Textural and photocatalytic characteristics of iron-cobalt based nanocomposites supported on SBA-15: Synergistic effect between Fe2+ and Fe0 on photoactivity

Abstract

The present work investigates the synthesis of iron-cobalt based nanocomposites supported on SBA-15 and shows a detailed study of their porosity and the photocatalytic activity in methylene blue degradation as a model dye. The textural characterization indicated the presence of interconnected pores after the impregnation process and insertion of Fe and Co on SBA-15. TEM images confirmed that the SBA-15 mesopores were partially filled by Fe and Co species after the addition of metals and an average particle size of 11 nm. The diffractograms revealed the formation of the Fe2SiO4 and CoFe2O4 phases for the O-SBA-15 sample (oxide supported on SBA-15) and the presence of the Fe7Co3 structure for the solid A-SBA-15 (alloy dispersed in mesoporous silica), indicating the phases that are partially blocking the mesopores. The photocatalysis results confirmed that the silica support is essential to optimize the photocatalytic activity of the Fe and Co species in the dye degradation, favoring the accessibility of active sites. The presence of the phase mixture, Fe2SiO4, and Fe7Co3, in OAM-SBA-15 (oxide and alloy supported on SBA-15) sample, favors the photocatalytic activity of methylene blue (MB) due to the synergistic effect between Fe2+ and Fe0. The degradation of the MB occur through a sequence of reactions both on the solid surface and on the solution.