Absorption Bands Research Articles

Photocatalytic, antioxidant, and antibacterial activities of biocompatible MgO flake-like nanostructures created using Piper betle leaf extract

In this study, biocompatible magnesium oxide (MgO) nanostructures were synthesized using an aqueous solution of Piper betle leaf methanolic extract. The color change during the synthesis process, i.e., colorless to dark brown solution, indicates the formation of MgO nano structures which is further confirmed through UV–Visible spectrum that exhibited characteristic absorption band at 329 nm. Results obtained from morphological analysis reveal that MgO nano flakes (MgO NFs) are present as triangular and polyhedral shapes having an average size ranging between 150 and 200 nm with clear lattice fringes. Secondary metabolites were clearly identified from the FTIR spectrum, and they helped in reduction and stabilization during the synthesis of MgO NFs. The XRD pattern displayed Braggs planes of (111), (220), (220), (311), and (222) with a face centered cubic (FCC) structure, which was further confirmed from the SAED pattern using HRTEM analysis. The as-synthesized MgO NFs manifested profound antimicrobial activity against gram positive as well as gram-negative bacteria with favorable biocompatibility. Furthermore, methylene orange dye was degraded almost completely (98.36 %) in the presence of MgO NFs photo catalysts within 1 h of sunlight illumination. In addition, MgO NFs displayed high level of antioxidant properties with recorded IC50 value of 15.89 μg/ml.

Improved pH performance of cresol red radiochromic dye for spectroscopic investigations

Optical properties of a synthetic dye cresol red (CR) were investigated at its absorption band maxima (λmax) using double beam scanning UV/VIS spectrophotometer for the sample solutions having initial optimized dye-concentration. Urbach Edge method was utilized for the investigations of absorption edge (AE= 2.35 eV) while Mott and Davis model was utilized for the investigations of band gap energy for direct (Eg,direct= 2.45 eV) and indirect (Eg,indirect= 2.23 eV) allowed transitions. The spectrophotometric-evaluations assisted most-sensitive working pH of sample solutions was optimized for a long spectrum of pH values from 1 to 12 for further investigations. Some spectrophotometric and comercial parameters e.g., molar extinction coefficient ε, stability, reproducibility and fading were figured out. The response efficacy was also observed to enhanc the sensitivity and stability of the CR solutions by incorporating a selected amount (by %vol) of a polar additive ethanol. The invariant aborbance related isosbestic wavelength for both acidic and alkaline samples remained unaffected from pH and firmly stood at 475 nm. The improved and reasonable pH values were found to be pH 4 and pH 9 and hence were opted for CR solutions and may further be applicable to the radiation-induced degradation phenomenon based on radiolytic bleaching.

A highly sensitive colorimetric and fluorometric sensor for the detection of cyanide

Certain anions play a vital role in metabolic reactions in our body, but the cyanide ion is highly toxic and poisonous to humans, animals, and the environment even at extremely low concentrations. To detect CN−ions, a highly sensitive electron donor-π-acceptor molecular system (IC) was designed based on the carbazole electron donor and 1,3-indanedione electron acceptor. The IC molecular probe was synthesized through simple organic transformations with good yields and characterized by all spectroscopic methods, including single-crystal X-ray diffraction. The IC probe molecule absorbs in the UV–visible region (200–550 nm), and fluorescence emission encompasses 400–750 nm with LE and CT emission bands. A systematic study suggests that the addition of cyanide ions caused both longer wavelength absorption bands and CT fluorescence emission intensity to decrease. Cyanide ion detection can be visualized with the naked eye, where the yellow color of the IC probe solution changes to colorless upon adding cyanide ion solution. Both UV–visible and fluorescence emission spectral changes with the addition of cyanide ions are attributed to the nucleophilic addition of cyanide at the vinylic carbon, which is confirmed by the 1H NMR, HRMS and fluorescence lifetime studies. The cyanide ion detection limit of the IC has been estimated to be 0.43 µM, far below the WHO permissible limit for cyanide ion concentration in potable water, thus broadening the utility of the IC probe in detecting cyanide in Tapioca. A prototype TLC testing strip has been fabricated for the qualitative determination of cyanide in THF/water medium.

