Synthesis of CuO and Cu₃N Nanoparticles in and on Hollow Silica Spheres

Copper oxide nanoparticles within hollow mesoporous silica spheres were prepared by binding/adsorbing Cu²⁺ or [Cu(NH₃)₄(H₂O)₂]²⁺ ions on the surface of carbon spheres, followed by formation of a mesoporous silica shell by sol-gel processing and calcination in air. The CuO nanoparticles can subsequently be converted into Cu₃N nanoparticles by nitridation with ammonia. The effect of the different copper precursors, i.e. Cu²⁺ and [Cu(NH₃)₄(H₂O)₂]²⁺, on the nanocomposites was studied. CuO nanoparticles on the outer surface of hollow silica spheres were obtained by thermal treatment of hollow CuSiO₃ spheres in air. Nitridation of the CuSiO₃ spheres with ammonia resulted in Cu₃N@SiO₂ composites, with aggregated Cu₃N nanoparticles on hollow silica spheres.