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Photoelectrochemical removal of chlorfenvinphos by using WO3 nanorods: influence of annealing temperature and operation pH
摘要： A visible-light driven photoelectrochemical degradation process has been applied to a solution polluted with the organophosphate insecticide chlorfenvinphos. Different WO3 nanosheets/nanorods have been used as photoanodes. These nanostructured electrodes have been fabricated by anodization of tungsten and, subsequently, they have been subjected to a thermal treatment (annealing). The combined influence of annealing temperature (400o C and 600o C) and operation pH (1 and 3) on the photoelectrocatalytic behavior of these nanorods has been examined through a statistical analysis. Morphological, structural and photoelectrochemical characterizations have also been carried out. The chlorfenvinphos degradation efficiency depended both on annealing temperature and, specially, operation pH. At pH 1 and using an annealing temperature of 600o C, chlorfenvinphos has been effectively degraded following pseudo-first order kinetics with a coefficient of 7.8×10-3 min-1, and notably mineralized (more than 65% of Total Organic Carbon decrease).
关键词： anodization,WO3 nanorods,chlorfenvinphos,regression model,Photoelectrochemical degradation
更新于2025-09-10 09:29:36
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Hierarchical 3D TiO <sub/>2</sub> Nanotube Arrays Sensitized by Graphene Oxide and Zn <sub/>x</sub> Cd <sub/>y</sub> S for High Performance Photoelectrochemical Applications
摘要： Photocatalysis and photoelectrocatalysis are highly promising for applications in the energy and environment sectors. Several photocatalytic devices based on TiO2 nanotubes grown on two-dimensional (2D) substrate (such as titanium foil) have been developed, but there has been little research on three-dimensional (3D) TiO2 nanotubes which are expected to offer significantly enlarged surface area and much improved photocatalytic efficiency. Here, a method of building 3D TiO2 nanotube arrays (3D-TNTAs) on titanium mesh by anodization via controlling the reaction time and electrolyte is reported. It is found that the electrochemically active area of such a titanium mesh is almost 4 times larger than that of the traditional titanium foil. Moreover, through making composites of graphene oxide and ZnxCdyS onto 3D TiO2 nanotubes, hierarchical nanotube arrays (ZnxCdyS/GO/3D-TNTAs) are made by calcination-deposition of graphene oxide followed by a facile successive ionic layer adsorption reaction (SILAR) treatment with ZnxCdyS. Characterization of the ZnxCdyS/GO/3D-TNTAs indicates that this hierarchical multi-layered nanostructure has a much improved photoelectrochemical property due to the enlarged surface area and improved electron–hole separation capability, demonstrating the great potential for applications in photoelectrocatalytic devices for environmental technologies.
关键词： anodization,SILAR method,photoelectrochemical property,3D TiO2 nanotube arrays
更新于2025-09-10 09:29:36
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High Photoconversion Efficiency Obtained from Novel TiO2 Photoanodes
摘要： High photoconversion efficiency for photoelectrochemical water splitting was obtained using nanocaves TiO2 and highly uniformed TiO2 nanotubes. The photoanodes were synthesized via electrochemical anodization of a titanium foil in a glycerol-based solution containing NH4F at 10 V. Pulse electrodeposition was used to incorporate Cu ions into the uniform TiO2 nanotubes. The photoconversion efficiency performance was examined under simulated visible light illumination (? ≥ 380 nm) in a 1 M solution of NaOH. The photocurrent density, the Mott-Schottky, the EIS, and the photoconversion efficiency measurements were determined. The highest photocurrent density i.e. 5.77 mA cm-2 at 1.23 V vs. RHE was obtained from nanocaves TiO2 photoanode. The incorporation of Cu resulted in a reduction in photocatalytic activity of the oxygen evaluation reaction (OER) and an increase of the hydrogen evolution reaction (HER).
关键词： Titanium dioxide nanotubes,water splitting,Photocurrent density,Photoelectrochemical,Anodization
更新于2025-09-09 09:28:46
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Preparation and Photocatalytic Properties of ZnO Deposited TiO <sub/>2</sub> Nanotube Arrays by Anodization
摘要： ZnO doped TiO2 nanotube arrays (ZnO-TNTs) with an average diameter of 60～80 nm and an average length of 2～4 μm were prepared on the Ti substrate by a one-step anodizing method using NH4F/ethylene glycol as the electrolyte. The phase structure, morphology, chemical composition, photocatalytic property and mechanism of TNTs were studied by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectra, photoluminescence and photocatalytic degradation of methylene blue under visible light. The results showed that highly ordered ZnO doped TNTs were successfully prepared by anodization. ZnO nanoparticles were dispersively distributed inside the walls of TNTs. ZnO-TNTs having a different amount of ZnO was prepared by adjusting the concentration of Zn(NO3)2·6H2O in the electrolyte. It was found that by changing doping amount of ZnO, the width of the TiO2 band gap and the recombination rate of photo-generated electron–hole pairs also changed. The TNTs which doped with 1 mM ZnO showed the best degradation rate of methylene blue (MB). At the concentration of 1 cm2·mL?1 of ZnO-TNTs, the degradation rate reached at the level of 81.9% with 8 mg·L?1 methylene blue aqueous solution. Compared with undoped TNTs, the band gap of ZnO-TNTs reduced from 3.25 eV to 2.75 eV, and the recombination rate of photo-generated electron–hole pairs decreased significantly. The film of ZnO-TNTs prepared by the one-step anodizing method depicted excellent photocatalytic properties under visible light.
