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Green Synthesis of High Temperature Stable Anatase Titanium Dioxide Nanoparticles Using Gum Kondagogu: Characterization and Solar Driven Photocatalytic Degradation of Organic Dye
摘要： The present study reports a green and sustainable method for the synthesis of titanium dioxide (TiO2) nanoparticles (NPs) from titanium oxysulfate solution using Kondagogu gum (Cochlospermum gossypium), a carbohydrate polymer, as the NPs formation agent. The synthesized TiO2 NPs were categorized by techniques such as X-Ray Diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy analysis, Raman spectroscopy, scanning electron microscope- Energy-dispersive X-ray spectroscopy (SEM-EDX), Transmission electron microscopy (TEM), High-resolution transmission electron microscopy (HR-TEM), UV-visible spectroscopy, Brunauer-Emmett-Teller (BET) surface area and particle size analysis. Additionally, the photocatalytic actions of TiO2 NPs were assessed with regard to their ability to degrade an organic dye (methylene blue) from aqueous solution in the presence of solar light. Various parameters affecting the photocatalytic activity of the TiO2 NPs were examined, including catalyst loading, reaction time, pH value and calcination temperature of the aforementioned particles. This green synthesis method involving TiO2 NPs explores the advantages of inexpensive and non-toxic precursors, the TiO2 NPs themselves exhibiting excellent photocatalytic activity against dye molecules.
关键词： methylene blue,titanium dioxide nanoparticles,gum kondagogu,green synthesis,photocatalysis
更新于2025-09-09 09:28:46
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A Versatile Dynamic Light Scattering Strategy for the Sensitive Detection of Plant MicroRNAs Based‐on Click Chemistry‐Amplified Aggregation of Gold Nanoparticles
摘要： Plant microRNAs (miRNAs) are naturally 2′-O-methylated at the 3′-terminal, so they cannot be efficiently detected by traditional target-triggered polymerization reactions. Herein, a simple but robust enzyme-free sensing strategy is developed for plant miRNA analysis by using dynamic light scattering (DLS) technique to monitor the click chemical ligation-amplified crosslinking of gold nanoparticles (AuNPs). Combining the enzyme-free cycling chemical ligation-mediated signal amplification, and the intrinsic outstanding ability of DLS for discriminating the extremely low level of particle aggregation in a large pool of monodisperse AuNPs, high sensitivity is achieved and as low as 78.6 fM plant miRNA can be easily detected.
关键词： crosslinking,click chemistry,plant microRNA,dynamic light scattering (DLS),gold nanoparticles
更新于2025-09-09 09:28:46
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Microwave-Assisted Solvothermal One-Pot Synthesis of RuO <sub/>2</sub> Nanoparticles: First Insights of Its Activity Towards Oxygen and Chlorine Evolution Reactions
摘要： A microwave-assisted solvothermal method is proposed as a rapid and low-cost fabrication procedure of RuO2 nanoparticles using citric acid as stabilizing agent in ethylene glycol, and H2O2 as oxidizing agent at 180 °C. Structural and morphological characterizations of the powder are investigated using X-Ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). XRD analysis shows that there is a synergic effect to obtain RuO2 nanoparticles when 6% v/v H2O2 is added followed by a calcination of the powder, due to reactive oxygen intermediates (1O2, HO(cid:0) 2, 2, HO* *OH) generated in the first stage. TEM and SEM images of as-synthesized material exhibit an uniform particle distribution (PSD) of RuO2 nanoparticles with averaged diameter of ca. 38 nm, and its indexing indicates the RuO2 stoichiometry with high degree of crystallinity. The preliminary electrocatalytic performance of RuO2 nanoparticles coated on Ti is investigated using voltammetry and electrochemical impedance spectroscopy (EIS), towards the oxygen (OER) and chlorine evolution reaction (CER) in 1 mol L(cid:0) 1 H2SO4 and 0.1 mol L(cid:0) 1 NaCl, respectively. Cyclic voltammograms of RuO2 display typical behaviors for OER and CER at 1.25 and 1.1 V vs Ag/AgCl, respectively. A Tafel slope of 44 mV dec(cid:0) 1 corrected for ohmic drop was obtained in sulfate media which confirmed the OER mechanism in the absence of chlorides; while this parameter is around 25 mV dec(cid:0) 1 in NaCl (CER), strongly depending on the chloride concentration and the extent of OER input. In NaCl media, the energy barriers represented by the charge transfer resistances for CER are overcome at more positive potentials than for OER, and a greater activity of the O2 evolution is observed as the potential became more positive.
