Titanium dioxide (TiO 2 ) exhibits dielectric properties that vary significantly with its physical morphology and thermal history. This work evaluates the dielectric responses of calcined nanopowder, electrospun nanofibers before and after heat treatment. Utilizing TEM, SEM, EDX, FTIR, and XRD allows for a detailed assessment of the morphological, and structure differences across the TiO 2 samples. The uncalcined nanofibers exhibit an amorphous structure with significant polyvinylpyrrolidone (PVP) content. Calcination transforms these amorphous precursors into crystalline fibers with a mixed anatase and rutile phase. Dielectric measurements carried out over a frequency range of 1 Hz to 1 MHz demonstrated that the calcined nanofibers feature a dielectric constant (ε′) that is both reduced and mostly stable across the measured frequency range. At higher frequencies, the dielectric constant was found to approach free-space permittivity, with the material additionally exhibiting low dielectric loss (ε″, tan δ), and reduced low AC conductivity (σ). The calcined TiO 2 nanopowders, and uncalcined fibers by contrast revealed higher ε′ values and more substantial losses. The calcined TiO 2 nanofibers thus exhibit superior insulating characteristics, demonstrating that nanostructuring combined with controlled thermal treatment can be effectively employed to alter dielectric performance. These findings carry meaningful implications for designing dielectric materials, particularly in enabling the optimization of low and stable dielectric permittivity alongside low-loss properties across a broad frequency range for electronic circuits applications.
Waterproof dam concrete’s permeability stability in goaf waterlogged environments critically impacts coal mine safety and groundwater sustainability. Underwater immersion, weak infiltration pathways are formed at the joint interfaces of the composite structure (concrete-concrete), potentially triggering water damage incidents. Optimization research on interface anti-seepage performance is urgently required. This study focuses on the composite structure of waterproof concrete dams, analyzing permeability modification by nano SiO 2 /TiO 2 /Al 2 O 3 at varying percentages on bi-material specimens post-immersion. Gas permeability, Liquid-measured porosity test, Ultrasonic velocity, and SEM were performed to evaluate the permeability evolution and interface stability of nanomaterial-modified concrete after different days of water immersion. Results indicate that post 14-day immersion, the permeability of ordinary concrete monomer specimens (OC) and bi-material specimens (C-C) increased to 0.236×10 -5 μm 2 and 0.760×10 -3 μm 2 , respectively, corresponding to degradation levels of 220.5% and 88.5%. Moreover, the permeability of C-C remained two orders of magnitude higher than that of OC, and their degradation followed a three-stage pattern: rapid amplification, moderate development, and gradual stabilization. Nanomaterial incorporation suppressed permeability deterioration, particularly the 0.5% TiO 2 group, showing optimal performance. Post-immersion, the 0.5%TiO 2 group showed 0.236×10 -3 μm 2 permeability, representing a 69.0% improvement relative to the C-C. Other groups demonstrated modification effects of 55.9% for 0.5%Al 2 O 3 , 52.6% for 1.0%Al 2 O 3 , 42.1% for 1.0%TiO 2 , and 24.4% for 0.5%SiO 2 , while the addition of 1.0%SiO 2 exhibited no significant improvement. Liquid-measured and ultrasonic tests showed the 0.5% TiO 2 group had 16.4% lower porosity and 14.2% higher wave velocity post-immersion. SEM analysis demonstrated that nano-TiO 2 effectively suppressed the expansion of interface cracks, and image binarization processing revealed a 49.6% reduction in fracture surface porosity in the 0.5%TiO 2 group, resulting in a denser interface microstructure and enhanced permeability stability. This study establishes key technical foundations for optimizing composite structural materials for waterproof concrete dams, thereby enhancing permeability stability in underground storage facilities and related engineering structures.