关键词： ZnO-TNTs,Anodization,Methylene Blue,Band Gap,Photocatalytic
更新于2025-09-09 09:28:46
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Nanostructured Titanium Dioxide Based on Titanium Alloys: Synthesis and Properties
摘要： Titanium dioxide (TiO2) has provoked a significant amount of scientific and technological interest due to their anticipated impact in the fields of photocatalysis, solar cells, lithium-ion battery electrodes, and biomedical devices. This is particularly apparent in the case of anodization and ion implantation for modifying Ti-based alloys. However, the lack of sufficient solar light absorption and limited hole diffusion significantly affect the performance of TiO2 in photocatalysis. Moreover, the biocompatibility and corrosion resistance of Ti-based biomedical device need to be enhanced to achieve a longer service life. In the present review, the MOx prepared by anodization is described first. Then, the electrolyte parameters during anodization are assessed by comparing various electrolytes including ethylene glycol, glycerol, formamide, and aqueous electrolytes. Additionally, the effects of ion implantation on the surface of Ti-based alloy are outlined. By analyzing the impact on various synthetic method and modification strategies of nanostructured TiO2, the essential elements of suitable in situ doping ratio and ion implantation dose are addressed. Finally, the outlook for anodization and ion implantation for constructing nanostructured TiO2 is discussed, highlighting challenges and key areas for future research and development.
关键词： Anodization,Water Splitting,Biocompatibility,TiO2-Based Ti Alloy,Ion Implantation
更新于2025-09-09 09:28:46
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Rapid Fabrication of Porous Anodic Alumina Films with Large Interpore Distances in an Ethylene Glycol and Ammonium Dihydrogen Phosphate-Based Electrolyte
摘要： Porous anodic alumina (PAA) ?lms have become popular nanotemplates due to the ordered hexagonal pore array structure. The fabrication of well-ordered PAA ?lms with larger interpore distances is still a challenge to date. Here, we develop a unique electrolyte system based on the reaction products of ethylene glycol (EG) with ammonium dihydrogen phosphate (ADP). In the novel electrolytes, stable high-voltage anodization with extremely high current densities (the peak value is close to 300 mA cm?2) can be realized at 400 V or even higher without breakdown. In 5 wt% EG-ADP-based electrolyte containing phosphoric acid, a well-ordered PAA ?lm with an interpore distance of ～610 nm can be fabricated at 250 V at a high growth rate of 1.3 μm · min?1.
关键词： Porous anodic alumina,high-voltage anodization,ethylene glycol,ammonium dihydrogen phosphate,interpore distance
更新于2025-09-09 09:28:46
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Effect of Anodization Parameters on the Surface Morphology and Photoelectrochemical Properties of TiO2 Nanotubes
摘要： Titanium sheets are anodized to prepare titanium dioxide nanotubes (TiO2 NTs) with varying chemical polishing times, anodizing voltages, anodizing times and NH4F electrolyte concentrations. The surface morphology of the TiO2 NTs is observed by a Scanning Electron Microscope (SEM) and used to characterize the inner diameter (di), centre to centre distance (l) and wall thickness (w). The photoelectrochemical performance of TiO2 NT arrays is described by measurements of the photocurrent density and the incident photon to current efficiency (IPCE). The data show l can be controlled by the anodizing voltage; in contrast, di and w are influenced by the anodizing time and NH4F electrolyte concentration. Furthermore, the effects of the anodization parameters on the TiO2 NTs’ surface morphology were determined to influence each other. Using the optimum condition of an anodizing voltage of 60 V at 60 min in 0.125 mass % NH4F ethylene glycol, TiO2 NTs were fabricated that showed a photocurrent density of 90.42 μA /cm2 and maximum IPCE of 18.76 % at 300 nm. The results indicate that the effects of the anodization parameters on the photocurrent response of TiO2 NTs are primarily achieved through control of the wall thickness and the ratio of the diameter to the wall thickness (di / w). For a wall thickness that is greater than a critical value, the ratio di / w can reach a range in which the TiO2 NTs show a high photocurrent output.
