Synthesis and Characterization of Silica−Copper Oxide Composite Derived from Microemulsion Processing

Abstract

Silica−copper composite powders with high surface areas of about 200−400 m2/g have been successfully synthesized by the controlled hydrolysis/polymerization of sodium metasilicate (Na2SiO3) and copper nitrate [Cu(NO3)2·3H2O] via partial-microemulsion and double-microemulsion processes at 28 °C. Each microemulsion system consists of sodium 1,4-bis(2-ethylhexyl) sulfosuccinate and sodium dodecyl sulfate, cyclohexane, and an aqueous solution of sodium metasilicate or copper nitrate. The partial-microemulsion method can produce silica−copper oxide composites consisting of nanoparticles ranging from 20 to 50 nm with an uniform elemental distribution. The composites also exhibit a narrow distribution of mesopores (3−6 nm) having specific surface areas ranging from 320 to 370 m2/g. This partial-microemulsion process is very attractive because ultrafine powders of silica−copper oxide composites can be produced from inexpensive Na2SiO3 using relatively low amounts of organic solvent and surfactants. However, the role of mixed anionic surfactants in the microemulsions affecting the formation of these nanocomposites is yet to be clarified.