UV Vis Absorption Spectra Research Articles

Antimicrobial and Antibiofilm Activity of Green Synthesized Silver Nanoparticles by Using In Vitro Grown Aloe vera L.

In this study, invitro grown Aloe vera L. tissues were used for AgNP synthesis. Adventitious root and callus tissues were grown in MS medium containing 1 mg/L IAA and 1 mg/L NAA. Using A. vera L. leaf, in vitro grown callus, and adventitious roots tissue extracts, AgNPs were synthesized. According to DLS analysis, PDI values and zeta potential values showed that AgNPs from adventitious root were more suitable in terms of size and surface charge. Characterization of adventitious root-derived AgNPs was performed by UV-Vis absorption spectrum, ICP/MS, SEM, FTIR, and XRD. According to HPLC results, catechin, gentisic acid, caffeic acid, coumaric acid, polydatin, coumarin, and ellagic acid were found in adventitious roots. Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC2 7853), MRSA (ATCC 33951) and Staphylococcus aureus (ATCC 6538) strains were used to determine the antibacterial and antibiofilm activity of AgNPs. The highest antibacterial activity was determined against P. aeruginosa. Lower concentrations of AgNPs caused changes in the structure of the biofilm formed by P. aeruginosa, which produced particularly strong biofilms, resulting in failure of biofilm maturation. Accordingly, AgNPs synthesized from Aloe vera L. adventitious roots had antibacterial and antibiofilm activity even at low concentrationsagainst the tested bacterial strains.

A Multifunctional Tb(III)-Based Metal-Organic Framework for Chemical Conversion of CO2, Fluorescence Sensing of Trace Water and Metamitron.

The utilization of metal-organic frameworks (MOFs) as fluorescent sensors for the detection of environmental and chemical reagent pollutants as well as heterogeneous catalysis for CO2 conversion represents a crucial avenue of research with significant implications for the protection of human health. In this work, a Tb(III)-based three-dimensional metal-organic framework, [Tb(L)·4DMF]n (Tb-MOF) (H3L = 5'-(4-carboxy-3-hydroxyphenyl)-3,3″-dihydroxy-[1,1':3',1″-terphenyl]-4,4″-dicarboxylic acid), has been structurally conformed by single-crystal X-ray crystallography. It possesses a 1D rhombus channel along the [010] direction, featuring a pore size of 6.02 × 9.13 Å. Tb-MOF was proved to be a multifunctional material for a fluorescent sensor and CO2 cycloaddition heterogeneous catalyst material. Fluorescence sensing studies revealed that Tb-MOF demonstrates high sensitivity, selectivity, and favorable regeneration properties, making it an effective chemosensor for detecting the metamitron (MMT) pesticide and trace water in organic solvents. The mechanism of fluorescence quenching by MMT and water was elucidated by a combination of XRD, UV-vis absorption spectra, IR spectra, theoretical calculations, and fluorescence lifetimes. The material was also utilized for the sensing of MMT and water in paper strips. Additionally, the open Tb3+ site as Lewis acidic centers makes Tb-MOF achieve efficiently catalytic conversion for CO2 and epoxides to cyclic carbonates. Moreover, a possible catalytic mechanism for the conversion of carbon dioxide to cyclic carbonates was proposed by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments. It also exhibited recyclability for up to five cycles without noticing an appreciable loss in sensing or catalytic efficiency.

