Cobalt-silicon mixed oxide nanocomposites by modified sol-gel method

Journal Article · Fri Dec 14 23:00:00 EST 2007 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2007.09.032· OSTI ID:21043761

Esposito, Serena ^[1]; Turco, Maria ^[2]; Ramis, Gianguido ^[3]; Bagnasco, Giovanni ^[2]; Pernice, Pasquale ^[4]; Pagliuca, Concetta ^[5]; Bevilacqua, Maria ^[3]; Aronne, Antonio ^[4]

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1. Laboratorio Materiali del Dipartimento di Meccanica, Strutture, Ambiente e Territorio, Facolta di Ingegneria dell'Universita di Cassino, Via G. di Biasio 43, I-03043 Cassino (Italy)
2. Dipartimento di Ingegneria Chimica, Universita di Napoli Federico II, P.le Tecchio, I-80125 Naples (Italy)
3. Dipartimento di Ingegneria Chimica e di Processo 'G.B. Bonino', Universita di Genova, P.le J.F. Kennedy, I-16129 Genova (Italy)
4. Dipartimento di Ingegneria dei Materiali e Produzione, Universita di Napoli Federico II P.le Tecchio, I-80125 Naples (Italy)
5. Laboratorio Materiali del Dipartimento di Meccanica, Strutture, Ambiente e Territorio, Facolta di Ingegneria dell'Universita di Cassino, Via G. di Biasio 43, I-03043 Cassino (France) (Italy)

Cobalt-silicon mixed oxide materials (Co/Si=0.111, 0.250 and 0.428) were synthesised starting from Co(NO{sub 3}){sub 2}.6H{sub 2}O and Si(OC{sub 2}H{sub 5}){sub 4} using a modified sol-gel method. Structural, textural and surface chemical properties were investigated by thermogravimetric/differential thermal analyses (TG/DTA), XRD, UV-vis, FT-IR spectroscopy and N{sub 2} adsorption at -196 deg. C. The nature of cobalt species and their interactions with the siloxane matrix were strongly depending on both the cobalt loading and the heat treatment. All dried gels were amorphous and contained Co{sup 2+} ions forming both tetrahedral and octahedral complexes with the siloxane matrix. After treatment at 400 deg. C, the sample with lowest Co content appeared amorphous and contained only Co{sup 2+} tetrahedral complexes, while at higher cobalt loading Co{sub 3}O{sub 4} was present as the only crystalline phase, besides Co{sup 2+} ions strongly interacting with siloxane matrix. At 850 deg. C, in all samples crystalline Co{sub 2}SiO{sub 4} was formed and was the only crystallising phase for the nanocomposite with the lowest cobalt content. All materials retained high surface areas also after treatments at 600 deg. C and exhibited surface Lewis acidity, due to cationic sites. The presence of cobalt affected the textural properties of the siloxane matrix decreasing microporosity and increasing mesoporosity. - Graphical abstract: Highly dispersed cobalt-silicon mixed oxide nanocomposites (Co/Si=0.111, 0.250 and 0.428) were obtained by a modified sol-gel method using almost solely aqueous solutions. The nature of cobalt species and their interactions with the siloxane matrix are strongly depending on both the cobalt loading and the heat treatment. All materials retained high surface areas also after treatments at 600 deg. C and exhibited surface Lewis acidity.

• OSTI ID: 21043761
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 12 Vol. 180; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
AQUEOUS SOLUTIONS
COBALT
COBALT IONS
COBALT NITRATES
COBALT OXIDES
COMPOSITE MATERIALS
DIFFERENTIAL THERMAL ANALYSIS
FOURIER TRANSFORMATION
GELS
HEAT TREATMENTS
INFRARED SPECTRA
NANOSTRUCTURES
SILICON OXIDES
SOL-GEL PROCESS
SURFACE AREA
SURFACES
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0400-1000 K
THERMAL GRAVIMETRIC ANALYSIS
X-RAY DIFFRACTION