关键词： surface morphology,wall thickness,TiO2 nanotubes,anodization,photoelectrochemical property
更新于2025-09-04 15:30:14
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Microstructure and Electrochemical Behavior of TiO <sub/>2</sub> Nanotubes Coated on Titanium-Based Substrate Before and After Thermal Treatment
摘要： The comparative study of the structure and electrochemical properties of TiO2 layers on the surfaces of commercially pure titanium and Ti6Al4V alloy were performed. The TiO2 surface layers produced by anodization in ethylene glycol-based electrolyte solution using Power Supply MCS-3204 MANSON at 20 V or 40 V for 60 minutes were formed on the titanium substrates by simultaneous surface oxidation and controlled dissolving of oxide film due the fluorine ions. The SEM and X-ray diffraction analyses were performed to determine the properties of the anodized layers before and after heat treatment at 500 °C for 120 minutes. The as-anodized TiO2 nanotubes exhibited an amorphous structure. An anatase phase appeared in annealed nanotube layers of both Ti based substrates. The corrosion behavior in simulated physiological solution was compared for not anodized, anodized and anodized heat treated conditions of both titanium surfaces. The results of the electrochemical measurements corresponded to the microstructure and treatment condition. The porous feature of the anodizing layers on Ti6Al4V substrate led to lower corrosion resistance that increased after the heat treatment.
关键词： TiO2 Nanotubes,XRD,Titanium Alloy,Anodization,Microstructure
更新于2025-09-04 15:30:14
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Exploring the photoelectrocatalytic behavior of free-standing TiO2 nanotube arrays on transparent conductive oxide electrodes: Irradiation direction vs. alignment direction
摘要： Although one-dimensional TiO2 nanotube arrays (TNA) grown on Ti substrates via electrochemical anodization are extensively studied in photoelectrochemistry, the photo(electro)catalytic activity of TNA detached from the Ti substrates remains unexplored. Herein, we synthesize TNA samples with various pore sizes (40?100 nm) and tube lengths (4?15 μm) via two-step electrochemical anodization, and transfer them to transparent conducting oxide (i.e. fluorine-doped tin oxide; FTO) substrates in normal (n) alignment (front plane outward) and reverse (r) alignment (backplane outward). The front and back planes of the as-fabricated TNA film are the same based on X-ray diffraction (anatase structure), X-ray photoelectron spectroscopy (Ti and O), and UV-vis transmittance data, though the tubes are open in the front and closed in the back. Regardless of the direction of irradiation (SE: FTO → TNA vs. EE: TNA → FTO), longer tubes generate a higher photocurrent (Iph) due to the large light absorption. However, for the same alignment of TNA (either n- or r-TNA), SE irradiation leads to a very large Iph (e.g., nSE > nEE), whereas n-TNA consistently generates a larger Iph than r-TNA for a given irradiation direction (i.e., n > r). The photocatalytic decomposition of phenol follows the same tendency (n > r); however, the Faraday efficiency (based on the photocharge) is higher with EE (nEE 28%, rEE 20%) than SE (rSE 11%, nSE 7%) irradiation. These photoelectrochemical and photocatalytic behaviors are explained in terms of charge carrier generation (FTO/TNA vs. TNA/solution), dissimilar charge carrier transfer pathways (e? transfer through tube framework vs. h+ transfer via radial direction), and charge injection at the tube (open vs. clogged tube mouth)/solution interface. The time-resolved photoluminescence (TRPL) emission and incident photon-to-current efficiency (IPCE) are also studied to gain insight into the charge transfer kinetics.
关键词： Photocatalysis,Anodization,Charge transfer,Photoelectrochemistry,Morphology
更新于2025-09-04 15:30:14
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Electrolyte Factors Influencing Separated Pore Growth of Anodic TiO2 Nanotube Arrays
摘要： This work presents an investigation of electrolyte properties in relation to the growth of TiO2 nanotube array films, particularly concerning the measurement of conductivity in the diethylene glycol-hydrofluoric-water electrolyte system. The work aims to elucidate the behavior of ions in the anodized electrolytes with a better insight into the relation between molar conductivity and concentration of the additives. Differing solvation of the fluoride ion in various composition of water in the DEG-H2O mixture is attributed to the major factor determining the capability of proton transfer, controlling the ionic mobilities and the molar conductivities. Applying the feature of the two-factorial experiment has demonstrated a clear interaction of electrolyte parameters and titanium concentration dissolving into the electrolyte, which is believed to be a combination effect on pore widening and separating of nanotubes. A proposed schematic drawing has been demonstrated, summarizing how the nanotube arrays are constructed as a consequence of varying electrolyte type and composition.
关键词： electrochemical anodization,tube separation,TiO2 nanotube arrays,electrolyte conductivity
更新于2025-09-04 15:30:14