Synthesis of silicon nanowires from carbothermic reduction of silica fume in RF thermal plasma

Abstract

Silica fume, which is a by-product of metallurgical-grade silicon production, is a low cost material with high SiO 2 concentration and small particle size (<1 mm). These properties make it a good candidate for radio-frequency (RF) thermal plasma processing. In this article, the use of silica fume as a reactant is promoted for the RF thermal plasma synthesis of high-charge capacity, high cyclability anode materials for lithium-ion batteries. In order to obtain these materials, the carboreduction of silica fume is followed by an in-flight growth of silicon nanowires in the plasma reactor. The impact of the addition of catalysts and the use of different plasma gases on the yield and the properties of the product has been investigated by X-ray diffractometry (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), and transmission electron microscopy (TEM). It is found that the addition of metal catalysts has a significant effect on the synthesis. It not only promoted the formation of silicon nanowires, but also improved the yield of the reaction upwards of 300%. An insight on the mechanisms leading to the silicon nanowires formation is also discussed in the results section.

Growth Mechanisms of Inductively-Coupled Plasma Torch Synthesized Silicon Nanowires and their associated photoluminescence properties

“…We conclude that the formation of SiNSs is mainly due to the spheroidization process inside the plasma chamber, while the SiNWs can grow according to both the OAG and VLS mechanisms (with a predominance of the OAG mechanism if no intentional metal catalyst is added, as is the case here). These results constitute a solid basis towards a better-controlled growth of SiNWs via the ICP technique, where the content and nature of the catalyst can be controlled39. The ICP is a genuinely bulk process, which can be advantageously exploited for large scale production of thin SiNWs needed to integrate Si into attractive large-area optoelectronic devices and flexible electronics.…”

Structural and photoluminescence properties of silicon nanowires extracted by means of a centrifugation process from plasma torch synthesized silicon nanopowder

“…Plasma torches are commonly used to produce powders of various nanomaterials and are well implemented in some industrial sectors [25]. Very recently, there has been a paper reporting on the direct synthesis of SiNWs with a certain success through the metal-catalyst assisted carbothermic reduction of silica fume in RF thermal plasma torch [26]. During the ICP torch based spheroidization process, part of the silicon powder feedstock sublimates and leads to the synthesis of silicon nanostructures which mainly accumulate in the filtration unit of the secondary collector of the reactor.…”

Numerical study of Si nanoparticle formation by SiCl4hydrogenation in RF plasma

“…Then, this study would open the way to the production of silicon nanoparticles at low operating cost. This point will be discussed more deeply in further work as it could be very interesting for many application fields, such as material processing (nanoparticle synthesis, material treatment [48]) or thermochemical processing (pyrolysis [57,58], waste treatment [59]).…”