Synthesis of anatase titanium dioxide (TiO2) with both controllable size and high energy facets is technologically important for its application in photocatalysis, photoelectrochemical cell, and solar cells. Herein, we report a simple and fluorine free hydrothermal method to synthesize hierarchically nanostructured mesoporous anatase TiO2 spheres (MATS) with controllable size, which covered with nearly 100% {001} facet. Mild H2SO4 was used as both a phase-inducer formation of anatase phase and a capping agent to promote oriented growth and formation of {001} facet. PVP acted as morphology control agent to prevent growing larger of the mesoporous anatase TiO2 spheres (MATS) with ∼600 nm in size. Detailed XRD and SEM studies suggested that formation of MTAS is a typical nucleation and growth process. The refining or reconstruction of TiO2 crystal structure during growth resulted in mesoporous crystalline framework that exhibits enhanced photocatalytic degradation of rhodamine B.

Anodically formed TiO2 nanotube arrays composed of the anatase phase with periodically modulated diameters (PMTiNTs) are excellent photocatalysts for the sunlight-driven transformation of carbon dioxide into hydrocarbons. Exploiting the full potential of this nanoarchitecture for CO2 photoreduction requires integration with metal nanoparticles that function as catalytic promoters for multistep electron transfer reactions. We studied the effect of different metallic and bimetallic nanoparticles on the rate of generation of light hydrocarbons by the photoreduction of CO2. All the metal nanoparticles were loaded on to the TiO2nanotubes using the technique of photodeposition, which standardized the coating process and enabled examination purely of the effect of different metals. Photodeposition was used not only due to its simplicity but also because it enabled us to engineer very fine coatings possessing excellent uniformity and depth penetration into the nanotubes. The best performing co-catalysts were found to be CuPt (atomic ratio of 0.33:0.67), Pt and NiPt (1:2), which when loaded onto the PMTiNTs yielded total hydrocarbon generation rates of 3.5, 0.85 and 0.8 mL g-1 hr-1 respectively. The time required to form PMTiNTs was reduced by a factor of 160 by using a recently reported recipe based on fluoride ion bearing electrolyte containing lactic acid. PMTiNTs formed using the ultrafast growth lactic acid-based electrolytes exhibited similar photocatalytic properties to samples obtained more slowly using conventional ethylene glycol-based electrolytes.

The synthesis of InP/ZnS core/shell nanocrystals and TiO2 nanotubes and the optimization study to couple them together were explored for quantum dot sensitized solar cells. InP/ZnS nanocrystals have advantages of tunable optical properties and intrinsic nontoxicity. Highly luminescent InP/ZnS nanocrystals were produced by precursor-based colloidal synthesis for a photosensitizer. In order to improve on air stability, ZnS shell was grown on InP core. The emission peak was observed at 550 nm. Transmission electron microscopy (TEM) image shows that the nanocrystals highly crystalline and monodisperse. TiO2 nanotube is main inorganic material which is capable of harvesting light as well as being a prominent anode electrode in solar cells. The nanotubular form of TiO2 enhances charge transfer and reduces interfacial charge recombination. Free-standing TiO2 nanotubes were produced by anodization using ammonium fluoride. The free-standing nanotubes were formed under the condition that chemical dissolution speed which depends on fluoride concentration was faster than the speed of Ti oxidation. Electrophoretic deposition was carried out to couple the InP/ZnS nanocrystals with the TiO2 nanotubes. Under an optimized applied voltage condition, the current during the electrophoretic deposition decreased continuously with time. The amount of the deposited nanocrystals was estimated by calculation and the deposited nanocrystals on the TiO2 nanotubes were observed in the TEM.

This paper addresses the application of engineered nanocrystalline ultrahydrophilic titanium oxide films to artificial orthopaedic implants. Titanium (Ti) is the material of choice for orthopaedic applications and has been used for over fifty years because of its known bio-compatibility. Recently it was shown that biocompatibility of Ti metal is due to the presence of a thin native sub-stoichiometric titanium oxide layer [1] which enhances the adsorption of mediating proteins on the surface thus enhancing cell adhesion and growth [2,3,4]. Improving the quality of surface oxide, i.e. fabricating stoichiometric oxides as well as nanoengineering the surface topology that matches the dimensions of adhesive proteins, is crucial for the increase of protein adsorption [2] and, as a result, the biocompatibility of Ti implant materials. We have fabricated ultrahydrophilic nano-crystalline transparent films of anatase phase of titania (TiO2) by ion beam assisted deposition (IBAD) processes in an ultrahigh vacuum system. Source material was 99.9% pure rutile TiO2. Various ion beam conditions were used to produce these coatings with different grain sizes (4 to 70 nm) that affect the wettability, roughness, and the mechanical and optical properties of the coating [5]. Our biological experiments have shown that biocompatibility of these ultrahydrophilic nanoengineered TiO2 coatings are superior to commonly used orthopaedic titanium and even hydroxyapatite.

