Synthesis of nanocomposites SiO 2@Co 3 O 4, SiO 2@ZnO, and SiO 2@CuO from rice husks: spectroscopy and optical properties

Abstract

In this work, we present two methodologies to prepare nano compounds derived from a mixture of metals oxides supported in biogenic silica nanoparticles. Cobalt, copper, and zinc salts were used to impregnate the silica nanoparticles by two different methods. In the first method, called, Direct method, the rice husks were impregnated with salts solutions of the metals of interest and then thermally treated and sintered to obtain the respective silica nanocomposite, in the second method, the Indirect method, silica nanoparticles were prepared from biogenic materials and then were impregnated with the metal solution and sintered. Samples obtained by both methods were characterized by SEM, DLS, and AFM, the composition was determined by LiBS and their optical properties by Uv–vis, FTIR and the variations in the bandgap of the metal oxides and the effect of the metal oxide’s confinement within the nanoparticle structure were studied. The bandgap values obtained for the samples correspond to those of oxide nanoparticles of the corresponding metals, with small variations due to confinement by being embedded in the SiO2 matrix.