Ultraviolet-visible Absorption Spectra Research Articles

Solvent Effect for the Structural Control of Molecular Architectures Consisting of Trinuclear Ruthenium Clusters and Ligands at the HOPG Surface.

The molecular architecture of a triruthenium complex and 1,4-di(4-pyridyl)benzene on highly oriented pyrolytic graphite was investigated by drop-casting mixed tetrahydrofuran and methanol solutions. Atomic force microscopy revealed the formation of one-dimensional molecular wires on highly oriented pyrolytic graphite after heating the mixed tetrahydrofuran solution, whereas large ring structures were formed in the methanolic solution. It was found that the molecular architectures composed of triruthenium complexes and 1,4-di(4-pyridyl)benzene strongly depend not only on the temperature of the solution but also on the organic solvents. The formation of the molecular architecture was supported by the ultraviolet-visible absorption spectra of the mixed solution and the electrochemical responses of the deposited film.

Incorporating ReS2 Nanosheet into ZnIn2S4 Nanoflower as Synergistic Z-Scheme Photocatalyst for Highly Effective and Stable Visible-Light-Driven Photocatalytic Hydrogen Evolution and Degradation.

Inspired by natural photosynthesis, the visible-light-driven Z-scheme system is very effective and promising for boosting photocatalytic hydrogen production and pollutant degradation. Here, a synergistic Z-scheme photocatalyst is constructed by coupling ReS2 nanosheet and ZnIn2S4 nanoflower and the experimental evidence for this direct Z-scheme heterostructure is provided by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance. Consequently, such a unique nanostructure makes this Z-scheme heterostructure exhibit 23.7 times higher photocatalytic hydrogen production than that of ZnIn2S4 nanoflower. Moreover, the ZnIn2S4/ReS2 photocatalyst is also very stable for photocatalytic hydrogen evolution, almost without activity decay even storing for two weeks. Besides, this Z-scheme heterostructure also exhibits superior photocatalytic degradation rates of methylene blue (1.7 × 10-2 min-1) and mitoxantrone (4.2 × 10-3 min-1) than that of ZnIn2S4 photocatalyst. The ultraviolet-visible absorption spectra, transient photocurrent spectra, open-circuit potential measurement, and electrochemical impedance spectroscopy reveal that the superior photocatalytic performance of ZnIn2S4/ReS2 heterostructure is mostly attributed to its broad and strong visible-light absorption, effective separation of charge carrier, and improved redox ability. This work provides a promising nanostructure design of a visible-light-driven Z-scheme heterostructure to simultaneously promote photocatalytic reduction and oxidation activity.

Visual fluorescence detection kit for Cr (VI) based on biological matrix-derived carbon dots and assisted for AA

In this study, a novel green donkey-hide gelatin carbon dots (D-CDs) were synthesized by hydrothermal method and a portable detector based on Cr (VI) fluorescent test strips was prepared. The synthesized D-CDs exhibited bright blue fluorescence which was used for the detection of Cr (VI) and ascorbic acid (AA). It still exhibited high sensitivity and acceptable selectivity under high concentration of other interfering ions. The morphology and elemental characteristics of D-CDs were characterized. Meanwhile, the “on-off” quenching mechanism of Cr (VI) on D-CDs was studied by ultraviolet-visible absorption spectra, fourier transform infrared spectroscopy and fluorescence spectra. Then a D-CDs/Cr (VI) fluorescence sensing platform was constructed, and reopened by AA, thus eliciting an “on-off-on” fluorescence reaction. Under the optimal conditions, the fluorescence intensity was quenched significantly with the increase of Cr (VI) concentration and restored by the good reducibility of ascorbic acid (AA), with the linear ranges of 0.5–400 μM and 1–400 μM, respectively. The detection limits of Cr (VI) and AA can be as low as 0.08 μM and 0.14 μM. Consequently, it has low toxicity and can be successfully used as a fluorescent probe to determine Cr (VI) in river water and AA in fruits with satisfactory results. It not only lays a foundation for the development of fluorescence sensor in the field of environment and food, but also provides a good application prospect for its detection of heavy metal ions and AA.