Preparation and Characterisation of CdO@Au Nanoparticles by Hybrid System Using Laser Ablation and Plasma Jet Methods for Cytotoxicity Against Rat Embryonic Fibroblast Cell Line

The purpose of the research is to see if cadmium oxide@gold (CdO@Au) nanoparticles produced using the laser ablation and plasma jet method in deionised water (DW) solution could be a viable alternative to typical materials in cytotoxicity of rat embryonic fibroblast (REF) normal cell line. The cadmium nanoparticle core was prepared using a Q-switched Nd:YAG laser at a wavelength of 1,064 nm, with laser pulse energies varying between 800 mJ and 1,000 mJ over 500 shots. Gold nanoparticles shell prepared using atmospheric pressure plasma jet. The structural analysis process used X-ray diffraction (XRD) and UV-vis absorption spectroscopy to study the surface plasmon resonance (SPR) to follow the fast changes in the nanoparticles (NPs) colloidal solutions brought on by the interaction between Au sheets and CdO core. From UV-visible transmittance and absorbance spectra, it was observed that the transmittance pattern that can be obtained decreases. At the same time, the energy gap increases with the increase of laser energy, and this may be due to the increase in absorption. The XRD investigation revealed that the polycrystalline structure of CdO@Au NPs and their preferred orientation along (111) direction. The normal REF cell line was employed in the study to investigate the cytotoxicity of CdO@Au nanoparticles. After 48 h of exposure, the CdO@Au NPs displayed the maximum toxicity at a concentration of 100%.

Rapid photocatalytic degradation of selective organic dyes using metal oxide-metal sulphide and its inverted nanocomposites

The chemical precipitation approach was employed to synthesize novel heterostructures, namely CeO2-ZnS and SnO2-ZnS, along with inverted nanocomposites ZnS-CeO2 and ZnS-SnO2. The nanocomposites were subjected to characterization using various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis absorption spectra, and photoluminescence spectra. The TEM images demonstrated particles that were homogeneous, well-dispersed, and comparatively tiny with a sphere-like structure. This indicates successful synthesis and desirable morphological properties of the nanocomposites. The integration of varied nanoparticles within a heterostructure commonly gives rise to synergistic effects, imparting superior properties to the composite compared to the individual components. These nanocomposites tested for their photocatalytic degradation efficiency using Rose Bengal (RB) and Crystal Violet (CV) dyes under natural sunlight and they exhibited approximately 95 % degradation rate. The degradation results demonstrated a significant enhancement in the photocatalytic efficiency of ZnS-CeO2 and CeO2-ZnS nanocomposites. This improvement was attributed to the effective recombination suppression of photogenerated electron-hole pairs, leading to the generation of highly reactive free radicals. The first-order kinetic rate constant for CeO2-ZnS was determined to be 0.52 min−1 for CV and 0.53 min−1 for RB. The present research work has the potential to offer a novel approach to the construction of new heterojunction photocatalysts and to provide a more profound understanding of the treatment of textile organic dyes.

Pseudohalogen regulation of benzimidazole small molecule acceptor to optimize molecular crystallinity in Q-PHJ organic solar cells

The cyano group is a pseudohalogen with chemical properties similar to halogens. It has the ability to regulate the stacking and energy levels of molecules in organic solar small molecule non-fullerene acceptor materials. In this study, we introduce two novel alkylated derivatives, BMIC-CN-Me and BMIC-CN-iPr, featuring a cyano-modified benzimidazole core. This central nucleus design is reported for the first time, offering a unique approach to molecular engineering in organic photovoltaics. BMIC-CN-Me, in particular, enhances device performance by meticulously managing molecular stacking through steric hindrance. Analysis via single-crystal X-ray diffraction reveals five distinct stacking modes, with an average intermolecular distance of approximately 3.31 Å, optimizing the efficiency of charge transfer. This precise molecular arrangement elevates the photoconversion efficiency (PCE) of the non-fullerene acceptor, based on the benzimidazole core, to an impressive 17.6 %. Moreover, the material demonstrates exceptional stability, retaining over 80 % of its initial efficiency after 1200 h in a glove box and maintaining more than 80 % of its original efficiency after 500 h of continuous simulated solar irradiation. Compared to the 2-methylimidazole-derived molecules acceptor, devices prepared using BMIC-CN-Me demonstrate superior performance due to their better-matched energy levels and UV–Vis absorption spectrum. Furthermore, when contrasted with BMIC-CN-iPr, BMIC-CN-Me exhibits a more tightly packed molecular arrangement. These factors contribute to more effective exciton dissociation, accelerated charge transport, and the suppression of recombination, leading to an enhanced fill factor and overall photoelectric conversion efficiency. The quasi-planar heterojunction architecture further bolsters device stability. The cyano-modified benzimidazole structure provides additional non-covalent interaction sites, which augment the material’s stability. Our findings indicate that the cyano substitution of the benzimidazole core not only enhances material stability and molecular aggregation but also significantly improves the performance of organic solar cells. This innovative approach to molecular design holds promise for the development of high-performing and durable organic photovoltaic materials.

