Dye-sensitized solar cell based on anodic TiO2 nanotubes produced from anodization in fluoride-free electrolyte

An increasing energy demand and environmental pollution create a pressing need for clean and sustainable energy solutions. T1O2 semiconductor material is expected to play an important role in helping solve the energy crisis through effective utilization of solar energy based on photovoltaic devices. Dye-sensitized solar cells (DSSCs) are potentially lower cost alternative to inorganic siliconbased photovoltaic. In the present work, we report about the fabrication of dye-sensitized solar cell (DSSCs) from anodic T1O2 nanotubes powder, produced by potentiostatic anodization of Ti foil in 0.1 M HCIO4 electrolyte, as photoanode. The counter electrode was made by electrodeposition of Pt from an aqueous solution of 5 mM F^PtCU onto fluorine-doped tin oxide glass substrate (FTO-glass). The above frontside illuminated DSSCs were compared with back-side-illuminated DSSCs fabricated from anodic T1O2 NTs that were grown on the top of Ti foil as photoanode. The highest cell efficiency was 3.54 % under 100 mW/cm2 light intensity (1 sun AM 1.5 G light, Jsc = 14.3 mA/cm2, Foe = 0.544 V, fill factor = 0.455). To the best of our knowledge, this is the first report on the fabrication of dyesensitized solar cell from anodic T1O2 NTs powder. The T1O2/FTO photoanodes were characterized by FE-SEM, XRD and Uv-visible spectroscopy. The catalytic properties of Pt/FTO counter electrodes have been examined by cyclic voltammetry

A novel method for synthesis of titania nanotube powders using rapid breakdown anodization

The present paper describes a new method utilizing rapid anodization to quickly synthesize high-quality, high aspect ratio, robust titanium dioxide nanotube powders. TiO2 nanotube powders, with a typical nanotube outer diameter of approximately 40 nm, wall thickness of approximately 8−15 nm, and length of about 10−35 μm, were synthesized by potentiostatic rapid breakdown anodization of titanium foils in aqueous electrolytes of 0.3 M NaCl or 0.1 M HClO4 under an applied potential of 20 V. High reactivity and ultrahigh reaction rate are cornerstones responsible for periodic release of TiO2 nanotubes into solution and formation of a white precipitate of TiO2 nanotubes. The reaction yield is approximately 4−6 g in less than 3 h, and the approximate cost of the material is $3.50/g, based on the laboratory-scale production. Various characterization techniques, including FESEM, HRTEM, EDX, XRD, XPS, FT-IR, UV−visible diffuse-reflectance, and N2 adsorption, have been used to probe morphology, microstructure, crystallographic, composition, bond configuration, optical properties, and surface area of the nanotubes. XPS and EDX investigations show that nanotubes formed in NaCl/phosphate electrolyte solutions contain a significant amount of phosphorus species, which strongly affects crystallization and phase transformation of TiO2. Namely, phosphate-incorporating nanotubes stabilized the anatase phase, and initiation of the rutile phase was observed at annealing temperatures ≥700 °C. The resulting nanotube powders have a significant level of OH groups with a band gap ranging from 3.04 to 3.23 eV. Our results indicate that rapid breakdown anodization is highly efficient in the production of good-quality TiO2 nanotube powders, which makes it an alternative to well-documented conventional methods

Gun current optimization for deposition of silicon carbide films by gas tunnel type plasma spraying

Polycrystalline silicon carbide films have been prepared by the gas tunnel type plasma spraying method (GTPS). The effect of gun current on microstructure and mechanical properties was investigated. Scanning electron microscopy, x-ray diffraction, energy dispersive spectroscopy, nanoindentation and abrasive wear were used to characterize the structure, thickness, composition and the mechanical properties of SiC films. Microstructural studies revealed the formation of cubi silicon carbide (C-SiC) at higher gun currents from 120 to 140 A. The SiC films have good-adhesion, dense, smooth and compact morphology. Determination of hardness of the SiC films by a nanoindentation technique shows that increasing gun current can improve hardness from 25.3 to 31.5 GPa. Generally, SiC film formed at higher gun currents exhibits better anti- wear resistance than that deposited at low gun current, mainly due to SiC films becoming harder. A comparison of the hardness of SiC films grown by gas tunnel type plasma spraying and SiC films grown by other methods was included. Finally, crystalline silicon carbide films with good morphology and mechanical properties have been obtained from the GTPS method that are suitable for thermoelectric and mechanical applications

Biomimetic hydroxyapatite formation on silica-loaded anodic TiO2 nanotubes

Abstract not available

Preparation and characterization of high aspect ratio TiO2 nanotube powders using rapid anodisation method in chloride-based electrolytes

This new method describes, for the first time, the application of rapid anodization in chloride-based electrolytes to quickly synthesize high quality, high-aspect ratio and robust titanium dioxide nanotube powders. This titania nanotubes powder produced from potentiostatic anodization of titanium foil in an electrolyte containing perchlorate or chloride ions. This would result in a more efficient usage of the titanium foil and in the production of large quantities (of the order of grams) titanium oxide tubes in less than 1 h. Further optimization of this route may provide a fast alternative method for the production of titanium oxide nanotube powders, now routinely synthesized via a hydrothermal method derived from the one pioneered by Kasuage et al. Various characterization techniques (viz., TEM, FESEM, XRD< DRUV-Visible, XPS) are used to study the morphology, phase, band gap and chemical composition