291885 A Simple,Facile Approach to Silicon Nanoparticles

Monday, October 29, 2012
Hall B (Convention Center )
Luke Minardi, Department of Chemical Engineering, Rowan University, Glassboro, NJ, Rigved Epur, Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA and Prashant Kumta, Bioengineering, University of Pittsburgh, Pittsburgh, PA

Silicon nanoparticles are ubiquitously used in various applications such as energy storage devices, semiconductors, biosensors, drug delivery etc. Current methods of producing silicon nanoparticles include chemical vapor deposition (CVD), laser pyrolysis and gas evaporation. These methods require expensive starting materials, complicated instrumentation, and skilled labor resulting in low yields of the final product. Mechanical milling is an attractive simple, economic and industrially viable approach for generating large quantities of material involving inexpensive precursors and processing equipment requiring minimal skilled labor intervention. Herein, we report a simple two step technique for large scale synthesis of silicon nanoparticles using high energy mechanical milling (HEMM) followed by acid etching. Silicon monoxide (SiO) was chosen as the silicon precursor which was reduced with Magnesium silicide (Mg2Si) during mechanical milling. Following HEMM process, the products were then subjected to two subsequent acid washes. Initially the products were washed with hydrochloric acid to dissolve the magnesium oxide (MgO) product followed by hydrofluoric acid (HF) for etching the silicon surface. The HF wash is critical for decreasing the particle size. X-Ray Diffraction (XRD) was used to study the kinetics of the mechano-chemical reducing reaction between SiO and Mg2Si to form silicon. XRD crystallite size analysis of the final product showed the formation of single phase silicon with a crystallite size ~ 45 nm. Raman spectra obtained on the silicon confirmed formation of nanocrystalline silicon. Surface area measurements indicated a very high surface area of ~190 m2/g. Morphological studies conducted using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the presence of agglomerates of nanosized silicon particles. Results of these current studies demonstrate the generation of nanostructured silicon via HEMM, a simple and easily scalable approach.

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