A new Conjugated mesoporous polymer as fluorescence sensor for the detection of nerve agent simulant dimethyl chlorophosphonate via specific nucleophilic substitution reaction

Conjugated micro/mesoporous polymers (CMPs) represent a category of porous organic materials formed via covalent bonds. Here, DAC-TFP CMP was synthesized using 3,6-diaminocarbazole (DAC) and 2-hydroxy-1,3,5-benzenetricarbaldehyde (TFP) as building blocks. DAC-TFP CMP is a porous conjugation polymer with remarkable thermal and chemical stability. DAC-TFP CMP suspension demonstrates selective "on-off" fluorescence response towards nerve agent simulant dimethyl chlorophosphonate (DMCP) in 1,4-dioxane with exceptionally low detection limits. DMCP and DAC-TFP CMP undergo a nucleophilic substitution reaction, leading to the formation of an N-P bond between N atom on carbazole of DAC-TFP CMP and P atom of DMCP. The new polymer DAC-TFP CMP@DMCP has electron donor-acceptor structure and the fluorescence quenching can be ascribed to the intramolecular charge transfer (ICT) from DAC-TFP CMP unit to DMCP group, as supported by XPS results and DFT calculation. Upon the addition of DMCP to the 1,4-dioxane suspension of DAC-TFP CMP, a subtle blue shift is observed in both the fluorescence emission spectra and UV-vis absorption spectra, providing further validation of the ICT mechanism. DAC-TFP CMP shows excellent recoveries in detecting DMCP in both soil and pesticide samples containing mesotrione and atrazine, highlighting its strong potential as a reliable chemosensor for DMCP detection and analysis.

Covalent triazine frameworks as particle electrode for three-dimensional photoelectrocatalytic degradation of oxytetracycline: Synergy effects, pathway, and mechanism.

Photoelectrocatalysis has been widely employed for degrading antibiotics due to its high efficiency. However, the application is significantly impeded by the rapid recombination of photogenerated charge carriers and the limited surface areas of photoelectrodes. In the study, high crystallinity covalent triazine frameworks were fabricated at low temperature of 150°C and firstly used as particle photoelectrode in the three-dimensional photoelectrochemical reactor to degrade oxytetracycline (OTC). SEM, TEM, XRD, XPS, and FT-IR confirmed the successful synthesis of high crystallinity covalent triazine frameworks. Compared to CTF-120 (71.2%) and CTF-180 (46.9%), CTF-150 exhibited excellent OTC removal. Electrochemical impedance, UV-vis absorption spectra, and Mott-Schottky tests showed that CTF-150 demonstrated more wide light absorption range of 501nm and narrow bandgap of 2.52eV, and smaller Rct value under illumination, in comparing to CTF-120 and CTF-180. When the initial concentration of OTC was 50mgL-1, the 86.2% of OTC removal and 62.7% of mineralization were obtained under light irradiation (λ>420nm), current of 10mA, pH of 6.4, electrolyte of 0.1M Na2SO4. The synergy effect between photocatalytic and electrocatalytic processes of CTF-150 not only enhanced by 38.5% current efficiency but also reduced energy consumption to 1.90 kWh m-3. CTF-150 had a wide range of acid-base application and displayed resistance on coexisting ions. Electron spin resonance detection, quenching experiments, and probe experiments illustrated that h+, •O2-, 1O2, and •OH contributed to the degradation of OTC and the generation pathways of •O2-, 1O2, and •OH were verified. Moreover, •O2-, 1O2, and h+ were the main reactive species responsible for OTC removal, while 1O2 was for OTC mineralization. Based on high-performance liquid chromatography-tandem mass spectrometry detection, OTC with benzene ring was decomposed to opening ring products. The acute toxicity, developmental toxicity, bioaccumulation factor and mutagenicity of OTC and its intermediates using T.E.S.T. showed the toxicity of 82.35% degradation products decreased.

