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Oxygen Vacancy Induced Structural Distortions in Black Titania - A Unique Approach using Soft X-Ray EXAFS at the O K-Edge
摘要： Unknown changes in the crystalline order of regular TiO2 result in the formation of black titania, which has garnered significant interest as a photocatalytic material due to the accompanying electronic changes. Herein, we determine the nature of the lattice distortion caused by an oxygen vacancy that in turn results in the formation of mid-band gap states found in previous studies of black titania. We introduce an innovative technique using a state-of-the-art silicon drift detector, which can be used in conjunction with extended x-ray absorption fine structure (EXAFS) to measure bulk interatomic distances. We illustrate how the energy dispersive nature of such a detector can allow us an unimpeded signal, indefinitely in energy space, thereby sidestepping the hurdles of more conventional EXAFS, which is often impeded by other absorption edges.
关键词： black titania,EXAFS,black TiO2,structural distortion,photocatalytic
更新于2025-09-23 15:22:29
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A novel bi-functional SiO2@TiO2/CDs nanocomposite with yolk-shell structure as both efficient SERS substrate and photocatalyst
摘要： A novel multi-functional yolk-shell SiO2@TiO2/CDs(y-STCs) nanocomposite with interesting structure of SiO2 cores, porous TiO2 shell, and cavities was synthesized by using a simple method. The experimental results indicate that the yolk-shell structure and modification of carbon dots (CDs) play important roles in the enhancement of SERS signals and photocatalytic performance. The y-STCs nanocomposite used as the SERS substrate showed excellent efficiency and reproducibility for the detection of rhodamine 6G (R6G). The detection limit of R6G was shown to be as low as 6 × 10?8 M. Furthermore, the fabricated y-STCs nanocomposite utilized as the photocatalytst for the degradation of dinitraphenols (DNP) can greatly shorten reaction time to 120 min compared with previous studies, and the DNP degradation rate could reach 96% under simulated sunlight irradiation. The y-STCs nanospheres also possessed excellent cycle stability for the photocatalytic degradation of DNP. Thus, the bi-functional y-STCs nanocomposite may have potential applications in the detection and photocatalytic degradation of organic pollutants.
关键词： SiO2@TiO2/CDs nanocomposite,Yolk-shell structure,SERS detection,Photocatalytic activity
更新于2025-09-23 15:22:29
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Introduction of Nitrogen Defects into a Graphitic Carbon Nitride Framework by Selenium Vapor Treatment for Enhanced Photocatalytic Hydrogen Production
摘要： Graphitic carbon nitride (g-C3N4) is a metal-free semiconductor photocatalyst that has attracted significant attention due to its promising application in photocatalytic hydrogen production. However, pristine g-C3N4 suffers from a high recombination rate of photo-generated charge carriers and also has a limited visible-light absorption range, resulting in low photocatalytic activity. Herein, we report on the preparation and testing of a g-C3N4 photocatalyst with tunable nitrogen defects that delivered improved photocatalytic activity. The nitrogen defects were gradually introduced into the g-C3N4 framework by a selenium vapor treatment of pure g-C3N4, which resulted in improved, stable catalytic activity for photocatalytic hydrogen production. Based on the experimental results and DFT calculations, we proposed that the enhanced photoactivity is attributed to the defect state (DS) formed by the nitrogen vacancy (VN) in the unit cell of g-C3N4 and a small widening of visible light absorption. This nitrogen-based photocatalyst with nitrogen deficiencies was found to deliver an average hydrogen generation rate of 1.16 mmolg-1h-1 at room temperature (25 oC), which was 3.4 times greater than pristine g-C3N4. This process of introducing nitrogen defects into the graphitic carbon provides a promising way for enhancing the photocatalytic activity of g-C3N4-based materials for hydrogen production.
关键词： nitrogen vacancies,photocatalytic hydrogen production,g-C3N4,bandgap
更新于2025-09-23 15:22:29
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Synthesis and photocatalytic activity of BiOBr hierarchical structures constructed by porous nanosheets with exposed (110) facets
摘要： BiOBr hierarchical structures were successfully synthesized through a solvothermal process assisted with citric acid using methanol as a solvent. The as-synthesized BiOBr hierarchical structures have diameters of ca. 1 μm, and assembled by numerous porous nanosheets with exposed (110) facets. Results indicated that the crystal growth and morphology structures of BiOBr were significantly influenced by the amount of citric acid, the solvothermal time and the solvent used in reaction. In addition, the as-synthesized BiOBr hierarchical structures exhibited high photocatalytic activity on the degradation of methyl orange under either UV light or simulated sunlight illumination, due to the larger specific surface area and unique hierarchical structures assembled by numerous BiOBr porous nanosheets.