Bio-coloration and Antibacterial Function of Wool grafted with pomegranate peel polyphenols catalyzed by laccase

With the deterioration of environmental problems and world energy consumption, the improvement of textile dyeing has been paid more and more attention by researchers. The application of natural dyes in the dyeing of wool fabrics had become a research hotspot. However, the main drawback of the application of natural dyes lies in the poor color stability on wool fabrics. Therefore, research on environmentally and economically friendly dyeing processes has gained crucial importance. In this paper, the effect of pomegranate pigment on the functional dyeing of wool fabric under the catalysis of laccase was discussed. The dyeing effect of different methods on wool fabric was compared and the laccase catalytic dyeing process was optimized. Firstly, the properties of pomegranate peel pigment were analyzed by Ultraviolet-visible absorption spectrum (UV-Vis) and Fourier infrared spectroscopy (FTIR). Then the surface morphology and properties of wool fabric were observed by scanning electron microscope (SEM), microscope and FTIR. Lastly the function and stability of dyed wool fabric were tested by color characteristic value, UV resistance, antibacterial property, color fastness and tensile strength. The results showed that better dyeing effect of wool fabric were obtained by dyeing firstly with pomegranate peel and then catalysis with laccase. The optimum process of laccase catalysis was as follows: catalysis time 8h, laccase dosage 3.3U, temperature 50℃, pH 5. The results of SEM, FTIR and microscope tests showed that the phenolic compounds in the pigment of pomegranate peel was catalyzed by laccase to form the deepened coloration polymers and the phenolic polymers were finally combined with the wool fabric. Laccase-catalyzed dyed wool fabric showed good performance stability, such as color fastness to rubbing and soap-washing, strong antibacterial property, great enhancement of UV resistance and excellent tensile strength. The application of laccase in the natural dyeing process of textiles can provide a better way to improve the dyeing properties.

Individual quantification of ozone and reactive nitrogen species in mixtures by broadband UV–visible absorption spectra deconvolution

Ozone (O3), nitrogen oxides (NO x ), and reactive nitrogen species (RNS) play critical roles in atmospheric-pressure plasma applications. Although it is crucial to individually quantify these species to understand atmospheric-pressure plasmas and increase their effectiveness, the lack of reliable and cost-effective diagnostics makes this difficult for many researchers. To address this problem, we introduce a new deconvolution method of broadband ultraviolet–visible absorption spectra for the simultaneous measurement of eight species—O3, NO, NO2, NO3, N2O4, N2O5, HONO, and HNO3. Processing of broadband spectra enables deconvolution of similar cross-section profiles and measurement of high densities exceeding the instrumental limit. Novel correction processes enable accurate analysis despite incomplete cross-section data and utilize a priori chemical knowledge to ensure theoretically reasonable results. Two case studies test the efficacy of the method: NO2 and N2O4 equilibria, and reactive species produced by a surface dielectric barrier discharge. With an analysis time of 15–20 ms per spectrum, the measured densities agree well with other theoretical and experimental results, and detection limits on the order of ppmv were achieved with a short path length of 15 cm. This spectral analysis method will facilitate the real-time monitoring of O3, NO x , and RNS in many scientific research and industrial applications of atmospheric pressure plasmas.

A novel algorithm to extrapolate ultraviolet absorption of chromophoric dissolved organic matter from remote sensing ocean color

