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h-BN-TiO2 nanocomposites were synthesized by the thermal hydrolysis of titanium peroxo-complexes in the presence of exfoliated h-BN. The bulk h-BN was prepared by annealing mixture of boric acid and urea, and high intensity ultrasound was used for its exfoliation. The prepared samples were characterized by X-ray powder diffraction (XRD), infrared spectroscopy, Raman spectroscopy, electron spin resonance (ESR), high resolution electron microscopy, BET surface area, and BJH porosity measurement. The UV-Vis diffuse reflectance spectroscopy was employed to estimate band-gap energies. The photoinduced charge on the surface of h-BN-TiO2 nanocomposites was visualized using electric force microscopy (EFM). The photocatalytic activity was determined by azo dyes Orange II and Reactive Black 5 photobleaching. The highest rate constant k = 0.0762 min−1 and 0.0164 min−1, under UV and visible light irradiation, respectively, showed sample denoted TiP050BN with moderate concentration of h-BN. [ABSTRACT FROM AUTHOR]

Highly photoactive Ga3+-doped anatase modification of titania was prepared by homogeneous hydrolysis of aqueous solutions mixture of titanium oxo-sulphate TiOSO4 and gallium(III) nitrate with urea. Incorporation of Ga3+ into the anatase lattice has a clear positive effect on the photocatalytic activity under UV and Vis light irradiation up to a certain extent of Ga. Ga3+ doping decreased the size of the crystallites, increased surface area, and affected texture of the samples. Higher amount of gallium leads to the formation of a nondiffractive phase, probably photocatalytically inactive. The titania sample with 2.18wt.% Ge3+ had the highest activity during the photocatalysed degradation in the UV and visible light regions; the total bleaching of dye Orange II was achieved within 29 minutes. Ga concentration larger than 5% (up to 15%) significantly inhibited the growth of the anatase crystal domains which formed the nondiffractive phase content and led to remarkable worsening of the photobleaching efficiency. [ABSTRACT FROM AUTHOR]

Abstract: The influence of input power on plasma sprayed coating was studied for a water-stabilized plasma spray torch (WSP®) and ceramic coatings formed from titanium dioxide (TiO2). All other spray setup parameters were secured during the experiment with electric supply power as the only variable factor. Physical characteristics of the coatings were tested by means of Raman spectroscopy and X-ray photoelectron spectroscopy which are able to determine the stoichiometry and surface chemical composition of the coatings. Further, stoichiometry and surface states are crucial for the photocatalytic efficiency of the coatings. The photocatalytic procedure involved was UV-induced decomposition of acetone. Links between the tested features are drawn. The lower supply power used during the spraying of TiO2 coating resulted in higher activity with respect to the photocatalytic point of view. Both the stoichiometry and surface composition are in the same time deviated from pure TiO2. [Copyright &y& Elsevier]

Nanometric particles of germanium-doped TiO2 were prepared by homogeneous hydrolysis of TiOSO4 and GeCl4 in an aqueous solution using urea as the precipitation agent. Structural evolution during heating of these starting Ge-Ti oxide powders was studied by X-ray diffraction (XRD) and high-temperature X-ray powder diffraction (HTXRD). The morphology and microstructure changes were monitored by means of scanning electron microscopy (SEM), Raman and infrared spectroscopy (IR), specific surface area (BET), and porosity determination (BJH). The photocatalytic activity of all samples was determined by decomposition of Orange II dye under irradiation at 365nm and 400 nm. Moderate doping with concentration upto value 2.05wt.% positively influences azo dye degradation under UV and Vis light. Further improvement cannot be achieved by higher Ge doping. Effect of the annealing (200, 400, and 700°C) on photocatalysis and other properties has been assessed. [ABSTRACT FROM AUTHOR]

TiO2/ZnS/CdS composites for photocatalytic hydrogen production from water were prepared by homogeneous hydrolysis of aqueous solutions mixture of TiOSO4, ZnSO4, and CdSO4 with thioacetamide. Hydrogen evolution was observed in the presence of palladium and platinum nanoparticles deposited on TiO2/ZnS/CdS composites. The morphology was obtained by scanning electron microscopy, the nitrogen adsorption-desorption was used for determination of surface area (BET) and porosity. The method of UV-VIS diffuse reflectance spectroscopy was employed to estimate band-gap energies of prepared TiO2/ZnS/CdS nanocomposites. The photocatalytic activity of the prepared samples were assessed by photocatalytic decomposition of Orange II dye in an aqueous slurry under UV irradiation at 365nm wavelength and visible light up to 400nm wavelength. Doped titanium dioxide by the CdS increased band-gap energy and doping with ZnS increased photocatalytic activity. The best photocatalytic activity for H2 evolution shows sample named TiZnCd7 on surface deposited with palladium, which contains 20.21% TiO2, 78.5% ZnS, and 1.29% CdS. [ABSTRACT FROM AUTHOR]