Ultrafine nano-silica, with its smaller particle size compared to conventional nano-silica, is typically synthesized via gas-phase methods that require complex raw materials and processes. Here, we report optimized conditions for preparing ultrafine nano-silica via a precipitation reaction between fluosilicic acid waste and aluminum hydroxide. The optimal conditions determined were as follows: reverse feeding, surfactant addition at 3.0%, aluminum-to-silicon ratio of 2.00, reaction time of 30 min, reaction temperature of 90 °C, and stirring rate of 250 rpm. Under these conditions, ultrafine nano-silica with a uniform particle size of approximately 11 nm was successfully synthesized. Characterization of samples prepared by different feeding methods showed that the reverse feeding method yielded ultrafine nano-silica with superior performance indicators compared to the forward feeding method. Analysis of system changes during synthesis indicated that the feeding method influenced the acidic or alkaline environment of the substrate, affecting SiF 4 hydrolysis and the subsequent dehydration and condensation of Si-(OH) 4 monomers, leading to variations in silica particle agglomeration. Further, an analysis of the effects of alkyl chains in surfactants on the surfaces of silica particles, including -OH substitution or Si-O-Si bond cleavage, provided insights into the action mechanism of surface groups on ultrafine nano-silica particles.
In this study, Arabic gum-capped ZnO NPs (ZnO NPs-Cap) were synthesized via a simple precipitation method, and a comparative study was performed with uncapped ZnO. The synthesized nanoparticles (NPs) were characterized using UV–visible (UV-vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDS) coupled with scanning electron microscopy (SEM). The absorption peak of ZnO NPs-Cap appeared at 366.5 nm, and the calculated band gap energy was 3.38 eV. Antibacterial activity was assessed against gram positive and negative foodborne pathogens. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of ZnO NPs and ZnO NPs-Cap against S. aureus , Bacillus cereus, E. coli and S. typhimurium bacterial strains revealed a clear superiority of ZnO NPs-Cap than uncoated ZnO. Time–kill assays performed at different concentrations and times has demonstrated a time-dependent reduction in bacterial viability for both formulations. The present study demonstrates that Arabic gum capping enhances the dispersion, stability, and antibacterial efficacy of ZnO NPs. The findings also provide useful insight into the biological activity and potential eco-toxicological implications of biopolymer-modified ZnO nanomaterials.
Using zinc nitrate hexahydrate as the precursor and Rhus vulgaris fruit extract as a natural reducing and capping agent, this study describes the environmentally friendly synthesis of zinc oxide nanoparticles (RV-ZnONPs). The presence of bioactive substances like phenols, flavonoids, tannins, alkaloids, saponins, terpenoids, steroids and glycosides responsible for the reduction of Zn 2+ ions nucleation and stabilization of ZnONPs. UV-Vis spectroscopy, X-ray diffraction (XRD), zeta potential analysis (XRD), transmission electron microscopy (TEM) and Fourier-transform infrared (FT-IR) spectroscopy were used to characterize the biosynthesized RV-ZnONPs. A distinctive absorption peak with an estimated band gap energy of 3.20 eV was found by UV–Vis analysis at approximately 371 nm. While TEM images revealed primarily irregular nanoparticles with an average size of ∼23. 5 nm, XRD confirmed the formation of highly crystalline ZnONPs with a hexagonal wurtzite structure and an average crystallite size of ∼22.7 nm. Excellent colloidal stability was demonstrated by the high negative zeta potential value (−35.1 mV) and FT-IR analysis verified the role of functional groups derived from plants in capping and stabilizing nanoparticles. The photocatalytic, antioxidant, and antibacterial properties of RV-ZnONPs were also assessed. Under UV irradiation, the RV-ZnONPs demonstrated effective photocatalytic degradation with maximum degradation rate of 65.4%. The degradation efficiency rose with nanoparticle concentration and reaction time. Antioxidant activity assessed by the DPPH assay demonstrated concentration-dependent free-radical scavenging with RV-ZnONPs showing a significantly lower IC 50 value (74.46 µg/mL) compared to the extract from crude fruit. Furthermore RV-ZnONPs demonstrated significant antibacterial activity against Staphylococcus aureus and Escherichia coli which was ascribed to membrane disruption, reactive oxygen species generation, and Zn 2+ ion release. This study highlights the promising potential of Rhus vulgaris fruit extract for environmental remediation antioxidant applications and antimicrobial treatments by demonstrating that it offers an efficient green pathway for the synthesis of stable and multifunctional ZnONPs.
