UV Vis Absorption Research Articles

Investigation on special reactivity of sulfite as an electron acceptor for the attenuated Fenton reaction and the abatement mechanism

Sulfur(IV) as a ubiquitous substance in the atmosphere and water bodies can be deliberately involved in different redox reactions based on the known ability to donate electrons, but the inhibition effect on the advanced oxidation processes (AOPs) especially the Fenton reaction, which played a vital role in aerosol aging and pollution treatment, still stayed fuzzy. In this work, it was first found that sulfite had an unexpected reactivity to accept electrons from Fe(II) monitored by the chemiluminescence (CL) method to reduce Fe(II) seriously. Dynamics calculation, UV–vis absorption, HPLC, and CL analysis indicated that sulfite anions can be transferred into SO2·- or dimer S2O42− through reacting with Fe(II). The direct consumption of Fe(II) in Fenton reaction only happened by sulfite among other inorganic anions during degrading different organic pollution, and the produced S2O42− showed an overpowering inhibitory ability on hydroxyl radical especially at pH 5.3, both resulting in a strong inhibition effect on the Fenton reaction. In contrast at pH 3.1, the fast depletion of sulfite by H2O2 and decomposition of S2O42− fell off the inhibition effect. Furthermore, abatement experiments showed that the effect of sulfite could be circumvented by using a non-iron-based oxidation system with other metal ions, additionally clarifying the reaction of Fe(II)-sulfite played the primary role in the inhibition. Significantly, this inhibition effect of sulfite on the Fenton reaction was demonstrated to take place both in the natural wastewater and degrading two acids from biomass burning in the atmosphere, identifying the attenuated Fenton reaction in the presence of sulfur(IV) in the environment

Design of novel electrochemical sensor functionalized with green nanoparticles for tetracycline monitoring

AbstractIncreasing the release of antibiotics in particular tetracycline in the environment is become one of the most concerns that threat human and animals' health. Regarding their low cost, sensitivity, portability, electrochemical sensors have received attention for tetracycline monitoring. With a nanostructure, diverse active functional sites, and good conductivity, green nanoparticles are considered now as an attractive material for sensors design. The objective of the present paper is then the design of electrochemical sensor functionalized with green nanoparticles based on gum Arabic for tetracycline detection. The green nanoparticles are synthesized by direct reduction of silver nanoparticle with gum Arabic polymer. The intrinsic properties of the obtained nanoparticles are examined using different techniques namely UV–Vis absorption (UV), X‐ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric TGA. To follow up, the sensor modification as well as tetracycline detection, cyclic voltammetry (CV) and square wave voltammetry are carried out. Correlation between the different results have demonstrated good dispersion and homogeneity of green nanoparticles, with good applicability in electrochemical measurements. In fact, the sensor has demonstrated wide concentrations range from 0.1 to 1250 nM with a limit of detection in the order of 0.056 nM, lower than those reported in the literature. The selectivity test, investigated against a various interfering with similar structure to tetracycline, have proven a good discrimination between all molecules. In addition, the sensor was successfully applied to real samples, and the found recovery rates are ranging from 90.4% to 106.9%. The obtained results confirm that green nanoparticles based on gum Arabic could commercially be viable for next generation of electrochemical sensor for tetracycline detection, and also could be applied for the detection of the variety of pharmaceutical pollutants in the environment.

Metal-free internal nucleophile-triggered domino route for synthesis of fused quinoxaline [1,4]-diazepine hybrids and the evaluation of their DNA binding properties

