Synthesis and Characterization of ZnO-TiO2/Carbon Fiber Composite with Enhanced Photocatalytic Properties

AMP-Coated TiO2 Doped ZnO Nanomaterials Enhanced Antimicrobial Activity and Efficacy in Otitis Media Treatment by Elevating Hydroxyl Radical Levels

Background

In the past decades, antimicrobial resistance (AMR) has been a major threat to global public health. Long-term, chronic otitis media is becoming more challenging to treat, thus the novel antibiotic alternative agents are much needed.

Methods

ZnO@TiO2@AMP (ATZ NPs) were synthesized through a solvothermal method and subjected to comprehensive characterization. The in vitro and in vivo antibacterial effect and biocompatibility of ATZ NPs were evaluated. For the antibacterial mechanism exploration, we utilized the Electron Paramagnetic Resonance (EPR) Spectrometer to detect and analyze the hydroxyl radicals produced by ATZ NPs.

Results

ATZ NPs exhibited a spherical structure of 99.85 nm, the drug-loading rate for ZnO was 20.73%, and AMP within ATZ NPs was 41.86%. Notably, the Minimum Inhibitory Concentration (MIC) value of ATZ NPs against Staphylococcus aureus (S. aureus), methicillin-resistant Staphylococcus aureus (MRSA), and Streptococcus pneumoniae (S. pneumoniae) were 10 μg/mL, and Minimum Bactericidal Concentration (MBC) value of ATZ NPs against S. aureus, and S. pneumoniae were 50 μg/mL. In comparison to the model group, the treatment of otitis media with ATZ NPs significantly reduces inflammatory exudation in the middle ear cavity, with no observable damage to the tympanic membrane. Both in vivo and in vitro toxicity tests indicating the good biocompatibility of ATZ NPs. Moreover, EPR spectroscopy results highlighted the superior ability of ATZ NPs to generate hydroxyl radicals (·OH) compared to ZnO NPs.

Conclusion

ATZ NPs exhibited remarkable antibacterial properties both in vivo and in vitro. This innovative application of advanced ATZ NPs, bringing great promise for the treatment of otitis media.

Herbal-Based Green Synthesis of TB-ZnO-TiO(II) Nanoparticles Composite From Terminalia bellirica: Characterization, Toxicity Assay, Antioxidant Assay, and Antimicrobial Activity

Background Terminalia bellirica leaf extract was used as an herbal to get an aqueous extract of Tb-ZnO-TiO2 (zinc and titanium dioxide) nanoparticles composite, and this was subsequently subjected to an analysis of its antioxidant properties and possible antimicrobial activity against gram-negative and gram-positive bacteria. Employing the 2,2-Diphenyl-1-picrylhydrazyl and hydrogen peroxide assay techniques for antioxidant properties. In addition to their biocompatibility, rapid biodegradability, and low toxicity, herbal-based nanoparticles (Tb-ZnO-TiO2 NPs composite) synthesized by T. bellirica have drawn a lot of interest as promising options for administering drugs and effective antimicrobial applications. Materials and methods The form and dimensions of the dispersion of the synthesized nanoparticles were investigated through scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy, and UV-visible for particle characterization. Nanoparticles were analyzed for antimicrobial activity using the well diffusion method. Ascorbic acid and vitamin E were used as two separate controls for antioxidant assay with different concentrations, and also toxicity assay was done by using zebrafish embryos. Results Tb-ZnO-TiO2 NPs composite were obtained as a powder, the X-beam diffraction (XRD) result revealed a small quantity of impurities and revealed that the structure was spherical in nature. A unique absorption peak for Tb-ZnO-TiO2 NPs composite may be seen in UV-Vis spectroscopy which is in the region of 260 to 320 nm. The Tb-ZnO-TiO2 NPs composite antibacterial efficacy was evaluated and showed noted antibacterial activity and free radical scavenging activity with less toxicity. Conclusion The results demonstrated the Tb-ZnO-TiO2 NPs composite has strong antioxidant qualities and enormous antibacterial activity obtained from T. bellirica extract. Therefore, the Tb-ZnO-TiO2 NPs composite synthesized nanoparticles can be used in biomedical applications as an effective antioxidant and antibacterial reagent.

