Applied Nanoscience最新文献

Functional nanoferrites are attracting interest in photocatalytic applications due to their intriguing and excellent optical and magnetic properties. In that order, as suitable adsorbents for wastewater treatment, graphene-based nanoferrites can be tuned. In this article, ZnFe₂O₄/GO nanocomposites have been prepared to study the structural, optical, magnetic, and photocatalytic properties through investigational (experimental) results and theoretical insights. Further, the synthesized nanocomposites fall under the mesoporous range with an average crystalline size of around 15–18 nm with good colloidal stability. Spherically agglomerated morphology has been observed by FE-SEM analysis. Magnetic characterizations were done by vibrating sample magnetometer (VSM) with superparamagnetic behavior at room temperature (RT). Optical insights reveal that the samples exhibit good photocatalytic properties with a degradation rate of 85.8% with methylene blue (MB) organic pollutant. Hence, this article aims to study the properties of prepared ZnFe₂O₄/GO nanocomposites through a detailed theoretical discussion of density functional theory (DFT).

Titanium dioxide nanoparticles (TiO₂ NPs) have garnered considerable attention due to their diverse applications. Introducing niobium (Nb) and nitrogen (N) doping, followed by functionalization with Mucuna pruriens beans methanolic extracts, offers a novel avenue to harness their antioxidant potential. This functionalization enables Nb-N doped TiO₂ NPs to engage with the bioactive compounds inherent to M. pruriens beans methanolic extracts, thereby fostering a synergistic enhancement of antioxidant activity. This study focuses on the functionalization of doped Nb-N-TiO₂ NPs and evaluates the antioxidative capabilities of those functionalized NPs to pure doped Nb-N-TiO₂ NPs. These functionalized NPs (FNb-N-TiO₂) underwent characterization through ultraviolet–visible spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning electron microscopy (SEM) analysis. Subsequently, their antioxidant capabilities were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Ferric Reducing Antioxidant Power Assay (FRAP) assays. Functionalized Nb-N-TiO₂ NPs FTIR peaks exhibited at 2430 and 2010 cm⁻¹; unrelated peak vibrations are associated with the (Nb-N) doping, and the increased transmittance signifies successful functionalization and potential bonding between M. pruriens extract phytochemicals. A distinctive triangular aggregation pattern in SEM ranging in size from 5 µm to 500 nm was seen in FNb-N-TiO₂. At a concentration of 500 μL⁻¹, FNb-N-TiO₂ exhibited exceptionally high antioxidant activity, reaching an impressive 70% compared with pure Nb-N-TiO₂ NPs at 51%. The results demonstrated that FNb-N-TiO₂ NPs exhibit significant antioxidant properties compared to their non-functionalized, pure Nb-N-TiO₂ NPs. In conclusion, this study substantiates the considerable antioxidant potential of doped Nb-N-TiO₂ NPs mediated by M. pruriens methanolic extract, thereby emphasizing their potential for diverse applications in both biomedical and environmental sciences.

Nanostructured materials have significantly influenced numerous scientific and technological areas, mainly due to the tuneability of their optical and electrical properties. When working with quantum dots (QDs)-based thin films, the high prevalence of trap states and low conductivity has been a remarkable challenge, which has been addressed by the fabrication of hybrid materials. However, on the road to improving their properties, fabrication of nanostructured hybrid materials, especially when involving 2D nanomaterials, still poses a challenging task, particularly when solution-processed approaches are considered. In the current work, the fabrication of a solution-processed QDs-2D nanomaterial hybrid, comprising PbS QDs and thermally reduced graphene oxide (rGO) is discussed. This study explores the nanostructured hybrid material's behavior when varying the weight percent ratio between the constituents, revealing a substantial impact of this parameter on the optoelectronic properties of the resulting hybrid material; particularly affecting the photogenerated charge carrier transfer, charge carrier mobility, charge carrier concentration and resistivity. Physical characterization of the hybrid material revealed a dramatic change in the interaction between the PbS QDs and the rGO as the weight percent of rGO increased in the hybrid material, showing a clear reduction of PbS QDs coverage on rGO’s surface, which also produced an increment in the signals related to the oxidation of PbS QDs and rGO. The sample with 5% wt. of rGO showed optimal optoelectronic properties for possible applications in photodetector technologies or solar cells, displaying a high photogenerated current with a charge carrier mobility, charge carrier concentration, and resistivity of approximately 2.26 cm²/V-s, 1.27 × 10¹⁴ cm⁻³ and 2.18 × 10⁴ Ω-cm, respectively. These findings serve as a foundational basis for the development of efficient optoelectronic devices based on this type of nanostructured hybrid material.