An unprecedented metal-free synthesis of fused quinoxaline 1,5-disubstituted-[1,4]-diazepine hybrids have been reported under mild conditions through a domino intermolecular SNAr followed by an internal nucleophile-triggered intramolecular SNAr pathway. Our strategy offers the flexibility for the introduction of a broad variety of functionalities at the N-1 position of fused diazepine moiety by using suitable diamine tails to design structurally diverse scaffolds. The DNA binding properties of representative quinoxaline diazepine hybrids were studied using UV–vis absorbance and EtBr displacement assay and were found to be governed by the functionalities at the N-1 position. Interestingly, compound 11f containing the N-1 benzyl substitution demonstrated significant DNA binding (KBH ∼ 2.15 ± 0.25 × 104 M−1 and Ksv ∼ 12.6 ± 1.41 × 103 M−1) accompanied by a bathochromic shift (Δλ ∼ 5 nm). In silico studies indicate possible binding of these diazepine hybrid 11f at the GC-rich major groove in the ct-DNA hexamer duplex and showed comparable binding energies to that of ethidium bromide. The antiproliferative activity of compounds was observed in the given order in different cell lines: (HeLa > HT29 > SKOV 3 > HCT116 > HEK293). Lead compound 11f demonstrated maximum cytotoxicity (IC50 value of 13.30 μM) in HeLa cell lines and also caused early apoptosis-mediated cell death in cancer cell lines. We envision that our work will offer newer methodologies for the construction of fused quinoxaline 1,5-disubstituted-[1,4]-diazepine class of molecules.

Nitrated benzothiadiazole-based D-A electrochromic polymers with tunable spectral properties

Nitrated benzothiadiazole (BT) is the promising acceptor units in constructing D-A-D electrochromic polymers, but its researches in the electrochromic field was very limited so far. In this work, four kinds of nitrated polymer precursors (Th-NO2-BT, EDOT-NO2-BT, Th-2NO2-BT, and EDOT-2NO2-BT) were synthesized by Stille coupling reaction with EDOT and thiophene units as the end groups (electron donor units) and mono-nitrated benzothiadiazole and di-nitrated benzothiadiazole as the core groups (electron acceptor units). The chemical structure and optical properties of the precursor were investigated by means of 1H NMR, UV–vis absorption and fluorescence spectra; the corresponding mono-nitrated polymer films were obtained in CH2Cl2-Bu4NPF6 system by electrochemical deposition method. The optical band gap of di-nitrated polymer precursor is obviously larger than the corresponding mono-nitrated polymer precursor (both ultraviolet and fluorescence spectra are obviously blue-shifted), accompanied with the obvious increased initial oxidation potential. Due to the fluorescence quenching effect of -NO2 group, their absolute quantum yields are all very low (0.0006–0.015). The spectroelectrochemistry and electrochromic kinetics of mono-nitrated polymer films (P(Th-NO2-BT) and P(EDOT-NO2-BT)) were studied. It was found that P(EDOT-NO2-BT) can show better electrochromic performance than P(Th-NO2-BT), with dark green in the neutral state and more obvious electrochromic performance in the near-infrared region (optical contrast: 38.4 %, coloration efficiency: 129.1 cm2/C, and fast response time: 1.4 s). This systematically study about the effects of nitro substitution effect on the properties of D-A electrochromic polymers, which will further expand the selection of the new acceptor units and the application prospect of nitrated electrochromic materials.

Red-emitting copper nanoclusters for ultrasensitive and selective detection of creatinine and its application in portable smartphone-based paper strips and polymer thin film

In this work, a quantitative paper-based sensor integrated with smartphone-application was developed using poly(sodium 4-styrenesulfonate) stabilized copper nanoclusters (PSS-CuNCs) as a fluorescence probe to detect creatinine (CRN). The surface morphology and optical properties of PSS-CuNCs were verified using UV-vis absorption, zeta-potential, photoluminescence, high resolution transmission electron microscopy (HR-TEM) and Fourier-transform infrared (FI-IR) spectroscopy. PSS-CuNCs exhibited strong red fluorescence with the emission peak centered at 654 nm upon excitation at 390 nm. PSS-CuNCs were also used to determine CRN because of their excellent fluorescence properties. The fluorescence of PSS-CuNCs was quenched significantly by adding different concentrations of CRN, which mainly originated from the formation of ground state complexation. The PSS-CuNCs probe showed high sensitivity with a low limit of detection (LOD) of 2.48 nM and high selectivity even in the presence of other interfering analytes. This assay was also used to measure CRN in real samples. Additionally, test paper-based assay has been developed to detect CRN using smartphones. The developed assay provides a reliable, cost-effective, sensitive and portable on-site method to measure CRN levels by utilizing fluorescence color changes. Incorporation of PSS-CuNCs into poly(vinyl alcohol) resulted in the formation of fluorescent transparent polymer thin films with high photostability.