Titanium dioxide (TiO2) exhibits dielectric properties that vary significantly with its physical morphology and thermal history. This work evaluates the dielectric responses of calcined nanopowder, electrospun nanofibers before and after heat treatment. Utilizing TEM, SEM, EDX, FTIR, and XRD allows for a detailed assessment of the morphological, and structure differences across the TiO2 samples. The uncalcined nanofibers exhibit an amorphous structure with significant polyvinylpyrrolidone (PVP) content. Calcination transforms these amorphous precursors into crystalline fibers with a mixed anatase and rutile phase. Dielectric measurements carried out over a frequency range of 1 Hz to 1 MHz demonstrated that the calcined nanofibers feature a dielectric constant (epsilon ') that is both reduced and mostly stable across the measured frequency range. At higher frequencies, the dielectric constant was found to approach free-space permittivity, with the material additionally exhibiting low dielectric loss (epsilon '', tan delta), and reduced low AC conductivity (sigma). The calcined TiO2 nanopowders, and uncalcined fibers by contrast revealed higher epsilon ' values and more substantial losses. The calcined TiO2 nanofibers thus exhibit superior insulating characteristics, demonstrating that nanostructuring combined with controlled thermal treatment can be effectively employed to alter dielectric performance. These findings carry meaningful implications for designing dielectric materials, particularly in enabling the optimization of low and stable dielectric permittivity alongside low-loss properties across a broad frequency range for electronic circuits applications.
Lignin, a renewable aromatic polymer found in lignocellulosic biomass, has several potential uses due to its antioxidant, antibacterial, and UV-absorbing qualities. The aim of this work was to extract soda lignin for sunscreen, antioxidant, and antibacterial properties from Oxytenanthera abyssinic (Ethiopian lowland bamboo) stems using an alkaline treatment. A 1, 4-dioxane-based nanoprecipitation technique was then used to create lignin nanoparticles produced from O. abyssinica (OA-LNPs) via a self-assembly process. The extraction procedure was optimized with temperature (23–120°C), time (1–24 hours) and NaOH concentration (5–15%). 1, 4-Dioxane-based nanoprecipitation was used to synthesis OA-LNPs which were then examined using SEM, EDX UV-Vis, FTIR and 1 HNMR for morphology size zeta potential and chemical structure. Antioxidant activity using DPPH assays, sun protection factor (SPF) measurements in commercial lotions and antibacterial testing against Gram-positive ( S. aureus and S . epidermidis ) and Gram-negative ( E. coli and K. pneumoniae ) strains were among the functional evaluations. Up to 294 mg/g of soda lignin were produced by the extraction. OA-LNPs had a spherical shape size ranging from 65 to 135 nm (mean 115 nm) a zeta potential of -30. 1 mV and no sulfur was found. They also retained phenolic and aromatic functionalities. The antioxidant activity of OA-LNPs was 11. 47 µg/mL which was higher than that of soda lignin (131.1 µg/mL). Due to UV absorption by phenolic groups SPF evaluations showed improvements in commercial lotions up to 114.8±1.3 when OA-LNPs were added. Antibacterial testing showed moderate efficacy against the tested strains with inhibition zones ranging from 12.43± 0.90 to 28.8± 1.11 mm. With better bioavailability and multifunctionality than Soda lignin (SL) these results highlight the environmentally friendly valorization of lignin from underutilized biomass and position OA-LNPs as promising candidates for sustainable applications in food packaging cosmetics and biomedicine.
In the past few decades, different efforts have been made toward chromium (VI) removal from wastewater. In this study, a Ti 3 C 2 T x /PANI composite was synthesized via in situ polymerization from (PANI) and Mxene (Ti 3 C 2 T x ). The composite was characterized using XRD, FTIR, SEM–EDS, XPS, and Raman spectroscopy. FTIR spectra revealed characteristic functional groups of both Ti 3 C 2 T x and PANI, with significant shifts and intensity changes upon Cr(VI) adsorption. EDS and XPS also showed the presence of Cr after adsorption. Raman spectroscopy further verified PANI polymerization and Cr(VI) adsorption. The adsorption performance for Cr(VI) is markedly influenced by the pH level of the solution, with optimal adsorption occurring at an acidic pH. The experimental findings showed good agreement with the Langmuir–Freundlich and Khan isotherm models, while the pseudo‐second‐order and MESO kinetic models best describe the adsorption process. The Ti 3 C 2 T x /PANI composite exhibits a high adsorption capacity of 342.5 mg g −1 and good stability, maintaining its adsorption efficiency over seven cycles. The adsorption mechanism involves electrostatic attraction, surface complexation, and physical adsorption. Notably, the developed Ti 3 C 2 T x /PANI composite exhibits a considerably higher Cr(VI) adsorption capacity than most previously reported MXene (Ti 3 C 2 T x ) and polyaniline (PANI)‐based adsorbents. This superior performance is attributed to the synergistic interaction between the conductive polymer PANI and the high surface reactivity of Ti 3 C 2 T x layers, which enhances active site accessibility and electron transfer during adsorption. The findings demonstrate the composite’s potential as an efficient and robust adsorbent for Cr(VI) adsorption.
