Electrospinning Fabricating Au/TiO2 Network-like Nanofibers as Visible Light Activated Photocatalyst

Electrospun Nanofibers from Waste Polyvinyl Chloride Loaded Silver and Titanium Dioxide for Water Treatment Applications

The electrospun nanofiber membrane from polyvinyl chloride (PVC) waste for water treatment applications has been successfully produced. The PVC precursor solution was prepared by dissolving the PVC waste in DMAc solvent, and a centrifuge was used to separate undissolved materials from the precursor solution. Ag and TiO₂ were added to the precursor solution before the electrospinning process. We studied the fabricated PVC membranes using SEM, EDS, XRF, XRD, and FTIR to study the fiber and membrane properties. The SEM images depicted that Ag and TiO₂ addition has changed the morphology and size of fibers. The EDS images and XRF spectra confirmed the presence of Ag and TiO₂ on the nanofiber membrane. The XRD spectra showed the amorphous structure of all membranes. The FTIR result indicated that the solvent completely evaporated throughout the spinning process. The fabricated PVC@Ag/TiO₂ nanofiber membrane showed the photocatalytic degradation of dyes under visible light. The filtration test on the membrane PVC and PVC@Ag/TiO₂ depicted that the presence of Ag and TiO₂ affected the flux and separation factor of the membrane.

The sensitivity enhancement of TiO2-based VOCs sensor decorated by gold at room temperature

Detection of hazardous toxic gases for air pollution monitoring and medical diagnosis has attracted the attention of researchers in order to realize sufficiently sensitive gas sensors. In this paper, we fabricated and characterized a Titanium dioxide (TiO₂)-based gas sensor enhanced using the gold nanoparticles. Thermal oxidation and sputter deposition methods were used to synthesize fabricated gas sensor. X-ray diffraction analysis was used to determine the anatase structure of TiO₂samples. It was found that the presence of gold nanoparticles on the surface of TiO₂enhances the sensitivity response of gas sensors by up to about 40%. The fabricated gas sensor showed a sensitivity of 1.1, 1.07 and 1.03 to 50 ppm of acetone, methanol and ethanol vapors at room temperature, respectively. Additionally, the gold nanoparticles reduce 50 s of response time (about 50% reduction) in the presence of 50 ppm ethanol vapor; and we demonstrated that the recovery time of the gold decorated TiO₂sensor is less than 40 s. Moreover, we explain that the improved performance depends on the adsorption-desorption mechanism, and the chemical sensitization and electronic sensitization of gold nanoparticles.

Advances in Electrostatic Spinning of Polymer Fibers Functionalized with Metal-Based Nanocrystals and Biomedical Applications

Considering the metal-based nanocrystal (NC) hierarchical structure requirements in many real applications, starting from basic synthesis principles of electrostatic spinning technology, the formation of functionalized fibrous materials with inorganic metallic and semiconductor nanocrystalline materials by electrostatic spinning synthesis technology in recent years was reviewed. Several typical electrostatic spinning synthesis methods for nanocrystalline materials in polymers are presented. Finally, the specific applications and perspectives of such electrostatic spun nanofibers in the biomedical field are reviewed in terms of antimicrobial fibers, biosensing and so on.

AuAg Nanoparticles Grafted on TiO2@N-Doped Porous Carbon: Improved Depletion of Ciprofloxacin under Visible Light through Plasmonic Photocatalysis

TiO2 nanoparticles (NPs) were modified to obtain photocatalysts with different composition sophistication and displaying improved visible light activity. All of them were evaluated in the photodegradation of ciprofloxacin. The band gap of TiO2 NPs was successfully tailored by the formation of an N-doped porous carbon (NPC)-TiO2 nanohybrid through the pyrolysis of melamine at 600 °C, leading to a slight red-shift of the absorption band edge for nanohybrid NPC-TiO2 1. In addition, the in-situ formation and grafting of plasmonic AuAg NPs at the surface of NPC sheets and in close contact with TiO2 NPs leads to AuAg-NPC-TiO2 nanohybrids 2−3. These nanohybrids showed superior photocatalytic performance for the degradation of ciprofloxacin under visible light irradiation, compared to pristine P25 TiO2 NPs or to AuAg-PVP-TiO2 nanohybrid 4 in which polyvinylpyrrolidone stabilized AuAg NPs were directly grafted to TiO2 NPs. The materials were characterized by transmission electron microscope (TEM), High Angle Annular Dark Field—Scanning Transmission Electron Microscopy—Energy Dispersive X-ray Spectroscopy HAADF-STEM-EDS, X-ray photoelectron spectroscopy and solid UV-vis spectroscopy. Moreover, the active species involved in the photodegradation of ciprofloxacin using AuAg-NCS-TiO2 nanohybrids were evaluated by trapping experiments to propose a mechanism for the degradation.