Synthesis of new synthetic hybrid glasses using metallic nano-particles and rare-earth: Effect of plasmonic diluents

Borophosphate-based glass materials have the potential to revolutionize optical technology because of their outstanding optical properties, long-lasting nature, and cost-effectiveness. The present research addresses the intricate functions of rare earth and metallic nanoparticles (NPs) in borophosphate glass, which have significant potential for optical photonic and medical applications by incorporating Dy3+ ions and Cu NPs. We developed novel hybrid glasses through the melt-quenching technique, which includes the creation of functional groups and the establishment of bonds between P2O5 and B2O3, as confirmed by FTIR and Raman spectroscopy. UV–visible absorption spectra were used to identify the presence of Cu⁺ and Cu (Saeed et al., 2021) [2]⁺ ions and Cu nanoparticles, with the absorption peaks indicating their respective states. Furthermore, the underlying mechanisms of energy transfer in a glass matrix that is co-doped with dysprosium ions (Dy3+) have been studied. The experimental findings of this research not only provide valuable information about the physical properties of borophosphate glass but also emphasize the collaborative relationship between the rare-earth ion and copper nano-powders. The Tauc plot analysis demonstrated a correlation between the concentration of Cu and Dy dopants and a decrease in the energy band gap of the glass. This suggests that these dopants influence the electronic structure of the glass. This study opens up possibilities for creating innovative photonic materials with customized optical attributes.

Experimental and theoretical studies for instantaneous detection of l-cysteine and l-histidine using a simple Cu(II)-dppy complex

Developing simple and effective receptors for instantaneous detection of l-amino acids is vital for the recognition of life-threatening diseases in their early stage. Here, we report the synthesis and characterization of 2,6-di(pyrazin-2-yl)pyridine (dppy) based ligand L (L = 2,2′-(4-(3,4-diethoxyphenyl)pyridine-2,6-diyl)dipyrazine) and its copper (II) complex, [Cu(NO3)2L]. The in-situ prepared [Cu(H2O)2L](NO3)2 receptor in aqueous acetonitrile (4:1 v/v, 10 mM HEPES buffer, pH 7.4) medium displayed instantaneous responses towards biologically important bio-thiol l-Cysteine (Cys) and essential amino acid l-Histidine (His) over other l-amino acids through UV–Visible absorption spectral studies. Additionally, the competitive experiments confirmed that in-situ prepared [Cu(H2O)2L](NO3)2 receptor selectively detects Cys (1 equivalent) in the presence of other l-amino acids. The detection limits of Cys and His were calculated to be 8.23 × 10−7 M and 2.55 × 10−6 M, respectively. The density functional theory (DFT) calculation shows that selectivity of [Cu(H2O)2L](NO3)2 towards Cys is due to the reduction of Cu(II) to Cu(I) in the presence of Cys, while Cys is oxidized to cystine (Cys-Cys). For His, selectivity observed due to the formation of [Cu(His)2] moiety between Cu(II) ion with one His via N,O coordination mode and another His via N,N,O-coordination mode.

