Search

In this study, titanium dioxide (TiO2) nanostructures were produced on pure titanium in different electrolytes at constant voltage of 20 V for 30 min. The crystallographic structure, surface morphology, and optical properties of the films were investigated by XRD, SEM, and UV-vis spectrum, respectively. The wettability of the samples was determined by contact angle measurement equipment. The photocatalytic properties of the TiO2 films were tested by the degradation of a methylene blue (MB) as the model reaction under UV light irradiation. The results showed that the electrolyte composition can play an important role in the surface morphology of nanostructured TiO2 films and therefore on various properties such as optics, electronics, sensing, and degradation. The SEM images of the samples demonstrated that surface morphology was directly affected by the electrolyte composition. It is known that the surface area is a dominant factor affecting the photocatalytic activity of a porous TiO2 layer prepared by anodic oxidation. The TiO2 film (sample C) anodized in 1 M Na2SO4 containing 5 wt.% NH4F exhibited better photocatalytic performance as compared to the other oxide films. This is because a higher surface area with dense pore structure favors more photocatalytic active areas. The photocatalytic degradation efficiency of MB using sample C was reached to 92.35% and rate constant 5.92 x 10(-3), respectively. Moreover, this sample showed lowest band gap energy that was almost 3.167 eV. We believe that new anodic TiO2 nanoporous structures are highly promising in photocatalytic decomposition of water and pollutants elimination.

In this work, Zn-Ni-, Zn-Co-, Ni-Co-, and Zn-Ni-Co-coated alloy films were electrodeposited on titanium substrate. The coated alloy films were annealed in order to form oxides at 800 °C in air for 2 h. The crystalline structures, surface morphologies, and chemical composition of the samples were examined using X-ray diffraction techniques (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX). Photocatalytic performance of samples was performed by means of the degradation of methylene blue (MB) under UV irradiation. The SEM results showed that the different morphologies such as needle-shaped nanowires, grains, and pores were formed on the surface. The results showed that the photocatalytic performance of the samples demonstrated differences according to alloy type. The Zn-Ni alloy coating exhibited better photocatalytic activity. Photocurrent measurements illustrated that Zn-Ni sample possessed the highest suppression of photogenerated charge carrier recombination and lowest charge transfer resistance (Rct) layer. It is expected that this work could provide a promosing way for fabricating Zn-based photocatalyts in environmental redemediation.

In this study, TiO2 powders were produced via sol-gel route at 500 degrees C for 2 h with distinct heating rates. TGA-DTA, XRD, SEM, Raman spectroscopy, XPS, UV-vis spectroscopy and photoluminescence characterization techniques were carried out for TiO2 powders. Photocatalytic efficiency of TiO2 powders on degradation of methylene blue (MB) solution was examined in terms of different heating rates. Thermodynamic and non-isothermal kinetic study of TiO2 powders were estimated. TiO2 powders showed anatase phase based on XRD results. Surface morphology of TiO2 powders did not change with different heating rates. It can be concluded that heating rate played important role on band gap and photocatalytic activity. The band gap of the TiO2 particles decreased from 3.25 to 2.95 with increasing heating rate. The photocatalytic activity results exhibit that T1 powders have the highest photocatalytic performances. The kinetic constant and photocatalytic degradation rate were 0.00678 min(-1) and 83.48%, respectively. This could be attributed to high crystalline structure and low bulk vacancies or defects. Furthermore, TiO2 powders showed good stability. This study exhibited a new way to enhance the photocatalytic performances of pure TiO2 powders.