68 research outputs found
Synthesis of titanate nanostructures using amorphous precursor material and their adsorption/photocatalytic properties
This paper reports on a new and swift hydrothermal chemical route to prepare
titanate nanostructures (TNS) avoiding the use of crystalline TiO2 as starting
material. The synthesis approach uses a commercial solution of TiCl3 as
titanium source to prepare an amorphous precursor, circumventing the use of
hazardous chemical compounds. The influence of the reaction temperature and
dwell autoclave time on the structure and morphology of the synthesised
materials was studied. Homogeneous titanate nanotubes with a high
length/diameter aspect ratio were synthesised at 160^{\circ}C and 24 h. A band
gap of 3.06\pm0.03 eV was determined for the TNS samples prepared in these
experimental conditions. This value is red shifted by 0.14 eV compared to the
band gap value usually reported for the TiO2 anatase. Moreover, such samples
show better adsorption capacity and photocatalytic performance on the dye
rhodamine 6G (R6G) photodegradation process than TiO2 nanoparticles. A 98%
reduction of the R6G concentration was achieved after 45 minutes of irradiation
of a 10 ppm dye aqueous solution and 1 g/L of TNS catalyst.Comment: 29 pages, 10 figures, accepted for publication in Journal of
Materials Scienc
Layer-by-layer deposition of open-pore mesoporous TiO 2- Nafion® film electrodes
The formation of variable thickness TiO2 nanoparticle-Nafion® composite films with open pores is demonstrated via a layer-by-layer deposition process. Films of about 6 nm diameter TiO2 nanoparticles grow in the presence of Nafion® by “clustering” of nanoparticles into bigger aggregates, and the resulting hierarchical structure thickens with about 25 nm per deposition cycle. Film growth is characterized by electron microscopy, atomic force microscopy, and quartz crystal microbalance techniques. Simultaneous small-angle X-ray scattering and wide-angle X-ray scattering measurements for films before and after calcination demonstrate the effect of Nafion® binder causing aggregation. Electrochemical methods are employed to characterize the electrical conductivity and diffusivity of charge through the TiO2-Nafion® composite films. Characteristic electrochemical responses are observed for cationic redox systems (diheptylviologen2+/+, Ru(NH3)3+/2+6, and ferrocenylmethyl-trimethylammonium2+/+) immobilized into the TiO2-Nafion® nanocomposite material. Charge conduction is dependent on the type of redox system and is proposed to occur either via direct conduction through the TiO2 backbone (at sufficiently negative potentials) or via redox-center-based diffusion/electron hopping (at more positive potentials)
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