Exo-6b2-Methyl-Substituted Pentabenzocorannulene: Synthesis, Structural Analysis, and Properties.

exo-6b2-Methyl-substituted pentabenzocorannulene (exo-PBC-Me) was synthesized by the palladium-catalyzed cyclization of 1,2,3-triaryl-1H-cyclopenta[l]phenanthrene. Its bowl-shaped geometry with an sp3 carbon atom in the backbone and a methyl group located at the convex (exo) face was verified by X-ray crystallography. According to DFT calculations, the observed conformer is energetically more favorable than the endo one by 39.9 kcal/mol. Compared to the nitrogen-doped analogs with intact π-conjugated backbones (see the main text), exo-PBC-Me displayed a deeper bowl depth (avg. 1.93 Å), redshifted and broader absorption (250-620 nm) and emission (from 585 to more than 850 nm) bands and a smaller optical HOMO-LUMO gap (2.01 eV). exo-PBC-Me formed polar crystals where all bowl-in-bowl stacking with close π ⋅ ⋅ ⋅ π contacts is arranged unidirectionally, providing the potential for applications as organic semiconductors and pyroelectric materials. This unusual structural feature, molecular packing, and properties are most likely associated with the assistance of the methyl group and the sp3 carbon atom in the backbone.

Exo‐6b2‐Methyl‐Substituted Pentabenzocorannulene: Synthesis, Structural Analysis, and Properties

Abstractexo‐6b2‐Methyl‐substituted pentabenzocorannulene (exo‐PBC‐Me) was synthesized by the palladium‐catalyzed cyclization of 1,2,3‐triaryl‐1H‐cyclopenta[l]phenanthrene. Its bowl‐shaped geometry with an sp3 carbon atom in the backbone and a methyl group located at the convex (exo) face was verified by X‐ray crystallography. According to DFT calculations, the observed conformer is energetically more favorable than the endo one by 39.9 kcal/mol. Compared to the nitrogen‐doped analogs with intact π‐conjugated backbones (see the main text), exo‐PBC‐Me displayed a deeper bowl depth (avg. 1.93 Å), redshifted and broader absorption (250–620 nm) and emission (from 585 to more than 850 nm) bands and a smaller optical HOMO–LUMO gap (2.01 eV). exo‐PBC‐Me formed polar crystals where all bowl‐in‐bowl stacking with close π ⋅ ⋅ ⋅ π contacts is arranged unidirectionally, providing the potential for applications as organic semiconductors and pyroelectric materials. This unusual structural feature, molecular packing, and properties are most likely associated with the assistance of the methyl group and the sp3 carbon atom in the backbone.

The nonlinear optical properties of meso-substituted porphyrins using spatial self-phase modulation

Herein, we studied the nonlinear optical properties of four meso-substituted porphyrins (H2MHTPP, H2THTPP, H2DETPP, and H2TETPP) by the spatial self-phase modulation (SSPM) method, using CW lasers with wavelengths of 532 nm and 780 nm. All samples exhibit strong nonlinear response due to the thermal optical nonlinear effect at 532 nm, which corresponds to the strong absorption band. In addition, four porphyrin samples were calculated that have nonlinear refractive index coefficients of the same order of magnitude (10−10 m2/W) at 532 nm. However, four porphyrins exhibited different optical nonlinear responses affected by the type and numbers of peripheral substituents at 780 nm. This work is of significance for reasonably adjusting the structure of compounds and improving their third-order nonlinear optical coefficients.

Presenting a new fluorescent probe, methyl(10-phenylphenanthren-9-yl)sulfane sensitive to the polarity and rigidity of the microenvironment: applications toward microheterogeneous systems.