Ternary heterogeneous Z-scheme photocatalyst TiO2/CuInS2/OCN incorporated with carbon quantum dots (CQDs) for enhanced photocatalytic degradation efficiency of reactive yellow 145 dye in water

This study delves into the advanced integration of a ternary heterogeneous Z-scheme photocatalyst, TiO2/CuInS2/OCN (OCN: O-g-C3N4), with carbon quantum dot (CQD) to improve the degradation efficiency of reactive yellow 145 (RY145) dye in water. Through a systematic examination, we elucidated the photocatalytic mechanisms and the role of radicals, electrons, and holes in the treatment process. Our findings revealed that this novel catalyst integration significantly boosted RY145 degradation efficiency, achieving 98.2%, which is markedly higher than the efficiencies which could be achieved using TiO2/CuInS2/OCN alone. Moreover, the TiO2/CuInS2/OCN/CQD photocatalyst demonstrated superior rate performance over its components. Comprehensive evaluations, including photoelectrochemical and radical tests, further confirmed the efficiency of the integrated system, adhering to Z-scheme principles. The catalyst showcased remarkable stability, with over 94% reusability after five reaction cycles. These findings pave the way for the potential use of the TiO2/CuInS2/OCN/CQD photocatalyst as an innovative solution for water pollutant treatment via photocatalytic technology.

Electrospun TiO2-GO/PAN-CA nanofiber mats: A novel material for remediation of organic contaminants and nitrophenol reduction

The outstanding properties of nanofiber composites have made them a popular choice for various structural applications. Recently, there has been a growing interest in using electrospun nanofibers as reinforcement agents, which possess exceptional properties that can enhance the performance of these composites. Herein, TiO2-graphene oxide (GO) nanocomposite incorporated into polyacrylonitrile (PAN)/cellulose acetate (CA) nanofibers were fabricated by an effortless electrospinning technique. The chemical and structural characteristics of the resulting electrospun TiO2-GO nanofibers were examined employing diverse techniques such as XRD, FTIR, XPS, TGA, mechanical properties, and FESEM. Remediation of organic contaminants and organic transformation reactions with electrospun TiO2-GO nanofibers were performed. The results indicated that the incorporation of TiO2-GO with various TiO2/GO ratios did not affect the molecular structure of PAN-CA. Still, they did significantly increase the mean fiber diameter (234-467 nm) and the mechanical properties of the nanofibers comprising UTS, elongation, Young's modulus, and toughness compared to PAN-CA. From various ratios of TiO2/GO (0.01TiO2/0.005GO and 0.005TiO2/0.01GO) in the electrospun NFs, the nanofiber containing a high content of TiO2 showed over 97% of the initial MB dyes were degraded after 120 min of visible light exposure and the same nanofibers also, achieved 96% nitrophenol conversion to aminophenol in just 10 min with activity factor kAF value of 47.7 g-1min-1. These findings illustrate the promise of TiO2-GO/PAN-CA nanofibers for use in various structural applications, particularly in the remediation of organic contaminants from water and organic transformation reactions.

The removal enhancement of organic contaminations and optimization of the photocatalytic efficiency by Box-Behnken design using ZnO-TiO2/porous graphene aerogel

In this study, zinc oxide-titanium dioxide/graphene aerogel (ZnO-TiO2/GA) was successfully synthesized through a simple and cost-effective hydrothermal self-assembly process. Besides, the surface response model and the experimental design according to the Box-Behnken model were selected to determine the optimal removal efficiency for crystal violet (CV) dye and para-nitrophenol (p-NP) phenolic compound. According to the obtained results, the highest degradation efficiency for CV dye of 99.6% was obtained under the following conditions: pH 6.7, CV concentration of 23.0 mg/L, and catalyst dose of 0.30 g/L. For p-NP, the degradation efficiency reached 99.1% under the following conditions: H2O2 volume of 1.25 mL, pH 6.8, and catalyst dose of 0.35 g/L. Therewithal, kinetic models of adsorption-photodegradation, thermodynamic adsorption, and free radical scavenging experiments were also investigated to propose the specific mechanisms involving the removal of CV dye and p-NP. According to the aforementioned results, the study provided a resulting ternary nanocomposite with great removal performance for water pollutants via the synergetic effects of adsorption and photodegradation processes.

