Ultraviolet-visible Spectroscopy Research Articles

Evidence of Preferential Aluminum Site Loss during Reaction-Induced Dealumination.

Understanding the mechanism of steam-induced dealumination of zeolite catalysts is of high relevance for tuning their performance and stability in multiple industrial processes. A combination of 27Al and 1H-1H double-quantum single-quantum magic angle spinning nuclear magnetic resonance and diffuse-reflectance ultraviolet-visible spectroscopies identified a preferential dealumination of tetrahedral aluminum sites in H-ZSM-5 zeolites. Framework aluminum atoms facing channels display reactivity toward steam higher than that of those in their intersections. Dealumination randomly occurs on isolated and proximate sites. However, the concentration of the latter sites decays more prominently. These findings contribute to a better understanding of the stability of zeolite catalysts in the presence of steam.

Stability of Non-Fullerene Acceptor–Based Organic Solar Cells: Chemical and Physical Properties at the Interfaces and Active Layer

Abstract Organic solar cells (OSCs) have improved power conversion efficiency (PCE); however, their stability remains challenging. This study evaluates the chemical stability and performance of non-fullerene acceptor-based OSCs (NFA-OSCs) using a blend of Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)] (PM6) and 2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2",3’':4’,5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (Y7). Inverted organic solar cells (iOSCs) were examined using indium tin oxide (ITO) as the cathode, N,N'-Bis(N,N-dimethylpropan-1-amine oxide)perylene-3,4,9,10-tetracarboxylic diimide (PDINO) as the electron transport layer (ETL), PM6:Y7 as the active layer, molybdenum trioxide (MoO3) as the hole transport layer (HTL), and silver (Ag) as the anode. Over 270 days, without voltage application, NFA-iOSCs were exposed to ambient conditions, room temperature (RT) of 19.4 ± 0.4 °C and a relative humidity (RH) of 50 ± 5 %, and monitored using time-of-flight secondary ion mass spectroscopy (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible spectroscopy (UV-Vis), and Raman spectroscopy. The results showed that the active layer maintained stability with minimal degradation with or without protective layers (Ag and MoO3). The TOF-SIMS and XPS analyses confirmed that oxygen did not diffuse into the layers where it was initially absent, thereby ensuring chemical stability. Raman spectroscopy results supported these findings, showing stable vibrational modes over time. This study highlights the degradation mechanisms of NFA-OSCs and the importance of protective layers in extending the device lifetime, contributing to the durability and commercial viability of OSCs, and advancing sustainable solar energy technologies.

Sustainable Green Synthesis of ZnO Nanoparticles from Bromelia pinguin L.: Photocatalytic Properties and Their Contribution to Urban Habitability

Aguama (Bromelia pinguin L.), a plant belonging to the Bromeliaceae family, possesses a rich content of organic compounds historically employed in traditional medicine. This research focuses on the sustainable synthesis of ZnO nanoparticles via an eco-friendly route using 1, 2, and 4% of Aguama peel extract. This method contributes to environmental sustainability by reducing the use of hazardous chemicals in nanoparticle production. The optical properties, including the band gap, were determined using the TAUC model through Ultraviolet–Visible Spectroscopy (UV–Vis). The photocatalytic activity was evaluated using three widely studied organic dyes (methylene blue, methyl orange, and rhodamine B) under both solar and UV radiation. The results demonstrated that the ZnO nanoparticles, characterized by a wurtzite-type crystalline structure and particle sizes ranging from 68 to 76 nm, exhibited high thermal stability and band gap values between 2.60 and 2.91 eV. These nanoparticles successfully degraded the dyes completely, with methylene blue degrading in 40 min, methyl orange in 70 min, and rhodamine B in 90 min. This study underscores the potential of Bromelia pinguin L. extract in advancing sustainable nanoparticle synthesis and its application in environmental remediation through efficient photocatalysis.

