Search results for "Titan"
showing 10 items of 1109 documents
The effect of the surface disordered layer on the photoreactivity of titania nanoparticles
2017
It is well known that the surface of metal oxide catalysts presents, usually, non-crystalline species containing impurities and low coordinated cations, which are observed in HRTEM images as a disordered layer of amorphous phase. Despite of being these species more accessible and less stable than the crystalline catalysts components, they have been rarely considered when analysing the catalyst activity. In this work, we have studied the effect of a treatment with HCl solution at pH = 0 on the characteristics of the disordered layer in two commercial anatase TiO2 samples, using techniques such as TGA, 1H MAS-NMR and HRTEM, and by determining these sample photocatalytic activity for the 4-nit…
A study of the interaction between iron(III)oxide and titanium(IV)oxide at elevated temperatures
1991
Abstract The bulk interaction between iron(III) oxide and titanium(IV) oxide occurs at temperatures in excess of 773 K. Initially iron(III) ions dissolve in the titanium(IV) oxide structure to produce a substitutional solid solution. Magnetic evidence suggests that there is a solubility limit of iron(III) ions in the region of ca. 3 atom %. Significantly the phase transition from the anatase phase to the rutile phase is observed to occur approximately 200 K lower in the presence of iron than when it is absent. Further reaction between iron(III) oxide and the saturated solution in the rutile phase occurs at 1073 K with the formation of pseudo-brookite. Under high vacuum conditions the therma…
Step-by-Step Growth of HKUST-1 on Functionalized TiO2 Surface: An Efficient Material for CO2 Capture and Solar Photoreduction
2018
The present study reports on a simple preparation strategy of a hybrid catalyst, TiO2/HKUST-1, containing TiO2 anatase nanoparticles (NPs) with tailored morphology and photocatalytic activity coupled with a porous metal-organic framework (MOF), namely HKUST-1, as an advanced material for the CO2 photocatalytic reduction. In detail, TiO2/HKUST-1 catalyst was prepared via an easy slow-diffusion method combined with a step-by-step self-assembly at room temperature. The growth of crystalline HKUST-1 onto titania surface was achieved by functionalizing TiO2 nanocrystals, with phosphoesanoic acid (PHA), namely TiO2-PHA, which provides an intimate contact between MOF and TiO2. The presence of a cr…
Preparation and photoactivity of nanostructured anatase, rutile and brookite TiO2 thin films
2006
Photoactive films consisting of pure anatase, brookite or rutile TiO2 were prepared by dip coating from water dispersions obtained by using TiCl4 as the precursor under similar mild experimental conditions
Effect of the addition of different doping agents on visible light activity of porous TiO2 photocatalysts
2018
Abstract The influence of the addition of different doping agents (N, W and Hf) on the macroporous TiO2 photoactivity toward the Rhodamine B degradation and ethanol photo-oxidation was evaluated. The samples were characterized by XRD, XPS, SEM, TEM, N2 adsorption-desorption, UV–vis Diffuse Reflectance and Photoluminescence spectroscopies to study also the changes in the physico-chemical properties due to the presence of dopants. The photonic effect and the high ordered porous structure of the macroporous TiO2 that lead to increase the path length of the light, were the key factors that allow to enhance the catalytic activity towards the dye and VOC degradation under visible and solar light …
Polyacrylonitrile block copolymers for the preparation of a thin carbon coating around TiO2 nanorods for advanced lithium-ion batteries.
2013
Herein, a new method for the realization of a thin and homogenous carbonaceous particle coating, made by carbonizing RAFT polymerization derived block copolymers anchored on anatase TiO2 nanorods, is presented. These block copolymers consist of a short anchor block (based on dopamine) and a long, easily graphitizable block of polyacrylonitrile. The grafting of such block copolymers to TiO2 nanorods creates a polymer shell, which can be visualized by atomic force microscopy (AFM). Thermal treatment at 700 °C converts the polyacrylonitrile block to partially graphitic structures (as determined by Raman spectroscopy), establishing a thin carbon coating (as determined by transmission electron m…
TiO2 anatase films obtained by direct liquid injection atomic layer deposition at low temperature
2014
International audience; TiO2 thin films were grown by direct liquid injection atomic layer deposition (DLI-ALD) with infrared rapid thermal heating using titanium tetraisopropoxide and water as precursors. This titanium tetraisopropoxide/water process exhibited a growth rate of 0.018 nm/cycle in a self-limited ALD growth mode at 280 degrees C. Scanning electron microscopy and atomic force microscopy analyses have shown a smooth surface with a low roughness. XPS results demonstrated that the films were pure and close to the TiO2 stoichiometric composition in depth. Raman spectroscopy revealed that the films were crystallized to the anatase structure in the as-deposited state at low temperatu…
Core-shell Zn-doped TiO2-ZnO nanofibers fabricated via a combination of electrospinning and metal-organic chemical vapour deposition
2010
Zn-doped TiO2 nanofibers shelled with ZnO hierarchical nanoarchitectures have been fabricated combining electrospinning of TiO2 (anatase) nanofibers and metal-organic chemical vapor deposition (MOCVD) of ZnO. The proposed hybrid approach has proven suitable for tailoring both the morphology of the ZnO external shell as well as the crystal structure of the Zn-doped TiO2 core. It has been found that the Zn dopant is incorporated in calcined electrospun nanofibers without any evidence of ZnO aggregates. Effects of different Zn doping levels of Zn-doped TiO2 fibers have been scrutinized and morphological, structural, physico-chemical and optical properties evaluated before and after the hierarc…
Preparation and photoactivity of samarium loaded anatase, brookite and rutile catalysts
2011
Abstract Pure and samarium loaded anatase, brookite and rutile nanopowders were synthesized by thermohydrolysis of TiCl 4 . The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (SSA) determination, UV–vis diffuse reflectance spectroscopy (DRS), atomic force microscopy (AFM), contact angle (CA) measurements and photoluminescence (PL) spectroscopy. The photocatalytic activity of pure and Sm-loaded TiO 2 polymorphs was investigated by employing the photodegradation of 4-nitrophenol as probe reaction in a liquid-solid system. Loading with Sm resulted in an improvement of the photoreactivity of the three TiO 2 polymorphs. The benefi…
Photocatalytic Degradation of 4-nitrophenol in aqueous suspension by using polycristalline TiO2 samples impregnated with a Cu(II)-phthalocyanine
2002
In this paper, the preparation of polycrystalline TiO2 samples impregnated with a modified Cu(II)-phthalocyanine (TiO2–CuPc) is reported along with an investigation on the photocatalytic behavior of this system compared with bare TiO2 (both in the anatase and rutile form) and with TiO2 samples impregnated with not functionalized commercial phthalocyanine (TiO2–CuPc) or with metal free phthalocyanine (TiO2–Pc). The photocatalytic degradation of 4-nitrophenol (4-NP) was studied as a probe reaction. The presence of modified CuPc showed to be beneficial only for TiO2 (anatase) while the commercial not functionalized CuPc also slightly for both TiO2 (anatase) and TiO2 (rutile). The metal free Pc…