Accurate estimation of the absorption of chromophoric dissolved organic matter (CDOM) in ultraviolet (UV) wavelength range is crucial for understanding photochemical and biochemical processes in the global ocean. Here, we propose a novel UV absorption extrapolation (UVAE) algorithm. It extrapolates the absorption coefficients (ag(λ) where λ is the wavelength in nm) of CDOM in the UV wavelength range from ocean color data in the visible wavelength range observed by satellite remote sensing. The extrapolation is based on the assumption that three characteristic Gaussian bands describe the CDOM UV–visible absorption spectra (275–443 nm). The UVAE algorithm retrieves the ag(275), ag(295), ag(330), and ag(380) using the characteristics of the spectral slope (S) of the absorbance spectra of CDOM at specific wavelength intervals, namely 275–295, 295–330, 330–380, and 380–443 nm. With the UVAE algorithm, the spatial variability of CDOM spectral features can be captured on a global scale using data from the Moderate-resolution Imaging Spectroradiometer (MODIS) Aqua mission. The retrieved ag(275), ag(295), ag(330), and ag(380) values match well with in-situ observed values, with mean absolute percent differences (MAPDs) of 19.2 %, 26.1 %, 36.9 %, and 46.6 %, respectively. The performance of the UVAE algorithm demonstrates a significant improvement compared to that of existing algorithms, especially for ag(λ) at lower wavelengths.

Engineered K-doped ZnO/borneol based hydrogel composite material for led-based photocatalytic degradation of methylene blue and evaluation of antimicrobial activity

The significant improvement of decolorization and disinfection technologies has been a hotspot in wastewater reutilization. In this study, we realized a novel construction of K-doped nano-ZnO and borneol based hydrogel composite material (K-ZnO/B-hydrogel) by low-temperature in situ sol–gel growth. The techniques such as fourier transform infrared (FTIR), X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS) were applied to recognize the synthesized hydrogel. The results revealed that K-doped ZnO nanoparticles had been uniformly decorated onto the B-hydrogel. Ultraviolet-visible (UV–vis) absorption spectra showed that impurity doping of potassium element into ZnO could reduce the band gap, improving the visible light absorption efficiency. Under LED illumination, the photodegrading rate of K-ZnO/B-hydrogel was approximately 2.3 times greater than that of K-ZnO/B-hydrogel on methylene blue (MB) removal. Remarkably, aside from CO2 and H2O, no by-products were generated during the photodegradation process. In addition, the antimicrobial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of K-ZnO/B-hydrogel achieved up to 99.9%, which were at least 1.5 times higher than K-ZnO/B-hydrogel. This composite will push ahead with a closed-loop wastewater treatment system for dye and pathogenic microorganism disposal, which combines the excellent adsorption ability of hydrogel and the outstanding photocatalytic ability of ZnO nanoparticles with easy sample handling and separation, and help to eliminate secondary pollution.

Preparation and characterization of chiral carbon dots with red emission

Methods for the synthesis of chiral carbon dots (CDs) possessing bright long-wavelength emission are highly desirable. Here, we develop red-emissive chiral CDs from hydrothermal treatment of L-/D-lysine and o-phenylenediamine (OPD). Pure chiral CDs are obtained by filtration and dialysis. Ultraviolet-visible (UV–vis) absorption spectra, photoluminescence (PL) spectra, PL quantum yield (QY), and PL decay of the chiral CDs are thoroughly studied. The chiral CDs exhibit bright red fluorescence with PL QY in the range of 26.6%–42.2% in different solvents. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) indicate that the chiral CDs have a mean particle size of 2.7 nm, and consist of graphite-like carbons and abundant functional groups at their surfaces. Circular dichroism spectroscopy shows new Cotton bands at about 300 and 610 nm for chiral CDs differed from those of L-/D-lysine, revealing the generation of optical chirality for CDs. Then transparent optical resins made of CDs/epoxy resin composites are prepared, possessing red fluorescence and circular dichroism, broadening potential applications of solid materials with chiroptical properties. Finally, we discuss the possible origins of chirality and fluorescence of the CDs. The exploitation of highly red-emissive chiral CDs may promote the development and application of chiral CDs.

Rapid and complete prediction of alizarin in solution by combining experimental data with computational methods

In the field of cultural heritage, understanding the nature of pigments and dyes is of great importance for conservation issues. Among the many natural dyes used in paintings or textiles, madder was one of the most important sources of red color at the time and was present in a wide variety of objects. However, due to extraction challenges, impurities, and high costs, a lot of information are not easily available. In this publication we designed a computational protocol able to reproduce the spectroscopic properties of two dyes, alizarin and alizarin red S. This framework allows us to compute both Ultraviolet–Visible absorption spectra and Nuclear Magnetic Resonance (NMR) with good accuracy as well as reproduce with precision the CIELAB color. We have also explored different types of interactions that impact these properties, notably the solvation effect. We found that microsolvation is sufficient to reproduce the experimental measurements made in water. The high accuracy of the computation method makes this technique particularly promising for a non-destructive study of dyes on works of art and the preservation of cultural heritage.

