Author
Sorachon Yoriya
Other affiliations: Foundation University, Islamabad
Bio: Sorachon Yoriya is an academic researcher from Pennsylvania State University. The author has contributed to research in topics: Nanotube & Materials science. The author has an hindex of 15, co-authored 16 publications receiving 2757 citations. Previous affiliations of Sorachon Yoriya include Foundation University, Islamabad.
Papers
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TL;DR: In this article, the fabrication of self-aligned highly ordered TiO2 nanotube arrays by potentiostatic anodization of Ti foil having lengths up to 134 μm is described.
Abstract: Described is the fabrication of self-aligned highly ordered TiO2 nanotube arrays by potentiostatic anodization of Ti foil having lengths up to 134 μm, representing well over an order of magnitude i...
845 citations
TL;DR: Paulose et al. as mentioned in this paper reported an extension of the fabrication technique to achieve TiO2 nanotube arrays up to 220 µm in length, with a length-toouter diameter aspect ratio of ≈1400, and their initial application in dye-sensitized solar cells and hydrogen production by water photoelectrolysis.
Abstract: The fabrication of highly-ordered TiO2 nanotube arrays up to 134 µm in length by anodization of Ti foil has recently been reported (Paulose et al 2006 J. Phys. Chem. B 110 16179). This work reports an extension of the fabrication technique to achieve TiO2 nanotube arrays up to 220 µm in length, with a length-to-outer diameter aspect ratio of ≈1400, as well as their initial application in dye-sensitized solar cells and hydrogen production by water photoelectrolysis. The highly-ordered TiO2 nanotube arrays are fabricated by potentiostatic anodization of Ti foil in fluoride ion containing baths in combination with non-aqueous organic polar electrolytes including N-methylformamide, dimethyl sulfoxide, formamide, or ethylene glycol. Depending upon the anodization voltage, the inner pore diameters of the resulting nanotube arrays range from 20 to 150 nm. As confirmed by glancing angle x-ray diffraction and HRTEM studies, the as-prepared nanotubes are amorphous but crystallize with annealing at elevated temperatures.
721 citations
TL;DR: This work considers the development of the various nanotube array synthesis techniques, different applications of the TiO(2) nanotubes, unresolved issues, and possible future research directions.
Abstract: Highly ordered vertically oriented TiO2 nanotube arrays fabricated by electrochemical anodization offer a large surface area architecture with precisely controllable nanoscale features. These nanotubes have shown remarkable properties in a variety of applications including, for example, their use as hydrogen sensors, in the photoelectrochemical generation of hydrogen, dye-sensitized and solid-state heterojunction solar cells, photocatalytic reduction of carbon dioxide into hydrocarbons, and as a novel drug delivery platform. Herein we consider the development of the various nanotube array synthesis techniques, different applications of the TiO2 nanotube arrays, unresolved issues, and possible future research directions.
245 citations
TL;DR: In this paper, the effect of the growth temperature, pH, stirring and reaction time on the resulting BiVO4 film morphology was investigated using X-ray diffraction, scanning electron microscopy, and transmission electron microscope with a growth mechanism.
Abstract: BiVO4 thin films comprised of ordered arrays of pyramidal-shaped nanowires vertically oriented to a fluorine doped tin oxide coated glass substrate have been successfully fabricated by seed-mediated growth in an aqueous BiVO4 suspension. The effect of the growth temperature, 40 to 95 °C, pH, stirring and reaction time on the resulting BiVO4 film morphology was investigated using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy with a growth mechanism proposed. We consider the effects of film morphology in application to photoelectrochemical water splitting.
178 citations
TL;DR: In this paper, anodic oxidation variables affecting the fabrication of vertically oriented TiO2 nanotube arrays using an electrolyte of dimethyl sulfoxide (DMSO) containing either hydrofluoric acid (HF), potassium fluoride (KF), or ammonium fluoride (NH4F).