Synthesis and characterization of new naphthalene diimides (NDIs) for application in electronic devices

This paper describes the synthesis of new naphthalene diimide (NDI) derivatives obtained in good yields from the reaction between 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) and different p-alkoxy-substituted anilines. The photophysical properties of the NDIs were investigated in solution and the solid state. UV‒visible absorption spectra in 1,4-dioxane, dichloromethane, and acetonitrile showed absorption maxima at approximately 375 nm, related to symmetry and spin allowed 1π-π* electronic transitions. These compounds did not exhibit fluorescence emission in the studied solvents. Electrochemical studies have indicated that the presence of different alkyl chains significantly affects the capacity of NDIs when used as organic cathodes in Al-graphite batteries due to variations in their ability to intercalate tetrachloroaluminate. The organic cathodes incorporating NDIs with varying alkyl chain lengths exhibited distinct capacities: 123.5 mA⋅h⋅g⁻1 for 3a, 101.6 mA⋅h⋅g⁻1 for 3b, and 157.3 mA⋅h⋅g⁻1 for 3c, with a capacity retention of approximately 54% after 15 charge‒discharge cycles. These findings highlight the crucial role of alkyl chain modification in optimizing the electrochemical performance of organic cathodes.

An inclusive comparison regarding aggregation of surface active ionic liquid and conventional surfactant with a cationic dye Acridine Red exposed in view of spectroscopic and theoretical study

The investigation was conducted on the interaction of acridine red (AR) with sodium dodecyl sulfate (SDS) and 1-butyl-3-methyl imidazolium octyl sulfate (BMImOS) in both premicellar and post micellar concentrations. The interaction between AR and room temperature ionic liquid (RTIL) 1-butyl-3-methyl imidazolium bromide (BMImBr) was studied to understand the effect of imidazolium cation on micellization. Spectroscopic experiments, such as UV–visible absorption spectroscopy, steady-state fluorescence spectroscopy, time-resolved fluorescence spectroscopy, and dynamic light scattering, have been introduced. Various important parameters like spectral shifts, anisotropy, and aggregation number have been determined spectroscopically. However, a fresh insight into density functional theory calculations has also been provided. The observed results have been explained in terms of the aggregation behavior of the amphiphiles. A prominent redshift accompanied by a change in intensity is observed in the presence of surfactant and SAIL. However, in the case of BMImBr, no such spectral shift has been observed; only a decrease in spectral intensity highlights the quenching ability of the imidazolium cation. Average lifetime also provides some additional information regarding the difference in the formation of aggregates by SDS and BMImOS, which is further established from particle size density obtained from DLS. The salt like role of 1-butyl-3-methyl imidazolium cation also has been logically explained by anisotropy measurement and the determination of aggregation number. Using Gauss View 5.0 and Gaussian 09 package, the energy of optimization of each set of amphiphiles along with dye has been determined to follow the interaction at the molecular level. TDDFT calculations have also been performed to determine the structure of HOMO and LUMO.

Synthesis, structure, theoretical calculation and photocatalytic property of a novel Mn(II) supra-molecular compound containing SCN- and 2,2′-bipyridine ligands

A novel supra-molecular compound [Mn(SCN)2(byp)2] 1 (byp = 2,2′-bipyridine) was synthesized under hydrothermal conditions. Noteworthily, the SCN- in the title compound is derived from the in situ reaction of salicylaldehyde thiosemicarbazone. X-ray single-crystal diffraction analysis shows compound 1 is only a mononuclear structure, but it is expanded into a 3D supramolecular structure via H-bonds and π···π stacking. Hirshfeld Surface analysis shows C⋯H, H⋯H and S⋯H interaction are the main contribution of intermolecular interactions in the formation of compound 1. All of title compounds were characterized by IR spectroscopy, elemental analysis, XRD, XPS and TG analysis. The energy framework of compound 1 is dominated by dispersion interaction. The photocatalytic degradation ability of compound 1 for methylene blue is verified by photocatalytic degradation experiments (pH = 4: 44.6 %; pH = 7: 76.2 %; pH = 10: 78.8 %). Furthermore, the potential photocatalytic mechanism of compound 1 is inferred by UV–vis absorption spectra and Mott–Schottky curve.

