Papers by Author: Jian Ling Zhao

Abstract: In this work, highly-ordered TiO₂ nanotube arrays were prepared by constant-voltage anodization, followed by electrodeposition of Ag to obtain Ag-loaded TiO₂ (Ag-TiO₂) nanotube arrays via alternating current (AC) process. The results of SEM and XRD show that the morphology and crystal structure of Ag-TiO₂ layer depend greatly on the electrodeposition parameters. Ag-TiO₂ nanotube arrays prepared in 2.5 mmol/L AgNO₃ solution by electrodeposition with applied voltage of 12 V for 1 minute performed the best photoelectrochemical current response and photocatalystic activity. The photocurrent density of Ag-TiO₂ is 43.32 μA/cm² under sunlight irradiation (70 mW/cm²), which is 4.2 times as that of unloaded TiO₂ nanotube arrays. Methyl orange (MO) degradation rate with the Ag-TiO₂ nanotube arrays achieves 52.13% after 90 min sunlight irradiation which is obvious higher than that of TiO₂ nanotube arrays. The mechanism of enhancing photoelectrochemical activity of decorating titania with Ag has also been discussed in the view of energy band theory.

Abstract: The zirconia nanotube arrays on zirconium substrates were formed in (NH4)2SO4 electrolytes containing different concentrations of NH4F (0.5-2.0 wt%). Highly self-organized zirconia nanotubes can be formed with a diameter ranging from 15 nm to 144 nm and a length of 32 μm. The morphology of the nanotubes was strongly influenced by the applied voltages and electrolyte concentrations. Electrochemical testing and scanning electron microscope observation indicated the nanotubes were formed due to the competition of zirconia formation and dissolution under the assistance of electric field.

Abstract: The self-organized nanotube arrays were fabricated in glycerol electrolyte containing different additives, such as deionized water or ethylene glycol. The effects of anodization conditions, including anodic voltage, electrolyte viscosity, additives and ion concentration on the pores size and morphology were studied. Combined with preoxidation process, high aspect ratio titania nanotube arrays were formed rapidly in glycerol and saturated NaF solutions at 60 V for 1 h. SEM observation showed that a film with the thickness of about 10μm was obtained. A possible mechanism of the nanotubes growth was presented.

Abstract: BaTiO3 films with a thickness up to 3 μm were fabricated under the hydrothermal conditions. It was found that the crystallinity of BaTiO3 increases with the concentration of Ba(OH)2 solutions. Along with the increasing of time, the crystallinity of BaTiO3 increases, reaches the maximum value and then decreases. The measured values of remanent polarization (Pr) and coercive field (Ec) are 1.74μC/cm2 and 24KV/cm. The leakage of the films at 1V is 10-7A/cm2. The dielectric constant and loss tangent of hydrothermal derived BaTiO3 film at a frequency of 1 KHz were 600 and 0.2, respectively.