Abstract
Rice, which provides a major source of food for billions of people, covers 1% of the surface of the earth. Rice husk (RH), the outer covering of paddy rice, is an important byproduct during the milling process, and residue ash is generated after the burning of RH that is called rice husk ash (RHA), which is a primary waste material in the agricultural industry. The main components in RH are lignin, cellulose, and hemicellulose, which are generally named lignocellulose. RH also contains ca. 15 to 28 wt% of silica. The high content of silica in RH presents opportunities for the preparation of value-added silicon-based materials. Since the 1970s, various silicon-based materials, including silica, silicon carbide, silicon nitride, silicon tetrachloride, zeolite, and silicates, have been successfully synthesized using RH as the silicon source. This field of research has been significantly advanced and expanded in the past decade spurred by the global attention on sustainable and renewable resources.