A Highly Sensitive and Selective Fluorescent Sensor for Folic Acid Detection Based on D-penicillamine Stabilized Ag/Cu Alloy Nanoclusters.

In this work, a highly sensitive and selective method for detecting folic acid (FA) was developed using D-penicillamine (DPA) stabilized Ag/Cu alloy nanoclusters (DPA@Ag/Cu NCs). The yellow emission of DPA@Ag/Cu NCs was found to be quenched upon the addition of FA to the system. The fluorescence intensity quenching value demonstrated a linear relationship with FA concentrations ranging from 0.01 to 1200 μM, with a limit of detection (LOD) of 5.3 nM. Furthermore, the detection mechanism was investigated through various characterization analyses, including high resolution transmission electron microscopy, fluorescence spectra, ultraviolet-visible absorption spectra, and fluorescence lifetime. The results indicated that the fluorescence quenching induced by FA was a result of electron transfer from FA to the ligands of DPA@Ag/Cu NCs. The selectivity of the FA sensor was also evaluated, showing that common amino acids and inorganic ions had minimal impact on the detection of FA. Moreover, the standard addition method was successfully applied to detect FA in human serum, chewable tablets and FA tablets with promising results. The use of DPA@Ag/Cu NCs demonstrates significant potential for detecting FA in complex biological samples.

Force/Acid-Activated and Radical-Regulated photochromic luminescence in a binuclear Zero-Dimensional complex for multi-level anti-counterfeiting

Traditional static optical anti-counterfeiting technology can only output a single emission signal, which is easy to replicate and difficult to meet the needs in current high-tech fields. Multi-level stimuli-responsive luminescent materials with internal logical relationship can improve the degree of anti-counterfeiting and resist against the flood of counterfeiting. In this work, we propose to use force and acid dual stimuli to restrict the dissipation path of photogenerated free radicals, which further lead to the radical-actuated photochromic luminescence (PCL) performance. Based on this strategy, a zero-dimensional (0D) dinuclear zinc complex Zn2(9-AC)4(IM)2 (1) with blue luminescent properties (450 nm) was designed and synthesized. The interaction between 9-AC and IM (as 9-AC/IM exciplex) can be cut off by force-induced rearrangement of structural units in the spatial dimensions or acid-induced protonation of 9-AC, achieving the luminescent transformation from 9-AC/IM exciplex (447 nm) to 9-AC/9-AC excimer (480 nm) or 9-HAC (485 nm). At the same time, the PCL performance was activated and the emission intensity quenching rate increased from 4.77 % to 93.86 % or 44.93 % under UV light irradiation, respectively. The solid-state ultraviolet–visible absorption spectra, electron paramagnetic resonance spectra and theoretical calculation confirmed that the activation of PCL performance is due to the fact that the 9-AC• radicals are more difficult to dissipate upon force- or acid-induced stimuli. Combining mechanochromic luminescence (MCL) and PCL, a dynamic anti-counterfeiting quick response (QR) code with multi-level and fast-responsive logic sequence have been designed, which are promising for the application in time-resolved information encryption. This work provides an effective strategy to construct multi-level stimuli-responsive luminescence as novel anti-counterfeiting materials by changing the photogenerated free radical dissipation pathway to activate PCL properties.

Electronic and Nonlinear Optical Properties of B(III)-Submonoazaporphyrin-π-Diimide Compounds: A Density Functional Theory Study.

