Relation between Morphology and Photoelectrochemical Performance of TiO2 Nanotubes Arrays Grown in Ethylene Glycol/Water

The TiO₂ nanotube films were prepared by anodizing Ti plates in 0.2 M NH₄F ethylene glycol/10% H₂O under different formation voltages keeping fixed the time length, or by keeping fixed the formation voltage and varying the time length. The morphology of the TiO₂ film obtained was observed by SEM images and different morphological parameters were derived from them. Furthermore, the optical and semiconducting properties of TiO₂ films were also measured. The photoelectrochemical performance toward water oxidation of the TiO₂ only showed to be dependent with the inner diameter of the nanotubes, that could be related to the interaction of the film with the light and the transport of species in the electrolyte inward or outward the film.     

Effect of hybrid fillers on the mechanical behavior of polypropylene based hybrid composites

The present study investigates the effect of hybrid fillers such as graphene nanoplatelets (GnPs) and Titanium di-oxide (TiO₂) in polypropylene (PP) composites on the mechanical properties. The compatibilizing agent of Maleic anhydride grafted polypropylene (MAPP) are used in the polypropylene based composites to increase the interfacial adhesion between matrix and fillers. The experiments are designed according to L₁₆ orthogonal array (OA) based design of experiments (DOE). The parameters selected for this study are GnPs, TiO₂ and MAPP with four different levels are used.By using Orthogonal array and Taguchi based experimental design, the performance characteristics of tensile modulus, tensile strength, elongation at break and toughness can be analyzed with more objective through a small set of experiments.Taguchi based analysis are used to find out the optimal parameters to maximize the tensile properties for the GnPs and TiO₂ reinforced PP hybrid composites. Further, analysis of variance (ANOVA) is investigated to identify the most significant parameters which influence the mechanical properties.From the analysis it was found that the optimal parameters of 3 ?wt% GnPs, 2 ?wt% TiO₂ and 6 ?wt% MAPP for maximum tensile modulus and tensile strength. The most significant parameter for tensile modulus and tensile strength is GnPs followed by TiO₂ and MAPP according to ANOVA analysis.     

Photo-Induced Ultrafast Electron Dynamics in Anatase and Rutile TiO2: Effects of Electron-Phonon Interaction

The photo-induced ultrafast electron dynamics in both anatase and rutile TiO\begin{document}$_{2}$\end{document} are investigated by using the Boltzmann transport equation with the explicit incorporation of electron-phonon scattering rates. All structural parameters required for dynamic simulations are obtained from ab initio calculations. The results show that although the longitudinal optical modes significantly affect the electron energy relaxation dynamics in both phases due to strong Fr?hlich-type couplings, the detailed relaxation mechanisms have obvious differences. In the case of a single band, the energy relaxation time in anatase is 24.0 fs, twice longer than 11.8 fs in rutile. This discrepancy is explained by the different diffusion distributions over the electronic Bloch states and different scattering contributions from acoustic modes in the two phases. As for the multiple-band situation involving the lowest six conduction bands, the predicted overall relaxation times are about 47 fs and 57 fs in anatase and rutile, respectively, very different from the case of the single band. The slower relaxation in rutile is attributed to the existence of multiple rate-controlled steps during the dynamic process. The present findings may be helpful to control the electron dynamics for designing efficient TiO\begin{document}$_{2}$\end{document}-based devices.     

A study of the effect of the synthesis conditions of titanium dioxide on its morphology and cell toxicity properties

In this study, titanium dioxide nanoparticles (NPs) were synthesized using the home microwave method, and the effect of the microwave irradiation time on the structure of NPs was investigated. In addition, the morphological effect of these NPs on the toxicity of HDMSCs cells was investigated. The crystalline structure and morphology of the NPs were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM); the cytotoxicity was determined by the methyl thiazolyl tetrazolium (MTT) assay. X-ray diffraction analysis revealed that all thin films had a polycrystalline nature with an anatase phase of TiO₂. It was also found that the crystallite size increased with increasing microwave radiation time. The FTIR spectrum showed Ti-O-Ti properties by the peak in the range between 527 and 580 cm^?1. Further, the FE-SEM images showed that the grain size increased with increasing irradiation time. The MTT assay results showed that the accumulation of NPs leads to toxicity.     

Binary Metal Oxide Adsorbed Graphene Modified Glassy Carbon Electrode for Detection of Riboflavin

Tungsten oxide (W) decorated titanium oxide (T) adsorbed onto a graphene (Gr) and modified the glassy carbon electrode for the electrochemical quantification of riboflavin (RF) in edible food and pharmaceuticals. For comparison, nanocomposites are formed using graphene oxide (GO), reduced graphene oxide (rGO) and pure graphite (G) sheets to study the electrochemical activities towards riboflavin. The ternary WTGr modified GCE shows the highest electrocatalytic activity due to synergetic interactions between the metal oxide and graphene. The electrochemical observations are supported by the SEM, HRTEM, XRD, UV-Vis, Zeta potential (ζ) and size data. The sensor shows a wide linear range 20 nM–2.5 μM with a detection limit 25.24 nM and sensitivity (4.249×10⁻⁸ A/nM). The fabricated sensor is validated in real samples.     