Structural, optical, and dielectric Properties of Sr2+ substituted Ba1-xSrx(Co1/2W1/2)O3 ceramics for wireless application

The solid solution of Ba1-xSrx(Co1/2W1/2)O3, (BSCWO), (0.0 ≤ x ≤ 0.60) ceramics has been prepared via conventional solid-state reaction route. In this work, the impact spawned by doping Sr2+ cation on the phase, dielectric, optical and morphological properties of (BSCWO), ceramics has been investigated with respect to the frequency range of 1-3GHz. The X-ray diffraction patterns revealed that the base sample has a tetragonal structure, while Sr+2 doped samples exhibit orthorhombic structure. The appearances of the surface and grain size distribution of samples are analyzed using scanning electron microscope (SEM). The FTIR study confirms the presence of metal-oxygen bond and functional groups. The dielectric properties of the prepared samples were strongly dependent on the frequencies and as well as on concentration. The UV-visible absorption spectra results, the band gap energy (Eg) drops from 2.56 to 2.37 eV with an increasing the Sr2+ contents. The EDX (energy dispersive x-rays) spectroscopy corroborate the presence of Ba, Sr, Co, and W elements. We observed the lowest dielectric loss (tan = 0.092) and the highest dielectric constant (εr = 51) at contents (x = 0.60), making it a promising option for wireless device applications.

Optical materials enhancing the chemical reactivity characteristics of N-benzyloxycarbonyl-L-phenylalanine: Spectroscopic, electronic properties, natural bond orbital, stability, electron-hole, Topology and molecular docking analyses

In the field of organic chemistry, the exploration of heterocyclic compounds is considered as vital, with roots in medicinal chemistry and the synthesis of organic composites. The optimized structural configuration with the geometrical values was obtained and related to the experimental data. The theoretical computational methods were carried out using a versatile basis set, B3LYP/6–311++G(d,p). The spectroscopic insights of N-Benzyloxycarbonyl-l-Phenylalanine (NBCLP) were performed, and the simulated assigned vibrational wavenumbers (PED contributions) were compared with the experimental information. Further, employing the optimized structure of FMO's molecular orbitals, energy parameters were attained for the various solvents. The detailed theoretical interpretations were assessed on the UV–Vis absorption spectra (TD-DFT/M062X) for different solvents, and their respective values were related to the experimental value. The electronic properties of the FMO's orbitals match the experimental UV–Vis absorption energy value. The reactivity regions (nucleophilic and electrophilic) were obtained using the MEP map, and the corresponding lone pair/donor-acceptor transitions along with the higher stabilization energies were discussed using NBO analysis. Moreover, using the Multiwave function analyzer interface, electron-hole analysis for the excited states, along with parameters such as excitation energy, charge transfer length, H, t, and Δr indices for the above-mentioned solvents, and topological analysis, viz., ELF, LOL, and RDG, were discussed for the header composite. To enhance the biological behavior, molecular docking-in silico analysis was accomplished, suitable protein receptors were attained, and the results show the measure of binding energy in the ligand-protein interactions. Consequently, the present investigations imply that NBCLP may be designated as a potent and satisfying medication for the ailment of tuberculosis.

