Commercial application of Nano-porous silicon

Metallurgical grade Si powder can be jet milled to produce a Si powder with mean particle size from 2 - 40 microns. Stain etching of the Si powder in HF and HNO3 aqueous solutions results in oxidation of silicon and its subsequent reaction with HF result s in dissolution and pore formation into sponge like particles with nano sized pores. The nano porous Si particles are generally classified according to their structural size. The size of the pores can be tailored through electrolyte concentration, temp erature and exposure time in the electrolyte. An important feature of the nano porous Si particles is the plurality of nanocrystals dispersed by nanopores creating sponge-like particles with huge surface area - demonstrating unique properties like: - Uniform nano sponge particles - High surface area and subsequent reactivity - Ability to carry other chemicals (doped catalysts, drug carrier etc.) - Photoluminescent properties Particles with an average size of 2 - 4 micrometers will be fully porous whe re the pores will be 3 - 5 nanometres in size. A BET surface area of +200 m2/g using the N-absorption method has been determined. These unique nanoporous features in silicon could be utilized in commercial applications like. - Explosives and fireworks - Biomedical applications - Catalysis - Absorbents - Sensors The stain etching of metallurgical grade Si powders is a low cost route to produce nano-porous particles and the process is easily scaleable to industrial size production.