Phytoextract-assisted synthesis of Fe2O3/MgO nanocomposites for efficient photocatalytic degradation of gentian violet

Organic-based pollutants are extensively released from various industries and they potentially harm the environment and human health. Photocatalysis is regarded as one of the most promising techniques for removal of organic contaminants from wastewater. Therefore, in this study, iron oxide-based nanocomposites were synthesized by an emerging green and sustainable method using Ethiopian endemic plant extract, Echinops kebericho M. as a capping and stabilizing agent. The phytoextract-assisted synthesized nanoparticles (NPs) α-Fe2O3 and nanocomposites (NCs) α-Fe2O3/MgO calcinated at a temperature of 400°C were characterized and used for their photocatalytic activities toward gentian violet (GV) dye degradation using ultraviolet–visible spectroscopy (UV-vis) at optimized catalyst dose, initial GV concentration, pH, and time conditions. The X-ray diffraction (XRD) analysis result revealed that the mean crystal size of α-Fe2O3 and α-Fe2O3/MgO is 11.2 and 15.4 nm, respectively. Characterization results of scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) clearly showed the successful deposition of MgO on α-Fe2O3. The maximum degradation of GV, 96.2%, was observed by using α-Fe2O3/MgO after 60 min under visible light irradiation. Thus, synthesized NCs were shown to have better GV degradation efficiency in a shorter time as compared to the previously reported nanomaterials. The results revealed photocatalytic degradation using endemic plant extract-assisted synthesized NCs, α-Fe2O3/MgO, is considered a greener, simple, and more efficient method for the removal of organic dyes.

Insight into Magnesium Doping on Morphology, Optical, and Electrical Properties of Cu2O Layer Synthesized by Electrodeposition Method

Cu2O stands out as a promising semiconductor material for solar energy conversion, primarily due to its exceptional light-absorbing qualities and its widespread availability. However, its efficiency is somewhat hindered by its relatively low carrier mobility and a limited absorption band for carriers. The introduction of magnesium (Mg) doping into Cu2O has emerged as a potential means to enhance its morphology, optical characteristics, and electrical properties, making it an intriguing avenue for exploration. To fabricate the Mg-doped Cu2O layers, an electrodeposition process was employed on an Indium Tin Oxide (ITO) substrate. The resulting films were then subjected to characterization using Field Emission Scanning Electron Microscopy (FESEM), Ultraviolet-Visible Spectroscopy (UV-Vis), and HALL Effect Measurement, focusing on their morphology, optical properties, and electrical behaviors. Notably, the concentration of magnesium played a significant role in shaping the properties of the Cu2O layer. The fabrication process extended up to a dopant concentration of 0.3 M for both undoped Cu2O and Mg-doped Cu2O layers, leading to morphological alterations. Specifically, the grain size increased with varying dopant concentrations, but it became smaller and more compact after doping with 0.3 M Mg. The average absorbance of visible light for both undoped and Mg-doped Cu2O layers fell within the range of 1~2 au. Intriguingly, a doping level of 0.3 M Mg led to the simultaneous achievement of high carrier mobility (29.98 cm2/Vs), low bulk carrier concentration (2.3.928 x 1021 cm-3), and high resistivity (5.3 x 10-5 Ω cm) in the Cu2O material. Additionally, Cu2O/ITO thin films exhibiting rectifying characteristics were successfully fabricated, confirming the semiconductor nature of the deposited p-type Cu2O layer. The primary objective of this study was to synthesize Cu2O layers doped with varying concentrations of Mg and thoroughly characterize their morphology, optical attributes, and electrical behaviors through the electrodeposition method. The study findings and implications were extensively discussed.