Titanium dioxide nanoparticles were synthesized by solvothermal treatment in the presence of oleic acid and oleylamine. As Ti(IV) reactant, crystals of [Ti8O12 (H2O)24]Cl8, HCl, 7H2O were preferred because their hydrolysis and condensation can be controlled in ethanol/water solution. The organic surfactants allowed the control of the shape and they can be removed by an acid treatment of the particles. The TiO2 nanoparticles can then be re-dispersed in an ethanol-based charging solution. A fixed applied voltage promotes the electrophoretic deposition of the nanoparticles (<15 nm in size) into pores of anodized aluminium oxide (AAO) template.

Dye-sensitized solar cells (DSSCs) are attractive alternatives to conventional solid-state photovoltaic devices because of performance, stability, environmental compatibility and cost. In contrast to the conventional systems where the semiconductor assumes both the task of light absorption and charge carrier transport, these two functions are separate in DSSC and, therefore, efficiency is very sensitive to the cell structure/composition. High-efficiency DSCs based on mesoporous nanocrystalline titanium dioxide (TiO2) electrodes have received considerable research attention in the past decade. Grain size and thickness of the mesoporous TiO2 film have shown a dominant effect on the efficiency of the photovoltaic devices.

We have investigated screen printed TiO2 films deposited on a textured fluorinated SnO2 (FTO) glass substrate, using Raman spectroscopy and spectroscopic ellipsometry. Materials were prepared by repeating a same screen-printing procedure once, twice and three times, using TiO2 paste with 10nm, 20 nm and 200nm particles sequentially. Raman spectra of PV devices cells taken at different excitation (266 nm, 325 nm, 364 nm, 532 nm, 633 nm, and 1064 nm) as well as pure TiO2 oxides are presented. Different excitation wavelengths allow to probe different depth of the sample. It was found that there is strong correlation of the position and the width of E2g mode of anatase at 144 cm-1 and size of TiO2 particles. The samples show that this peak shifts to the high frequency region and becomes broader for small size particles. The position and broadening of the peak can be described by optical confinement model that depends on the size of nano-crystals. Results showed varying grain sizes as correlated with different TiO2 paste applied. Thickness, optical constants and porosity of TiO2 films were determined by spectroscopic ellipsometry. In this work, we have demonstrated the use of Raman Spectroscopy and Spectroscopic Ellipsometry for non-destructive characterization of nanocrystalline TiO2 films for dye-sensitized solar cells.

The capability of tuning the functional properties of nanosize TiO2 nanoparticles (NPs) by suitable control of surface chemistry, phase stability and crystal size plays a key role on their safe use and enhanced efficacy in actual and envisioned applications, including nanomedicine, environmental remediation, and food safety, among others. On this basis, any attempt to develop a size-controlled synthesis method and an efficient surface treatment protocol becomes indispensable. Accordingly, we have synthesized TiO2 NPs via a modified aqueous processing route using HNO3 as a catalyst and polyvinylpyrrolidone as particle size controller and a dispersing agent. The NPs surface was treated by using Ethylenediamine (EDA) as a source for amine species. Bare and amine-treated TiO2 NPs were characterized by X-ray diffraction (XRD) and FTIR spectroscopy. The photocatalytic activity of TiO2 NPs was assessed by irradiating an aqueous solution of Methylene Blue (MB) dye containing different amounts of the NPs. XRD analyses evidenced the formation of two phases of crystalline TiO2 with an average crystallite size estimated at 15.3 nm. Bare and amine-treated TiO2 NPs exhibited significant activity under UV light illumination (365 nm). Bare NPs exhibited a dye photo degradation capability of about 38.02% with particle concentration of 0.5 g/l while amine-treated NPs reported 66.18% dye photo degradation capability with particle concentration of 0.5 g/l.