Electrospun Nanofibers for Dura Mater Regeneration: A Mini Review on Current Progress

Dural defects are a common problem in neurosurgical procedures and should be repaired to avoid complications such as cerebrospinal fluid leakage, brain swelling, epilepsy, intracranial infection, and so on. Various types of dural substitutes have been prepared and used for the treatment of dural defects. In recent years, electrospun nanofibers have been applied for various biomedical applications, including dural regeneration, due to their interesting properties such as a large surface area to volume ratio, porosity, superior mechanical properties, ease of surface modification, and, most importantly, similarity with the extracellular matrix (ECM). Despite continuous efforts, the development of suitable dura mater substrates has had limited success. This review summarizes the investigation and development of electrospun nanofibers with particular emphasis on dura mater regeneration. The objective of this mini-review article is to give readers a quick overview of the recent advances in electrospinning for dura mater repair.

The influence of heterostructured TiO2/ZnO nanomaterials for the removal of azo dye pollutant

In recent times, there has been an inspired research on combining semiconducting metal oxides for improved industrial applications. Significantly, wastewater removal is concerned and the researchers are finding new methodologies for removing azo dyes that possess a high level of carcinogenic effects. In this connection, this work investigates the photocatalytic activity of synthesized TiO2/ZnO nanocomposite irradiated under UV and visible light. The application of the work involves the removal of methylene blue (MB) dye solution. Initial work begins with the novel synthesis of TiO2/ZnO coupled system by integrated sol-gel and thermal decomposition methods. Then, various characterization techniques brought out the existing properties of the prepared TiO2/ZnO catalyst. The X-ray diffraction measurements showed the assorted tetragonal and hexagonal structures. The spherical shape mixed with hexagonal shaped particles were perceived via transmission electron microscopy (TEM). Besides, from photoluminescence spectrum (PL) results, the TiO2/ZnO coupled system displayed slowing down of charge recombination, because of the intermediate states that helps in intensifying the photocatalytic activity. The dual absorption bands corresponding to UV region were deep-rooted from UV-vis spectroscopy. Further, the valuable application of the catalyst in removing methylene blue (MB) dye under both UV and visible light was carried out. The catalyst had displayed 90% of degradation within 40 min under UV light conditions. The other hand, visible light illumination of the catalyst provides divergent results as it possess lesser light absorption. Therefore, this catalyst was unable to yield visible light photocatalytic activity. Hence, this captivating research would bring the wastewater treatment progression using UV light.

Investigation of Photocatalyst Composites for Pollutant Degradation in a Microslit Reactor Utilizing High Throughput Screening Techniques

The high-throughput screening investigations on TiO₂ based photocatalyst composites presented here have been carried out in a 60-fold parallel photoreactor. Additional catalyst testing was performed in a microslit reactor system with immobilized catalysts. For further enhancing the photocatalytic activity of TiO₂ (P25), composites of P25 and, for example, Bi₂ O₃ , CeO₂ , g-C₃ N₄ , WO₃ or ZnO were formulated in different nominal molar ratios. The catalysts' performances were assessed by their conversion of 17α-ethinyl estradiol (EE2) in aqueous solutions, determined by LC-MS. Findings show rapid EE2 conversions in short residence times. The extensive testing of catalysts led to the conclusion that the photocatalytic conversion is rather a function of residence time than a function of the materials utilized. This makes adequate process development seem more important than material development. The novelty of this contribution lies in the unique combination of testing a wide range of composite catalysts in a unique microreactor geometry.

Titanium dioxide nanoparticles: Recent progress in antimicrobial applications

For decades, the antimicrobial applications of nanoparticles (NPs) have attracted the attention of scientists as a strategy for controlling the ever-increasing threat of multidrug-resistant microorganisms. The photo-induced antimicrobial properties of titanium dioxide (TiO₂ ) NPs by ultraviolet (UV) light are well known. This review elaborates on the modern methods and antimicrobial mechanisms of TiO₂ NPs and their modifications to better understand and utilize their potential in various biomedical applications. Additional compounds can be grafted onto TiO₂ nanomaterial, leading to hybrid metallic or non-metallic materials. To improve the antimicrobial properties, many approaches involving TiO₂ have been tested. The results of selected studies from the past few years covering the most recent trends in this field are discussed in this review. There is extensive evidence to show that TiO₂ NPs can exhibit certain antimicrobial features with disputable roles of UV light. Hence, they are effective in treating bacterial infections, although the majority of these conclusions came from in vitro studies and in the presence of some additional nanomaterials. The methods of evaluation varied depending on the nature of the research while researchers incorporated different techniques, including determining the minimum inhibitory concentration, cell count, and using disk and well diffusion methods, with a noticeable indication that cell count was the most and dominant criterion used to evaluate the antimicrobial activity. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Recent advances in self-powered and flexible UVC photodetectors

