dependence of photocatalytic activity of tio2-sio2 nanopowders

structural properties and chemical composition change the photocatalytic activity in tio2-sio2 nanopowder composite. the sio2-tio2 nanostructure is synthesized based on sol–gel method. the nanoparticles are characterized by x-ray fluorescents (xrf), x- ray diffraction (xrd), tunneling electron microscopy (tem), field emission scanning electron microscopy (fe-sem), uv-vis. spectrophotometer and furrier transmission create infrared absorption (ftir) techniques. the rate constant k for the degradation of methylen blue in its aqueous solution under uv irradiation is determined as a measure of photocatalytic activity. dependence between photocatalytic activity and sio2 content in the composite is determined. rate constant k is found dependent on the content of sio2 in the composite that calcined at 900 oc. the addition of low composition sio2 to the tio2 matrix (lower than 45%) enhances the photocatalytic activity due to thermal stability and increasing in the surface area. the effects of chemical compositions on the surface topography and the crystallization of phases are studied.