In the past few decades, different efforts have been made toward chromium (VI) removal from wastewater. In this study, a Ti3C2Tx/PANI composite was synthesized via in situ polymerization from (PANI) and Mxene (Ti3C2Tx). The composite was characterized using XRD, FTIR, SEM-EDS, XPS, and Raman spectroscopy. FTIR spectra revealed characteristic functional groups of both Ti3C2Tx and PANI, with significant shifts and intensity changes upon Cr(VI) adsorption. EDS and XPS also showed the presence of Cr after adsorption. Raman spectroscopy further verified PANI polymerization and Cr(VI) adsorption. The adsorption performance for Cr(VI) is markedly influenced by the pH level of the solution, with optimal adsorption occurring at an acidic pH. The experimental findings showed good agreement with the Langmuir-Freundlich and Khan isotherm models, while the pseudo-second-order and MESO kinetic models best describe the adsorption process. The Ti3C2Tx/PANI composite exhibits a high adsorption capacity of 342.5 mg g-1 and good stability, maintaining its adsorption efficiency over seven cycles. The adsorption mechanism involves electrostatic attraction, surface complexation, and physical adsorption. Notably, the developed Ti3C2Tx/PANI composite exhibits a considerably higher Cr(VI) adsorption capacity than most previously reported MXene (Ti3C2Tx) and polyaniline (PANI)-based adsorbents. This superior performance is attributed to the synergistic interaction between the conductive polymer PANI and the high surface reactivity of Ti3C2Tx layers, which enhances active site accessibility and electron transfer during adsorption. The findings demonstrate the composite's potential as an efficient and robust adsorbent for Cr(VI) adsorption.
Separators are considered a key component in lithium-ion batteries (LIBs); however, currently commercial polyolefin separators fall short in meeting the demands of high-performance LIBs due to their low porosity and other issues. In this paper, a novel coaxial electrospray/electrospinning device consisting of an outer nozzle and an inner nozzle is presented, which can simultaneously prepare composites containing nanofibers and nanoparticles. With this device, a new type of LIB separator was successfully fabricated by simultaneously spinning fibers of PVDF and spraying particles of KH570/SiO2 in situ onto an ultra-high molecular weight polyethylene (UHMWPE) separator. The average diameter of the fibers prepared from the inner nozzle is 0.46 mu m, and the average diameter of the particles prepared from the outer nozzle is 70.81 nm. According to the analytical results, the porosity of the separator increases from 37.85% to 81.33%, and the longitudinal shrinkage decreases from 7.28% to 2.63% compared to the unmodified separator. Additionally, the initial charge/discharge specific capacity of the experimental separator increases from 107.8 to 152.0 mAhg-1. Excellent cycling stability of the separators is also exhibited after 50 charging and discharging cycles.