Polymer-modified screen-printed electrode-based electrochemical sensors for doxorubicin detection

In the last decade, intensive research has been performed in the field of analytical electrochemistry, seeking designs of electrochemical sensors capable of providing better analytical characteristics in terms of sensitivity, selectivity, reliability, ease of fabrication and use, and low cost, especially for pharmaceutical drug monitoring. Our research has primarily focused on developing screen-printed electrode-based sensors and their application as electrochemical platforms for drug determination and monitoring, specifically emphasizing their suitability for surface modification. A commercial screen-printed graphene electrode was used as the electrochemical sensing component, which was subsequently modified with polymers, such as polyvinylidene fluoride and chitosan. All studied electrodes were tested using a doxorubicin hydrochloride (DOX) solution with a concentration of 0.002 mol L-1 dissolved in 0.1 mol L-1 phosphate-buffered saline at pH 6.7. Cyclic voltammetry was used as an electrochemical characterization technique to gather data on all tested electrodes' electrochemical activity. The morphological characterization of the electrodes was done using scanning electron microscopy. The changes in the electrolyte during the electrochemical measurements were followed through ultraviolet-visible spectroscopy. The modified electrodes demonstrated a favorable electrochemical response to DOX and exhibited higher electrical conductivity than the commercial one. The characterization results indicated that the Ch-modified electrode exhibited excellent electrochemical conductivity and demonstrated strong electrochemical performance. The evaluations of this electrode comprised the definition of the lowest limit of detection and limit of quantification among the tested electrodes, with values of 9.822 and 32.741 µmol L-1, respectively, within a linear concentration range from 1.5 to 7.4 µmol L-1. Additionally, the electrodes showed excellent repeatability, stability, and reproducibility, confirming their suitability for sensitive DOX detection.

Screening and inclusion of luteolin for β-cyclodextrin: molecular simulations and experiments

In this study, we first established a guest small molecule screening mechanism by molecular simulation and then screened lignans from ten polyphenolic compounds to identify the most suitable guest molecule for encapsulation with β-cyclodextrin (β-CD). Subsequently, the subject–guest interactions and encapsulation mechanisms of lignans with β-CD, 2-hydroxypropyl-cyclodextrin, and 2,6-dimethyl-cyclodextrin (DM-β-CD) were investigated using a combination of molecular simulation and experimental methods, respectively. Molecular simulations were performed to calculate the microstructural parameters, including solubility parameters, binding energies, and mean square displacements. The simulation results demonstrated that DM-β-CD exhibited the strongest interaction with luteolin and formed the most stable inclusion complex. The inclusion complexes of luteolin with the three cyclodextrins were prepared by the freeze-drying method, and the formation of the inclusion complexes was demonstrated using infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and ultraviolet-visible spectroscopy. Phase solubility studies confirmed the formation of 1:1 stoichiometric inclusion complexes of lignans with cyclodextrins. Furthermore, 2,2-diphenyl-1-pyridine hydrazine free radical scavenging experiments demonstrated that the inclusion complexes exhibited enhanced antioxidant capacity. In light of these findings, it can be concluded that among the three cyclodextrins, DM-β-CD was optimally encapsulated with luteolin.

Studies of Structural and Optical Properties of Nickel Chloride and Glycine Doped Potassium Hydrogen Phthalate (KHP) Crystal

A semi-organic single crystal of potassium hydrogen phthalate (KHP, K(C6H4COOH.COO)) doped with Nickel Chloride (NiCl2) and Glycine (C₂H₅NO₂) was successfully harvested at room temperature to enhance the characteristics of KHP using a slow evaporation approach. The concentration of 1 mol % of Nickel Chloride and 6 mol % Glycine was used during the fabrication of the Nickel Chloride and Glycine doped KHP single crystal. Powder X-Ray diffraction (XRD), ultraviolet visible spectroscopy (UV-Vis), and Fourier transform Infrared (FTIR) analysis were used to analyze the grown single crystal. Powder XRD investigation verified an orthorhombic crystal structure and lattice parameter .To evaluate optical energy band gap and optical transparency using UV-Vis spectral. According to, FTIR analysis, and dielectric studies, it is evident that the crystal modification noticeably by adding dopant.

