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High-temperature tungsten trioxides obtained by concentrated solar energy: physicochemical and electrochemical characterization
摘要： High-crystalline tungsten trioxides (WO3) have been synthesized by an environmentally friendly method using concentrated solar energy. The obtained tungsten trioxides (WO3) at three different temperatures and two oxygen mole fractions used for the highest synthesis temperature were characterized by XRD, SEM, and XPS. Higher crystallinity and concentration of W5+ was observed in tungsten trioxides as the synthesis temperature increased. Nevertheless, despite of the different synthetic conditions used, a mixture of two different crystalline structures was observed in all solar-prepared tungsten trioxides: monoclinic and triclinic. Comparing oxides obtained at 1000 °C, higher concentration of W5+ and more defects were found when using lower oxygen molar fraction (WO3-1000-2). Their electrochemical performance was evaluated using cyclic voltammetry (CV) in a conventional three-electrode cell in the following three aqueous electrolytes: acidic, alkaline, and neutral media. In the acidic medium, all the tungsten trioxides showed a capacitive behavior, which was enhanced for oxides obtained at 1000 °C due to a mixed valence of W. On the other hand, in the alkaline medium, a catalytic behavior was detected with higher activity towards hydrogen evolution reaction for the oxide with more defects, higher crystallinity, and monoclinic phase, obtained at 1000 °C and a lower oxygen molar fraction in the synthesis. Finally, in the neutral medium, the oxides synthesized at 1000 °C presented a capacitive behavior whereas the oxides prepared at the lowest temperatures (600 and 800 °C) presented electrochemical processes related to a catalytic behavior for water reduction, which must correspond to their minor concentration of defects, as confirmed by XPS.
关键词： High-temperature synthesis,Concentrated solar energy,Green synthesis,WO3,Tungsten trioxides
更新于2025-09-04 15:30:14
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Antioxidant and Photocatalytic Activity of Aqueous Leaf Extract Mediated Green Synthesis of Silver Nanoparticles Using <i>Passiflora edulis f. flavicarpa</i>
摘要： The purpose of this study is to minimize the negative impacts of synthetic procedures and to develop environmentally benign procedures for the synthesis of metallic nanoparticles. In the present study, Passiflora edulis f. flavicarpa (P. edulis) aqueous leaf extract mediated green synthesis of silver nanoparticles are described. The synthesized silver nanoparticles were characterized by UV-Vis Spectroscopy, Fluorescence Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) Transmission Electron Microscopy (TEM) and Cyclic Voltammetry (CV). The silver nanoparticles (AgNPs) showed antibacterial activities against both gram positive (staphylococcus) and gram negative (Escherichia coli) bacteria. The efficacy of the synthesized silver nanoparticles (AgNPs) was demonstrated as catalyst in the photocatalytic degradation of Methyl Orange (MO) and Methylene Blue (MB) dyes which were measured spectrophotometrically. The study revealed that biosynthesized silver nanoparticles using Passiflora. edulis f. flavicarpa, plant extract was found to be very effective as antioxidant agent.
关键词： Photocatalytic Activity,Green Synthesis,Silver Nanoparticles,Passiflora edulis f. flavicarpa,Antioxidant
更新于2025-09-04 15:30:14
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Phyto-Mediated Photo Catalysed Green Synthesis of Silver Nanoparticles Using Durio Zibethinus Seed Extract: Antimicrobial and Cytotoxic Activity and Photocatalytic Applications
摘要： In the present study, we have developed a green approach for the synthesis of silver nanoparticles (DSAgNPs) using aqueous extract of Durio zibethinus seed and determined its antibacterial, photocatalytic and cytotoxic effects. Surface plasmon resonance confirmed the formation of DSAgNPs with a maximum absorbance (λmax) of 420 nm. SEM and TEM images revealed DSAgNPs were spherical and rod shaped, with a size range of 20 nm and 75 nm. The zeta potential was found to be ?15.41 mV. XRD and EDX analyses confirmed the nature and presence of Ag and AgCl. DSAgNPs showed considerable antibacterial activity, exhibited better cytotoxicity against brine shrimp, and shown better photocatalytic activity against methylene blue. Based on the present research work, it can be concluded that DSAgNPs could be used in the field of water treatment, pharmaceuticals, biomedicine, biosensor and nanotechnology in near future.