Novel nanocomposite of spiky-shaped gold nanourchins/ titanium dioxide/nafion for amplified signal and efficient electrochemiluminescence detection of ovomucoid

This work reports on the first electrochemiluminescence (ECL) immunosensor employing a novel nanostructured composite of titanium dioxide (TiO₂) and gold nanourchins (AuNU) to detect protein allergen Ovomucoid (Ovm) found in eggs. TiO₂ and AuNU were dispersed in Nafion and drop-casted onto SPGE with Tris(2,2'-bipyridyl)-ruthenium (II) ([Ru(bpy)₃]²⁺) and tri-n-propylamine (TPrA) served as strong luminophore/co-reactant pairs as a source of ECL signals. The linear range, limit of detection, reproducibility and practical applications of the sensor were assessed. The fabricated ECL immuosensor produced a promising limit of detection of as low as 0.01 pg/mL. Two linear ranges of 0.01-50 pg/mL and 100-750 pg/mL with corresponding correlation coefficients of R² = 0.99136 and R² = 0.97829) respectively, were determined. Despite its simple fabrication method, this label-free immunosensor also showcased excellent selectivity, reproducibility, interference-resistance and yielded outstanding recoveries between 97.42 and 104.05% of Ovm analysis in spiked real food samples.

The Surface Modification of Ag3PO4 using Tetrachloroaurate(III) and Metallic Au for Enhanced Photocatalytic Activity

The improvement of Ag3PO4 photocatalytic activity was successful by incorporating tetrachloroaurate(III) (AuCl4−)  and metallic Au on the surface of Ag3PO4. The photocatalysts were synthesized using the coprecipitation and chemisorption method. Coprecipitation of Ag3PO4 was carried out under ethanol-water solution using the starting material of AgNO3 and Na2HPO4.12H2O. AuCl4− ion and metallic Au were incorporated on the surface of Ag3PO4 using a chemisorption method under auric acid solution. The photocatalysts were characterized using XRD, DRS, SEM, and XPS. The AuCl4− ion and metallic Au were simultaneously incorporated on the Ag3PO4 surface. The high photocatalytic activity might be caused by increasing the separation of hole and electron due to capturing photogenerated electrons by metallic Au and Au(III) as electron acceptors. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Electrospun Ceramic Nanofibers for Photocatalysis

Ceramic fiber photocatalysts fabricated by electrospinning hold great potential in alleviating global environmental and energy issues. However, many challenges remain in improving their photocatalytic efficiencies, such as the limited carrier lifetime and solar energy utilization. To overcome these predicaments, various smart strategies have been invented and realized in ceramic fiber photocatalysts. This review firstly attempts to summarize the fundamental principles and bottlenecks of photocatalytic processes. Subsequently, the approaches of doping, surface plasmon resonance, and up-conversion fluorescent to enlarge the light absorption range realized by precursor composition design, electrospinning parameter control, and proper post heat-treatment process are systematically introduced. Furthermore, methods and achievements of prolonging the lifetime of photogenerated carriers in electrospun ceramic fiber photocatalysts by means of introducing heterostructure and defective composition are reviewed in this article. This review ends with a summary and some perspectives on the future directions of ceramic fiber photocatalysts.