Silver Doped Polypyrrole Nanocomposite-based Gas sensor for Enhanced Ammonia Gas Sensing Performance at Room Temperature

Nanocomposite, which comprise organic and inorganic materials have gained increasing interest in the application for enhanced sensing response to both reducing and oxidation gases. In this study, a nanocomposite is chemical polymerization synthesized by reinforcing Ag nanoparticles with different concentration doped into the matrix of Polypyrrole (PPy). This nanocomposite is used as a sensing platform for ammonia detection with different concentration (ppm). The homogeneous distribution of Ag nanoparticles onto the PPy matrix provides a smooth and dense surface area, further accelerating the transmission of electrons. The synergistic effect of PPy@Ag matrix is responsible for the outstanding conductivity, compatibility and catalytic power of the proposed gas sensor. The structure, morphology, and surface composition of as-synthesized samples were respectively, examined via X-ray diffraction, field emission scanning electron microscopy, Ultraviolet-visible spectroscopy, Thermogravimetric analysis and Fourier transform infrared spectroscopy. The results indicated that sensor based on the PPy@Ag5 (2 gm) nanocomposite showed the highest response toward ammonia as compare to pure PPy at room temperature with a response value is 58 % to 100 ppm. Overall, the obtained findings demonstrated that the PPy@Ag nanocomposite are promising materials for gas sensing applications in environmental monitoring.

Dielectric Characteristics of Iridium Substituted Co0.05-xTi0.95O2 Dilute Magnetic Semiconductors for Electrical Device Applications

In the current study, a cost effective solid-state method have been used to prepare iridium (Ir) substituted and cobalt doped titanium dioxide (TiO2) dilute magnetic semiconductors (DMS) materials {i.e.; IrxCo0.05-xTi0.95O2; 0.00 ≤ x ≤ 0.05 DMS}. The impact of Ir substitution on structural, optical and dielectric properties for the prepared IrxCo0.05-xTi0.95O2; 0.00 ≤ x ≤ 0.05 DMS samples have been investigated using X-ray diffractometer, ultraviolet-visible spectroscopy and LCR (inductor, capacitor and resistor) meter, respectively. The structural analysis confirms the tetragonal rutile phase formation with space group p42/mnm-136, while the values of band gap energy increase with increasing Ir concentrations in prepared DMS materials and band gap value approaches the band gap energy of void band gap materials for large applications. The dielectric constant and tangent loss have been studied as a mapping of frequency (20Hz - 20MHz) at room temperature. Both the dielectric constant and tangent loss linearly decrease with increase in applied frequency and become stable at high frequency values, therefore, these DMS materials could be beneficial for storage and electrical device applications.

Influence of LaMnO3 Nanocrystallite Size on its Optical and Raman Spectra

: In the current study, nanocrystalline LaMnO3 perovskite was prepared by combustion method and annealed at different annealing temperatures. The X-ray diffraction (XRD) patterns provided evidence that the structure formed has a Rhombohedral structure with R3 ̅c space group. The remarkable growth in the crystallite size, reduction in microstrain, and dislocation density were observed with annealing temperature. Ultraviolet-visible spectroscopy was used to determine the optical band gap by the Tauc-plot method. The optical band gap was found to be 3.5 ± 0.4eV and 2.9 ± 0.5eV for 600°C and 1200°C annealed samples, respectively. The observed results were influenced by crystallite size. Raman spectra of the LaMnO3 nanocrystallites revealed five Raman-active modes, like out-of-phase rotation modes and bending mode of MnO6 octahedra. Moreover, the intensity of vibrational modes also varied significantly with annealing temperature.

Polymeric Schiff base containing phenylhydrazine and 2-thiobarbituric acid: Synthesis, characterization, antibacterial and antifungal studies

Polymeric Schiff base ligand (MFT) derived from 2-hydroxyacetophenone, phenylhydrazine, formaldehyde, and 2-thiobarbituric acid was synthesized via condensation reaction. The synthesized MFT ligand was complexed with the metal acetates of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) to form a polymeric Schiff base-metal complexes. The ligand and its metal polychelates were characterized by Fourier transform infra red (FT-IR), Ultraviolet-visible spectroscopy (UV-vis.), X-ray diffraction (XRD), Proton nuclear magnetic resonance spectroscopy (1H NMR), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX) and Electron paramagnetic resonance spectroscopy (EPR). The EPR spectrum of MFT-Cu(II) supported a distorted octahedral or square-planar geometry. The synthesized materials were also screened against bacterial (S. aureaus, S. mutans, B. cereus, S. pyrogenes, S. viridans, S. epidermids, C. xerosis, E. coli, K. pneumonia, P. vulgaris, P. aeruginosa) and fungal strains (A. niger, F. oxysporum, and A. oryzea). Moreover, the MFT-Zn(II) complex have demonstrated good thermal stability, as well as strong antibacterial and antifungal activities compared to the ligand and other metal polychelates.