关键词： photocatalytic,citric acid,hierarchical structures,solvothermal,BiOBr
更新于2025-09-23 15:22:29
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Translucent packed bed structures for high throughput photocatalytic reactors
摘要： Translucent photocatalytic reactor structures are investigated as a possible alternative to numbering up as a method for the scale-up of microreactors. The structure and the light source design is elaborated to introduce this concept. The light field was characterized using a ray tracing algorithm. A rectangular reactor made from glass was designed using borosilicate spheres small enough to create an array of interconnected microchannels in the reactor. It was found that ray tracing can be used as a proper tool to easily design multiple-LED light sources and predict respective irradiance patterns. The performance of the reactor was assessed using the apparent rate constant, the space-time yield and the photocatalytic space-time yield, a recently introduced performance parameter which takes into account the lamp power and the reactor productivity. The apparent rate constant of the reactor for an incoming irradiance of 191 W m?2 was found to be 0.82 min?1, which is, to our knowledge, in the range of microreactors and 1–2 orders of magnitude higher than any high throughput immobilized reactor in literature. With a photocatalytic space-time yield of 0.657 m3 day?1 m?3 reactor kW?1 our reactor was amongst the best reported performers in terms of productivity and energy efficiency. This performance is related to the high specific illuminated surface area of 4267 m2 m?3 and high catalyst load of 1.9 g L?1.
关键词： Light distribution,Structured reactors,Photocatalysis,Photocatalytic degradation,LED,Reactor engineering
更新于2025-09-23 15:22:29
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Co2+ Substituted ZnCuFe2O4 (0.0?≤?x?≤?0.5) Ferrites: Synthesis, Magneto-structural and Optical Properties for Their Photocatalytic Performance
摘要： The cobalt (Co2+) has been successively substituted in ZnCuFe2O4 to obtain Zn0.5?xCoxCu0.5Fe2O4 (0.0 ≤ x ≤ 0.5) ferrites by auto-combustion technique. Prior to photocatalytic degradation, all as-synthesized ferrites were characterized to study their structure, composition, morphology, magnetic and optical behavior. The shifting of tetrahedral as well as octahedral stretching peaks towards higher frequencies observed in the Fourier transform infrared spectroscopy indicates that Co2+ ion is substituted in ZnCuFe2O4. X-ray diffraction pattern confirms the formation of single-phase cubic spinel with decrease in average lattice constant from 8.3915 to 8.3224 ? with increase in Co2+ substitution. The photocatalytic performance of obtained ferrite catalyst was determined using methylene blue (MB) as model dye under visible light and direct sunlight. The degradation of MB with as-obtained photocatalyst under sunlight improves (91%) which proves the effective utilization of visible light active magnetic photocatalyst.
关键词： Photocatalytic degradation,Magnetic materials,Methylene blue,Sol-gel method,Spinel ZnCuFe2O4
更新于2025-09-23 15:22:29
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Gaseous bubble-assisted in-situ construction of worm-like porous g-C3N4 with superior visible light photocatalytic performance
摘要： Metal-free graphitic carbon nitride (g-C3N4) displays benign photocatalytic properties for contaminants photodegradation under visible photoirradiation. Devising a simple modification strategy for the improved photocatalytic activity of g-C3N4 has always been desired. Herein, we report a spherical worm-like g-C3N4 nanostructure via facile ammonium lauryl sulfate (ALS) gaseous bubbles templating approach. This strategy employing ALS as gaseous bubbles templating agent bestowed not only g-C3N4 with improved specific surface areas, a porous structure with more exposed photocatalytic reactive sites and mass diffusion of reactants molecules, but also rendered extended optical absorption range and suppression of the photoinduced charge carriers recombination. As a result, the ALS-mediated g-C3N4 photocatalysts unfolded excellent photocatalytic performance regarding photodegradation of rhodamine B (RhB) and phenol under visible photoirradiation. Additionally, the quenching effects of various scavengers proved that the holes (h+) and superoxide anions (?O2-) radicals were the main active species responsible for ameliorated photocatalytic performance for rhodamine B and phenol photodegradation. Our work offers a straightforward approach for developing high-performance metal free photocatalysts with great potential for environmental remediation.