Ultraviolet-C (UVC) radiation is employed in various applications, including irreplaceable applications in military and civil fields, such as missile guidance, flame detection, partial discharge detection, disinfection, and wireless communication. Although most modern electronics are based on Si, UVC detection technology remains a unique exception because the short wavelength of UV radiation makes efficient detection with Si difficult. In this review, recent challenges in obtaining ideal UVC photodetectors with various materials and various forms are introduced. An ideal photodetector must satisfy the following requirements: high sensitivity, fast response speed, high on/off photocurrent ratio, good regional selectivity, outstanding reproducibility, and superior thermal and photo stabilities. UVC detection is still in its infancy compared to the detection of UVA as well as other photon spectra, and recent research has focused on different key components, including the configuration, material, and substrate, to acquire battery-free, super-sensitive, ultra-stable, ultra-small, and portable UVC photodetectors. We introduce and discuss the strategies for fabricating self-powered UVC photodetectors on flexible substrates in terms of the structure, material, and direction of incoming radiation. We also explain the physical mechanisms of self-powered devices with various architectures. Finally, we present a brief outlook that discusses the challenges and future strategies for deep-UVC photodetectors.

Remarkable Recycling Process of ZnO Quantum Dots for Photodegradation of Reactive Yellow Dye and Solar Photocatalytic Treatment Process of Industrial Wastewater

The mineralization of five industrial sunlight-exposed wastewater samples was investigated, and the recycling process of ZnO quantum dots (ZQDs) for five reusable times was estimated under the approved Egyptian Environmental Law COD (Chemical Oxygen Demand), which has to be less than 1000 ppm. An improved sol-gel process at a low calcination temperature that ranged between 350 and 450 °C was employed to synthesize ZnO quantum dots (ZQDs). The purity, high crystallinity, and structure of the prepared catalysts were determined by TEM and XRD analysis. The energy bandgap, the crystal size values, and the surface area for Z1 and Z2 were determined based on the TEMs, DRSs, and EBTs, which were equal to 6.9 nm, 3.49 eV, and 160.95 m2/g for Z1 and 8.3 nm, 3.44 eV, and 122.15 m2/g for Z2. The investigation of the prepared samples was carried out by studying the photocatalytic activity and photoluminescence, and it was found that the degradation rate of reactive yellow dye as an industrial pollutant of the Z1 sample was significantly higher than other samples, by 20%. The data collection has shown that photocatalytic efficiency decreases with an increase in the crystallite size of ZQDs.

Enhanced Photocatalytic Activity of WS2/TiO2 Nanofibers for Degradation of Phenol under Visible Light Irradiation

Binary composite WS2/TiO2 nanofibers (WTN) were elaborated by electrospinning technique. The photocatalytic efficiency of the binary nanofibers was changed via different ratios between WS2 and TiO2. The structural, morphological and optical properties of the prepared nanofibers were evaluated by Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and UV-Vis diffuse reflectance spectroscopy (UV-vis/DRS), respectively. The prepared nanofibers showed a remarkable performance in photocatalytic efficiency of phenol compound degradation under visible light. WTN nanofibers showed superior photocatalytic activity (83%) and high stability of several cycles under visible light. Therefore, WS2/TiO2 nanofibers have great prospects for the treatment of wastewater from toxic organic contamination due to their excellent photocatalytic performance reusability and recyclability.

