화학공학소재연구정보센터
Materials Chemistry and Physics, Vol.138, No.1, 17-28, 2013
Synthesis and characterization of Co-Fe nanoparticles supported on mesoporous silicas
Co-Fe bimetallic samples containing 25 wt% total of metal content were prepared by incipient wetness impregnation of cobalt nitrate and iron nitrate salts over hexagonal mesoporous silica (HMS) and SBA-15 supports. Changes in the textural properties and reduction behavior were compared with monometallic cobalt/iron-based samples. The samples were characterized by N-2 physisorption, X-ray diffraction (XRD), H-2-temperature programmed reduction (TPR), transmission electron microscopy (TEM) and H-2 chemisorption. The amount of incorporated metal was estimated by atomic absorption spectroscopy (AAS). Morphological properties revealed that after introduction of the metal to the SBA-15 support, the specific area, pore volume and pore diameter decreased to a lesser extent for bimetallic samples. XRD measurements detected the formation of Co3O4 and CoFe2O4 phases for both bimetallic samples. TPR profiles indicated similar behavior for both the bimetallic and monometallic samples. Higher temperatures were observed for the reducibility of Co-Fe/HMS as compared to Co-Fe/SBA-15. Dispersion values of the bimetallic samples were higher than Fe monometallic samples and lower than Co monometallic samples according to hydrogen chemisorption. The particle size distribution of the bimetallic samples estimated by TEM microphotographs showed a smaller fraction of larger size particles for Co-Fe/SBA-15. (C) 2012 Elsevier B.V. All rights reserved.