Preparation of water-soluble CdSeS alloy quantum dots with small particle size and high fluorescence lifetime by using hydrodynamic cavitation technology and their application in Ag+ detection

In this study, hydrodynamic cavitation (HC) is used as a novel and simple large-scale preparation technique. Water-soluble CdSeS alloy quantum dots (QDs) were successfully prepared by using Cd(NO3)2·4H2O, Na2S·9H2O and selenium powder as cadmium, sulfur and selenium sources. The effects of cycle time, reaction temperature, inlet pressure and Se/S molar ratio on the morphology, size and optical properties of CdSeS QDs were investigated. The prepared CdSeS QDs were characterized by X-ray diffractometer, X-ray photoelectron spectroscopy, transmission electron microscopy, UV–vis absorption spectra, fluorescence emission spectra and fluorescence attenuation curves. Finally, under the conditions of 12 h cycle time, 3.0 bar inlet pressure, 60 °C reaction temperature and 0.5/0.5 Se/S molar ratio, the ternary alloy CdSeS QDs with 2.62 nm average particle size and 482.62 ns fluorescence lifetime was obtained. Furthermore, a mechanism of preparing CdSeS QDs by using the HC method was proposed to explain the process of CdSeS precipitates conversion to CdSeS QDs. In addition, it is also found that Ag+ has a quenching effect on the prepared CdSeS QDs, which means that CdSeS QDs can be used as a fluorescence probe to specifically detect Ag+. This work not only provides a new possibility for large-scale preparation of high-performance QDs but also helps to understand the mechanism of CdSeS QDs as a metal ion selective fluorescence probe.

Fabrication of Yellow-Emitting Chiral Silicon Nanoparticles and Fluorescence/Colorimetric Dual-Mode Recognition of Lysine Enantiomers together with Nanobioimaging.

Long-wavelength emission fluorescent chiral silicon nanoparticles (c-SiNPs) hold significant potential for biological imaging and complex sample analysis due to their superior optical properties. However, the synthesis of these materials remains a considerable challenge. The activity of lysine is intrinsically linked to its configuration, making it crucial to develop a rapid, sensitive, and selective method for differentiating lysine enantiomers in biochemical and biomedical fields. In this study, N-[3-(trimethoxysilyl)propyl]ethylenediamine and chlorogenic acid were innovatively employed as precursors, and the yellow-emitting c-SiNPs with an emission wavelength of 572 nm were synthesized at room temperature for the first time by adjusting experimental parameters. The obtained c-SiNPs exhibited excellent optical properties, stability, and cell compatibility. Furthermore, the c-SiNPs demonstrated outstanding fluorescence and colorimetric recognition capabilities for lysine enantiomers. Consequently, fluorescence/colorimetric dual-mode sensing methods with high selectivity and sensitivity for the recognition of lysine enantiomers were established, and the linear ranges of these methods for d-lysine were 0.050-20 and 0.10-30 mM, with detection limits of 7.5 and 17 μM, respectively. Additionally, the c-SiNPs demonstrated an ability to bioimaging d-lysine within HeLa cells. Using density functional theory to calculate the recognition mechanism and correlating this with fluorescence and ultraviolet-visible (UV-vis) absorption spectra data, it was confirmed that the recognition mechanism was associated with the Gibbs free energy, binding energy, and hydrogen bond number difference between the c-SiNPs and lysine enantiomers. The method developed in this study for preparing c-SiNPs provided a reference for synthesizing fluorescent c-SiNPs with longer emission wavelengths. Moreover, the established method for identifying lysine enantiomers holds significant guiding implications for the use of high-purity lysine.

Improving visible light-driven CO2 conversion to high calorific fuels over sustainable highly crystalline and holey sulphur doped graphitic carbon nitrides