Abstract: We detail anodic oxidation variables affecting the fabrication of vertically oriented TiO2 nanotube arrays using an electrolyte of dimethyl sulfoxide (DMSO) containing either hydrofluoric acid (HF), potassium fluoride (KF), or ammonium fluoride (NH4F). Various anodization variables including F- ion concentration, voltage, anodization time, water content, and previous use of the electrolyte can be combined to achieve nanotube arrays with length and morphology relevant to required applications. Using an anodization potential of 60 V with an electrolyte of 2% HF in DMSO, 70 h duration, nanotubes are achieved having a length of 101 μm, inner diameter 150 nm, and wall thickness 15 nm for a calculated geometric area of 3475. The weak adhesion of the DMSO fabricated nanotubes to the underlying oxide barrier layer and low tube-to-tube adhesion facilitates their separation for applications where dispersed nanotubes are desired. We examine the photoelectrochemical properties of 45 μm long nanotube arrays, crystalli...
144 citations
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9,432 citations
TL;DR: Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting and its Applications d0 Metal Oxide Photocatalysts 6518 4.4.1.
Abstract: 2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519
6,332 citations
TL;DR: In this article, a review of recent developments in the area of TiO 2 photocatalysis research, in terms of new materials from a structural design perspective, has been summarized.
Abstract: TiO 2 photocatalysis is widely used in a variety of applications and products in the environmental and energy fields, including self-cleaning surfaces, air and water purification systems, sterilization, hydrogen evolution, and photoelectrochemical conversion. The development of new materials, however, is strongly required to provide enhanced performances with respect to the photocatalytic properties and to find new uses for TiO 2 photocatalysis. In this review, recent developments in the area of TiO 2 photocatalysis research, in terms of new materials from a structural design perspective, have been summarized. The dimensionality associated with the structure of a TiO 2 material can affect its properties and functions, including its photocatalytic performance, and also more specifically its surface area, adsorption, reflectance, adhesion, and carrier transportation properties. We provide a brief introduction to the current situation in TiO 2 photocatalysis, and describe structurally controlled TiO 2 photocatalysts which can be classified into zero-, one-, two-, and three-dimensional structures. Furthermore, novel applications of TiO 2 surfaces for the fabrication of wettability patterns and for printing are discussed.
2,733 citations
TL;DR: In this article, three major ways to utilize nanostructures for the design of solar energy conversion devices are discussed: (i) mimicking photosynthesis with donor−acceptor molecular assemblies or clusters, (ii) semiconductor assisted photocatalysis to produce fuels such as hydrogen, and (iii) nanostructure semiconductor based solar cells.
Abstract: The increasing energy demand in the near future will force us to seek environmentally clean alternative energy resources. The emergence of nanomaterials as the new building blocks to construct light energy harvesting assemblies has opened up new ways to utilize renewable energy sources. This article discusses three major ways to utilize nanostructures for the design of solar energy conversion devices: (i) Mimicking photosynthesis with donor−acceptor molecular assemblies or clusters, (ii) semiconductor assisted photocatalysis to produce fuels such as hydrogen, and (iii) nanostructure semiconductor based solar cells. This account further highlights some of the recent developments in these areas and points out the factors that limit the efficiency optimization. Strategies to employ ordered assemblies of semiconductor and metal nanoparticles, inorganic-organic hybrid assemblies, and carbon nanostructures in the energy conversion schemes are also discussed. Directing the future research efforts toward utiliza...
2,119 citations
TL;DR: Analysis of photocurrent measurements indicates that the light-harvesting efficiencies of NT-based DSSCs were higher than those found for D SSCs incorporating NPs owing to stronger internal light-scattering effects.
Abstract: We report on the microstructure and dynamics of electron transport and recombination in dye-sensitized solar cells (DSSCs) incorporating oriented TiO2 nanotube (NT) arrays. The morphology of the NT arrays, which were prepared from electrochemically anodized Ti foils, were characterized by scanning and transmission electron microscopies. The arrays were found to consist of closely packed NTs, several micrometers in length, with typical wall thicknesses and intertube spacings of 8−10 nm and pore diameters of about 30 nm. The calcined material was fully crystalline with individual NTs consisting of about 30 nm sized crystallites. The transport and recombination properties of the NT and nanoparticle (NP) films used in DSSCs were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. While both morphologies display comparable transport times, recombination was much slower in the NT films, indicating that the NT-based DSSCs have significantly higher charge-collection efficiencies than...
2,008 citations