ABSTRACT
A layer of titanate nanotubular (H-TiNT) particles between Fe2O3 film and FTO substrate was inserted and heat-treated to improve electrochemical property of Fe2O3 for water splitting. Heat-treatment of the synthesized F2O3/H-TiNT/FTO thin film was found to significantly affect photoelectrochemical properties of the film through electrochemical impedance analysis. The film showed larger oxidation-reduction peaks of I-V characteristics and capacitive properties under UV-Vis light illumination with heat treatment temperatures during transformation of H-TiNT into anatase TiO2 phase. The overall results showed an appropriate heat treatment was a promising way to improve the electrochemical property of the photoanode film.
ABSTRACT
The effect of TiO2 layer applied to the conventional Fe2O3/FTO photoanode to improve the photoelectrochemical performance was assessed from the viewpoint of the microstructure and energy band structure. Regardless of the location of the TiO2 layer in the photoanodes, that is, Fe2O3/TiO2/FTO or TiO2/Fe2O3/FTO, high performance was obtained when α-Fe2O3 and H-TiNT/anatase-TiO2 phases existed in the constituent Fe2O3 and TiO2 layers after optimized heat treatments. The presence of the Fe2O3 nanoparticles with high uniformity in the each layer of the Fe2O3/TiO2/FTO photoanode achieved by a simple dipping process seemed to positively affect the performance improvement by modifying the energy band structure to a more favorable one for efficient electrons transfer. Our current study suggests that the application of the TiO2 interlayer, together with α -Fe2O3 nanoparticles present in the each constituent layers, could significantly contribute to the performance improvement of the conventional Fe2O3 photoanode.
Subject(s)
Electrodes , Ferric Compounds/chemistry , Hydrogen/chemistry , Oxygen/chemistry , Solar Energy , Tin Compounds/chemistry , Titanium/chemistry , Water/chemistry , Equipment Design , Equipment Failure Analysis , Ferric Compounds/radiation effects , Hydrogen/isolation & purification , Hydrogen/radiation effects , Light , Materials Testing , Oxygen/isolation & purification , Oxygen/radiation effects , Tin Compounds/radiation effects , Titanium/radiation effectsABSTRACT
Hydrogen titanate nanotube (H-TiNT) particles were coated porously on a fluorine-doped tin oxide glass using the layer-by-layer self assembling method and then heat-treated at temperatures below 600 degrees C for 10 min in air. The microstructure, crystallinity, and optical absorbance of the heat-treated H-TiNT thin film were investigated using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and UV-vis spectroscopy, respectively. Also, I-V characteristics of the fibrous H-TiNT particles in the thin film using linear cycle voltammetry under ultraviolet-A irradiation were analyzed to have a maximum current value at applied voltages with the increase in heating temperature for economic water splitting.
ABSTRACT
To prepare one-dimensional nanostructured Na2Ti6O13 powder, the starting materials of TiO2, NaCl and Na2CO3 were mixed and then heat-treated at 1000 degrees C for 2 hrs in air under molten state of NaCl. Changes in shape and phase, photo absorbance and photocatalytic ability of TiO2 particle were observed controlling added amount of Na2CO3 under constant weight ratio of TiO2 to NaCl using SEM, X-ray diffractometer, Raman spectroscopy, and UV-Vis spectroscopy. The TiO2 particle was changed into rod-shape Na2Ti6O13 with the addition of Na2CO3, showing increase in optical energy band-gap of the powder as well as gradual decrease of the photo-decomposition ability.
ABSTRACT
CuInS2 powders have been successfully prepared by simple heating a mixture of copper nitrate, indium nitrate and thiourea in ethylene glycol. The prepared powders were fully characterized by SEM, XRD and UV-Vis spectroscopy. The particle shape of the powders obtained with an optimal condition showed spherical shape with about 50 nm in size. The XRD results showed more enhanced crystallized CuInS2 with chalcopyrite structure with increasing reaction time. The values in band-gap energy of nano-sized CuInS2 powders would be estimated 1.63 eV, blue-shifted from that of micron-sized powders due to size quantization effect.
ABSTRACT
The functional silica/polyamide-imide composite films were prepared via simple ultrasonic blending, after the silica nanoparticles were modified by cationic surfactant-cetyltrimethyl ammonium bromide (CTAB). The composite films were characterized by scanning electron microscope (SEM), thermo gravimetric analysis (TGA) and thermomechanical analysis (TMA). CTAB-modified silica nanoparticles were well dispersed in the polyamide-imide matrix, and the amount of silica nanoparticles to PAI was investigated to be from 2 to 10 wt%. Especially, the coefficients of thermal expansion (CET) continuously decreased with the amount of silica particles increasing. The high thermal stability and low coefficient of thermal expansion showed that the nanocomposite films can be widely used in the enamel wire industry.
ABSTRACT
In this study, various sized and shaped titanates were prepared using rutile phase TiO2 nano-powders in strong basic solution of NaOH having various metallic ions as chlorides by hydrothermal process. Obtained powders were fully characterized using SEM, TEM, XRD, and BET. The XRD results show that all obtained powders have layered structure. However, the shapes of particles doped with Zr4+ and Li+ show nano-belt and nano-plate, respectively, compared to those with nano-tubes of undoped, Ni2+ and Fe3+ doped. These results suggest that particle shape of titanates can be controlled only by small amount of doping elements in NaOH aqueous solutions.
ABSTRACT
One-dimensional (1-D) layered titanate nanotubes and nanoribbon thin films were prepared via the hydrothermal reaction of Ti metal flakes with concentrated NaOH solution. TEM, SEM, and XRD studies of the reaction products revealed that 20-nm-wide and about 1-microm-long nanoribbons formed in 5 M NaOH aqueous solution at 140 degrees C for 12 h, while 6 aproximately 8-nm-wide and several hundred-nanometer-long nanotubes formed with 10 M NaOH. The effect of post treatments on the thermal stablity, phase structure and morphology of the as-prepared nanotubes films was investigated. Different morphologies and crystallinity changes of the as-prepared nanotubes films during heat treatment process are attributed to the sodium impurity.
