Discovery of WO3/TiO2 Nanostructure Transformation by Controlling Content of NH4F to Enhance Photoelectrochemical Response

2012 ◽  
Vol 620 ◽  
pp. 173-178 ◽  
Author(s):  
Chin Wei Lai ◽  
Srimala Sreekantan
Keyword(s):  
Ammonium Fluoride ◽  
Anodic Oxide ◽  
Photocurrent Density ◽  
Electrochemical Anodization ◽  
Nanoporous Structure ◽  
Nanotubular Structure ◽  
Insufficient Amount ◽  
Photoelectrochemical Response ◽  
Anodization Process ◽  
Anodic Oxide Layer

We report on the effect of the tungsten (W) cathode in controlling the morphology and properties of titanium (Ti) anodic oxide layer via an electrochemical anodization process. The content of ammonium fluoride (NH4F) was varied in ethylene glycol (EG) electrolyte containing hydrogen peroxide (H2O2) in order to obtained the high ordered nanotubular structure. When amount of NH4F was upto 5 wt%, highly ordered WO3-TiO2nanotubes structure was observed. If insufficient amount of NH4F is applied, the nanoporous structure will be favored. Highly ordered WO3-TiO2nanotubes structure exhibited higher photocurrent density ( 0.9 mA/cm2) as compared to the WO3-TiO2nanoporous structure.

scholarly journals Surface Morphology and Growth of Anodic Titania Nanotubes Films: Photoelectrochemical Water Splitting Studies

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Chin Wei Lai
Keyword(s):  
Oxide Layer ◽  
Water Splitting ◽  
Active Surface ◽  
Ammonium Fluoride ◽  
Photocurrent Density ◽  
Photon Absorption ◽  
Electrochemical Anodization ◽  
Nanoporous Structure ◽  
Active Surface Area ◽  
Surface Morphologies

Design and development of one-dimensional nanoarchitecture titania (TiO) assemblies have gained significant scientific interest, which have become the most studied material as they exhibit promising functional properties. In the present study, anodic TiO2films with different surface morphologies can be synthesized in an organic electrolyte of ethylene glycol (EG) by controlling an optimum content of ammonium fluoride (NH4F) using electrochemical anodization technique. Based on the results obtained, well-aligned and bundle-free TiO2nanotube arrays with diameter of 100 nm and length of 8 µm were successfully synthesized in EG electrolyte containing ≈5 wt% of NH4F for 1 h at 60 V. However, formation of nanoporous structure and compact oxide layer would be favored if the content of NH4F was less than 5 wt%. In the photoelectrochemical (PEC) water splitting studies, well-aligned TiO2nanotubular structure exhibited higher photocurrent density of ≈1 mA/cm2with photoconversion efficiency of ≈2% as compared to the nanoporous and compact oxide layer due to the higher active surface area for the photon absorption to generate more photo-induced electrons during photoexcitation stage.

scholarly journals Anodic Fabrication of Ti-Ni-Si-O Nanostructures on Ti10Ni5Si Alloy

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1315 ◽  
Author(s):  
Ting Li ◽  
Dongyan Ding ◽  
Nan Li
Keyword(s):  
Pore Diameter ◽  
Ammonium Fluoride ◽  
Anodic Oxide ◽  
Electrolyte Solutions ◽  
Phase Region ◽  
Electrochemical Anodization ◽  
Average Pore ◽  
Self Organized ◽  
Inner Diameter ◽  
Ti2ni Phase

Ti-Ni-Si-O nanostructures were synthesized on Ti10Ni5Si alloy through an electrochemical anodization in electrolyte solutions containing ammonium fluoride (NH4F). The anodic oxide structures were affected by the electrochemical anodization parameters, including the electrolyte viscosity, water content, anodization potential and anodization time. Using an anodization potential of 40 V for 90 min in an ethylene glycol/glycerol electrolyte with 3 vol.% deionized water, highly ordered self-organized nanotube arrays were obtained in the α-Ti phase region of the alloy substrate, with an average inner diameter of 70 nm and a wall thickness of about 12 nm. Self-organized nanopore structures with an average pore diameter of 25 nm grew in the Ti5Si3 phase region. Only etching pits were found in the Ti2Ni phase region. The Ti-Ni-Si-O nanostructures were characterized using scanning electron microscopy and energy dispersive spectroscopy. In addition, a formation mechanism of different nanostructures was presented.

scholarly journals A Novel Solar Driven Photocatalyst: Well-Aligned Anodic WO3Nanotubes

