Metal Oxide-Related Dendritic Structures: Self-Assembly and Applications for Sensor, Catalysis, Energy Conversion and Beyond.

In the past two decades, we have learned a great deal about self-assembly of dendritic metal oxide structures, partially inspired by the nanostructures mimicking the aesthetic hierarchical structures of ferns and corals. The self-assembly process involves either anisotropic polycondensation or molecular recognition mechanisms. The major driving force for research in this field is due to the wide variety of applications in addition to the unique structures and properties of these dendritic nanostructures.

Sol-gel synthesis of 2-dimensional TiO: self-assembly of Ti-oxoalkoxy-acetate complexes by carboxylate ligand directed condensation.

2-Dimensional (2D) metal oxides have many potential industrial applications including heterogeneous catalysis, water splitting, renewable energy conversion, supercapacitor applications, biomaterials, gas separation and gas storage. Herein we report a simple and scalable method for the preparation of 2D TiO nanostructures by reaction of titanium isopropoxide with acetic acid at 333 K in isopropanol, followed by calcination at 673 K to remove the organic ligands. Both the products and reaction intermediates have been studied using electron microscopy, X-ray diffraction, N physisorption, nuclear magnetic resonance, thermogravimetric analysis, and X-ray photoelectron, Raman, and infrared spectroscopy.

Synthesizing 1D and 2D metal oxide nanostructures: using metal acetate complexes as building blocks.

1D and 2D metal oxide nanostructures are important for potential applications in alternative energy, batteries, supercapacitors, catalysts, biomaterials, and electronic nanodevices. Many current approaches for making the desired nanomaterials require multiple steps, which are often exotic and complex for production on a commercial scale. In contrast, the sol-gel reactions between metal alkoxides and organic acids have emerged as a simple protocol for producing metal oxides and inorganic/organic hybrid materials with a controllable 1D or 2D architecture.

Selective Adsorption of Thiols Using Gold Nanoparticles Supported on Metal Oxides.

Selective capture of thiols from a synthetic hydrogen sulfide containing mixture using supported nanogold materials has been explored for the potential removal of thiols from sour gas production fluids. In this research, TiO2-, Al2O3-, SiO2-, and ZnO-supported gold nanoparticles have been studied for their usage as regeneratable adsorbents to capture CH3SH, C2H5SH, and i-C3H7SH. Au/TiO2 and Au/Al2O3 showed promising properties for removing the thiols efficiently from a gas-phase mixture; however, Au/Al2O3 did catalyze some undesirable side reactions, e.

A comparison of several nanoscale photocatalysts in the degradation of a common pollutant using LEDs and conventional UV light.

A comparative study on the photocatalytic activities of four different catalysts, P-25 TiO(2), TiO(2) nanofibers, tin-doped TiO(2) nanofibers under UV light irradiation at 350 nm, and coumarin (C-343) coated TiO(2) nanofibers at 436 nm light emitting diodes (LED) is reported. Catalysts performance has been compared based on their reflectance spectrum and activity. A common water contaminant 4-chlorophenol was used as a substrate to compare the activity of the different catalysts under both direct and dye sensitized conditions.

Study of the sol-gel reaction mechanism in supercritical CO2 for the formation of SiO2 nanocomposites.

Direct sol-gel reactions in supercritical CO2 (scCO2) have attracted significant interest for synthesizing nanomaterials by reacting alkoxides with a carboxylic acid. In this study, the hydrolysis of silicon alkoxides (TEOS or TMOS) was carried out using scCO2 as the solvent to generate silica nanoparticles within the matrix of polyethylene for the synthesis of polymeric nanocomposites. This methodology provides advantages of combining the sol-gel reactions and drying into a one-step process for producing polymer nanocomposites.

Synthesis of TiO(2)-PMMA nanocomposite: using methacrylic acid as a coupling agent.

Inorganic-polymer nanocomposites are of significant interest for emerging materials due to their improved properties and unique combination of properties. Methacrylic acid (MA), a functionalization agent that can chemically link TiO2 nanomaterials (n-TiO2) and polymer matrix, was used to modify the surface of n-TiO2 using a Ti-carboxylic coordination bond. Then, the double bond in MA was copolymerized with methyl methacrylate (MMA) to form a n-TiO2-PMMA nanocomposite.

FTIR study on the formation of TiO2 nanostructures in supercritical CO2.

TiO(2) nanospherical and fibered structures were obtained via a one-step sol-gel method in supercritical carbon dioxide (scCO(2)) involving polycondensation of the alkoxide monomers titanium isopropoxide (TIP) and titanium butoxide (TBO) with acetic acid (HAc). The resulting materials were characterized by means of electron microscopy (SEM and TEM), X-ray diffraction (XRD), thermal analysis (TGA), and attenuated total reflection Fourier transmission infrared (ATR-FTIR) analysis. Depending on the experimental conditions, TiO(2) anatase nanospheres with a diameter of 20 nm or TiO(2) anatase/rutile nanofibers with a diameter of 10-100 nm were obtained.

Direct synthesis of zirconia aerogel nanoarchitecture in supercritical CO2.

The objective of the present study was to synthesize porous ZrO2 aerogels with a nanostructure via a direct sol-gel route in the green solvent supercritical carbon dioxide (scCO2). The synthesis involved the coordination and polycondensation of a zirconium alkoxide using acetic acid in CO2, followed by scCO2 drying and calcination. Either a translucent or opaque monolith was obtained, which was subsequently characterized by electron microscopy, X-ray diffraction, thermal analysis, N2 physisorption, and infrared spectroscopy analysis.

Formation of titania nanofibers: a direct sol-gel route in supercritical CO2.

In this letter, we present a new method to synthesize titania nanofibers with nanocrystallites via a sol-gel route in supercritical CO2. The nanofibers were formed by the esterification and condensation of titanium alkoxides using acetic acid as the polymerization agent in supercritical CO2 from 40 to 70 degrees C and 2500 to 8000 psia. The TiO2 nanofiber morphology was characterized by means of SEM and HRTEM, which indicated that the diameters ranged from 9 to 100 nm.