Three hypothetical complexes were designed using diimides (PMDI, NTCDI, and PTCDI) as the acceptor unit and B(III)-submonoazaporphyrin (1) as the donor unit. These complexes have smaller HOMO-LUMO energy gaps (3.39-3.96 eV) than pristine 1 (6.61 eV). Further, the energy gap can be tuned by changing the number of benzene rings of these diimides. Remarkably, these proposed complexes possess considerable first hyperpolarizabilities (β0) (4865-6921 a.u.), and the regularity of the β0 values remained the same in the gas phase and toluene solvent conditions. There is an inverse relationship between the energy gap and the polarizability/first hyperpolarizability. In addition, absorption spectra, frontier molecular orbitals, and hole electron distributions were obtained using time-dependent density functional theory calculations to emphasize the relationship between structure and properties. Ultraviolet-Visible absorption spectra reveals that all complexes show satisfying IR working regions. Further analysis of the first hyperpolarizability density reveals the nature of the excellent NLO properties of the studied systems. This study can provide valuable insights for the development of potential high-performance NLO molecules.

Introducing hafnium to atomically small- and medium-sized tin clusters (HfSnn0/-/2- (n = 4–17)): A computational investigation of geometrical and growth behavior, spectral properties, electronic configuration and thermochemistry

The global and local minimum configurations of single Hf atom doped Sn clusters are conducted via density function theory (DFT) combined with artificial bee colony algorithm (ABCluster). Furthermore, DFT method is also used to systematically investigate on their structural growth evolution, spectral and electronic information, thermochemical properties following the size of tin clusters doped Hf atom. Structurally, the ground-state geometries of neutral, anion and di-anion are discovered that, from n = 4, the number of Sn atoms in cluster, HfSnn0/-/2- adsorb additional Sn atom on the prior architecture one by one until forming n = 17 for HfSnn-10/-, as well as forming n = 16 for HfSnn-12-. And for the HfSn110/- and HfSn102- as beginning the species veritably develop sealed architectures. The strongest vibrational modes of sealed nanoclusters are stretching modes of Hf atom with infrared actives and breathing modes of the Sn cage framework with Raman actives, respectively. The natural population analysis (NPA) elucidates the stronger relationship between the Hf atoms and the tin frameworks in sealed clusters than that in unsealed clusters. The results of thermochemical properties, molecular orbital shell (MOs), adaptive natural density partitioning (AdNDP) and ultraviolet visible absorption spectrum (UV–Vis) indicate that, the HfSn16 with high symmetry of Td exhibits thermochemical stability and optoelectronic properties, which is utilized potentially as zero-dimensional unit of self-assembling fluorescent nanomaterials.

Enhanced visible light photocatalytic degradation of styrene by g-C3N4 quantum dots/P25 nanocomposites

The enhancement of the visible light response of P25 is of significant importance for the photocatalytic degradation of volatile organic compounds (VOCs). Graphitic carbon nitride quantum dots (CNQD) are nano-sized counterparts of g-C3N4, exhibiting excellent optical properties. Using a simplified hydrothermal one-step approach, CNQD-loaded P25 (CNQD/P25) was obtained in this work. Under visible light, CNQD/P25 achieved styrene degradation rate of 95 % within 240 minutes, surpassing the 60 % degradation rate of pure P25 under identical conditions. This indicates that the presence of CNQDs greatly enhances the photocatalytic performance of P25 in the visible light region. Further investigations revealed that CNQD/P25 exhibited noticeable enhancement in the ultraviolet-visible absorption spectrum, demonstrating increased visible light absorption. CNQD/P25 demonstrated higher photocurrent response, lower photoresistance, and weaker fluorescence response compared to P25 at similar conditions. Therefore, the presence of CNQDs can enhance visible light absorption of P25, increases the number of photo-generated electrons, optimizes charge separation efficiency, and simultaneously reduces the recombination rate of electrons and holes.

Non-enzymatic Detection of Uric Acid in Serum and Urine by Fluorescent and Visual Dual-Mode Sensor Based on 3-aminophenylboric Acid Functionalized Carbon Dots.