Natural Sunlight Driven Photocatalytic Removal of Toxic Textile Dyes in Water Using B-Doped ZnO/TiO2 Nanocomposites

A novel B-doped ZnO/TiO2 (B–ZnO/TiO2) nanocomposite photocatalyst was prepared using a mechanochemical–calcination method. For the characterization of the synthesized B–ZnO/TiO2 photocatalyst, XRD, FESEM-EDS, FTIR, UV-Vis DRS, BET, PL, and XPS techniques were used. The bandgap energy of B–ZnO/TiO2 was reduced, resulting in enhanced visible-light absorption. Significant PL quenching confirmed the reduction in the electron–hole recombination rate. Furthermore, reduced crystallite size and a larger surface area were obtained. Hence, the B–ZnO/TiO2 photocatalyst exhibited better photocatalytic activity than commercial TiO2, ZnO, B–ZnO, and ZnO/TiO2 in the removal of methylene blue (MB) dye under natural sunlight irradiation. The effects of various parameters, such as initial concentration, photocatalyst amount, solution pH, and irradiation time, were studied. Under optimal conditions (MB concentration of 15 mg/L, pH 11, B–ZnO/TiO2 amount of 30 mg, and 15 min of operation), a maximum MB removal efficiency of ~95% was obtained. A plausible photocatalytic degradation mechanism of MB with B–ZnO/TiO2 was estimated from the scavenger test, and it was observed that the •O2− and •OH radicals were potential active species for the MB degradation. Cyclic experiments indicated the high stability and reusability of B–ZnO/TiO2, which confirmed that it can be an economical and environmentally friendly photocatalyst.

Synthesis and Photoelectrocatalytic Applications of TiO2/ZnO/Diatomite Composites

ZnO and TiO2 are semiconductor nanomaterials that are widely used in photocatalysis. However, the relatively high recombination rate and low quantum yield of photogenerated electron–hole pairs limit their practical applications. In this study, a series of TiO2/ZnO/diatomite composites with various compositions were successfully prepared via a two-step precipitation method. They exhibited stronger UV–visible absorption properties and substantially lower fluorescence intensities than those of ZnO and ZnO/diatomite, which was mainly due to the low recombination rate of the photogenerated electron–hole pairs in the composite system. The reaction intermediates of methylene blue were detected by liquid chromatography–mass spectrometry, and the degradation process was determined. The best composite catalyst was used for the degradation of gaseous methylbenzene and gaseous acetone. The gaseous acetone degradation product was determined to be acetaldehyde via gas chromatography–mass spectrometry. The results show that the composite catalyst exhibited a good photocatalytic degradation of both liquid pollutants and harmful volatile gases. When applied to the hydrogen and oxygen evolution reactions, the composite catalyst retained a good photoresponsivity and electrolytic efficiency.

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.

Exploring the impact of calcination parameters on the crystal structure, morphology, and optical properties of electrospun Fe2TiO5 nanofibers

Nanostructured Fe₂TiO₅ (pseudobrookite), a mixed metal oxide material holds significant promise for utilization in energy and environmental applications. However, its full application is still hindered due to the difficulty to synthesize monophasic Fe₂TiO₅ with high crystallinity and a large specific surface area. Herein, Fe₂TiO₅ nanofibers were synthesized via a versatile and low-cost electrospinning method, followed by a calcination process at different temperatures. We found a significant effect of the calcination process and its duration on the crystalline phase in the form of either pseudobrookite or pseudobrookite–hematite–rutile and the morphology of calcined nanofibers. The crystallite size increased whereas the specific surface area decreased with an increase in calcination temperature. At higher temperatures, the growth of Fe₂TiO₅ nanoparticles and simultaneous coalescence of small particles was noted. The highest specific surface area was obtained for the sample calcined at 500 °C for 6 h (S_BET = 64.4 m² g⁻¹). This work opens new opportunities in the synthesis of Fe₂TiO₅ nanostructures using the electrospinning method and a subsequent optimized calcination process for energy-related applications.

Nanostructured Fe₂TiO₅ (pseudobrookite), a mixed metal oxide material holds significant promise for utilization in energy and environmental applications.