Annealing construction of in situ heterojunction for photocatalytic degradation of bisphenol A

Here, we report the synthesis of bismuth oxyiodide (BiOI) photocatalysts with oxygen vacancy defects by a one-pot solvothermal method followed by annealing in a nitrogen atmosphere. This method allows the oxygen vacancy concentration to be tuned and provides new insights into defect engineering of photocatalytic materials. We found that the Bi2O3/BiOI heterojunction formed after annealing at 400°C significantly improves the photocatalytic performance, which provides a new strategy for the optimal design of structures for efficient photocatalysts. Using a combination of characterization techniques such as X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), as well as density-functional theory (DFT) calculations, we have elucidated the photocatalytic mechanism of the Bi2O3/BiOI heterojunctions, highlighting their role in facilitating the photogenerated charge-carrier separation and transfer. The optimized A-B40 samples exhibited photocatalytic degradation efficiencies of up to 99.7% for bisphenol A (BPA), highlighting their potential for remediation of environmental pollutants. This study presents a method for the preparation of high-performance BiOI-based photocatalysts, which offers valuable theoretical and experimental prospects for the development of eco-friendly photocatalytic materials.

Preparation of polyvinyl alcohol/carboxymethyl cellulose sodium/chitosan paper-based antimicrobial indicator cards using mixed anthocyanin with stability-colorimetric sensitivity: Monitoring freshness of carp

In this study, an anthocyanin solution with both high stability and sensitivity was successfully prepared through a blending method, and the optimal ratio was determined. Ultraviolet-visible spectroscopy analysis demonstrated that an increase in the proportion of black bean peel anthocyanins resulted in a deeper color and a more pronounced color change effect. Moreover, the stability of the blended anthocyanins was markedly enhanced with an increase in the proportion of purple cabbage anthocyanins, resulting in a slower decomposition rate under light, temperature, oxidation, and varying pH conditions. The blended anthocyanins, employed as a pH indicator, were utilized to prepare an antibacterial indicator card. It was observed that the mechanical properties of the coated paper remained unaltered by the ratio of the mixed pigments. The mixed pigments enhanced the stability of the antibacterial indicator card with respect to environmental fluctuations while facilitating more rapid and sensitive color transitions in the presence of ammonia and under disparate pH conditions. The application of indicator cards with five different anthocyanin ratios to fish resulted in a shelf life extension of 1–2 days compared to the control group and enabled real-time monitoring of fish freshness. A comprehensive evaluation demonstrated that the optimal indicator performance was attained when the mass ratio of black bean peel anthocyanins to purple cabbage anthocyanins was 1:1.

Synthesis, and Characterization of Silver Nanoparticles Functionalized with a Chalcone for Potential Antioxidant Activity

Silver nanoparticles (AgNPs) possess unusual optical, electrical, and catalytic properties. Hence, they are promising candidates in biomedical applications due to their shape and high surface area. Therefore, in present study, AgNPs were functionalized by using chalcone derivative as reducing and capping agent. The synthesized chalcone derivative was characterized by Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), and mass spectroscopic techniques (MS). The resulting AgNPs were thoroughly characterized by different techniques, including ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), and FTIR. The monodispersed AgNPs were produced with 49.5 ±6 nm diameter based on DLS results, and TEM results showed a spherical shape with a size of 30±5 nm. Also, the absorption peak at 394 nm in the UV-Vis spectrum confirmed the production of AgNPs. The biological applications of both chalcone derivative and AgNPs as antioxidant agents were evaluated. The obtained results were promising for the development of antioxidant drugs derived from silver nanoparticles functionalized chalcone derivative with hydroxy and methoxy substituents.