Electrospun PVP/TiO2 Nanofibers for Filtration and Possible Protection from Various Viruses like COVID-19

In this study, TiO2 nanofibers were prepared with Polyvinylpyrrolidone (PVP) polymer using sol-gel method via electrospinning technique. Owing to the advantages of small fiber diameter, tunable porosity, low cost, large surface to volume ratio, structure control, light-weight, and less energy consumption, electrospun nanofibers are evolving as an adaptable material with a number of applications, in this case for filtration and environmental/virus protection. Different samples of TiO2/PVP nanofibers have been prepared by changing the parameters to achieve the best result. As the polymer concentration was increased from 6 to 8 wt.% of PVP, diameter of the resultant fibers was seen to be increased, implying decrease in the pore-size of the fibers up to 1.4 nm. Surface morphology has been checked via Scanning Electron Microscope (SEM) images. Crystalline nature has been analyzed by X-ray Crystallography. Using the Bruanauer-Emmett-Teller (BET) test, surface area and porosity has been checked for the suitable application. The synthesized TiO2/PVP nanofibers have tremendous practical potentials in filtration and environmental remediation applications.

Efficient Photocatalytic Degradation of Organic Pollutant in Wastewater by Electrospun Functionally Modified Polyacrylonitrile Nanofibers Membrane Anchoring TiO2 Nanostructured

In this study, polyacrylonitrile (PAN_P) nanofibers (NFs) were fabricated by electrospinning. The PAN_P NFs membrane was functionalized with diethylenetriamine to prepare a functionalized polyacrylonitrile (PAN_F) NFs membrane. TiO₂ nanoparticles (NPs) synthesized in the laboratory were anchored to the surface of the PAN_F NFs membrane by electrospray to prepare a TiO₂ NPs coated NFs membrane (PAN_Coa). A second TiO₂/PAN_P composite membrane (PAN_Co) was prepared by embedding TiO₂ NPs into the PAN_P NFs by electrospinning. The membranes were characterized by microscopic, spectroscopic and X-ray techniques. Scanning electron micrographs (SEM) revealed smooth morphologies for PAN_P and PAN_F NFs membranes and a dense cloud of TiO₂ NPs on the surface of PAN_Coa NFs membrane. The attenuated total reflectance in the infrared (ATR-IR) proved the addition of the new amine functionality to the chemical structure of PAN. Transmission electron microscope images (TEM) revealed spherical TiO₂ NPs with sizes between 18 and 32 nm. X-ray powder diffraction (XRD) patterns and energy dispersive X-ray spectroscopy (EDX) confirmed the existence of the anatase phase of TiO₂. Surface profilometry da-ta showed increased surface roughness for the PAN_F and PAN_Coa NFs membranes. The adsorption-desorption isotherms and hysteresis loops for all NFs membranes followed the IV -isotherm and the H3 -hysteresis loop, corresponding to mesoporous and slit pores, respectively. The photocatalytic activities of PAN_Coa and PAN_Co NFs membranes against methyl orange dye degradation were evaluated and compared with those of bare TiO₂ NPs.The higher photocatalytic activity of PAN_Coa membrane (92%, 20 ppm) compared to (PAN_Co) NFs membrane (41.64%, 20 ppm) and bare TiO₂ (49.60%, 20 ppm) was attributed to the synergy between adsorption, lower band gap, high surface roughness and surface area.

Recent progress on Ag/TiO2 photocatalysts: photocatalytic and bactericidal behaviors

For many decades, titanium dioxide (TiO₂) semiconductor has been extensively applied in several environmental applications due to its higher photocatalytic performances toward different organic pollutants, pharmaceutical compounds, and bacteria. However, its shortfall response to visible light, and the expeditious recombination rate of the photogenerated electron-hole pairs, hampers its utilization. Doping TiO₂ semiconductor with silver nanoparticles is a sound strategy to (1) extend its photocatalytic activity to visible light, (2) prevent the electron/holes pairs recombination due to the formation of the Schottky barrier at the interfaces with TiO₂ that act as an electron-trapping center, and (3) enhance its bactericide performances. This review focuses on the recent progress on silver-doped titanium dioxide (Ag/TiO₂)-based photocatalysts. It addresses a wide range of Ag/TiO₂ synthesis techniques, their physicochemical properties and discusses thoroughly the important role of silver (Ag) nanoparticles in enhancing the removal capacity and antibacterial performances of the Ag/TiO₂ photocatalysts.