Facile synthesis, morphological, optical, catalytic and photocatalytic properties of Ag nanoparticles decorated Ce doped ZnO hybrid plasmonic nanorods

Designing plasmonic metal–semiconductor hybrid nanostructures for photodecomposition of industrial textile effluent has been considered as a great way to boost the catalytic and photocatalytic capability by promoting effective separation of photoexcited charge carriers. Herein, fabrication of Ag nanoparticles decorated Ce doped ZnO nanostructures were demonstrated via facile wet chemical method. The morphology and structure of the fabricated photocatalysts were analysed using FESEM, XRD and Raman spectroscopy whereas PL, TRPL and UV–vis absorption spectroscopy were employed to examine their optical behaviour. Catalytic response of the synthesized catalysts was studied for 4-NP to 4-AP reduction and the results are more favourable for Ag loaded Ce doped ZnO catalysts and achieved 96.4 % reduction of 4-NP in only 4 min. Photocatalytic measurements showed that higher Ag NP loading onto Ce doped ZnO nanostructures led to superior photodegradation ability over other photocatalysts for the degradation of synthetic dyes and levofloxacin antibiotic. The sunlight driven photodecolorization of harmful synthetic dyes and levofloxacin were studied and efficacy of 97.5, 97.1, 85.1, and 70.9 % were achieved for MG, MB, RhB and MO dyes, respectively in 12 min and 97.2 % efficiency for degradation of levofloxacin was achieved in 20 min of sunlight exposure. Furthermore, the key reactive species was identified and tentative photodegradation process was explained. This work provides an excellent plasmonic-semiconductor catalyst and photocatalyst with good photostability and practical applicability indicating its enormous potential for application in environmental remediation.

Physical, mechanical, structural, optical and gamma ray shielding behavior of (90-x-y)B2O3–5PbO–5BaO-xZnO-yTiO2 glasses

The influence of changing the concentrations of ZnO and TiO2 on the (90-x-y)B2O3–5PbO–5BaO-xZnO-yTiO2, x = y = 10, 15, 20 and 25 mol% glasses have been investigated. Their density rises from 3.469 g/cm³ to 4.207 g/cm³. The elastic modulus of the glass samples increased from 50.970 to 73.195 GPa for Young modulus, 45.540–64.107 GPa for bulk modulus, 20.640–29.732 GPa for the shear modulus and 73.060–103.750 GPa for the longitudinal modulus respectively. This is referring to the effect of ZnO and TiO2 on the structure of the glasses. The UV–Vis absorption behavior exhibits a decrease in the energy band gap values from 3.312 to 3.146 eV. The increase in cutoff wavelength in UV spectra is useful for many applications, such as UV shielding, where the objective is to effectively obstruct UV rays while preserving optimal visibility. The relation between the thickness of the glass and the transmission factor (TF) has been studied to evaluate their shielding behavior. The TF decreases with the increase in the thickness from 0.5 to 1 cm. Also, TF decreases with the addition of ZnO within the structure of the investigated samples. Therefore, it can be suggested that increasing the concentration of ZnO in glass samples is another good way to reduce TF values.

One-pot radiolytically synthesized reduced graphene oxide-gold nanoparticles composites and exploration in energy storage

Graphene and its composites are of primary importance, particularly in the field of energy storage. Numerous bottom-up and top-down methods have been proposed in the literature to produce these materials with enhanced physicochemical properties. Recently, an innovative and green methodology was developed based on ionizing radiation, allowing the quantitative synthesis of graphene oxide-based materials. With the aim to extend this strategy for the preparation of hybrid nanomaterials, the objective of this work was the one-pot synthesis of nanocomposites composed of reduced graphene oxide – gold nanoparticles (rGO-AuNPs) via gamma ray-induced radiolytic reduction. UV–Vis Absorption Spectroscopy, Fourier Transform Infrared Spectroscopy, Raman Spectroscopy and X-ray Photoemission Spectroscopy were utilized to comprehensively evaluate the reduction degree of graphene oxide and the formation of gold nanoparticles. Atomic Force Microscopy and Scanning Electron Microscopy were employed to obtain the morphological and topographical information on synthesized nanocomposites. Thermal properties were investigated by Thermogravimetric Analysis and electrical properties were investigated using Cyclic Voltammetry and Potentiostatic Charge and Discharge method. The results demonstrated the successful reduction of graphene oxide and gold ions through the drastic transformation of oxygen-containing functional groups and the formation of gold nanoparticles. Electrical characterization results highlighted the excellent electrical properties of radiosynthesized rGO-AuNPs composites and their great potential for supercapacitance application.