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Chin Wei Lai ◽  
Sharifah Bee Abd Hamid ◽  
Srimala Sreekantan
Keyword(s):  
Surface Morphology ◽  
Formation Mechanism ◽  
Tungsten Trioxide ◽  
Average Diameter ◽  
Ammonium Fluoride ◽  
Sodium Sulphate ◽  
Electrochemical Anodization ◽  
Methyl Blue ◽  
Photocatalytic Ability ◽  
Nanotubular Structure

Well-aligned anodic tungsten trioxide (WO3) nanotubes were successfully synthesized by anodization of W foil at 40 V in a bath with electrolyte composed of 1 M of sodium sulphate (Na2SO4) and 0.5 wt% ammonium fluoride (NH4F). The effect of electrochemical anodization times on the formation mechanism of anodic WO3nanotubular structure was investigated. It was found that minimum of 15 min is required for completing transformation from W foil to WO3nanotubular structure with an average diameter of 50 nm and length of 500 nm. The photocatalytic ability of the samples was evaluated by degradation of methyl blue (MB) dye. The results indicate that the surface morphology of anodic WO3affected the photocatalytic MB degradation significantly under solar illumination.

Fabrication and Photoelectrochemical Properties of Self-Organized Mixed Oxide Nanotubes by Anodization of Ti-2Al-1.5Mn Alloy

2011 ◽  
Vol 219-220 ◽  
pp. 1333-1336 ◽  
Author(s):  
Shi Kai Liu ◽  
Yan Tao Li ◽  
Hai Bin Yang ◽  
Wen Jun Zou ◽  
Zheng Xin Li
Keyword(s):  
Mixed Oxide ◽  
Visible Region ◽  
Ammonium Fluoride ◽  
Electrochemical Anodization ◽  
Nanotube Arrays ◽  
Photoelectrochemical Properties ◽  
Self Organized ◽  
Photoelectrochemical Response ◽  
Ion Doping ◽  
Application Prospects

Nanotubular films on the surface of Ti-2Al-1.5Mn (TC1) alloy were fabricated by electrochemical anodization technique in aqueous ammonium fluoride solutions at 20V for 3h. The photoelectrochemical activities of the nanotube arrays were investigated, as well as their phase, structure, composition and photoabsorption properties. The photo-absorption in the visible region and the photoelectrochemical response were improved obviously. It is attributed to the Mn ion doping of TiO2 lattices. Furthermore, the resulted nanotube arrays are expected to have bright application prospects for solar utilization.

scholarly journals Single Step Formation of C-TiO2Nanotubes: Influence of Applied Voltage and Their Photocatalytic Activity under Solar Illumination

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Chin Wei Lai ◽  
Srimala Sreekantan
Keyword(s):  
Photocatalytic Activity ◽  
Applied Voltage ◽  
Active Surface ◽  
Ammonium Fluoride ◽  
Single Step ◽  
Electrochemical Anodization ◽  
Nanotube Arrays ◽  
Surface Areas ◽  
High Uniformity ◽  
Anodization Process

Self-aligned and high-uniformity carbon (C)- titania (TiO2) nanotube arrays were successfully formed via single step anodization of titanium (Ti) foil at 30 V for 1 h in a bath composed of ethylene glycol (EG), ammonium fluoride (NH4F), and hydrogen peroxide (H2O2). It was well established that applied voltage played an important role in controlling field-assisted oxidation and field-assisted dissolution during electrochemical anodization process. Therefore, the influences of applied voltage on the formation of C-TiO2nanotube arrays were discussed. It was found that a minimal applied voltage of 30 V was required to form the self-aligned and high-uniformity C-TiO2nanotube arrays with diameter of ~75 nm and length of ~2 μm. The samples synthesized using different applied voltages were then subjected to heat treatment for the conversion of amorphous phase to crystalline phase. The photocatalytic activity evaluation of C-TiO2samples was made under degradation of organic dye (methyl orange (MO) solution). The results revealed that controlled nanoarchitecture C-TiO2photocatalyst led to a significant enhancement in photocatalytic activity due to the creation of more specific active surface areas for incident photons absorption from the solar illumination.

