title: Tailoring the oxidation state of cobalt through halide functionality in sol-gel silica.
abstract: The functionality or oxidation state of cobalt within a silica matrix can be tailored through the use of cationic surfactants and their halide counter ions during the sol-gel synthesis. Simply by adding surfactant we could significantly increase the amount of cobalt existing as Co3O4 within the silica from 44% to 77%, without varying the cobalt precursor concentration. However, once the surfactant to cobalt ratio exceeded 1, further addition resulted in an inhibitory mechanism whereby the altered pyrolysis of the surfactant decreased Co3O4 production. These findings have significant implications for the production of cobalt/silica composites where maximizing the functional Co3O4 phase remains the goal for a broad range of catalytic, sensing and materials applications.
authors.affiliation: The University of Queensland, FIMLab-Films and Inorganic Membrane Laboratory, School of Chemical Engineering, Brisbane, Qld 4072, Australia.
authors.forename: Gianni
authors.initials: G
authors.lastname: Olguin
authors.forename: Christelle
authors.initials: C
authors.lastname: Yacou
authors.forename: Simon
authors.initials: S
authors.lastname: Smart
authors.forename: João C Diniz
authors.initials: JC
authors.lastname: da Costa
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D006219:Halogens / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D044367:Phase Transition; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D006219:Halogens; D010087:Oxides; D003035:Cobalt; D012822:Silicon Dioxide; C060728:cobalt oxide
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