Photocatalytic Degradation of Thiacloprid Using Tri-Doped TiO2 Photocatalysts: A Preliminary Comparative Study

Different tri-doped TiO2 photocatalysts (Fe-N-P/TiO2, Fe-N-S/TiO2, Fe-Pr-N/TiO2, Pr-N-S/TiO2, and P-N-S/TiO2) were successfully prepared and tested in the photocatalytic removal of thiacloprid (THI) under UV-A, visible, and direct solar light irradiation. The physical-chemical properties of the prepared catalysts were analyzed by different characterization techniques, revealing that dopants are effectively incorporated into the anatase TiO2 lattice, resulting in a decrease of the energy band gap. The reduction of photoluminescence intensity indicates a lower combination rate and longer lifespan of photogenerated carriers of all doped samples in comparison with the un-doped TiO2. The doped photocatalysts not only significantly promote the photodegradation under UV-A light irradiation but also extend the optical response of TiO2 to visible light region, and consequently improve the visible light degradation of THI. Fe-N-P tri-doped TiO2 sample exhibits the highest THI photodegradation degree (64% under UV-A light, 29% under visible light and 73% under solar light).

Photocatalytic-Fenton Process under Simulated Solar Radiation Promoted by a Suitable Catalyst Selection

Considering water scarcity, photo-based processes have been presented as a depollution technique, which should be optimized in order to be applied in the future. For that, the addition of an active photocatalyst and the usage of solar radiation are mandatory steps. Thus, Fe3O4–SiO2–TiO2 was synthesized, and its performance was evaluated using simulated solar radiation and methylene blue as a model pollutant. Under optimal conditions, 86% degradation was attained in 1 h. These results were compared to recent published data, and the better performance can be attributed to both the operational conditions selection and the higher photocatalyst activity. Indeed, Fe3O4–SiO2–TiO2 was physico-chemically characterized with techniques such as XRD, N2 isotherms, spectrophotometry, FTIR, electrochemical assays and TEM.

Synthesis and Characterization of CeO2/CuO Nanocomposites for Photocatalytic Degradation of Methylene Blue in Visible Light

Removal of hazardous organic dyes from polluted water bodies requires the introduction of strong adsorbents and photocatalysts to industrial wastewaters. Herein, photocatalytic CeO2 nanoparticles and CeO2/CuO nanocomposite were synthesized following a co-precipitation method for low cost elution of methylene blue (MB) from water. The crystallinity and surface structure of the as-prepared materials have been analyzed using characterization techniques including X-ray powder diffraction (XRPD), field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), ultra-violet visible spectroscopy (UV–Vis), and Fourier-transform infrared spectroscopy (FTIR). The average particle size of both the nano scaled samples were approximately 20–30 nm. The photocatalytic properties of CeO2/CuO were investigated under visible light against methylene blue (MB). The results showed 91% photodegradation of MB organic pollutant in 3 h as monitored by UV–Vis spectroscopy. Absorbance peaks appeared at around 670 nm corresponding to degradation of MB. Such output displayed the effectiveness of Ce nanocomposites for environmental benefits. Hence, CeO2/CuO nanocomposite could be useful for treatment of industrial wastewaters by removing hazardous MB dye.

Immobilized TiO2/ZnO Sensitized Copper (II) Phthalocyanine Heterostructure for the Degradation of Ibuprofen under UV Irradiation

Photocatalytic coatings of TiO2/ZnO/CuPc were developed on stainless steel substrates by subsequent sol gel dip coating for TiO2, spray pyrolysis for ZnO, and spin coating for copper (ii) phthalocyanine (CuPc) deposition. The latter compound was successfully prepared using a Schiff-based process. The materials and coatings developed were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy with attached energy dispersive spectroscopy (SEM-EDS), UV-Vis spectroscopy, room temperature photoluminescence (RTPL) spectroscopy, H1-nuclear magnetic resonance (1H-NMR) spectroscopy, C13-nuclear magnetic resonance (13C-NMR) spectroscopy, and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS). The as-deposited TiO2/ZnO/CuPc on stainless steel retained in pristine state the structural and morphological/spectroscopic characteristics of its respective components. Estimated energy band gap values were 3.22 eV, 3.19 eV, 3.19 eV for TiO2, ZnO, TiO2/ZnO respectively and 1.60 eV, 2.44 eV, and 2.92 eV for CuPc. The photocatalytic efficiency of the fabricated TiO2/ZnO/CuPc coatings was tested toward ibuprofen (IBF). After 4 h irradiation under 365 nm UV, an increased degradation of about 80% was achieved over an initial 5 mg/L ibuprofen (IBF). This was much higher compared to about 42% and 18% IBF degradation by TiO2/ZnO and TiO2 thin film, respectively. In all cases, the stability of the best-performing photocatalyst was investigated showing a small decline to 77% of IBF degradation after the 5th cycle run. The effect of pH, reactive oxygen species (ROS) probe, shed light on a possible catalytic mechanism that was suggested.

