Project description:BackgroundGraphene oxide composites with photocatalysts may exhibit better properties than pure photocatalysts via improvement of their textural and electronic properties.ResultsTiO2-Graphene Oxide (TiO2 - GO) nanocomposite was prepared by thermal hydrolysis of suspension with graphene oxide (GO) nanosheets and titania peroxo-complex. The characterization of graphene oxide nanosheets was provided by using an atomic force microscope and Raman spectroscopy. The prepared nanocomposites samples were characterized by Brunauer-Emmett-Teller surface area and Barrett-Joiner-Halenda porosity, X-ray Diffraction, Infrared Spectroscopy, Raman Spectroscopy and Transmission Electron Microscopy. UV/VIS diffuse reflectance spectroscopy was employed to estimate band-gap energies. From the TiO2 - GO samples, a 300 μm thin layer on a piece of glass 10×15 cm was created. The photocatalytic activity of the prepared layers was assessed from the kinetics of the photocatalytic degradation of butane in the gas phase.ConclusionsThe best photocatalytic activity under UV was observed for sample denoted TiGO_100 (k = 0.03012 h-1), while sample labeled TiGO_075 (k = 0.00774 h-1) demonstrated the best activity under visible light.
Project description:In this work, the solar light-induced redox photoactivity of ZnO semiconductor material was used to prepare CuxO-ZnO composite catalysts at room temperature with a control of the chemical state of the copper oxide phase. Cu₂(I)O-ZnO and Cu(II)O-ZnO composite catalysts were prepared by using Cu(acac)₂ in tetrahydrofuran-water and Cu(NO₃)₂ in water as metallic precursor, respectively. Prior to the implementation of the photon-assisted synthesis method, the most efficient photoactive ZnO material was selected from among different ZnO materials prepared by the low temperature polyol and precipitation methods with carbonates and carbamates as precipitation agents. The photocatalytic degradation of the 4-chlorophenol compound in water under simulated solar light was taken as a model reaction. The ZnO support materials were characterized by X-ray diffraction (XRD), surface area and porosimetry measurements, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the synthesis method strongly influenced their photoactivity in terms of 4-chlorophenol degradation and of total organic carbon removal. The most photoactive ZnO material was prepared by precipitation with carbonates and calcined at 300 °C, benefitting from a high specific surface area and a small mean crystallite size for achieving a complete 4-chlorophenol mineralization within 70 min of reaction, with minimum Zn2+ released to the solution. Besides thermal catalysis applications, this work has opened a new route for the facile synthesis of Cu₂O-ZnO heterojunction photocatalysts that could take place under solar light of the heterojunction built between the p-type semi-conductor Cu₂O with direct visible light band gap and the ZnO semiconductor phase.
Project description:In this work, a series of thermosensitive ionic liquid functionalized polymers, PNx(IL)y, with controllable morphology and particle size were prepared by free radical polymerization. Then, using the polymer PN64(IL)8 with uniform morphology as a templating agent, the ZnO composite photocatalytic materials doped with rare earth metal Ce were prepared in combination with a microwave-assisted and templated hydrothermal reaction method. Series different Ce-doping amount photocatalytic materials ZnO-Ce-x‱ were characterized by XRD, SEM, TEM, XPS, and other methods. The results demonstrated that the templated materials PN64(IL)8 can prepare ZnO-Ce-2‱ with uniform petaloid ambulacra shape, good distribution of elements, and excellent photocatalytic performance. Photocatalytic degradation experiments of methyl orange (MO) showed that when the Ce-doping amount is only 2‱, the degradation rate of organic dyes can reach 96.5% by reacting the photocatalytic materials in water for 1 h. In addition, this kind of photocatalyst can be used for the degradation of high-concentration MO, as well as being easily recovered and effectively reused by simple filtration. Therefore, the structure of this kind of photocatalyst is controllable in the preparation process with an extremely low Ce-doping amount compared with current reports, and it has a good application prospect in the field of wastewater treatment technology.
Project description:Dumbbell Ag2CO3-ZnO heterojunctions were synthesized for the first time via a simple in situ precipitation method. The as-prepared Ag2CO3-ZnO heterojunction showed high photocatalytic activity in the decomposition of methyl orange aqueous solution under simulated solar irradiation. The high improvement of photocatalytic activity compared to that of pure ZnO can be attributed to the formation of the Ag2CO3-ZnO heterojunction. Furthermore, the mechanism of photocatalytic activity was investigated in detail. The free radical trapping experiments indicated that the superoxide radical (·O2 -) was an important active species in the photocatalytic process. This paper provides a new prospect for the preparation of photocatalysts with high catalytic performance in the degradation of dye wastewater.
