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Advanced Coating Materials || Anodic Oxide Nanostructures: Theories of Anodic Nanostructure Self-Organization
摘要： This chapter reviews the morphologies, growth kinetics, and theories of growth kinetics of anodic oxide films. Experimentally, it is possible to control the growth conditions of these films to yield several distinct morphologies, including orderly arranged nanoporous and nanotubular films. Fundamental processes that lead to self-ordering of nanoscale features, including interfacial reactions, ionic transport, stress generation, and space charge accumulation, are discussed. Various theories are included to explain the growth mechanism of oxide film.
关键词： barrier film,Anodic oxide film,porous film,EIS,anodization
更新于2025-09-23 15:23:52
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EFFECT OF VOLTAGE ON TIO2 NANOTUBES FORMATION IN ETHYLENE GLYCOL SOLUTION
摘要： Anodization of Ti foils in ethylene glycol (EG) containing ammonium fluoride (NH4F), and hydrogen peroxide (H2O2) was carried out to study the effect of voltage on the formation of TiO2 nanotubes. The crystalline phase of the TiO2 nanotubes without further heat treatment were studied. The TiO2 nanotube arrays were produced by anodization of Ti foil at three different voltage; 10, 40, and 60 V in a bath with electrolytes composed of ethylene glycol (EG), ammonium fluoride (NH4F), and hydrogen peroxide (H2O2). The H2O2 is a strong oxidizing agent which was used as oxygen provider to increase the oxidation rate for synthesizing highly ordered and smooth TiO2 nanotubes. Anodization at voltage greater than 10 V leads to the formation of tubular structure where higher anodization voltage (~ 60 V) yield to larger tube diameter (~ 180 nm). Crystallinity of the nanotubes is improved as the voltage was increased. The transformation of amorphous to anatase can be obtained for as anodized TiO2 without any heat treatment. The Raman spectra results show the anodization at 40 V and 60 V gives anatase peak in which confirms the crystalline phase. The stabilization of the crystalline phase is due to the oxygen vacancies and ionic mobilities during the anodization at high voltage.
关键词： anatase,TiO2 nanotubes,crystallization,anodization
更新于2025-09-23 15:23:52
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Enhancing visible light photocatalytic performance with N-doped TiO <sub/>2</sub> nanotube arrays assisted by H <sub/>2</sub> O <sub/>2</sub>
摘要： N-doped TiO2 nanotube arrays were prepared by an electrochemical anodization method and subsequent ammonia annealing. Microstructures, morphology, optical properties and photocatalytic properties of the N-doped TiO2 nanotube arrays were measured and analyzed. In the degradation of Acid Orange II(AO-II), the photocatalytic degradation efficiency of the N-doped TiO2 nanotube arrays assisted by H2O2 are 12 times, 2 times and 5 times higher than TiO2 nanotube arrays, TiO2 nanotube arrays assisted by H2O2 and H2O2, respectively. Experimental results show that the N-doped TiO2 nanotube arrays is a promising photocatalytic material for organic pollutant degradation under visible light, especially under the assistance of H2O2.
关键词： photocatalytic performance.,N-doped TiO2,H2O2,Electrochemical anodization
更新于2025-09-23 15:23:52
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Rational Management of Photons for Enhanced Photocatalysis in Structurally-Colored Nanoporous Anodic Alumina Photonic Crystals
摘要： A comprehensive study on the engineering of titanium dioxide-functionalized nanoporous anodic alumina distributed Bragg reflectors (TiO2-NAA-DBRs) for photocatalysis enhanced by the “slow photon” effect is presented. The photocatalytic performance of these composite photonic crystals (PCs) is assessed by monitoring photodegradation of a variety of organic molecules with absorbance bands across the spectral regions. This study demonstrates that photocatalytic performance of TiO2-NAA-DBRs is enhanced by the “slow photon” effect when the edges of the PC’s photonic stopband (PSB) fall within the absorbance band of the organic molecules. The photocatalytic performance is significantly enhanced when the PSB’s red edge is in close proximity to the absorbance band of the organic molecules. Overall photocatalytic degradation is also dependent on the total pore length of the PC structure, charge of the organic molecules, percentage of vis-NIR irradiation and matrix complexity (i.e. interfering ions and molecules) when the PC’s PSB is partially or entirely misaligned with respect to the absorbance band of the organic molecules. Finally, the real-life application of TiO2-NAA-DBRs to degrade pollutants such as pesticides in environmental matrices is demonstrated. This study provides new insights into the development of rationally engineered, high-performing, safe and reusable photocatalyst systems.