The spectroscopic characteristics of the common flower Clitoria ternatea are explored for the first time. When excited, the extract shows two emission crests at 436 and 663 nm corresponding to anthocyanin delphinidin and betalains betacyanin, respectively. For practical utility, the extract is made into thin films, giving a broad emission band from 450 to 530 nm. But by this line, the luminescence spectra showed a falloff with time, through a decay rate of 0.2463 cps/h owing to aging. An anti-oxidizing agent (Y₂O₃)–extract complexes with different extract concentrations (1–5 ml) under different heating conditions (100–200 °C) are produced to overcome this scenario. The XRD and Raman spectra depict the fruitful complex formation in cubic structure with space group Ia3. Using UV–visible info, the bandgap is computed to be 2.381 eV. When Y₂O₃ and Clitoria extract are taken in the same measure, decent emission bands around 450–550 nm and 630–690 nm are observed by the FRET mechanism; giving a ninefold increment in PL intensity with CIE coordinates in the vicinity of near-white light. The trials are repeated numerous times to ensure reproducibility and the outcomes are compared with the conventional Y₂O₃:Dy³⁺-doped system, showing prime results by the Y₂O₃:Clitoria complex (1:1, 100 °C). This unprecedented investigation concludes the enhanced photoluminescence from Clitoria extract, which could replace conventional rare earth doping and provide a novel methodology for designing and fabricating lighting devices.

Polymer nanomaterials are an emanating area of research incited by the wide range of applications in solar cells, catalysis, sensors, drug delivery, electronics, bioimaging, etc., due to their outstanding mechanical, optical and electronic properties. Small dimensions in the nanometre range and a high surface-to-volume ratio of polymer nanomaterials possess distinctive features compared to bulk counterparts. In this work, doped polyvinyl alcohol (PVA) nanostructures were prepared by a one-step hydrothermal synthesis method and studied the morphological, structural and optical properties. The attained nanomaterials exhibit a spherical shape, and their average size was calculated as 3.98 nm by HR-TEM analysis. The obtained nanomaterials are dissolved in N,N-dimethyl formamide (DMF) solvent and can be employed for optoelectronic devices due to their amorphous structure and direct bandgap. Green luminescence was observed under UV light, and non-biocidal activity showed against Escherichia coli, Pseudomonas fluorescens, E. coli DH5α, Bacillus subtilis and Staphylococcus aureus.

Membrane-based desalination technology stands out as a promising solution to obtain potable water by creating opportunities for water recovery. The productivity and fouling of the reverse osmosis (RO) membranes are the most common problems in desalination processes. The effect of Melamine-grafted graphene Oxide (MEL/GO) in the RO membrane preparation has a gap in existing knowledge through understanding the specific effects and synergies of these materials in membrane synthesis and desalination performance. In this study, we employed the phase inversion technique to synthesize polyamide (PA) RO membranes incorporating MEL/GO. Various membrane properties were investigated, including hydrophilicity, porosity, surface and cross-sectional morphology, permeability, and membrane performance. It was found that the optimum MEL and GO concentrations were 0.1 and 0.3% w/w, respectively. The performance of MEL, GO, and MEL/GO-incorporated membrane (Mm0.1, MG0.3, and Mm0.1/G0.3, respectively) with previously mentioned optimized concentrations resulted in enhanced performance characteristics against plain membrane (M0) free from MEL and GO. Specifically, the water flux significantly increased from 10.01 LMH/bar for M0 to 73.47 LMH/bar, 23.35 LMH/bar, and 88.21 LMH/bar for the Mm0.1, MG0.3, and Mm0.1/G0.3 membranes, respectively. Moreover, the salt rejection percentage experienced a substantial enhancement from 71.74% for the M0 to 96.57% for the Mm0.1/G0.3 membrane. This study's novelty was introducing MEL into the GO layer for the first time, enriching the amine functional group and facilitating water transportation. The results highlight the potential of these highly hydrophilic nanofillers for advanced membrane technology in desalination applications.

Antibiotics are life-saving drugs that fight bacterial infections by killing or inhibiting their reproduction. However, the overuse and misuse of this drug can contaminate water as it can reach the water surface very quickly through various pathways. The consumption of contaminated water may lead to the development of antibiotic resistance, which has been proliferating across the world recently. Azithromycin (AZM), an essential antibiotic drug, has been identified in wastewater and surface water, prompting apprehension regarding its potential environmental and public health consequences. The present investigation assessed the efficacy of photocatalytic degradation of AZM in water samples under sunlight. Exploiting the surface chemistry and high surface area of cellulose nanocrystals (CNC), nanocomposites with high loading (80 wt%) of titanium dioxide (TiO₂) nanoparticles on a minimal amount of scaffold (20 wt% CNC) were synthesized and used as catalysts. Maximum removal efficiency of 98.8% was achieved in 5 h at a catalyst dose of 175 mg/L for an AZM solution with 10 mg/L concentration. Synthesized CNC–TiO₂ nanocomposites demonstrated superior performance both in terms of high degradation efficiency and lowest catalyst loading per the g of AZM compared the material reported in the literature for the degradation of AZM. In conclusion, CNC–TiO₂ nanocomposites are highly effective catalysts for the photocatalytic degradation of AZM. The developed method further ensures the hygiene of water sources and prevents the spread of antibiotic resistance.

