prepared by the reduction of CoCl 2 (99.9%, anhydrous) in tetrahydrofuran (THF, 99.90% pure packaged under nitrogen) using lithium hydrotriethylborate (LiBH(C 2 H 5 ) 3 , 1 M solution in THF) as a reducing agent and 3-(N,Ndimethyldodecylammonia)-propanesulfonate (SB12, 98%) as a stabilizer in the microfluidic reaction process, which has been discussed extensively in our previous publications [25,28,31,32,35,[37][38][39][40][41]. Co@Au nanoparticles with different shell thickness were prepared by the combination of the displacement method and the reduction-deposition process using KAuCl 4 as Au source, which was described in our recent publication.…”

Microfluidics-Nano-Integration for Synthesis and Sensing

“…It is demonstrated that single-source precursors favour the formation of mono-disperse metal nanoparticles Small copper nanoparticles with a narrow size distribution were produced in a microfluidic device by Kumar et al [26], and Packirisamy et al [27]. The most important property of microdevice-prepared copper nanoparticles is an improved stability to oxidation, very important for any application.…”