Anodic synthesis of TiO2 nanotubes by step-up voltages

2021 ◽  
pp. 002199832110237
Author(s):  
V Sivaprakash ◽  
R Narayanan
Keyword(s):  
Corrosion Resistance ◽  
Tio2 Nanotubes ◽  
Biomedical Applications ◽  
Phase Changes ◽  
Electrochemical Anodization ◽  
Corrosion Resistant ◽  
Anodization Process ◽  
Anodic Synthesis ◽  
Input Potential

Fabrication of TiO2 nanotubes (NTs) has extensive application properties due to their high corrosion resistant and compatibility with biomedical applications, the synthesis of TiO2 nanotubes over titanium has drawn interest in various fields. The synthesis of TiO2 NTs using novel in-situ step-up voltage conditions in the electrochemical anodization process is recorded in this work. For manufacturing the NTs at 1 hour of anodization, the input potential of 30, 40 and 50 V was selected. With increasing step-up voltage during the anodization process, an improvement in the NTs was observed, favoring corrosion resistance properties. The surface of NTs enhances the structure of the ribs, raising the potential for feedback over time. XRD was used to analyze phase changes, and HR-SEM analyzed surface topography. Impedance tests found that longer NTs improved the corrosion resistance.

scholarly journals Ni/Si-Codoped TiO2 Nanostructure Photoanode for Enhanced Photoelectrochemical Water Splitting

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4102 ◽  
Author(s):  
Ting Li ◽  
Dongyan Ding
Keyword(s):  
Water Splitting ◽  
Annealing Temperature ◽  
Photocurrent Density ◽  
Electrochemical Anodization ◽  
Codoped Tio2 ◽  
Lower Charge ◽  
Si Doped ◽  
Tio2 Nanostructures ◽  
Tio2 Photoanode ◽  
Pec Water Splitting

We synthesized Ni/Si-codoped TiO2 nanostructures for photoelectrochemical (PEC) water splitting, by electrochemical anodization of Ti-1Ni-5Si alloy foils in ethylene glycol/glycerol solutions containing a small amount of water. The effects of annealing temperature on PEC properties of Ni/Si-codoped TiO2 photoanode were investigated. We found that the Ni/Si-codoped TiO2 photoanode annealed at 700 °C had an anatase-rutile mixed phase and exhibited the highest photocurrent density of 1.15 mA/cm2 at 0 V (vs. Ag/AgCl), corresponding to a photoconversion efficiency of 0.70%, which was superior to Ni-doped and Si-doped TiO2. This improvement in PEC water splitting could be attributed to the extended light absorption, faster charge transfer, possibly lower charge recombination, and longer lifetime.

Synthesis and Structure of Titania Nanotubes For Hydrogen Generation

2013 ◽  
Vol 741 ◽  
pp. 84-89 ◽  
Author(s):  
Sangworn Wantawee ◽  
Pacharee Krongkitsiri ◽  
Tippawan Saipin ◽  
Buagun Samran ◽  
Udom Tipparach
Keyword(s):  
Oxalic Acid ◽  
Hydrogen Generation ◽  
Ammonium Fluoride ◽  
Photocurrent Density ◽  
Sodium Sulphate ◽  
Titania Nanotubes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dc Power ◽  
Anodic Voltage

Titania nanotubes (TiO2NTs) working electrodes for hydrogen production by photoelectrocatalytic water splitting were synthesized by means of anodization method. The electrolytes were the mixtures of oxalic acid (H2C2O4), ammonium fluoride (NH4F), and sodium sulphate (VI) (Na2SO4) with different pHs. A constant dc power supply at 20 V was used as anodic voltage. The samples were annealed at 450 °C for 2 hrs. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) were used to characterized TiO2NTs microstructure. TiO2NTs with diameter of 100 nm were obtained when pH 3 electrolyte consisting of 0.08 M oxalic acid, 0.5 wt% NH4F, and 1.0 wt% Na2SO4was used. Without external applied potential, the maximum photocurrent density was 2.8 mA/cm2under illumination of 100 mW/cm2. Hydrogen was generated at an overall photoconversion efficiency of 3.4 %.

scholarly journals Study the Effect of Water Content on the Structure of Electrochemically Prepared TiO2 Nanotubes

2022 ◽  
Author(s):  
Sara Al-Waisawy ◽  
Ahmed Kareem Abdullah ◽  
Hadi A. Hamed ◽  
Ali A. Al-bakri
Keyword(s):  
Water Content ◽  
Pure Titanium ◽  
Electrochemical Anodization ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Titania Nanotube Arrays ◽  
Anodization Process ◽  
Titania Films ◽  
Average Size

In this research, the pure titanium foil was treated in glycerol base electrolyte with 0.7 wt.% NH4F and a small amount of H2O at 17 V for 2 hours by electrochemical anodization process in order to prepare Titania nanotube arrays at room temperature (~25 ºC), different water content was added to the electrolyte as a tube enhancing agent. The high density uniform arrays are prepared by using organized and well aligned these tubes. The average size of tube diameter, ranging from 57 to 92 nm which found it increases with increasing water content, and the length of the tube ranging from 2.76 to 4.12 µm, also found to increase with increasing water content and ranging in size of wall thickness from 23 to 35 nm. A possible growth mechanism is presented. The X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were utilized to study the structure and morphology of the Titania films.

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