Mesoporous tertiary oxides via a novel amphiphilic approach

We report a facile biomimetic sol-gel synthesis using the sponge phase formed by the lipid monoolein as a structure-directing template, resulting in high phase purity, mesoporous dysprosium- and gadolinium titanates. The stability of monoolein in a 1,4-butanediol and water mixture complements the use of a simple sol-gel metal oxide synthesis route. By judicious control of the lipid/solvent concentration, the sponge phase of monoolein can be directly realised in the pyrochlore material, leading to a porous metal oxide network with an average pore diameter of 10 nm

Synthesis of Well-Defined, Surfactant-Free Co₃O₄ Nanoparticles:The Impact of Size and Manganese Promotion on Co₃O₄ Reduction and Water Oxidation Activity

Abstract: A surfactant-free synthetic route has been developed to produce size-controlled, cube-like cobalt oxide nanoparticles of three different sizes in high yields. It was found that by using sodium nitrite as salt-mediating agent, near-quantitative yields could be obtained. The size of the nanoparticles could be altered from 11 to 22 nm by changing the cobalt concentration and reaction time. These surfactant-free nanoparticles form ideal substrates for facile deposition of further elements such as manganese. The effect of size of the cobalt oxide nanoparticles and the presence of manganese on the reducibility of cobalt oxide to metallic cobalt was investigated. Similarly, the effect of these parameters was investigated with a visible light promoted water oxidation system with cobalt oxide as catalyst, together with [Ru(bpy) 3] 2+ light harvester dye and an electron acceptor. Graphical Abstract: A novel surfactant-free synthetic route has been developed to produce size-controlled, cube shaped cobalt oxide nanoparticles in high yields. [Figure not available: see fulltext.]. </p

Synthesis and shape modification of organo-functionalised silica nanoparticles with ordered mesostructured interiors

Organo-functionalised MCM-41 nanoparticles have been prepared by a dilution/neutralisation method involving the surfactant-templated co-condensation of 3-aminopropyltriethoxysilane, allyltriethoxysilane or 3-mercaptopropyltriethoxysilane with tetraethoxysilane under alkaline conditions. The presence of covalently coupled organic groups within the hexagonally ordered silica mesophase was confirmed by solid-state C-13 and Si-29 MAS NMR spectroscopy. TEM studies show that amine- and allyl-functionalised nanoparticles are single-domain oblate ellipsoidal crystals, in which the cylindrical micelles are aligned parallel to the morphological minor axis. In contrast, the thiol-functionalised nanoparticles were synthesised in the form of nanofilaments elongated specifically along the channel direction of the MCM-41 hexagonal mesostructure. A mechanism is proposed in which changes in the nanoparticle morphology are attributed predominantly to an increase in surface charge associated with the anionic mercaptopropyl groups that inhibits the side-on attachment of silica-surfactant micelles to partially ordered primary nanoclusters. In contrast, nanoparticles with neutral side chains, such as amino and allyl moieties, as well as unfunctionalised MCM-41, develop by side-on attachment to radially arranged defect sites of a modulated hexagonal mesophase associated with the oblate ellipsoidal morphology

Mesoporous tertiary oxides via a novel amphiphilic approach

ABSTRACT We report a facile biomimetic sol-gel synthesis using the sponge phase formed by the lipid monoolein as a structure-directing template, resulting in high phase purity, mesoporous dysprosium- and gadolinium titanates. The stability of monoolein in a 1,4-butanediol and water mixture complements the use of a simple sol-gel metal oxide synthesis route. By judicious control of the lipid/solvent concentration, the sponge phase of monoolein can be directly realised in the pyrochlore material, leading to a porous metal oxide network with an average pore diameter of 10 nm