Project description:In recent years, the presence of numerous xenobiotic substances, such as antibiotics, has been detected in water environments. They can be considered as environmental contaminants, even if their effect on human health has yet to be totally understood. Several approaches have been studied for the removal of these kinds of pollutants. Among these compounds, tetracycline (TC), a broad-spectrum antibiotic, is one of the most commonly found in water due to its widespread use. In the context of reducing the presence of TC in aqueous solution, in this contribution, a composite catalyst based on zinc oxide (ZnO) and iron oxide (γ-Fe2O3) was developed and its photocatalytic properties were investigated. The catalytic materials were synthesized by a microwave-assisted aqueous solution method and characterized by Field Emission Scanning Electron Microscope (FESEM), X-Ray Fluorescence (XRF) and Brunauer-Emmett-Teller (BET) analysis. The TC concentration was evaluated by spectrophotometer measurements at specific time intervals. The performed photocatalytic experiments clearly demonstrated that the ZnO/γ-Fe2O3 composite catalyst presents significant photocatalytic activity, indeed a TC degradation efficiency of 88.52% was registered after 150 min. The presence of iron oxide in the structure of the catalyst enhances both the surface area and the pore volume, facilitating the adsorption of the analyte on the surface of nanostructures, a fundamental phase to optimize a photodegradation process. Moreover, ZnO was found to play the key role in the photocatalytic process assisted by γ-Fe2O3 which enhanced the TC degradation efficiency by 20%.
Project description:The present investigation examined how substituting some Cu2+ ions for Zn2+ ions could increase zinc oxide (ZnO) photocatalytic activity toward the reduction of Rhodamine B. Phase composition, the presence of functional groups, optical properties, emission spectra, and surface morphology of ZnO nanoflakes (NFs) were evaluated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-visible spectroscopy (UV-vis), photoluminescence (PL) spectrophotometer, and scanning electron microscopy (SEM). To investigate the photocatalytic capabilities of Cu-doped ZnO NFs driven by visible light/sunlight, Rhodamine B dyes were photocatalytically degraded in water using UV-visible absorption spectroscopy. Using Williamson-Hall analysis of the XRD data, it was discovered that the internal strain of the Cu-doped ZnO NFs was altered. UV-vis absorption showed that the energy gap of the semiconducting ZnO NFs shrank when Cu was substituted. FT-IR studies revealed that the surface of the Cu-doped ZnO NFs contained greater amounts of reactive oxidizing species. PL studies revealed that the ZnO NFs' surface defects were being caused by the Cu substitution. According to SEM research, more surface fault NFs formed when the concentration of Cu increased. The photocatalytic activity was enhanced by the production of these NFs. The UV-vis absorption spectra showed that Cu-doped ZnO NFs were more effective than pure ZnO at degrading the rhodamine B dye (RhB). Finally, it was shown that replacing Zn2+ ions with Cu2+ ions improved the photodegradation of the rhodamine B dye. According to this study, Cu-doped ZnO NFs are an excellent choice for wastewater treatment.
Project description:Water pollution, arising from the presence of toxic dyes and chemicals, is a global challenge, urging the need for eco-friendly solutions in water decontamination. This study focused on the synthesis of copper oxide nanoparticles (CuO NPs), zinc oxide nanoparticles (ZnO NPs), and a bimetallic CuO-ZnO nanocomposite (CZ NC) through an environmentally friendly method employing Tragia involucrata L. leaf extract. Comprehensive analysis of structural and optical properties involved using various analytical techniques such as XRD, FT-IR, XPS, UV-DRS, PL, FE-SEM, EDAX, TEM, SAED, zeta potential, TGA, and BET. In comparison to pristine CuO and ZnO NPs, the CZ-NC demonstrated notably enhanced photocatalytic activity in the degradation of Rhodamine B dye (RhB). The optimum conditions for RhB degradation were found to be a pH of 9 and a catalyst dosage of 1 mg/mL for a concentration of 10 ppm. Under these conditions, CuO NPs, ZnO NPs, and CZ-NC demonstrated high efficiencies of 78%, 83%, and 96.1% respectively over 105 min. Through LC-HRMS, the identification of degradation products offered valuable insights into the pathway of photocatalytic degradation. Furthermore, toxicity analysis of intermediates, conducted through ECOSAR software, indicated the formation of non-toxic by-products (ChV/LC50/EC50 > 100) after the completion of the reaction. Furthermore, the recycled catalysts exhibited sustained stability for up to 4 cycles, with only a minor decrease in activity of up to 6.8%. This confirms their catalytic efficacy in purifying polluted water. This research significantly contributes to the progress of environmentally friendly nanocomposites, enhancing their efficacy in the realm of environmental remediation.