Titanium dioxide (TiO2) nanostructures have garnered significant attention for their exceptional photocatalytic and antibacterial properties in wastewater treatment applications. In this study, a simple, surfactant-free hydrothermal method was developed to synthesize flower-like and microrod-like TiO2 architectures directly on fluorine-doped tin oxide (FTO) substrates, aiming to enhance photocatalytic efficiency and antimicrobial performance. X-ray diffraction (XRD) confirmed the formation of the anatase phase with distinct TiO2 and SnO2 crystallographic planes, indicating high phase purity and crystallinity. Field emission scanning electron microscopy (FESEM) revealed uniformly distributed microrods (diameter 40-60 nm, length 1-2 mu m) forming three-dimensional flower-like assemblies, offering increased surface area and improved charge-transport pathways. Fourier transform infrared (FTIR) spectra identified Ti-O-Ti and Ti-OH functional groups, crucial for hydroxyl radical formation and interfacial charge transfer. The antibacterial activity, evaluated using the agar well diffusion method against Escherichia coli, Staphylococcus epidermidis, Proteus vulgaris, and methicillin-resistant Staphylococcus aureus (MRSA), exhibited inhibition zones ranging from 12 to 18.5 mm, with MRSA showing the highest susceptibility. The antibacterial mechanism is attributed to the combined effects of reactive oxygen species (ROS) generation and surface-induced membrane disruption. Photoluminescence (PL) analysis displayed a strong UV emission at 330 nm, confirming suppressed electron-hole recombination and enhanced charge separation efficiency. The hydrophilic nature of the TiO2 surface (contact angle approximate to 35 degrees) facilitates efficient pollutant adsorption and self-cleaning behavior. Overall, the study demonstrates that the hierarchical, morphology-controlled TiO2 microrod structures synthesized via this economical and eco-friendly hydrothermal route exhibit superior photocatalytic degradation (similar to 92% of methylene blue within 120 min) and potent antibacterial efficacy. Despite limited visible-light activity, the findings open avenues for band-gap engineering and hybridization with graphene, Ag, Cu, or ZnO to extend solar utilization. The developed TiO2 films hold strong potential as scalable, reusable, and sustainable photocatalysts for integrated wastewater purification and microbial disinfection technologies.
In recent years, several studies have been published on the synthesis of carbon nanomaterials—such as carbon nanospheres, carbon nanoframes, carbon nanorods, carbon nanoblocks, and carbon octadecahedrons—in concentrated salt systems. These novel carbon nanomaterials reported in the literature have attracted widespread interest. The fabrication approach described in these studies leverages the interaction between surfactants and concentrated salts to produce carbon nanomaterials. Unlike traditional synthetic routes, the assembly route of carbon nanomaterials in concentrated salt systems is characterized by the controllable construction of diverse carbon nanostructures. As an extension of conventional carbon nanomaterial manufacturing methods, this strategy holds significant development potential in the field of carbon nanomaterial production. Based on existing literature reports on concentrated salt systems, this review summarizes the theory and practice of carbon nanomaterial formation in such systems, along with the formation’s underlying mechanisms, advantages, and future development trends.
In the contemporary scientific landscape, the demand for sustainable and nontoxic synthesis of metallic nanoparticles has grown significantly, with biological or green synthesis approaches being preferred over conventional physical and chemical methods due to their eco-friendly, cost-effective, and nonhazardous nature. In this study, zinc oxide nanoparticles (ZnONPs) were synthesized via a simple and environmentally benign process using an aqueous leaf extract of Alternanthera philoxeroides as a natural bio-reducing and stabilizing agent, along with zinc acetate as the precursor salt. The formation of A. philoxeroides-mediated ZnONPs was confirmed by a characteristic surface plasmon resonance (SPR) band at 351 nm in the ultraviolet-visible (UV-Vis) spectrum and by energy dispersive X-ray (EDX) analysis showing elemental zinc and oxygen. Fourier transform infrared (FTIR) spectroscopy displayed peaks at 3,397, 2,930, 1,633, 1,408, 1,312, 1,072, 1,025, 821, and 619 cm-1, indicating phytochemicals responsible for reduction and capping. Zeta potential analysis yielded a value of -16.4 mV, reflecting moderate stability. X-ray diffraction (XRD) confirmed the crystalline wurtzite structure, further supported by the selected area electron diffraction (SAED) pattern. Field emission scanning electron microscopy (FESEM) revealed spherical nanoparticles with an average size of 15 nm, and high-resolution transmission electron microscopy (HRTEM) showed a size distribution between 3 and 35 nm with distinct lattice fringes. Antibacterial evaluation using the agar well diffusion method demonstrated the highest inhibition against Staphylococcus aureus, while antioxidant activity assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay exhibited a half-maximal inhibitory concentration (IC50) of 85.42 mu g per milliliter (mu g/mL), indicating strong radical neutralization capacity. These results highlight the potential of bio-synthesized ZnONPs for diverse biomedical, pharmaceutical, and industrial applications, warranting further investigation into their cytotoxicity, targeted drug delivery potential, and performance in real-world biomedical systems.