关键词： Ammonium lauryl sulphate,g-C3N4,Photocatalytic activity,Porous,Gaseous bubbles
更新于2025-09-23 15:22:29
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Construction of Ag@AgCl decorated TiO2 nanorod array film with optimized photoelectrochemical and photocatalytic performance
摘要： A novel Ag@AgCl/TNR film photocatalyst was successfully obtained by a facile multistep route. Using a well-organized TiO2 nanorod array (TNR) film as the starting material, Ag nanoparticles were uniformly deposited on the TNR film via a photochemical reduction, and in situ oxidation of Ag by FeCl3 solution resulted in the formation of Ag@AgCl/TNR film. The structure, morphology, composition, optical, photocatalytic and photoelectrochemical properties of the obtained films were investigated in detail. The results showed that core-shell Ag@AgCl can effectively promote the transfer of photo-generated electron-hole pairs, suppress their recombination, and enhance the visible light absorption. The Ag@AgCl/TNR film with 60 min oxidation time (S60) showed the highest photocurrent and best transfer performance of interfacial electrons in the electrochemical impedance spectroscopy (EIS) Nyquist plots. For the photodegradation of methyl orange (MO), the S60 exhibited the highest photocatalytic efficiency (90.8%) and good stability under visible light irradiation, which can be comparable and even better than the previous reports. A detailed photocatalytic mechanism was proposed on the basis of the fact that Ag nanoparticles with surface plasma resonance (SPR) can be excited by visible light and this unique structure effectively transfers photo-generated electrons from Ag to TiO2 conduction band, accomplished by the transfer of compensative electrons from a donor (Cl-) to Ag nanoparticles.
关键词： Nanorod array,Photocatalytic activity,Photocurrent,TiO2,Ag@AgCl
更新于2025-09-23 15:22:29
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Photocatalytic Degradation of Aflatoxin B1 by activated carbon supported TiO2 catalyst
摘要： The photocatalytic efficiency of activated carbon supported TiO2 catalyst (AC/TiO2) for degradation of aflatoxin B1 (AFB1) under UV-Vis light was evaluated in this study. AC/TiO2 was prepared by simple hydrothermal synthesis and characterized by scanning electron micrograph (SEM), X-ray diffraction (XRD) and FT-IR. The various factors including catalyst dosage, pH value and light source affecting the degradation efficiency of AFB1 were also investigated. The higher degradation efficiency of AFB1 by AC/TiO2 composite (98 %) than bare TiO2 (76 %) were attributed to a higher surface area and enhanced visible light intensity by the synergy of AC and TiO2. The degradation process of AFB1 was fitted with the pseudo-first-order kinetic model. In addition, the catalyst can be easily separated from the solution and keep good activity. The hole (h+) and the hydroxyl radicals (?OH) were found to play an important role in the degradation of AFB1. These results demonstrated that AC/TiO2 possess synergy of high absorption capacity and photoactivity, thus supplying a simple, efficient and green approach for the degradation of AFB1.
关键词： AC/TiO2 catalyst,Photocatalytic Degradation,Aflatoxin B1
更新于2025-09-23 15:22:29
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Synergetic utilization of photoabsorption and surface facet in crystalline/amorphous contacted BiOCl-Bi2S3 composite for photocatalytic degradation
摘要： Photoabsorption and surface property of semiconductor are two key factors to determine its photocatalytic performance. In this work, BiOCl-Bi2S3 composites composed of Bi2S3 nanoparticles bonded on BiOCl nanoplates enclosed with {001} and {110} crystal facets were synthesized through an in-situ ion exchange method at room temperature. The transformed Bi2S3 made BiOCl-Bi2S3 composites efficient visible light absorption, ensuring the quantity of photoinduced carriers as well as intimate crystalline-amorphous contact interface to benefit the separation of photoinduced carriers. Moreover, BiOCl nanoplates enclosed with {001} and {110} crystal facets can convenient transfer carriers to {001} crystal facets. The photocatalytic performance of BiOCl-Bi2S3 composites was evaluated by the methylene blue photodegradation under visible light irradiation and the results indicate that BiOCl-Bi2S3 composites have good photocatalytic ability due to enhanced light absorption, efficient separation and transfer of carriers. Based on the active species trapping experiments, transient photocurrents, electrochemical impedance spectroscopy and energy band structure, a possible photocatalytic mechanism of methylene blue over the BiOCl-Bi2S3 composites was proposed.
关键词： Surface property,Visible light,BiOCl-Bi2S3,Contact interface,Photocatalytic mechanism,Crystal facet
更新于2025-09-23 15:22:29