The effectiveness of CO2 reduction through g-C3N4 (CN) is considerably hindered by poor visible light absorption and the high rate of recombination of electron-hole (e−/h+) pairs. An effective method for increasing CO2 photoreduction efficiency is to incorporate non-metal components into the CN to modify its electronic properties and enhance its performance. This research presents the findings of our inquiry into sulfur-doped graphitic carbon nitrides (S–CN) for CO2 reduction through visible light. The XPS study reveals that the substitution of nitrogen atoms in the heptazine ring by sulfur (S) doping significantly influences the electronic configuration of CN, while the UV–visible absorbance spectra reveals that the CN band gap value 2.64 eV has reduced to 2.50 eV after S doping. Therefore, S–CN exhibits exceptional visible-light absorption, separation and migration of photoexcited e−/h+, corroborated by photoluminescence and transient photocurrent response experiments. Besides, S–CN demonstrated remarkable CO2 reduction capabilities without any cocatalyst or sacrificial agent, achieving CO/CH4 formation rates of 25/3 μmolg−1h−1, outperforming traditional CN. Our research highlights the relevance of impeding the e−/h+ recombination process to boost solar energy conversion output, suggesting potential for productive solar fuel generation using g-C3N4.

Design and synthesis of star-shaped non-fullerene acceptors based on triarylamine core for organic photovoltaic applications

Abstract Non-fullerene acceptors were synthesized with triphenylamine (TPA) and 9-phenylcarbazole core functionalized with oxindole moiety as well as electron accepting groups such as cyano and trifluoromethyl groups leading to precisely tuned molecular electronic structures and intermolecular arrangements. This approach maintained high thermal stability and excellent electron mobility while optimizing optoelectronic properties, providing a novel strategy for developing organic photovoltaic materials. LUMO levels of three receptors are comparable to PC61BM. The decomposition temperatures of all three acceptors exceeded 380°C under N2 flow, indicating the exceptional thermal stability. Notably, the acceptor consisting of TPA core with three oxindole moieties exhibited the red-shifted and intense UV-vis absorption spectrum and the narrowest optical bandgap (Egopt = 2.14 eV). Furthermore, the higher electron mobility was observed compared to analogues with 9-phenylcarbozle unit. The power conversion efficiency (PCE) of the device based on TPA core acceptor and regio-regular poly(3-hexylthiophene) surpassed those of the devices based on the other two acceptors.

A TEMPO-N3 Complex Enables the Electrochemical C-H Azidation of N-Heterocycles through the Cleavage of Alkoxyamines.

A TEMPO-N3 charge-transfer complex enables the electrochemical C-H azidation of various N-heterocycles. The TEMPO+ ion, generated from TEMPO, assists in producing N3• by forming a TEMPO-N3 complex with N3-. The formation of this complex is supported by UV-vis absorption spectra, cyclic voltammetry studies, and ESI-HRMS studies. The reaction likely proceeds by forming a highly labile azidooxygenation adduct, which undergoes oxidative alkoxyamine mesolytic cleavage. Subsequent deprotonation of the resulting carbocation exclusively produces the azidation product. It is important to note that substituted olefins generally yield azidooxygenation or diazidation as the final product. Our study demonstrates that N-heterocycles deliver a selective monoazidation product, possibly due to steric reasons. ESI-HRMS studies provide evidence for forming azidooxygenation and alkoxyamine radical cation adducts. The regio- and chemoselectivity of this azidation reaction using the TEMPO-N3 complex have been discussed.

Synthesis, structure elucidation and characterization of new heterocyclic compound: 2-aminobenzimidazolium-4-carboxybutanoate

The molecular compound of 2-amino benzimidazolium-4-carboxybutanoate (AB4CB) was synthesized from 2-aminobenzimidazole (AB) and 4-carboxybutanoic acid (4CB) in equimolar ratio. A brown color single crystal was successfully grown by slow evaporation solution growth technique (SEST). The single crystal X-ray diffraction technique reveals that the grown crystal is in tetragonal crystal system with centrosymmetric I41/a space group. The structure is stabilized through NH…O intermolecular hydrogen bond interaction. From FTIR and Raman spectroscopy, the shift in the wavenumber of fundamental bands such as NH, CH and C = O stretching vibrations evidences the existence of strong hydrogen bond formation, which enhances the bioactivity of the compound. 1H and 13C NMR spectral analyses were used to predict the presence of proton and carbon in the tittle compound. The UV–Vis absorption spectrum exhibits proton transfer from anion to cation by π-π* transition. The decomposition temperature of the grown crystal was measured by TGA/DTA studies and it shows the crystal was stable upto 259ºC. This compound demonstrates good antibacterial and antifungal activities against various bacteria and fungi when compare with standard drugs Penicillium G and Ketoconazole respectively. Further, the binding modes of the compound are ascertained by molecular docking studies against Escherichia coli and Candida albicans.