Herein, we developed a sophisticated dual-mode sensor that utilized 3-aminophenylboric acid functionalized carbon dots (APBA-CDs) to accurately detect uric acid (UA). Our innovative process involved synthesizing APBA-CDs that emitted at 369nm using a one-step hydrothermal method with 3-aminophenylboric acid and L-glutamine as precursors, ethanol and deionized water as solvents. Once UA was introduced to the APBA-CDs, the fluorescence of the system became visibly quenched. The results of Zeta potential, Fourier transformed infrared (FTIR) spectra, fluorescence lifetime, and other characteristics were analyzed to determine that the reaction mechanism was static quenching. This meant that after UA was mixed with APBA-CDs, it combined with the boric acid function on the surface to form complexes, resulting in a decrease in fluorescence intensity and a blue shift in the absorption peak at about 295nm in the Ultraviolet-visible (UV-vis) absorption spectra. We were pleased to report that we have successfully used the dual-reading platform to accurately detect UA in serum and human urine. It provided a superior quantitative and visual analysis of UA without the involvement of enzymes. We firmly believe that our innovative dual-mode sensor has immense potential in the fields of biosensing and health monitoring.

Stable MOF-In2S3/ZnFe layered dioxide heterostructures for improving photocatalytic degradation: Degradation pathways, kinetics, and charge migration

In this paper, MOF-In2S3 were modified by ZnFe-layered dioxides (LDO) with strong stability to obtain high catalytic performance composite. The successful preparation of ZnFe-LDO/MOF-In2S3 not only retains the advantages of large specific surface area of MOF-In2S3 and the stability of ZnFe-LDO, but also improves its charge separation efficiency and the light absorption region through the construction of heterojunctions. As expected, the experimental results show that ZnFe-LDO/MOF-In2S3 has superior photo-electrocatalytic properties. The photocatalytic degradation efficiency of ZnFe-LDO/MOF-In2S3 for TCH and OTC reach 92.92% and 80%, respectively, within 25 min. And the corresponding degradation rate constants are up to 1.41332 and 0.45451 L·mg−1·min−1, respectively, which are accord with the pseudo-second-order kinetic constants. The intermediate of 0.6LDO/M-I degradation of TCH was proposed by liquid mass spectrometry (LC-MS). Notably, a special transient surface photovoltage (TPV) technique was used for discussing the charge transfer kinetics and the lifetime of photogenerated carriers. Based on Mott-Schottky (M-S), Ultraviolet-visible absorption spectrum (UV), X-ray Photoelectron Spectroscopy (XPS) results, electron paramagnetic resonance (EPR) results, and active substance capture experiment results, a Z-scheme heterojunction system was proposed. The above research work proposed a new approach to enhance the stability of catalytic materials by using the aid of layered dioxides. In addition, the characterization of surface photovoltage provides a new way to study charge transfer.

Chicken Meat and Beef Identification in UV-Vis Absorbance Spectrum by Applying Savitzky-Golay Method

Spectroscopy is one of the techniques suitable for validation of the quality, safety, and hygiene of meat due to some advantages, such as rapid detection capability, ease of use, and non-destructive measurement. Utilizing an ultraviolet-visible (UV-Vis) spectrometer, with a wavelength range of 200 nm to 1100 nm, this paper proposes a method for processing spectrum data profiling of chicken meat and beef. A 360-time reflectance spectrum was acquired from each chicken breast and beef loin at the optimum integration time of 60 ms. Subsequently, the spectrum was converted into an absorbance spectrum, and the apparent noise was excluded by applying the Savitzky-Golay (SG) method. The result shows the difference in spectrum between chicken meat and beef in which the chicken meat has two peaks at the wavelength of 284.79 nm and 422.69 nm, meanwhile, the beef shows three peaks at wavelengths of 282.46 nm, 419.03 nm, and 577.97 nm. It was found that the SG method enhanced the absorbance spectrum, showing the difference in spectrum behaviors in the wavelength range of 450∼600 nm. Consequently, to shorten the computational time, building a light, cheap, and compact prototype reading device within this specific wavelength range will be the next target in the near future.