Project description:The effectiveness of photocatalysts can be impacted by the high compounding efficiency of photogenerated carriers, which depends on the morphology of the photocatalyst. Here, a hydrangea-like N-ZnO/BiOI composite has been prepared for achieving efficient photocatalytic degradation of tetracycline hydrochloride (TCH) under visible light. The N-ZnO/BiOI exhibits a high photocatalytic performance, degrading nearly 90% of TCH within 160 min. After 3 cycling runs, the photodegradation efficiency remained above 80%, demonstrating its good recyclability and stability. The major active species at work are superoxide radicals (·O2 -) and photo-induced holes (h+) in the photocatalytic degradation of TCH. This work provides not only a new idea for the design of photodegradable materials but also a new method for the effective degradation of organic pollutants.
Project description:Functional nanocomposites with biopolymers and zinc oxide (ZnO) nanoparticles is an emerging application of photocatalysis in antifouling coatings. The reduced chemical stability of ZnO in the acidic media in which chitosan is soluble affects the performance of chitosan nanocomposites in antifouling applications. In this study, a thin shell of amorphous tin dioxide (SnOx) was grown on the surface of ZnO to form ZnO-SnOx core-shell nanoparticles that improved the chemical stability of the photocatalyst nanoparticles, as examined at pH 3 and 6. The photocatalytic activity of ZnO-SnOx in the degradation of methylene blue (MB) dye under visible light showed a higher efficiency than that of ZnO nanoparticles due to the passivation of electronic defects. Chitosan-based antifouling coatings with varying percentages of ZnO or ZnO-SnOx nanoparticles, with or without the glutaraldehyde (GA) crosslinking of chitosan, were developed and studied. The incorporation of photocatalysts into the chitosan matrix enhanced the thermal stability of the coatings. Through a mesocosm study using running natural seawater, it was found that chitosan/ZnO-SnOx/GA coatings enabled better inhibition of bacterial growth compared to chitosan coatings alone. This study demonstrates the antifouling potential of chitosan nanocomposite coatings containing core-shell nanoparticles as an effective solution for the prevention of biofouling.
Project description:Recently, the conjugation of metal oxide nanoparticles with organic moieties has attracted the attention of many researchers for various applications. In this research, the green and biodegradable vitamin C was employed in a facile and inexpensive procedure to synthesize the vitamin C adduct (3), which was then blended with green ZnONPs to fabricate a new composite category (ZnONPs@vitamin C adduct). The morphology and structural composition of the prepared ZnONPs and their composites were confirmed by several techniques: Fourier-transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), UV-vis differential reflectance spectroscopy (DRS), energy dispersive X-ray (EDX) analysis, elemental mapping, X-ray diffraction (XRD) analysis, photoluminescence (PL) spectroscopy, and zeta potential measurements. The structural composition and conjugation strategies between the ZnONPs and vitamin C adduct were revealed by FT-IR spectroscopy. The experimental results for the ZnONPs showed that they possessed a nanocrystalline wurtzite structure with quasi-spherical particles with a polydisperse size ranging from 23 to 50 nm, while the particle size appeared greater in the FE-SEM images (band gap energy of 3.22 eV); after loading with the l-ascorbic acid adduct (3), the band gap energy dropped to 3.06 eV. Later, under solar light irradiation, the photocatalytic activities of both the synthesized ZnONPs@vitamin C adduct (4) and ZnONPs, including the stability, regeneration and reusability, catalyst amount, initial dye concentration, pH effect, and light source studies, were investigated in detail in the degradation of Congo red dye (CR). Furthermore, an extensive comparison between the fabricated ZnONPs, composite (4), and ZnONPs from previous studies was performed to gain insights to commercialize the catalyst (4). Under optimum conditions, the photodegradation of CR after 180 min was 54% for ZnONPs and 95% for the ZnONPs@l-ascorbic acid adduct. Moreover, the PL study confirmed the photocatalytic enhancement of the ZnONPs. The photocatalytic degradation fate was determined by LC-MS spectrometry.