关键词： Microwave,CER,OER,Electrocatalysis,Solvothermal,RuO2 Nanoparticles
更新于2025-09-09 09:28:46
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Photoelectrochemical activity of Ag loaded TiO2 nanotube arrays produced by sequential chemical bath deposition for water splitting
摘要： We report on remarkable improvement of photoelectrochemical (PEC) properties of TiO2 nanotubes by loading of Ag nanoparticles into them. The silver nanoparticles were loaded on the nanotubes by sequential chemical bath deposition (S-CBD) with different number of deposition cycles. Various characterizations including field emission scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray analysis (EDX), all confirm that the silver nanoparticles were deposited inside and outside of TiO2 nanotubes. In addition, the PEC properties of the samples were investigated using linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The PEC analyses clearly show that the photoelectrochemical activity of the Ag-loaded samples are considerably higher than the bare TiO2 nanotubes (about 3 times). This mostly originates from the improvement of light absorption due to the plasmonic effects in addition to better separation and transport of electron–hole pairs in the Ag-loaded samples relative to the bare TiO2 nanotubes. All results indicate that the maximum efficiency were obtained for the 8-cycle of S-CBD Ag-loading on the bare TiO2 nanotubes.
关键词： TiO2 nanotubes,sequential chemical bath deposition,water splitting,photoelectrochemical,Ag nanoparticles
更新于2025-09-09 09:28:46
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Effect of Synthesis Temperature on Structural, Optical, and Magnetic Properties of ZnO Nanoparticles Synthesized by Combustion Method
摘要： ZnO nanoparticles at different temperatures were synthesized by using the combustion method. The effect of synthesis temperature on the properties of the nanoparticles was studied by using XRD, FESEM, EDS, TEM, photoluminescence (PL), Raman, diffuse reflectance spectra (DRS), and VSM characterization techniques. The XRD results reveal that the grown nanoparticles have a hexagonal wurtzite structure without any impurities and agreed with EDS results. FESEM and TEM micrographs show that the ZnO nanoparticles possess a spherical shape with agglomeration free, and the size increases with increase of synthesis temperature. From DRS studies, it was noticed that the band gap decreases with increase of synthesis temperature. In PL studies, blue peak at 465 nm may be due to defect-related transitions. A sharp intense peak in Raman spectra at 485 cm?1 represents E2H mode is a characteristic of a hexagonal wurtzite structure. The magnetic studies show that the magnetization decreases from 0.0172 to 0.0042 emu/g as the synthesis temperature increases from 400 to 550 °C. ZnO synthesized at 500 °C has a large squareness ratio. These materials are potential candidates for memory devices.
关键词： Combustion method,Spintronics,Ferromagnetism,ZnO nanoparticles
更新于2025-09-09 09:28:46
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Effect of polyethylene glycol and propyltrimethoxysilane on structural and optical properties of zinc oxide nanoparticles synthesized by sol–gel process
摘要： Zinc oxide nanoparticles (ZnO NPs) are prepared by sol–gel process, using both polyethylene glycol (PEG-400) as surfactant and propyltrimethoxysilane (PTMS) as capping agent. Surface modi?cation is performed in situ procedure. The physical parameters such as strain and stress values are calculated via the Williamson–Hall plot (W&H) assuming a uniform deformation model (UDM) and uniform stress deformation model, and by the size and strain plot method (SSP). The results show that the crystallite size estimated from Scherrer’s formula, (W&H), (UDM), (SSP) and the particle size estimated from DSL are inter-correlated, which con?rm the small size and the isotropic nature of our ZnO NPs. The FTIR spectroscopy illustrates that PEG-400 and PTMS could be adsorbed at the ZnO NPs surface. The distinct emission peak in the blue band is located at 490 nm and E2 (high) mode is situated at 436 cm-1. Both results con?rm the oxygen de?ciency in the ZnO NPs.
关键词： Propyltrimethoxysilane,Sol–gel synthesis,Zinc oxide,Nanoparticles,PEG-400,DRX
更新于2025-09-09 09:28:46
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Fast dispersive liquid–liquid microextraction based on magnetic retrieval of in situ formed an ionic liquid for the preconcentration and determination of benzophenone-type UV filters from environmental water samples
摘要： This work concerns the development of a novel and rapid in situ dispersive liquid–liquid microextraction method for magnetic retrieval of ionic liquid as a new approach for the separation of benzophenone type (BP-type) UV filters via quantification using UPLC with PDA detection. The analytes determined in this study were a group of three benzophenones: 2,4-dihydroxybenzophenone (BP1), 2,2′,4,4′-tetrahydroxybenzophenone (BP2) and 2-hydroxy-4-metoxybenzophenone (BP3). The hydrophilic ionic liquid found suitable for use as an extraction solvent of the targeted analytes was didecyldimethylammonium chlorate (DDAC). An anion exchanger, NaClO4 was added to promote a metathesis reaction and in situ formed the IL, [DDA][ClO4]. The experimental parameters such as the concentration of IL, the molar ratio of DDAC to NaClO4, amount of iron oxide added and volume of water sample were investigated and optimised using a step-by-step optimisation process. The optimum experimental parameters were as follows: 30 mL of sample volume, 1% concentration of DDAC, the molar ratio of DDAC to NaClO4—1:2, and 5 mg of Fe3O4 magnetic nanoparticles. The proposed extraction method is simple and requires no more than 5 min. The detection limit (LOD) obtained for target analytes ranged from 12.320.0 ng L?1, while the correlation coefficient (r2) was from 0.9995 to 0.9999. Finally, the developed method was successfully applied to the determination of BP-type UV filters in environmental water samples, and satisfactory results were obtained.