The present study investigates a chemical oxidation method for graphene oxide (GO) synthesis with a facile modification in the Tour method. The study aims to optimize the modified synthesis process with a reduced amount of acid intercalants, shortening the production time and improving the quality of GO for large-scale production of graphene derivatives. The present study results show a reduction in acid reagent usage and processing time by approximately 70% and 90%, respectively, compared to the Tour method, and the final process yield exhibited a significant improvement of approximately 114% (ranging from 77% to 188%) for the modified method as compared to the Tour method. Finally, synthesized GO samples are characterized using XRD, FTIR, and UV-Vis spectroscopy. The GO crystalline structure analysis revealed an interlayer spacing thickness of up to 0.82 nm, which is attributed to higher oxygenated functional groups between layers. Additionally, the synthesized GO exhibited an estimated crystallite size of similar to 8 nm with approximate number of layers of 10 +/- 1, which is significantly low compared to precursor graphite having 55 +/- 3 nm crystallite size and an estimated number of layers around 165 +/- 3. The study also highlighted the impact of oxidation parameters, namely, processing temperature, time, and graphite inputs, on produced GO output product yield, oxidation level, crystallite size, and an average number of layers, where it is confirmed that the processing temperature has obvious effects as compared to other parameters.
Unpleasant breathing can occur due to bad odors from wearing a medical mask. Electrospinning has been used to incorporate Eucalyptus extract into polyvinyl alcohol (PVA) to overcome the problem of medical masks and as an alternative, as part of an antiflu breathing face mask. This research aims to extend the shelf life of the pleasant odor by encapsulating Eucalyptus essential oil (EO) in nanofibers by coaxial electrospinning. Initially, nanofibers were produced using a blend structure of Eucalyptus aqueous extract (EA) and PVA, along with a core-shell structure of EO and PVA by electrospinning. The morphology of the nanofibers was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), showing average diameters of 270 +/- 47 nm for the blend nanofibers and 343 +/- 126 nm for the core-shell nanofibers. TEM confirmed a core-shell structure presumably caused by the nonmiscibility of EO and PVA, as well as the high viscosity of the PVA solution. The loading capacity (LC) and encapsulation efficiency (EE) were calculated for the core-shell nanofibers to be 16.43 +/- 3.29 and 55.20 +/- 2.31, respectively. The presence of EO in the nanofibers was shown through FT-IR spectroscopy. At the same time, variations in peak intensity allowed tracing the displacement of EO and the aging of the nanofibers. A released study showed that after 7 hours of release in a conditioning room with 30 degrees C and 70% humidity, the percentages of remaining Eucalyptol in the nanofibers were 68.36% and 83.63% for the blend and the core-shell structure, respectively. The size of the pores in these nanofibers on a layer ranged from 50 nm to 200 nm.
Microring resonators (MRRs) are the important devices for the development of silicon-based optoelectronic integrated chips. Their composition of optical modules, such as optical modulators, switches, and optical logic gates, have greatly contributed to the development of the silicon-based optoelectronics. However, due to the large radius of MRRs and the weak optical interaction of the silicon material itself, how to further improve integration and reduce power consumption is a great challenge. Combining graphene, which has many unique properties, with silicon-based MRRs provides a good solution. Therefore, based on the interaction principle of graphene and light and the transmission principle of all-pass silicon-based MRRs, this article proposes for the first time a one-bit optical numerical comparator based on MRRs, whose structure consists of four silicon-based MRRs with a radius of 1.8 mu m covering a single layer of graphene. The logic function of the one-bit optical numerical comparator is realized by adjusting the different chemical potentials of the graphene. Simulation results shows that, with a TE mode light source at 1555.21 nm, the proposed optical numerical comparator obtains a minimum extinction ratio of 19.7 dB and a contrast ratio of 19.7 dB. Compared with the previously reported optical numerical comparators based on silicon-based MRRs or ring resonators, the proposed optical numerical comparator has many advantages, such as high extinction ratio, high contrast ratio, compact structure, and high stability. It is beneficial to the development of silicon-based photonic integrated devices.