A molecule, methyl(10-phenylphenanthren-9-yl)sulfane (MPPS), with a straightforward structure, has been synthesized, characterized, and explored as a new fluorescent probe for microheterogeneous systems. The photophysical properties of MPPS have been studied through experimental and theoretical calculations using the range-separated hybrid functional CAM-B3LYP in conjunction with a 6-311++g(d,p) basis set. Theoretical calculations show that the freely rotating phenyl ring forms a 94° dihedral angle with the phenanthrene ring in the ground state. Experimentally found two absorption bands correspond to the n → π* and π → π* transitions supported by the frontier molecular orbital calculations. Two excited singlet states, E-1 and E-2 (the former being more stable than the latter in the gas phase), exist with dihedral angles between the phenyl and phenanthrene rings as 142° and 133°, respectively, in the gas phase. Two emitting states in a condensed medium of varying polarities are supported by the steady-state fluorescence and fluorescence intensity decay data. Emission energies, fluorescence intensities, and excited singlet state lifetimes change with the polarity of the solvents. To support that the free rotation in the molecule is responsible for these changes, the fluorescence properties of another molecule, methyl(10-(o-tolyl)phenanthren-9-yl)sulfane (MTPS), with restricted rotation of the substituted benzene, i.e., o-tolyl ring have been studied. The fast-intensity decay component of MPPS is ascribed to the conformer in the E-1 state. The molecule has proved to be an excellent polarity probe explored to determine the critical micelle concentrations (cmc) values of different surfactants, which agree well with the literature reports. Different regions of binding isotherm (specific, non-cooperative, cooperative, and massive binding) of a gemini surfactant, 12-6-12,2Br- with bovine serum albumin (BSA) have been successfully demonstrated by the steady-state and time-resolved fluorescence and fluorescence anisotropic properties of MPPS. Docking results show that MPPS resides in the hydrophobic pocket of BSA. The fluorescence quenching of BSA by MPPS reveals the location of Trp residues of BSA. Thus, a polarity and molecular rigidity-sensitive fluorescent molecule, MPPS has been presented here that can potentially be used to monitor the changes in the microenvironment of biomolecules in different processes.

Aromaticity in the Spectroscopic Spotlight of Hexaphyrins.

Spectroscopic properties are commonly used in the experimental evaluation of ground- and excited-state aromaticity in expanded porphyrins. Herein, we investigate if the defining photophysical properties still hold for a diverse set of hexaphyrins with varying redox states, topologies, peripheral substitutions, and core-modifications. By combining TD-DFT calculations with several aromaticity descriptors and chemical compound space maps, the intricate interplay between structural planarity, aromaticity, and absorption spectra is elucidated. Our results emphasize that the general assumption that antiaromatic porphyrinoids exhibit significantly attenuated absorption bands as compared to aromatic counterparts does not hold even for the unsubstituted hexaphyrin macrocycles. To connect the spectroscopic properties to the hexaphyrins' aromaticity behaviour, we analyzed chemical compound space maps defined by the various aromaticity indices. The intensity of the Q-band is not well described by the macrocyclic aromaticity. Instead, the degeneracy of the frontier molecular orbitals, the HOMO-LUMO gap, and the |ΔHOMO-ΔLUMO|2 values appear to be better indicators to identify hexaphyrins with enhanced light-absorbing abilities in the near-infrared region. Regions with highly planar hexaphyrin structures, both aromatic and antiaromatic, are characterized by an intense B-band. Hence, we advise using a combination of global and local aromaticity descriptors rooted in different criteria to assess the aromaticity of expanded porphyrins instead of solely relying on the absorption spectra.

Synergistic microwave absorption effect of graphene-BN-Fe3O4 composite at thin thickness

With the quick evolution of information technology, it is necessary to develop high-performance microwave absorbers to attenuate electromagnetic waves. Herein, we prepared graphene-BN-Fe3O4 composites by a facile solvothermal method using graphene as the dielectric loss component, Fe3O4 as the magnetic loss component and BN as the dielectric modulating component. BN and graphene form a 2D/2D structure adhered with Fe3O4. When the ratio of BN to graphene is 1:1 with Fe3O4 content of 60 %, the absorber exhibits excellent electromagnetic wave absorption performance. A RLmin of −42.31 dB is obtained with an effective band of 4.5 GHz at 1.04 mm, while the maximum EAB of samples can reach 4.59 GHz (13.41–18 GHz) with a RLmin value of –33.16 dB at 1.05 mm. The prepared composite exhibits a wide absorption band at a thin thickness. Enhanced microwave absorption performance is achieved mainly due to the synergistic effect of increased interface polarization loss, appropriate conductive loss, and improved impedance matching.

Photoacoustic Spectroscopy of Titanium Dioxide, Niobium Pentoxide, Titanium:Niobium, and Ruthenium-Modified Oxides Synthesized Using Sol-Gel Methodology.