Tailoring Photocatalytic Performance: Lanthanum Doping in Nickel Oxide for Efficient Degradation of Some Industrial Cationic Dyes in Visible light radiation

Metal oxide nanoparticles have emerged as an important component in heterogeneous photocatalysis, which uses light-induced reactions on the surface of a catalyst to drive chemical transformations. The improved photocatalytic activity of lanthanum-doped metal oxide nanoparticles has been the subject of research due to their special qualities, which include enhanced photocatalytic performance, stability and absorption of visible light. This study involves co-precipitation approach to synthesize nickel oxide nanoparticles and nickel oxide nanoparticles doped with lanthanum. The nanoparticles were determined using UV-Visible absorption spectrophotometry, X-ray diffraction spectroscopy, Energy-disperse spectroscopy, Photoluminescence spectroscopy and Field emission scanning electron microscopy. For the photodegradation of malachite green and rhodamine B dyes, synthesized nanoparticles were employed as photocatalysts. Compared to pure NiO, the photochemical activity of 4% Lanthanum-doped NiO was higher. The degrading efficiency of 4% La-doped NiO is 89% effective towards rhodamine B and 87% for malachite green. In addition, entrapment was done to identify primary active species responsible for photocatalytic activity. The present study likely provides new insights and novelty into the photocatalytic mechanisms at play, including how lanthanum doping affects the generation and dynamics of reactive oxygen species (ROS) like hydroxyl radicals and superoxide anions, which are responsible for the breakdown of dye molecules.

Compact microstructured Cu2ZnSnS4 thin films with enhanced optoelectronic properties via (NH4)2S tunable hybrid colloidal ink coating and transformation

Kesterite Cu2ZnSnS4 (CZTS) is a quaternary semiconductor material composed of earth-abundant elements that is a promising material for sustainable thin film photovoltaics and other optoelectronic applications. In this work, CZTS thin films are deposited using aqueous colloidal suspensions of binary sulfides (Cu and Zn) and thiostannate complexes formed by in situ reaction of SnS2 with (NH4)2S. In a departure from previous works that used only dissolved thiostannate complexes, we utilize a hybrid state of tin sulfide as both nanoparticles and thiostannate complexes to improve thin film quality. This finding was made by adjusting the (NH4)2S concentration in our aqueous inks, which modified the relative abundance of thiostannate complexes vis-à-vis the amount of SnS2 nanoparticles. In the absence of (NH4)2S, the unstable ink yields nonuniform, partially oxidized thin films. Meanwhile, thiostannate complex formation with the use of (NH4)2S (2–10 vol%) can suppress the presence of secondary phases such as CuxS in the absorber layer and protects against oxidation (avoiding undesirable SnO2 formation). Lowering the aqueous (NH4)2S concentration to 2 vol% yielded the most stable ink formulation, featuring a hybrid state of tin sulfide as both colloidal particles and dissolved thiostannate complexes. The hybrid tin sulfide ink produced compact thin films and reduced the level of Cu-Zn antisite defects in the kesterite crystal structure. We attribute the compact microstructure attained with the hybrid tin sulfide formulation to thiostannate complexes acting as linkers among the three binary sulfides (Cu, Zn, and Sn), enabling their orderly packing into an amorphous, quaternary initial state which is then annealed to grow crystalline kesterite CZTS. UV-Vis absorption characterization shows the Tauc bandgap for 2 vol% hybrid ink coated films to be 1.40 eV with reduced absorption tails based on Urbach energy measurements, while photoluminescence studies showed significantly enhanced emission.