关键词： antibacterial,silver,Durio zibethinus seed,green synthesis,cytotoxicity,nanoparticles
更新于2025-09-04 15:30:14
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In vitro and In vivo evaluation of green-hydrothermal synthesized ZnO nanoparticles
摘要： ZnO nanoparticles synthesized using Gallic acid isolated from Phyllanthus emblica aqueous extract that designated as Pe ZnO, was subjected for structural and morphological characterization. For in vitro cyto-toxicity assessment of Pe ZnO, Hemolytic assay and Cell Counting Kit assay (CCK 8) on balb 3T3 fibroblasts were conducted while silkworm Bombyx mori larvae were used for in vivo bio-toxicity assay. In dentistry, clinically advocated ZnO (presented as D ZnO) of ~2 μm size was used as control. Characterization results revealed that Pe ZnO is highly crystalline with hexagonal wurtzite structure and morphologically spherical with an average size of 38 nm as confirmed by X-ray diffraction, electron microscopy and dynamic light scattering techniques. Haemolysis assay at all the tested concentrations exhibit that, lysis of Red Blood Cells by Pe ZnO remained well within toxicity limit of 3% whereas D ZnO showed ~5.2% hemolysis. Interestingly, Pe ZnO nanoparticles caused less than 36% growth inhibition of 3T3 cells at the highest concentration (2 μL) against 44% by D ZnO. Notably, in vivo study showed 26.67 and 96.67% death of the larvae at highest concentration 0.032 mg/mL of Pe ZnO and D ZnO respectively indicating Pe ZnO is less toxic than commercially available ZnO. Thus, we proved that green hydrothermally synthesized ZnO (PeZnO) is highly biocompatible and therefore propose to consider as potent compound for further evaluation using mammalian models followed by clinical trials.
关键词： Hydrothermal,3T3 fibroblasts,Green synthesis,ZnO,Bombyx mori,toxicity,Hemolysis
更新于2025-09-04 15:30:14
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Facile <i>Justicia adhatoda</i> leaf extract derived route to silver nanoparticle: Synthesis, characterization and its application in photocatalytic and anticancer activity
摘要： The aim of the present study is to investigate the photocatalytic and anticancer activity of green synthesized silver nanoparticle (AgNPs) using leaf extract of Justicia adhatoda. Several techniques were used to confirm and characterize the synthesized AgNPs. The synthesis of nanoparticle was identified by the formation of dark brown color in the reaction mixture and SPR band noted at 425 nm. The obtained AgNPs were spherical in shape with its average sizes in the ranges of 12.0, 26.7 and 47.9 nm, respectively, it can be tuned by varying the concentration of AgNO3 analyzed by High resolution Scanning Electron Microscope and Transmission Electron Microscope (HRSEM with EDAX and TEM). The formation and size distribution of obtained AgNPs were determined by Dynamic Light Scattering (DLS) method. The negative zeta potential values were observed, causing dispersion stability of synthesized AgNPs. Fourier transform infrared spectroscopy (FTIR) and Surface Enhanced Raman (SERS) analyzed the existence of alcohols, amides and etc., in the leaf extract which behave as capping and reducing agents for the synthesis. The Face Centered Cubic (FCC) nature of AgNPs was depicted by X-Ray Diffraction analysis. The photocatalytic activity is established by size-dependent nature of AgNPs, using an organic dye (methylene blue) as a substrate. Besides, the AgNPs showed significant anticancer activity against Human lung cancer cell line (A549). From in-vitro investigation and dye degradation experimental studies confirmed that the synthesized AgNPs have potent photocatalytic as well as anticancer activity.
关键词： anticancer,photocatalytic degradation,J.adhatoda,AgNPs,Green synthesis
更新于2025-09-04 15:30:14
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Green synthesis of g-C <sub/>3</sub> N <sub/>4</sub> -Pt catalyst and application to photocatalytic hydrogen evolution from water splitting
摘要： The g-C3N4-Pt photocatalyst was successfully prepared by the combination of a biosynthesis method and sol deposition, which were used for hydrogen evolution from water splitting. The layers of g-C3N4 are thinned and the Pt nanoparticles simultaneously become tightly bound to g-C3N4 by secondary calcination in the process of synthesizing the g-C3N4-Pt photocatalyst. Analysis of the morphological structure and instrumental characterization of the optical performance revealed that the Pt nanoparticles were successfully loaded and well dispersed on the surface of g-C3N4. Furthermore, the absorption wavelength range of the g-C3N4-Pt photocatalyst in visible light was widened and the absorption increased. The activity and photostability of the g-C3N4-Pt photocatalyst for hydrogen evolution under visible light irradiation (λ≥420 nm) were excellent. The rate of H2 evolution reached 582.4 mmol h?1 g?1, and the quantum efficiency (QE) reached 2.70% at 420 nm.
关键词： green synthesis,hydrogen evolution,visible-light photocatalysis,G-C3N4-Pt photocatalyst
更新于2025-09-04 15:30:14