关键词： In situ MR IL-DLLME,Ionic liquid,Benzophenones,BP-type UV filters,Magnetic nanoparticles
更新于2025-09-09 09:28:46
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Iridium oxide (IV) nanoparticle-based electrocatalytic detection of PBDE
摘要： Polybrominated diphenyl ethers (PBDEs) are a type of flame retardants which are currently banned in EU and USA due their hazardousness for humans and mammals. However, these compounds were highly used during more than 30 years and still persist in the environment since they are resistant to degradation. Herein we present a biosensor for the detection of PBDEs using screen printed carbon electrodes (SPCEs) based on the electrochemical monitoring of water oxidation reaction (WOR) catalyzed by iridium oxide (IV) nanoparticles (IrO2 NPs). Our assay shows a limit of detection of 21.5 ppb of PBDE in distilled water. We believe that such an IrO2 NPs-based electrocatalytic sensing system can lead to a rapid, sensitive, low cost and miniaturizable device for the detection of PBDEs.
关键词： PBDEs,Electrocatalysis,Iridium Oxide Nanoparticles,Flame retardants,Screen Printed Carbon Electrodes
更新于2025-09-09 09:28:46
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Three in one: Mesogenic aromatic acid as a liquid crystal matrix, a chiral dopant in liquid crystals and a stabilizer for nanoparticles
摘要： Studies of thermodynamics of the N*-I phase transitions and optical properties of the new liquid crystal - (R)-2-[4”-(trans-4-butylcyclohexyl)-2’-chloro-p-terphenyl-4-oxy) propanoic acid are carried out. The aim of these studies is to analyse the capabilities of that liquid crystal to simultaneously serve as a matrix for inorganic semiconductor nanoparticles (NP) as well as a chiral dopant for liquid crystals and a chiral ligand stabilizing the surface of CdSe NPs. The chiral doping of a nematic liquid crystal was proven by the measurements of selective transmittance of the visible light. The embedding of NPs in a nematic liquid crystal leads to the increase in TN*I, which is explained by the shape anisotropy of the NPs. The anisotropy of the ligand shell may result from the interaction between the ligand and LC matrix inducing the change of the spherical shape of the shell toward the ellipsoidal one. TN*I of the liquid crystal matrix of (R)-2-[4”-(trans-4-butylcyclohexyl)-2’-chloro-p-terphenyl-4-oxy) propanoic acid (R-MPA) decreases with the embedding of NPs stabilized by the same ligands, which is in a good agreement with prior experimental results and theory, but there exists a considerable quantitative difference.
关键词： optical properties,liquid crystal,thermodynamics,nanoparticles,chiral dopant
更新于2025-09-09 09:28:46
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Paper-based Versatile SERS Chip with Smartphone-based Raman Analyzer for Point of Care Application
摘要： With the advanced development of the miniaturized Raman spectroscopy, surface enhanced Raman spectroscopy (SERS) has extended its applications into the field of Point of Care Testing (POCT) and demonstrated its great significance in virtue non-invasive property and capability of fingerprint identification. In the SERS-based analysis and/or sensing system, the preparation of low cost, high-performance SERS substrate is critically important. In this manuscript, vacuum filtration is utilized to fabricate the silver nanoparticles (AgNPs) embedded nylon filter membrane (ANFM) as flexible paper-based SERS chips. By characterizing the typical analytes with the miniaturized smartphone-based Raman analyzer, the proposed SERS chips have successfully demonstrated good sensitivity, repeatability and stability. The lowest concentration as detected can approach 1 pmol for Rhodamine 6G (RH6G) and 10 pmol for both crystal violet (CV) and malachite green (MG), respectively. With the help of microporous structure of the membrane, the ANFM based SERS chips can implement the separation of small molecules from complex mixture and can achieve “purified” SERS signals of targeted molecules. Besides, with the function of anti-friction resistance and flexibility, the ANFM can serve as SERS papers to pre-concentrate the contaminates by multiple swapping and further enhance the SERS signals for point of care analysis. Therefore, we demonstrate multi-functions of the flexible ANFM based SERS chips, which provides a promising solution for the POCT analysis with SERS technique on account of its flexibility and low fabrication cost.
关键词： silver nanoparticles,SERS chips,nylon filter membrane,Point of Care Testing,smartphone-based Raman analyzer,Surface-enhanced Raman spectroscopy
更新于2025-09-09 09:28:46