Gold-decorated TiO2 nanofibrous hybrid for improved solar-driven photocatalytic pollutant degradation

TiO₂-based nanomaterials are among the most promising photocatalysts for degrading organic dye pollutants. In this work, Au-TiO₂ nanofibers were fabricated by the electrospinning technique, followed by calcination in air at 500 °C. Morphological and structural analyses revealed that the composite consists of TiO₂ nanofibers with embedded Au nanoparticles that are extensively distributed throughout the porous fibrous structure of TiO₂. The photocatalytic performance of these Au-embedded TiO₂ nanofibers was evaluated in the photodegradation of Rhodamine B and methylene blue under solar simulator irradiation. Compared with pristine TiO₂ nanofibers, the Au-embedded TiO₂ nanofibers displayed far better photocatalytic degradation efficiency. The plasmon resonance absorption of Au nanoparticles in the visible spectral region and the effective charge separation at the heterojunction of the Au-TiO₂ hybrid are the key factors that have led to the considerable enhancement of the photocatalytic activity. The results of this study clearly demonstrate the potential of Au-TiO₂ electrospun nanofibers as solar-light-responsive photocatalysts for the effective removal of dye contaminants from aquatic environments.

Graphene Oxide Coated Zinc Oxide Core–Shell Nanofibers for Enhanced Photocatalytic Performance and Durability

Recently, heterogeneous structured semiconductor photocatalysts have received significant interest in promoting global cleaning from the environmental pollution. Herein, we report the synthesis of graphene oxide (GO) wrapped zinc oxide (ZnO) core–shell nanofibers (ZnO@G CSNFs) by the simple core–shell electrospinning and subsequent annealing for efficient photocatalytic performance and stability. The heterostructured catalyst consisted of ZnO forming an enclosed core part while the GO was positioned on the surface, serving as a protective shell. Field emission scanning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction were used to confirm the synthesis of the desired product. Enhanced photocatalytic activity ZnO@G CSNFs was found compared to the corresponding ZnO NFs. Similarly, incorporation of GO into the ZnO nanofiber in a core–shell format significantly suppressed the photocorrosion. This study highlights the usefulness of using GO as the coating material to boost the photocatalytic performance of ZnO-based photocatalysts.

Analysis of resistance to bending of metal electroconductive layers deposited on textile composite substrates in PVD process

In the article a description of the behaviour of metallic layers created in the process of physical vacuum deposition on a composite textile substrates during their cyclical bending process is presented. Either the results of experimental research or the theoretical considerations of changes in the structure resistance as a function of the number of fatigue cycles are presented. It was confirmed mathematically that at the beginning of the bending process, in the case of a small number of bends, single cracks appear on the surface of the layer. After exceeding a certain number of bends, the nature of defects on the surface of the layer changes and the dominating mechanism of changes is the widening and elongation of already existing cracks. It has been confirmed mathematically that changes in resistance in these cases depend respectively on the number of bending cycles and next on quadratic value of number of cycles. A correspondence between the mathematical description and experimental results was obtained.

Fabrication of spent FCC catalyst composites by loaded V2O5 and TiO2 and their comparative photocatalytic activities

The spent fluid catalytic cracking catalyst (FCC) has been loaded with different content of V₂O₅ and TiO₂ through a modified-impregnation method. X-ray Diffraction (XRD), ultraviolet-visible spectrophotometry (UV-Vis), Scanning Electron Microscope (SEM), and Fourier Transform Infrared spectroscopy (FT-IR) are used to characterize the structure and morphology of these samples. Their photocatalytic activity was evaluated by degradation of methylene blue (MB) solution under 300 W Xenon lamp irradiation. The interplanar spacing of the zeolite Y (111) plane is affected by the amount of the loaded V₂O₅ on spent FCC catalyst. The (111) plane of spent FCC catalyst loaded with V₂O₅ and TiO₂ sample is 1.404 nm, which is higher than that of the zeolite Y (1.395 nm). The amount of adsorption of MB and the photocatalytic activity for the degradation increased with increasing the interplanar spacing of the (111) plane of sample. We fabricated of spent FCC catalyst composites by loaded V₂O₅ and TiO₂, which effectively solved the spent FCC catalyst disposal problem. The efficiency of the developed sample provides a potentially economical way of degrading MB.