Effect of SbCl5 Doping on the Electrical and Optical Properties of Polyamide Nylon 6 Films

Polyamide nylon 6 (PA6) films were fabricated using a solution casting method and the films were doped with SbCl5. The electrical conductivity increased with the dopant concentration due to the increase in formation of radical cations through the charge transfer from the isolated double bonds (–C=O–) in the polymer chains. The DC electrical conductivity reached a maximum of 0.01 S/cm for 0.5 ml SbCl5 doped films. Structural and optical characteristics of the pure and doped films were examined using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Diffraction (XRD), and Ultraviolet-Visible (UV-Vis) absorption spectra. The doped films exhibited discernible shifts in the optical band gap energy. The direct band gap values of PA6 films were reduced from 4.5 eV to 1.7 eV when doped with 0.5 ml SbCl5. ATR-FTIR spectral studies, and optical studies indicated the formation of charge transfer complexes with the amide group of nylon 6, resulting in the electrical conduction. The XRD studies disclosed the reduction in the crystallinity of the doped films. The thermal stability was studied using differential scanning calorimetry (DSC) and thermogravimetric analysis-derivative thermogravimetric (TGA-DTG) studies. The melting and crystallization temperatures were recorded from the DSC thermograms. The peak melting temperature of PA6 reduced from 217 °C to 186 °C for 0.5 ml SbCl5 doped films. The peak of crystallization observed at 182 °C for pure films was absent, for the doped samples. The peak degradation temperatures for both pure and doped samples were above 400 °C, revealing the thermal stability of both materials. The thermally stable, semi-crystalline and semiconducting polymer films, we suggest, would be suitable for optoelectronic applications.

Transient chemical and structural changes in graphene oxide during ripening

Graphene oxide (GO)—the oxidized form of graphene—is actively studied in various fields, such as energy, electronic devices, separation of water, materials engineering, and medical technologies, owing to its fascinating physicochemical properties. One major drawback of GO is its instability, which leads to the difficulties in product management. A physicochemical understanding of the ever-changing nature of GO can remove the barrier for its growing applications. Here, we evidencde the presence of intrinsic, metastable and transient GO states upon ripening. The three GO states are identified using a π−π*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi -{\\pi }^{*}$$\\end{document} transition peak of ultraviolet–visible absorption spectra and exhibit inherent magnetic and electrical properties. The presence of three states of GO is supported by the compositional changes of oxygen functional groups detected via X-ray photoelectron spectroscopy and structural information from X-ray diffraction analysis and transmission electron microscopy. Although intrinsic GO having a π−π*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi -{\\pi }^{*}$$\\end{document} transition at 230.5 ± 0.5 nm is stable only for 5 days at 298 K, the intrinsic state can be stabilized by either storing GO dispersions below 255 K or by adding ammonium peroxydisulfate.

Influence of Dilution Upon the Ultraviolet-Visible Peak Absorbance and Optical Bandgap Estimation of Tin (IV) Oxide and Tin(IV) Oxde-Molybdenum(IV) Sulfide Solutions

The study investigated the constraints associated with the dilution technique in determining the optical bandgap of nanoparticle dispersion and modified nanocomposites, utilizing ultraviolet-visible absorbance spectra and Tauc plot analysis. A case study involving SnO2 dispersion and SnO2-MoS2 nanocomposite solutions, prepared through the direct solution mixing method, was conducted to assess the implications of dilution upon the absorbance spectra and bandgap estimation. The results emphasize the considerable impact of the dilution technique on the measured optical bandgap, demonstrating that higher dilution factors lead to shift in bandgap values. Furthermore, the study highlights that dilution can induce variations in the average nanoparticle sizes due to agglomeration, thereby influencing bandgap estimation. In the context of nanocomposites, the interaction between SnO2 nanoparticles and exfoliated MoS2 nanosheets diminishes with increasing dilution, leading to the estimated optical bandgap being primarily attributable to SnO2 nanoparticles alone. These observations underscore the necessity for caution when employing the dilution technique for bandgap estimation in nanoparticles dispersion and nanocomposites, offering valuable insights for researchers and practitioners in the field.