Effects of electron beam irradiation on the optical and structural properties of PEDOT: PSS thin films deposited by spin coating technique

This study investigates the effect of electron beam irradiation on the structural and optical properties of Poly (3,4-ethylenedioxythiophene) polystyrene sulphonate (PEDOT: PSS) semiconductor films. PEDOT: PSS was deposited on thin films using spin coating technique at varying speeds of 1000, 2000, 3000, and 4000 rpm. Based on the pre-characterisation analysis, the thin film fabricated at 4000 rpm is identified as optimal. The fabricated PEDOT: PSS thin films were irradiated at doses of 10, 20, 30, 40 and 50 kGy at an energy of 1 MeV. The films were characterised using Atomic Force Microscopy (AFM), Ultraviolet–visible Spectroscopy (UV-Vis), X-ray diffractometer and energy dispersive X-ray spectroscopy (EDX). The optical properties of PEDOT:PSS thin film show that the transmittance was decreased after exposure to electron beam radiation, indicating a degradation with increasing total ionising dose (TID). The bandgap of irradiated PEDOT: PSS thin film shows a decreasing trend from 3.36 eV (unirradiated) to 3.30 eV (50 kGy) after the thin film was exposed to electron beam radiation at a maximum dose of 50 kGy. On the aspect of surface morphology, the AFM results show that the surface roughness of the PEDOT: PSS decreased with increasing TID, resulting in a smoother surface from 1.84 to 1.28 nm. Based on the XRD result obtained, the crystalline phase of the PEDOT: PSS thin film was maintained while the grain size improved from 264.87 nm (unirradiated) to 377.45 nm after exposure to electron beam radiation mainly at 30 and 40 kGy, indicating an optimised threshold exposure within the range. The findings provide valuable insight for developing organic semiconductors with enhanced structural, morphological and optical band gap properties after electron beam radiation exposure.

Enhanced Fenton-Photocatalytic Degradation of Rhodamine B over Cobalt Ferrite Nanoparticles Synthesized by a Polyvinylpyrrolidone-Assisted Grinding Method.

A simple grinding method using polyvinylpyrrolidone (PVP) as a capping agent is introduced to synthesize CoFe2O4 nanoparticles. The effects of calcination temperature (ranging from 450 to 850 °C) on the structural, morphological, physical, and optical properties of the materials are investigated using various techniques, including thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), N2 adsorption isotherm, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), and vibrating sample magnetometry (VSM). The presence of PVP significantly suppresses the agglomeration of the materials, resulting in a nanocrystalline size of 18 nm for a sample calcined at 650 °C, which is approximately 38% smaller than that of the sample synthesized without PVP. Among the materials studied, the sample calcined at 650 °C exhibits unique properties, including optimal average pore size, specific surface area, and band gap energy, contributing to its superior photocatalytic degradation of rhodamine B via the Fenton reaction. Systematic experiments are performed to investigate the effects of pH, catalyst dosage, dye, and H2O2 concentrations and competitive anions on the rhodamine B degradation. Additionally, the Fenton photodegradation of RhB on CoFe2O4 is well-fitted to the first-order kinetic model. The redox pairs of Co(III)/Co(II) and Fe(III)/Fe(II) in the CoFe2O4 spinel structure might facilitate the formation of Fenton radicals, contributing to the decomposition of RhB through a proposed four-step mechanism. Notably, the material exhibits a strong magnetic response and maintains its excellent performance over five cycles, demonstrating the high potential for reusability as a photocatalyst.