Highly Efficient Visible-Light Photocatalysts: Bi2O3@TiO2 Derived from Ti-MOFs for Eriochrome Black T Degradation: A Joint Experimental and Computational Study

Herein, we synthesized Ti-MOF through a solvothermal method and subsequently calcined it to form anatase TiO2. We further developed a Bi2O3@TiO2 mixed oxide using impregnation and calcination processes. These oxides showed significant photocatalytic activity for degrading Eriochrome Black T (EBT) dye under visible light irradiation. We characterized the prepared samples using various techniques, including XRD, XPS, FTIR, BET, SEM, EDX, TEM, and UV-DRS analyses. Our results indicated that TiO2 and 10%Bi2O3@TiO2 achieved 80% and 100% degradation of EBT dye solution (50 ppm) within 30 min in acidic medium with a 50 mg catalyst dose, respectively. The calcination of the Ti-MOF into TiO2 improved its sensitivity to visible light. The Bi2O3@TiO2 composite was also effective in degrading other organic pollutants, such as Congo Red (degradation ~99%), Malachite Green (degradation ~95%), Methylene Blue (degradation ~81%), and Safranine O (degradation ~69%). The impregnation of Bi2O3 increased the surface acidity of TiO2, enhancing its photocatalytic activity by promoting hydroxyl group formation through increased water adsorption. Additionally, 10%Bi2O3@TiO2 demonstrated excellent chemical stability and reusability, maintaining high degradation efficiency over four cycles. Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations were performed to understand the degradation mechanisms. UV-Vis absorption spectrum simulations suggested that the anionic HEB−2 (O24) or EB−3 forms of the EBT dye are likely to undergo degradation. This study highlights the potential of Bi2O3@TiO2 composites for effective photocatalytic applications in environmental remediation.

Biofabrication and Characterisation of Ni‐Doped SnO2 Nanoparticles With Enhanced Cytotoxicity, Antioxidant, Antimicrobial and Photocatalytic Activities

ABSTRACTThe present work focuses on Annona muricata leaf extract–mediated green synthesis of pure and nickel‐doped tin oxide nanoparticles for 3%, 5% and 7% concentrations. The properties of the obtained nanoparticles were investigated through XRD, FTIR, XPS, HRTEM–SAED, SEM–EDX and UV–visible spectroscopy techniques. The XRD pattern reveals all samples have tetragonal structures with high crystallinity. The Sn–O stretching vibration has been confirmed through FTIR spectra. The XPS results demonstrate that Sn0.93Ni0.07O2 nanoparticles have Sn3d, Ni2p and O1s oxidation states. EDX spectra contain Ni, Sn and O elements, which indicate the purity of the samples. UV–visible absorption spectrum shows decreases in optical energy bandgap with increases in nickel dopant concentration. The samples exhibit notable antibacterial activity against P. aeruginosa and S. aureus. Also, Sn0.93Ni0.07O2 nanoparticle has higher antifungal activity against A. niger than against C. albicans. Moreover, SnO2 nanoparticles have considerable antioxidant activity in DPPH scavenging compared to Sn0.93Ni0.07O2 nanoparticles. Furthermore, SnO2 nanoparticles have a better cytotoxic effect for L929 normal fibroblast cell lines with an LD50 value of 146.42 μg/mL. Additionally, the photocatalytic activity of SnO2 and Sn0.93Ni0.07O2 nanoparticles was done against methylene blue dye under direct sunlight irradiation. Overall, environmentally friendly synthetic pure and Ni‐doped SnO2 nanoparticles can be used in wastewater filter technologies as well as in medical aids due to their better cytotoxic, antioxidant and antimicrobial effects.