Abstract: Pure titania and titania doped with Zn2+ were prepared by homogeneous hydrolysis in aqueous solution with urea and thioacetamide as precipitating agents. The materials were characterized by XRD, TEM, BET and BJH analysis, which show microporous, nanaocrytsalline anatase phase titania in the size range 4–5nm and specific surface area 200–500m2/g. Adsorption and photocatalytic decomposition of 2-chloroethyl ethyl sulfide (CEES) was measured on dry and water pre-covered titania surfaces, respectively. Illumination with UV light leads to rapid decomposition of CEES on all samples resulting in formation of surface bound ethoxy, chloro ethoxy, aldehydes, acetone and carboxylates. Volatile sulphur moieties (Socyanate (Ti-NCO) are observed which is related to the synthesis methods employed. A procedure for removing residual synthesis products from the particles was devised and the intrinsic photodegradation rate was determined on the purified samples and compared with the as prepared samples. The photodegradation rate is notable higher for the purified TiO2 nanoparticles prepared by the urea route with respect to the “as prepared”. In the case of the Zn doped TiO2 samples a diminution in photodegradation rate is observed after purification. The results are correlated with the amount of volatile residual synthesis products present on the different particles. All materials have comparable or higher photo-reactivity than P25 (Degussa). On a humidified surface, the effects from synthesis residues, in particular volatile sulphur moieties, are reduced due to reactions with water and improved photoreaction rates for all samples are observed. [Copyright &y& Elsevier]

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010. [ABSTRACT FROM PUBLISHER]

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010. [ABSTRACT FROM PUBLISHER]

Abstract: Nanosized titanium dioxide photocatalysts with varying amount of anatase and rutile phases have been synthesized. Homogeneous precipitation of aqueous solutions containing TiOSO4 with urea was used to prepare porous spherical clusters of anatase TiO2. Photoactive titania powders with variable amount of anatase and rutile phases were prepared by heating of pure anatase in the temperatutre range 800–1150°C. The structure evolution during heating of the starting anatase powders was studied by XRD analysis in overall temperature range of phase transformation. The morphology and microstucture characteristics were also obtained by HRTEM, BET and BJH. The spherical particle morphology of TiO2 mixtures determined by SEM was stable in air up to 900°C. The photocatalytic activity of the sample titania TIT85/825 heated to 825°C in air, contained 77.4% anatase and 22.6% rutile was higher than that nanocrystalline anatase powder. Titania sample TIT85/825 reveals the highest catalytic activity during the photocatalyzed degradation of 4-chlorophenol in aqueous suspension. [Copyright &y& Elsevier]

Surface catalyzed reactions can be a convenient way to deactivate toxic chemical warfare agents (CWAs) and remove them from the contaminated environment. In this study, pure titanium oxide, magnesium hydroxide, and their composites TiO 2 /Mg(OH 2 ) were prepared by thermal decomposition and precipitation of the titanium peroxo-complex and/or magnesium nitrate in an aqueous solution. The as-prepared composites were examined by XRD, XPS, HRTEM, and nitrogen physisorption. Their decontamination ability was tested on CWA surrogates and determined by high-performance liquid chromatography (HPLC) and gas chromatography coupled with mass spectrometry (GC-MS). Dimethyl methyl phosphonate (DMMP) was used as a G simulant for the nerve agents sarin (GB) and soman (GD) while 2-chloroethyl ethyl sulfide (2-CEES) and 2-chloroethyl phenyl sulfide (2-CEPS) were used as surrogates of sulfur mustard (HD). The activity of the as-prepared composites was correlated with acid-base properties determined by potentiometric titrations and pyridine adsorption studied by in situ DRIFTS. The mixing of Ti and Mg led to an increase of the surface area and the amount of surface -OH groups (with an increasing amount of Ti) that caused improved degradation of DMMP., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)