US scientists Convert Agricultural Waste to SiC
Scientists at the US Naval Research Laboratory (NRL) are exploring ways to convert agricultural waste products such as rice husks, corn stalks, corncobs, sorghum leaves, wheat chaff, peanut shells, and other residues into SiC that can be used for a variety of electronic and structural applications.
Scientists are aware that these agricultural wastes have significantly high silica content in a molecular state, similar to hydrocarbons. Armed with this knowledge, NRL's Syed B. Qadri and his research team have discovered agricultural waste products can be economically transformed into SiC consisting of nanostructures and nanorods in various polytypes.
The NRL team accomplished this by pyrolysis (the heating of an organic material, such as biomass, in the absence of oxygen) to produce the crystalline phases of SiC in various shapes of nanocrystals, nanorods, and nanowires.
By selectively heating and cooling the agricultural waste products, they were able to systematically investigate the role of temperature rise and cooling rates. They observed that this heating and cooling process directly impacts the extended defect formation mechanisms that help in modifying the optical, electrical, and structural properties of these nanoparticles.
SiC is useful in many commercial electronic and structural devices. More recently, SiC nanoparticles have been demonstrated as a promising alternative to plasmonic metals in mid-infrared nanoscale optics, chemical sensing, and optical metamaterials. Qadri explains: "These SiC nanowires and nanotubes produced from agricultural waste products will have many industrial and potential nanotechnology applications."
The NRL research team is investigating the potential for use of SiC for chemical sensing, optical metamaterials, structural composites, and nanoscale electronic. Looking to the future, SiC nanoparticles also promise to provide enhancements in IR spectroscopy.