Cu2O/TiO2 Heterostructure‐Based Photoelectrochemical Photodetector with Enhanced Performance and Stability

Cu2O/TiO2 heterostructure is prepared by electrodepositing Cu2O on rutile phase TiO2 particles. The morphology, structural, and optical properties of Cu2O/TiO2 heterostructure are determined by scanning electron microscopy, Raman spectroscopy, X‐ray diffractometer, and UV–vis absorption spectrum. The Cu2O/TiO2 heterostructure photoelectrochemical‐type photodetector is constructed based on this heterostructure. Experimental results show that the photoresponsivity and visible light absorption of the Cu2O/TiO2 heterostructure are significantly enhanced compared to those of TiO2 and Cu2O which demonstrate that the Cu2O/TiO2 heterostructure with a special interfacial structure is conducive to accelerating the separation and transfer of photogenerated carriers. The photoresponsivity and photocurrent density of Cu2O/TiO2 can reach 154 μA W−1 and 15.6 μA cm−2 at 0 V. In addition, the photocurrent density of the Cu2O/TiO2 heterostructure steadily increases with the enhancement of irradiation power density. Moreover, no significant attenuation of the photocurrent density is observed in the prepared Cu2O/TiO2 heterostructure after 1800 s of photo‐on/off cycles. These results suggest that the Cu2O/TiO2 heterostructure‐based photodetector holds great potential in the photodetection field.

Adjustable emission color by gadolinium tungstate phosphor for multiple applications

Crystalline monoclinic structure Gd2(WO4)3 phosphors were prepared by calcining a co-precipitated precursor at 800°C. The XRD patterns exhibited strong signals at the (-221) and (023) planes. The UV-vis absorption spectrum showed strong absorbance in the UV range, with an estimated bandgap energy of about 4 eV. When excited the synthesized phosphors emitted green (Tb3+), red (Eu3+), yellow (Dy3+), and reddish orange (Sm3+), respectively. Utilizing these luminescent properties, flexible composite sheets were fabricated by mixing the phosphors with PDMS. When applied to UV-LED chips. The composites could be molded into various shapes figures. Under normal light, the composites appeared white, but under UV light, they displayed distinct colors, demonstrating their potential for anti-counterfeiting applications. Additionally, when the synthesized phosphor powder was sprinkled onto a glass substrate with fingerprints and illuminated with a UV lamp, the unique features of the fingerprints were clearly visible, indicating potential use in forensic fingerprint analysis.

Photoconductance Induced by Excited-State Intramolecular Proton Transfer (ESIPT) in Single-Molecule Junctions.

Excited-state intramolecular Proton Transfer (ESIPT) molecules have been drawing considerable attention due to their unique photophysical properties and potential applications in optoelectronic devices. Although ground and excited-state tautomerism in various proton transfer systems associated with ESIPT has been extensively studied both experimentally and theoretically, the charge-transport characteristics of ESIPT molecules at the single-molecule level has been little investigated. In this work, scanning tunneling microscope-based fixed junction technique (STM-FJ) is employed with theoretical calculations to explore the electronic properties of SMe-PhOH (with ESIPT properties), together with its photoconductance induced by ESIPT photocycle processes under continuous light illumination (254/275/295/310nm). The conductance variation of SMe-PhOH with different UV wavelengths exhibits a continuous photoconductance distribution, which is highly consistent with the results of its UV-vis absorption spectrum. Theoretical calculations indicate that the interaction between localized HOMO and delocalized LUMO of SMe-PhOH K*-state gives rise to Fano resonance, thereby leading to enhanced conductance compared with its E-state. It reveals the microscopic mechanism of ESIPT process at the nanoscale and provides a constructive perspective for optimizing the photoresponsive properties of ESIPT-type molecules, as well as designing high-performance single-molecule devices.