The interaction between resveratrol and catalase was studied by multispectral method and molecular docking simulation

In this research, we delved into the interaction mechanism between Resveratrol (RES) and Catalase (CAT) utilizing a suite of advanced analytical techniques, including multispectral analysis and molecular docking simulation. A comprehensive assessment of their binding characteristics, modalities, distances, and the subsequent impact on CAT's secondary structure was conducted through fluorescence spectroscopy, ultraviolet spectroscopy, circular dichroism, three-dimensional fluorescence spectroscopy, synchronous fluorescence spectroscopy, and molecular docking simulation. By employing the Stern-Volmer equation to determine KSV and Kq values, Our findings indicate that the RES-CAT interaction results in static fluorescence quenching, By conducting experiments, the binding constant KA and the number of binding sites n for CAT and RES were determined, with the number of binding sites n being close to 1, indicating the presence of a specific binding site between CAT and RES. Parameters at 298 K. The negative values of ΔH and ΔS suggest that van der Waals forces and hydrogen bonding are predominant in mediating the interaction between CAT and RES. The negativity of ΔG indicates the spontaneity of the reaction. The Fӧrster resonance energy transfer theory calculation revealed a binding distance of 4.917 nm, substantiating the occurrence of non-radiative energy transfer between RES and CAT. Furthermore, the UV-VIS absorption spectrum, synchronous fluorescence spectrum, three-dimensional fluorescence spectrum, and circular dichroism analyses collectively demonstrated that RES induces alterations in CAT's secondary structure, augmenting the polarity around tryptophan (Trp) residues, reducing hydrophobic interactions, and bolstering hydrophilicity. This work offers novel insights into the antioxidant mechanisms of resveratrol within biological systems and holds significant theoretical and practical implications for the medical application and development of resveratrol.

Photoelectrocatalytic property and DFT calculations of TiO2 with broadened infrared light absorption by Gd2O3:Er3+

In this paper, erbium-doped gadolinium oxide rare earth oxide nanoparticles (Gd2O3:Er3+) with good light absorption capacity from the visible to the infrared region were prepared by polyol method, and then compounded with TiO2 by hydrothermal method. SEM, TEM, XPS, UV-vis and electrochemical workstation were used to study the morphology, structure, UV-vis light absorption and photoelectrochemical (PEC) properties of Gd2O3:Er3+/TiO2. The results showed that the Gd2O3:Er3+ spherical nanoparticles with a particle size of about 15 nm were uniformly distributed on the surface of the TiO2 nanorod array, and the Gd2O3:Er3+/TiO2 nanocomposites had good light absorption capacity in the infrared region. Furthermore, the photocurrent densities of Gd2O3/TiO2 and Gd2O3:Er3+/TiO2 were 2.08 and 2.75 times higher than those of TiO2, respectively, manifesting that the broadening of infrared light absorption can improve the PEC property of TiO2. Meanwhile, the DFT calculation results showed that the energy band of Gd2O3:Er3+/TiO2 was significantly narrower than that of TiO2, indicating that Gd2O3:Er3+/TiO2 had a redshift phenomenon of UV-vis absorption. The calculation results of state density showed that the f orbital of Gd2O3:Er3+ intersected with the d orbital of TiO2, indicating that there is an electron transfer between Gd2O3:Er3+ and TiO2.

Enhanced Photocatalytic Performance of Two-Dimensional NixRe1-xSe2 (x = 0 & 0.25) Crystalline Material: Exploring its Potential as a High-Efficiency Catalyst