Sonocatalytic injury of cancer cells attached on the surface of a nickel–titanium dioxide alloy plate

The present study demonstrates ultrasound-induced cell injury using a nickel–titanium dioxide (Ni–TiO₂) alloy plate as a sonocatalyst and a cell culture surface. Ultrasound irradiation of cell-free Ni–TiO₂ alloy plates with 1 MHz ultrasound at 0.5 W/cm² for 30 s led to an increased generation of hydroxyl (OH) radicals compared to nickel–titanium (Ni–Ti) control alloy plates with and without ultrasound irradiation. When human breast cancer cells (MCF-7 cells) cultured on the Ni–TiO₂ alloy plates were irradiated with 1 MHz ultrasound at 0.5 W/cm² for 30 s and then incubated for 48 h, cell density on the alloy plate was reduced to approximately 50% of the controls on the Ni–Ti alloy plates with and without ultrasound irradiation. These results indicate the injury of MCF-7 cells following sonocatalytic OH radical generation by Ni–TiO₂. Further experiments demonstrated cell shrinkage and chromatin condensation after ultrasound irradiation of MCF-7 cells attached on the Ni–TiO₂ alloy plates, indicating induction of apoptosis.     

Enhanced photocatalytic performance of TiO2 particles via effect of anatase–rutile ratio

In the present work anatase–rutile transformation temperature and its effect on physical/chemical properties as well as photocatalytic activity of TiO₂ particles were investigated. The characterisation of the synthesised and annealed TiO₂ particles were determined by X-Ray Powder Diffraction (XRD), scanning electron microscope (SEM), dynamic light scattering (DLS) and Brunauer–Emmett–Teller surface area analysis (BET). The refraction in the ultraviolet–visible (UV–vis) range was assessed using a dual-beam spectrophotometer. The photocatalytic performance of the particles was tested on methylene blue solution. The XRD data indicated that the percentage of rutile increased with the annealing temperature and almost 100% of anatase transformed to rutile at 1000 °C. In addition, the phase transformation was a linear function of annealing temperature so phase composition of TiO₂ can be controlled by changing the annealing temperature. The SEM and BET results presented the increase of agglomerate size and the decrease of specific surface area with the increasing annealing temperature. This proved that anatase has smaller particle size and higher surface area than rutile. The photocatalytic activity of the annealed TiO₂ powders reduced with the increase of annealing temperature. The samples annealed at 900 °C and 925 °C with anatase: rutile ratio of 92:8 and 77:23, respectively, showed the best activity. These results suggested that the photocatalytic activity of TiO₂ particles is a function of phase composition. Thus it can be enhanced by changing its phase composition which can be controlled by annealing temperature.     

Influence of Titanium Dioxide Content on the Crystallization Behavior and Solar Reflectance of Polyethylene/Titanium Dioxide Composites

Titanium dioxide (TiO₂) particles were introduced to improve the solar reflectance of high-density polyethylene (HDPE). The organic-inorganic hybrids were fabricated by melt blending. A series of characterizations were taken to study the crystallization behavior, morphology, solar reflectance, and real cooling property. TiO₂ particles acted as nucleation agents in the HDPE matrix and made the HDPE form thick lamellar crystals. TiO₂ particles could disperse well into the HDPE matrix under 2.5 wt.% loading but agglomerated with 3 wt.%. Solar reflectance was related to the reflective index of TiO₂ and the microstructure of HDPE. The real cooling property depended on the solar reflectance and the dispersion of the TiO₂ particles in the HDPE matrix.     

Application of sol–gel TiO2 film for an extended-gate H+ ion-sensitive field-effect transistor

In this study, a sol–gel TiO₂ thin film has been spin-coated on a commercial ITO glass substrate as the extended-gate field effect transistor (EGFET) for hydrogen ion sensing. The as-deposited films are further annealed at various temperatures (T_a) under ambient atmosphere. It is found that the bi-layer structure of TiO₂/ITO EGFET exhibits good linear sensitivity from pH 1 to 11. Anatase TiO₂ appeared as early as T_a = 200 °C and a brookite (121) diffraction evolved at T_a = 500 °C. No prominent influence on the surface fine structures could be found at higher T_a. Due to the reduction or disappearance of the surface hydroxyl groups on TiO₂, the sensitivities of the TiO₂/ITO pH-EGFET device are rapidly reduced. However, the influence of the conductivity decay for ITO substrates annealed at high T_a could not be excluded. A maximum sensitivity 61.44 mV/pH is achieved as T_a = 300 °C.The bi-layer structure of TiO₂/ITO exhibits better long-term stability than the traditional ITO sensing membranes. In addition, the asymmetric hysteresis is more significant in alkaline buffer solutions, which could be explained by a site-binding model because the diffusion of H⁺ ions into the buried sites of the sensing film is more rapid than that of OH⁻ ions.     

N2/Ar等离子体改性对CuO/TiO2可见光光催化活性的影响

研究了N2/Ar介质阻挡放电处理对负载CuO的TiO2可见光光催化活性的影响.采用X射线衍射、紫外-可见分光吸收光谱、透射电镜、X射线光电子能谱和电子自旋共振进行了表征,详细考察了等离子改性参数包括气氛组成、处理时间和处理功率对改性效果的影响,并通过降解甲基橙溶液考察了可见光光催化活性.结果表明,最佳等离子处理条件为N2与Ar比例为8:2,处理时间为20 min,放电电流为1.0 A.最后,使用改性后的光催化剂对模拟含汞废水进行了处理.