Synthesis of cobalt–iron bimetallic nanocrystals supported on mesoporous silica using different templates

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 358; no. 1; pp. 79 - 87
• Main Authors: Bragança, L.F.F.P.G., Avilez, Roberto R., Silva, Maria Isabel Pais da
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 05-04-2010; Elsevier
• Subjects: Atomic absorption analysis; Bimetallic CoFe/HMS; Bimetals; Chemisorption; Chemistry; Co/HMS; Cobalt; Colloidal state and disperse state; Exact sciences and technology; Fe/HMS; General and physical chemistry; Hexagonal mesoporous silica; Iron; Porous materials; Reduction; Silicon dioxide; Spectroscopy; Surface physical chemistry; Bimetallic CoFe/HMS; Co/HMS; Fe/HMS; Hexagonal mesoporous silica; Binary compound; Support; Hydrogen; Iron; Cobalt; Porous material; Physisorption; Silica; Template; Chemical reduction; Crystallites; Synthesis; Iron nitrate; Structure; Nanocrystal; Chemisorption; Transition element compounds; Thermogravimetry; Transition metal; Differential thermal analysis; X ray diffraction; Dispersion; Mesoporosity; Impregnation; Pore; Cobalt nitrate
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2010.01.025

CoFe 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). A series of HMS silicas have been prepared by a neutral assembly pathway using two types of structure director: dodecylamine (DDA) and tetradecylamine (TDA). The effect of different templates in the formation of HMS mesoporous silica and bimetallic CoFe supported samples has been investigated and characterized by N
2 physisorption, X-ray diffraction (XRD), temperature programmed reduction (TPR), hydrogen chemisorption, thermogravimetric (TGA) and differential thermal (DTA) analyses. The amount of incorporated metal was estimated by atomic absorption spectroscopy (AAS). Also, a series of supported monometallic cobalt/iron samples were synthesized and compared to bimetallic ones. The textural properties revealed a lower percentage decrease in BET area and total pore volume for the CoFe/HMS (DDA) sample. XRD results showed α-Fe
2O
3 phase formation and higher Co
3O
4/CoFe
2O
4 crystallite sizes for CoFe/HMS (TDA) sample. The latter also presented lower reduction temperatures and a slightly lower dispersion (%) compared to CoFe/HMS (DDA).