Pt–BiVO4/TiO2 composites as Z-scheme photocatalysts for hydrogen production from ethanol: the effect of BiVO4 and Pt on the photocatalytic efficiency

The photodeposition of platinum particles on the BiVO₄/TiO₂ composite surface promotes the H₂ production by reducing H⁺ species.

Decoration of Zinc Oxide Nanorods into the Surface of Activated Carbon Obtained from Agricultural Waste for Effective Removal of Methylene Blue Dye

Zinc oxide (ZnO) nanorods incorporated activated carbon (AC) composite photocatalyst was synthesized using a hydrothermal process. The AC was prepared from lapsi (Choerospondias axillaris) seed stone, an agricultural waste product, found in Nepal by the chemical activation method. An aqueous suspension of AC with ZnO precursor was subjected to the hydrothermal treatment at 140 °C for 2 h to decorate ZnO rods into the surface of AC. As-obtained ZnO nanorods decorated activated carbon (ZnO/AC) photocatalyst was characterized by various techniques, such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) spectroscopy. Results showed that highly crystalline hexagonal ZnO nanorods were effectively grown on the surface of porous AC. The photocatalytic property of the as-prepared ZnO/AC composite was studied by degrading methylene blue (MB) dye under UV-light irradiation. The ZnO/AC composite showed better photocatalytic property than that of the pristine ZnO nanorods. The enhanced photocatalytic performance in the case of the ZnO/AC composite is attributed to the combined effects of ZnO nanorods and AC.

Turning Waste into Useful Products by Photocatalysis with Nanocrystalline TiO2 Thin Films: Reductive Cleavage of Azo Bond in the Presence of Aqueous Formate

UV-photoexcitation of TiO₂ in contact with aqueous solutions of azo dyes does not imply only its photocatalytic degradation, but the reaction fate of the dye depends on the experimental conditions. In fact, we demonstrate that the presence of sodium formate is the switch from a degradative pathway of the dye to its transformation into useful products. Laser flash photolysis experiments show that charge separation is extremely long lived in nanostructured TiO₂ thin films, making them suitable to drive both oxidation and reduction reactions. ESR spin trapping and photoluminescence experiments demonstrate that formate anions are very efficient in intercepting holes, thereby inhibiting OH radicals formation. Under these conditions, electrons promoted in the conduction band of TiO₂ and protons deriving from the oxidation of formate on photogenerated holes lead to the reductive cleavage of N=N bonds with formation and accumulation of reduced intermediates. Negative ion ESI–MS findings provide clear support to point out this new mechanism. This study provides a facile solution for realizing together wastewater purification and photocatalytic conversion of a waste (discharged dye) into useful products (such as sulfanilic acid used again for synthesis of new azo dyes). Moreover, the use of TiO₂ deposited on an FTO (Fluorine Tin Oxide) glass circumvents all the difficulties related to the use of slurries. The obtained photocatalyst is easy to handle and to recover and shows an excellent stability allowing complete recyclability.

Preparation of Fe3+ Doped High-Ordered TiO2 Nanotubes Arrays with Visible Photocatalytic Activities

In this paper, the Fe³⁺ doped rutile phase TiO₂ nanotubes arrays (NTAs) were prepared in a low temperature water-assistant crystallization method. It is noteworthy that the Fe³⁺ doping hardly hinders either the crystallization of rutile TiO₂ NTAs or the highly-ordered nanotubular morphologies. Moreover, Fe³⁺ did not form other compound impurities, which indicated that Fe³⁺ substitute Ti⁴⁺ into the lattice of TiO₂. With the introduction of Fe³⁺, the light absorption range of TiO₂ NTAs extends from the ultraviolet band to the visible light range. Photocatalytic testing results indicate that Fe³⁺ doped TiO₂ NTAs can effectively improve the degradation rate of methyl orange aqueous solution in visible light, and the TiO₂ NTAs with 0.2 mol/L Fe³⁺ doping exhibits the highest photocatalytic degradation efficiency.