The raising demand for efficient and stable energy sources for indoor applications demands the development of high-performance photovoltaic (PV) materials. This study examines the potential of the all-inorganic CsPbIBr2 perovskite material as a promising photoactive absorber for perovskite solar cells (PSCs) designed for indoor applications. CsPbIBr2 exhibits a favorable balance between optical bandgap and phase stability among other all-inorganic constituents. Additionally, CsPbIBr2 possesses a wide direct bandgap of 2.05 eV, elevated absorption coefficient, and high carrier mobilities, compelling it well-suited for harnessing photon energy from indoor lighting sources. Our research commenced with an experimental CsPbIBr2-based solar cell demonstrating a power conversion efficiency (PCE) of 11.01% under 1-sun illumination, with an initial device structure of ITO/ZnO/CsPbIBr2/Spiro-OMeTAD/Au. We initiated our investigation using SCAPS-1D to validate the simulation approach, replicating experimental current-voltage characteristics and identifying a critical limitation in the single electron transport layer (ETL) design: suboptimal band alignment. This insight drives a comprehensive optimization strategy relating a double ETL configuration, exploring optimal transport layer materials, followed by analyzing absorber layer thickness and defect concentrations. Through this methodical approach, we progressively enhanced the cell's performance, achieving a remarkable 21.85% a PCE under 200 lux, and a 2900 K indoor LED illumination. The simulation results provided in this study reveal the prospective of CsPbIBr2 PSCs as a promising candidate for indoor PV applications.
Electrospinning is a promising technique for enabling the manipulation of the structural properties of nano- or microfibrous mats by altering electrospinning parameters. In this paper, it is aimed to examine the morphological variations of electrospun mats fabricated by combinations of different collector types and feeding units. In horizontal electrospinning setup, PVA polymer solutions are transformed to polymer jets by the help of needle-based feedings with single- and multinozzles. Electrospun fibers are deposited on four different collector types with identical collector-nozzle distance, feeding rate, applied voltage, and environmental conditions. It is concluded that the coarsest nanofibers are fabricated by multineedle/disc collector combination and the disc collector causes flat nanofiber handling with multineedle feeding but not with single needle feeding. On plate collector, thicker electrospun mats are obtained whichever feeding type is used. Average pore sizes on mats are found higher in multineedle feeding, especially with deposition between rods of birdcage collector. Changing the feeding type from multineedle to single needle causes to manufacture of electrospun mats with a narrower surface area and an increase is observed in packing density, basis weight and % porosity but a decrease in pore size and mat thickness with this manipulation. Nanosized but flattened electrospun fibers are handled by multineedle/disc collector and two distinct compositions are incorporated by deposition of nanofibers on birdcage collector.
Gold nanoparticles (AuNPs) have been targeted as novel contrast agent for computerized tomography (CT). However, AuNPs suffer from low-contrast factor in the X-ray regime. Functionalization of AuNPs with folic acid or sugar-based molecules to induce selective uptake have displayed contrast enhancement with improved image brightness and CT signal intensity. However, it was not clear what the basic mechanism for the contrast enhancement was and whether it was related to the uptake enhancement or to a fundamental electromagnetic interaction effect. In this work, we conducted near-field Mie as well as finite-difference time-domain (FDTD) field distribution of the scattering to discern the effect of a thin dielectric coating layer on the contrast functionality of AuNPs. Our results show that upon the incorporation of the dielectric shell (thin film or nanoparticle layer), the cross section of X-ray scattering is enhanced, with silicon being more effective than silica coating, with multiresonance spectral response. The directionality and range and strength of the near field increase for silicon coating (high electron density or high k material in the visible). The effect may be understood in terms of several features. Even though the refractive indices of all materials in the X-ray regime are similar to 1.0, the wavelength dependence of their approach may exhibit sizeable differences The enhancement is understood in terms of high densities of polarization charge especially in silicon, which allows multipole resonances. The multiplicity of resonances leads to enhanced scattering and directionality (angular distribution) with reduced range. A silicon-coating layer on AuNP may not only alleviate the contrast limitation, but it may afford synergistic integration of luminescence and scattering functionalities in the visible and X-ray regimes.
Graphene is a single layer of carbon atoms arranged in a hexagonal lattice structure, forming a two‐dimensional (2D) material with exceptional mechanical, electrical, and thermal properties. Graphene has emerged as one of the most promising nanomaterials because of its unique combination of exceptional properties: the thinnest and the strongest materials, an excellent conductor of electricity, and optically transparent as well. This article provides an overview of graphene materials regarding its basic structure, preparation methods, and unique properties. The four commonly used methods for preparing graphene are compared, and the advantages and disadvantages of each are expounded and briefly summarized. And the basic physical properties of graphene materials obtained by each method, namely, in mechanics, electricity, thermal, and optics, were elaborated in detail, and the related applications of graphene prospects are further discussed.