关键词： Stopband,Pulse Anodization,Photocatalysis,Slow Photons,Photonic Crystals
更新于2025-09-23 15:23:52
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Intrinsic Au-decoration on anodic TiO2 nanotubes grown from metastable Ti–Au sputtered alloys—High density co-catalyst decoration enhances the photocatalytic H2 evolution
摘要： Recent work demonstrated that intrinsic Au nanoparticle decoration of TiO2 nanotube arrays (NTs) can be achieved by electrochemical anodization of Ti–Au alloy substrates. However, for a Ti–Au cast alloy produced by melt-alloying, the Au concentration cannot exceed the solubility limit of Au in Ti of 0.2 at.% – this sets constraints on the intrinsic Au nanoparticle loading on anodic TiO2 NTs. Here we explore “metastable” Ti–Au metal substrates that are produced by Ti and Au cosputtering and we establish Au concentrations that far exceed the solubility limit in cast Ti–Au alloys. We show the use of these “metastable” Ti–Au sputtered layers for the anodic formation of TiO2 NTs with a much higher density of Au nanoparticle loading than using classic alloys. Under optimized conditions (Au nanoparticle density) photocatalytic H2 production from such Au@TiO2 platforms provides a 15 times higher photocatalytic H2 evolution rate than the best rates achieved with conventional alloys.
关键词： Anodic TiO2 nanotube,Metastable Ti–Au alloy,Sputtering,Anodization,Photocatalytic H2 evolution
更新于2025-09-23 15:23:52
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Preparation and properties of Co3O4-doped TiO2 nanotube array electrodes
摘要： Co3O4-doped TiO2 nanotube array electrodes were prepared by anodizing the Co–Ti alloys with different Co contents. Morphologies, elemental compositions, crystal structures, and electrochemical properties of the samples were characterized through scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and electrochemical workstation. The effects of Co content, annealing temperature and testing electrolyte on the electrochemical properties of the electrodes were studied. Results show that the areal capacitance values of TiO2 nanotube arrays were obviously improved by doping with Co3O4. The electrochemical properties of Co3O4-doped TiO2 nanotube array electrodes were best when the Co content in the alloys was 9%; the annealing temperature was 100 °C and the testing electrolyte was 0.5 M Na2SO4. The Co3O4-doped TiO2 nanotube array electrodes prepared under the optimal conditions had a high areal capacitance value of 937.9 μF cm?2 when the scan rate was 10 mV s?1 and the electrodes exhibited good rate and superior cycling performance.
关键词： Co–Ti alloys,Electrochemical properties,Co3O4,Anodization,TiO2 nanotube arrays
更新于2025-09-23 15:22:29
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Electrical and Photoelectrical Characteristics of с-Si/Porous–Si/CdS Heterojunctions
摘要： Depending on the sizes of the CdS crystallites and silicon pores, electrical and photoelectrical characteristics of c-Si/porous–Si/CdS heterojunctions prepared by electrochemical deposition and anodization, respectively, are studied. The optimal pore size (10–16 nm) is determined, which provides the maximum photoelectric conversion efficiency (7.71%) of heterojunctions.