Use of BODIPY and BORANIL Dyes to Improve Solar Conversion in the Fabrication of Organic Photovoltaic Cells Through the Co-Sensitization Method

This work addresses the implementation of the co-sensitization technique to increase the energy efficiency of organic dye-sensitized solar cells (DSSCs). Fluorescent dyes derived from boron complexes— (BORANIL) and (BODIPY)— were successfully synthesized and used as co-sensitizers in different volume percentage ratios to verify the most effective concentration for photon capture through these sensitizers. The dyes were optically characterized using ultraviolet–visible spectroscopy (UV-VIS) and Fourier transform infrared (FTIR), analyzing them through the optical performance of each hybrid combination of dyes, an optimization of the photon collection capacity in the tests performed in a volume percentage ratio of 25:75 or 1:3. The morphology and surface roughness of the electrodes were analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. Through electrochemical characterizations, it was found that the highest photovoltaic conversion efficiency was obtained with the ATH1005 (D) dye mixed with ATH032 (G) in the proportion of 25%:75% or DG 1:3, with efficiency (η) of 3.45%, against 2.43% and 1.90% for DG 1:1 and DG 3:1 cells, respectively. Cells with BODIPY dyes also present higher conversion efficiencies compared to BORANIL cells. The results corroborate the presentation of organic solar cells as a viable option for electricity generation.

Synthesis and photocatalytic activity of Ag/AgCl for removal of BTX vapors under visible light: modeling by ANN

Abstract Among volatile organic compounds, benzene, toluene, and xylene (BTX) are the most harmful organic compounds and the removal of these harmful compounds is mandatory. In the current study, Ag/AgCl composite was successfully synthesized via deposition–precipitation along with the photoreduction method. The scanning electron microscopy, x-ray powder diffraction, photoluminescence spectroscopy, Fourier transform infrared spectra, and ultraviolet-visible diffuse reflectance spectroscopy were employed to characterize the synthesized products. The photocatalytic property of the products was investigated by evaluating on photodegradation of BTX vapors under the radiation of visible light. The results showed that Ag/AgCl exhibits enhanced visible-light photocatalytic activity compared with AgCl. The strong surface plasmon resonance of metal Ag nanoparticles anchored on the AgCl surface can be responsible for the enhanced visible-light photocatalytic activity of the Ag/AgCl. The influence of the basic operational parameters such as type of BTX, the concentration of BTX, photocatalyst shape, relative humidity, and radiation time on the removal efficiency of BTX was studied. The data obtained from removal tests were modeled by a three-layered feed-forward artificial neural network. The optimized ANN architecture was strong at predicting the removal efficiency of the BTX contaminants with R2 > 0.99 and a very low mean square error. The sensitivity analysis using Garson’s method displayed that all explored process parameters influence the photocatalytic removal of the BTX contaminants. The obtained ANN model is used to predict the photodegradation of BTX at different conditions.

Nanoparticle-protein interactions: Spectroscopic probing of the adsorption of serum albumin to graphene oxide‑gold nanocomplexes surfaces

Graphene oxide‑gold nanocomposites (GO-AuNCPs) are promising candidates in nanomedicine. They will inevitably bind with biomolecules such as serum albumin (SA) in the body while they enter the organism. The interaction between GO-AuNCPs and human serum albumin (HSA)/bovine serum albumin (BSA) were investigated by using multispectroscopic methods, elucidating the binding principles through molecular simulations. The results of ultraviolet-visible (UV–vis) absorption spectroscopy and steady-state fluorescence spectroscopy indicated that GO-AuNCPs interacted with HSA/BSA with different degrees of interaction. The binding of GO-AuNCPs and HSA/BSA was a spontaneous endothermic reaction, and the quenching mechanism is static quenching. The binding constant (Ka) value of BSA binding to GO-AuNCPs at the same temperature was greater than that for HSA, indicating a stronger affinity of BSA for GO-AuNCPs. Molecular simulation revealed that the binding sites of GO-AuNCPs on HSA/BSA were located within the slits of the subdomains IB and IIIA, rather than within any known binding regions. This significant finding was validated by using of site markers phenylbutazone (PB) and flufenamic acid (FA). Synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, and circular dichroism (CD) spectroscopy showed that the conformation of HSA/BSA was altered upon the addition of GO-AuNCPs, resulting in slight structural changes of tryptophan and tyrosine residues. Although the secondary structure of HSA/BSA was changed, the α-helix remained dominant. The results provide a theoretical and experimental foundation for developing of safe and effective nanomaterials, which is of great theoretical significance.