Water pollution, stemming primarily from dye effluent discharge in urban and industrial zones, remains a critical environmental issue. Photocatalysis emerges as a promising eco-friendly, cost-effective, solar-dependent, and recyclable solution. This study synthesizes Ni0.25Re0.75Se2 via a simple Direct Vapour Transport (DVT) technique, exploring the impact of doping on ReSe2's structural, optical, and photocatalytic properties. Characterization techniques (PXRD, FESEM, EDAX, Raman spectroscopy, UV-visible absorbance spectroscopy, XPS) were employed for analysis. Photocatalytic experiments with organic dyes like Methylene Blue (MB), Acridine Orange (AO), Crystal Violet (CV) demonstrated efficient AO dye degradation (95.67%) in 60 minutes using Ni0.25Re0.75Se2, showcasing effective catalytic properties under 20W LED bulb. Trapping experiments identified hydroxyl radicals and holes as pivotal for AO dye degradation. Ni0.25Re0.75Se2 exhibited stability under varying pH, non-leaching behavior, and retained efficiency over cycles, showcasing potential for sustained use in industrial wastewater treatment. This research advances sustainable solutions to combat water pollution in urban and industrial environments.

N-Acetyl Cysteine-Cadmium Telluride NAC-CdTe QDs for Detecting the Damaged DNA in Cancerous Diseases

In this study water-soluble N-Acetyl Cysteine Capped-Cadmium Telluride QDs (NAC/CdTe nanocrystals) using N-acetyl cysteine as a stabilizer were prepared to investigate the utility of quantum dots (QDs) in distinguishing damaged DNA, (extracted from blood samples of leukaemia patients), from intact DNA (extracted from blood samples of healthy individuals) to be used for biosensing application. Based on the optical characterization of the prepared QDs, the XRD results revealed the formation of the NAC-CdTe-QDs with a grain size of 7.1nm. Whereas, the SEM test showed that the spherical size of the NAC-CdTe-QDs lies within 11~33nm. NAC-CdTe-QDs have superior PL emission properties at of 550nm and UV-Vis absorption peak at 300nm. The energy gap measurement through PL and UV–Vis was found to be 2.2eV and 2.3 eV, respectively. The interaction between the synthesized QDs and the extracted genomic DNA (both cancer damaged DNA and healthy undamaged DNA) was analysed optically, and compared to the normal reference DNA. The results showed a shift in the maximum fluorescence emission intensities (observed at 540nm nm for a damaged sample and 535 for a reference cell). Based on the obtained fluorescence results, the present study reached the conclusion that the prepared core/shell QDs could be employed as probes for diagnosing genetically disrupted DNA that is associated with malignant diseases from healthy DNA.

Study on the regulation of ε-CL-20 by an external electric field.

To explore the influence of the external electric field (EEF) on ε-CL-20. The molecular structure, frontier molecular orbitals (FMOs), global reactivity parameters (GRP), surface electrostatic potential, nitro charge, and UV-Vis spectra of ε-CL-20 under EEF were studied using density functional theory (DFT). The calculation results show that the electric field applied along N16-N24 has a significant effect on the structure of ε-CL-20. With an increase in the positive EEF, the bond length of the initiating bond decreases, and the bond order and bond dissociation energy increase, which increases the thermal stability of ε-CL-20 to a certain extent. In addition, with an increase in the positive EEF intensity, the LUMO migrates from both sides of the positive electric field to one side of the nitro group, and the HOMO migrates from the skeleton to the nitro group. It is worth noting that in the negative EEF, when the electric field strength changed from 0 to 0.016 a.u., the negative charge of the total nitro group gradually decreased. When the electric field strength becomes 0.02 a.u., the negative charge of the total nitro group suddenly increases, and ε-CL-20 is significantly polarized. When the electric field strength is sufficiently strong, the occupied and unoccupied orbitals of the ε-CL-20 molecule change, resulting in a change in the energy level difference between the occupied and unoccupied orbitals, which further excites the corresponding excited state, resulting in a new UV-Vis absorption peak. Based on the density functional theory (DFT), the structural optimization and energy calculation were carried out by using B3LYP/6-311 + G(d, p) and B3LYP/def2-TZVPP methods, respectively. After optimization convergence, vibration analysis was performed without imaginary frequencies to obtain stable configurations. Then the molecular structure, frontier molecular orbitals (FMOs), global reactivity parameters (GRP), surface electrostatic potential, nitro charge, and UV-Vis spectra were analyzed.