关键词： porous silicon,heterojunction,anodization,electrochemical deposition
更新于2025-09-23 15:22:29
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TiO2 Nanotubes with Nanograss Structure: The Effect of the Anodizing Voltage on the Formation Mechanism and Structure Properties
摘要： Titanium dioxide nanotubes (TiO2 NTs) with a nanograss structure were synthesized in a fluoride organic electrolyte based on ethylene glycol under a potentiostatic anodization regime. By varying the anodization voltage, significant morphological differences were obtained, and the upper NTs’ surface has a nanograss appearance caused by the thinning of top tube walls, the result of the vertical splitting mechanism of nanograss growth. The samples were characterized using techniques such as scanning electron microscopy, x-ray diffraction, UV–visible spectroscopy and Mott–Schottky (MS) analysis. The obtained results show that samples annealed at 500°C for 3 h crystallized into anatase form and displayed the apparition of rutile phase at higher anodization voltage, where the morphology was significantly improved with thicker tube walls. The MS measurement of all samples displays a n-type semiconductor nature and the flat band potential (Ufb) takes less negative values by the increasing anodization voltage. As a result, TiO2 NTs with a nanograss structure expedite electron–hole separation, therefore, providing a lower recombination rate.
关键词： nanograss,TiO2 nanotubes,anodization process,nanomaterials,properties
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - Kuala Lumpur (2018.8.15-2018.8.17)] 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - Engineering the Properties of Nb<inf>2</inf>O<inf>5</inf>-ZnO Nanostructures via Dual Synthesis Techniques
摘要： In this paper, dual techniques; anodization and hydrothermal, were introduced to synthesize the Nb2O5-ZnO nanostructures. The purpose of this research is to engineer the properties of the Nb2O5-ZnO nanostructures which can offer new optical and electrical behaviors and also lead to large surface area. Synthesis of Nb2O5 has been conducted by anodizing the Niobium foil in the electrolyte containing NH4F and ethylene glycol. Meanwhile, ZnO was hydrothermalized with Zinc Nitrate precursor solution for 18 hr at different temperatures. All samples were characterized using FESEM, XRD and UV-Vis absorbance spectra. The morphological and properties changes of the Nb2O5-ZnO nanostructures are systematically investigated as a function of hydrothermal temperature.
关键词： ZnO,dual synthesis,anodization,Nb2O5,nanostructure,hydrothermal
更新于2025-09-23 15:21:21
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AIP Conference Proceedings [Author(s) 3RD INTERNATIONAL SCIENCES, TECHNOLOGY & ENGINEERING CONFERENCE (ISTEC) 2018 - MATERIAL CHEMISTRY - Penang, Malaysia (17–18 April 2018)] - Synthesis of gold nanoparticles (AuNPs) onto anodized titania nanotubes (TNTs) by spin coating technique
摘要： Gold nanoparticles (AuNPs) have received copious interests due to their unique properties such as small in size, reactive, high surface area and can be potentially applied in myriad fields including physics, chemistry, medicine and material sciences. However, the nanosized of gold particles makes them very reactive and undergo aggregation without protection. For that reason, supporting materials are introduced to prevent the aggregation of the AuNPs. In particular, metal oxide for example, titanium dioxide or titania nanotubes (TNTs) has been used as a support material because of its inertness, high porosity and great surface areas. Nevertheless, achieving precise control of attachment AuNPs on the TNTs substrate by conventional methods such as thermal evaporation and conservative heating are far from satisfactory. Herein, in this work, a new approach has been developed to synthesize controlled and uniformed attachment of AuNPs onto fabricated electrochemically-anodized TNTs by a spin coating technique. This preliminary work used different spin rate of 500, 1000 and 2000 revolutions per minute (rpm), following by heat treatment at 250 °C for 2 hours. The FESEM micrograph showed the anodized TNTs with good morphological structures were successfully fabricated at a voltage of 50 V in a mixture of ethylene glycol containing 0.5 wt. % ammonium fluoride solution, with an average nanotubes diameter of 150 nm. Meanwhile, the attachment of AuNPs on the fabricated TNTs has been effectively achieved at a higher spin rate of 2000 rpm and the EDX analysis confirmed the deposition of AuNPs over the TNTs. The AuNPs-TNTs also were tested for the catalytic reduction of p-nitrophenol (p-NP), in which is discussed shortly in this paper.
关键词： Gold nanoparticles,spin coating,titania nanotubes,electrochemical anodization
更新于2025-09-23 15:21:01