Abstract

The potential cooling solutions for the next generation are represented by nanofluids, offering several advantages for various technological applications. The intriguing realm of glycine-based acetone-based ({{text{Al}}}_{2}{{text{O}}}_{3}) nanofluids was explored in the present investigation, with meticulous attention to details given to scrutinizing their stability and thermophysical properties. The stability of the nanofluids was determined through a trifecta of analytical methods, namely visual inspection, UV absorbance measurement, and zeta potential analysis, all applied with caution. The results revealed that stability was observed for a duration of 3 days without glycine, and an impressive 6 week period was achieved when supplemented with the surfactant. The incorporation of glycine enhanced the stability of the colloidal suspension without compromising its thermophysical attributes. Furthermore, the study involved an in-depth examination of the density, viscosity, specific heat, and thermal conductivity of the prepared nanofluids, yielding interesting outcomes. The data showed a marked increase in nanofluid density, viscosity, and thermal conductivity with a corresponding rise in volume concentration, while specific heat exhibited a noticeable reduction. These significant observations were meticulously compared to various existing theoretical models and proposed correlations in the literature. The heat transfer performance of the nanofluid in the context of pulsating heat pipes was evaluated and the results proved riveting. The nanofluid demonstrated superior performance compared to the base fluid, confirming its remarkable efficacy.

In the current paper, hematite (α Fe₂O₃) nanoparticles (NPs) were prepared by the chemical co-precipitation method. These synthesized nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), Raman spectroscopy, and vibrating sample magnetometry (VSM). The XRD studies for the nanoparticles revealed rhombohedral symmetry with space group: R3c (167), and the particle size is about 33.34 nm. The morphological studies carried out by SEM indicated that these prepared samples have a spherical morphology with some porosity. The specific surface area of this sample was calculated by the Brunauer–Emmett–Teller (BET) technique. FTIR spectroscopy confirms the Fe–O and O–Fe–O vibrations corresponding to stretching at the expected positions (520 cm⁻¹) related to the structure. From Raman data, modes corresponding to α-Fe₂O₃ are seen. From DC magnetisation studies, the current sample shows ferrimagnetic behavior. In addition, the value of M_s is 1.027 and value of M_r is 322.787×10^–6. Further nanofluids of these nanoparticles with different concentrations of transformer oil were prepared. The performance of this nanofluid as a coolant in transformer oil was also studied. The 0.2 g/l concentration shows the maximum improvement in breakdown voltage. Hence, under optimal conditions, these ferrofluids can perform well for insulating purposes.

Schiff base compounds were reported to make a complex with Cu²⁺ and Ag⁺ and subsequent reduction produced Cu⁰ and Ag⁰ nanoparticles separately via UV irradiation. Here, we synthesized a Schiff base, which initially formed a complexation with Cu²⁺ and made Cu⁰ nanoparticles after 8 h aging. In that reaction mixture, addition of Ag⁺ resulted in Ag⁰ nanoparticles. Emissive semi-carbazone (a Schiff base synthesized from semicarbazide and salicylaldehyde) was employed for the first time to selectively and sensitively detect Cu²⁺ (linear range of detection 10^–4 to 5 × 10^–8 M and limit of detection 13 μM) with the formation of copper oxide nanoparticles via complexation–reduction method. The introduction of Ag⁺ in it produced Ag⁰ and Cu⁰ (CuO via aerial oxidation) nanoparticles with a gigantic increase of fluorescence to obtain selective and sensitive Ag⁺ detection (linear detection range 10^–3–10^–7 M, and limit of detection 7. 7 μM). Thus, Cu²⁺ and Ag⁺ were detected based on turn-off/on fluorescence in one pot. As the evolution of copper and silver nanoparticles was the fundamental reason for sensing, response time is similar to the stable fluorescence behavior of oxidized SC (capping agent) with in situ generated copper and silver nanoparticles. CuO-induced fluorescence quenching was due to the formation of the trapped plasmon, while Ag⁺-induced fluorescence enhancement was owing to the lightning rod effect. The synergism of Cu and Ag was also investigated in this paper as a driving force of the lightning rod effect for the first time. Both the metals (Cu and Ag) were estimated in natural water, justifying the utility of the sensing platform for practical applications. Besides, the evolution of brilliant red color with semi-carbazone for Ag⁺ was employed for the colorimetric sensing of Ag⁺.