The aim of this work was the development and morphological/chemical, spectroscopic, and structural characterization of titanium dioxide, niobium pentoxide, and titanium:niobium (Ti:Nb) oxides, as well as materials modified with ruthenium (Ru) with the purpose of providing improvement in photoactivation capacity with visible sunlight radiation. The new materials synthesized using the sol-gel methodology were characterized using the following techniques: scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), photoacoustic spectroscopy (PAS), and X-ray diffraction (XRD). The SEM-EDS analyses showed the high purity of the bases, and the modified samples showed the adsorption of ruthenium on the surface with the crystals' formation and visible agglomerates for higher calcination temperature. The nondestructive characterization of PAS in the ultraviolet visible region suggested that increasing calcination temperature promoted changes in chemical structures and an apparent decrease in gap energy. The separation of superimposed absorption bands referring to charge transfers from the ligand to the metal and the nanodomains of the transition metals suggested the possible absorption centers present at the absorption threshold of the analyzed oxides. Through the XRD analysis, the formation of stable phases such as T-Nb16.8O42, o-Nb12O29, and rutile was observed at a lower temperature level, suggesting pore induction and an increase in surface area for the oxides studied, at a calcination temperature below that expected by the related literature. In addition, the synthesis with a higher temperature level altered the previously existing morphologies of the Ti:Nb, base and modified with Ru, forming the new mixed crystallographic phases Ti2Nb10O29 and TiNb2O7, respectively. As several semiconductor oxide applications aim to reduce costs with photoexcitation under visible light, the modified Ti:Ru oxide calcined at a temperature of 800 °C and synthesized according to the sol-gel methodology used in this work is suggested as the optimum preparation point. This study presented the formation of a stable crystallographic phase (rutile), a significant decrease in gap energy (2.01 eV), and a visible absorption threshold (620 nm).

Ratiometric fluorescence probe based on carbon dots and p-phenylenediamine-derived nanoparticles for the sensitive detection of manganese ions.

A ratiometric fluorescence probe based on carbon quantum dots with 420nm emission (bCQDs) and a p-phenylenediamine-derived fluorescence probe with 550nm emission (yprobe) is constructed for the detection of Mn2+. The presence of Mn2+ results in the enhanced absorption band at 400nm of yprobe, and the fluorescence of yprobe is significantly enhanced based on the chelation-enhanced fluorescence mechanism. The fluorescence of bCQDs is then quenched based on the inner filtration effect. The ratio (I550/I420) linearly increases with the increase of Mn2+ concentration within 2.00 × 10-7-1.50 × 10-6M, and the limit of detection is 1.76 × 10-9M. Given the fluorescence color changing from blue to yellow, the visual sensing of Mn2+ is feasible based on bCQDs/yprobe coupled with RGB value analysis. The practicability of the proposed method has been verified in tap water, lake water, and sparkling water beverage, indicating that bCQDs/yprobe has promising application in Mn2+ monitoring.

Spectroscopic assessments on Sm3+ ions doped phospho-borate glasses mixed with fluoride modifiers for the applications of reddish-orange visible light

Sm3+ions doped Phospho-Borate glasses were synthesized and their physical and spectroscopic parameters were studied to evaluate its potential reddish-orange emission for photonic applications. Structural investigation made through XRD analysis confirms the amorphous nature. The evaluated bonding parameters from the absorption spectral analysis confirm the ionic bonding of the Sm–O network in the prepared glasses. Four emission bands were observed from the luminescence spectra, and the HT 4G5/2 → 6H7/2 is observed at 601 nm. The oscillator strength values elucidate the intensity of the absorption bands, and the PBKZnF:Sm sample exhibits a higher oscillator strength value. The Judd-Ofelt intensity parameters were observed to trail the trend Ω4 > Ω6. > Ω2 for the majority of the samples. The CIE 1931 color chromaticity investigation confirms that the present glass samples are suitable for reddish-orange media. Barium and strontium-incorporated glasses exhibit outstanding lasing potential, which was confirmed through the efficiency of the quantum yield and some of the radiative parameters like effective bandwidth, transition probability and stimulated emission cross-section. Radiative parameters have been calculated from the luminescence spectra. Amid all transitions, 4G5/2 →6H7/2 transition has higher transition probability and higher stimulated emission cross-section values for all the prepared glass samples. Barium-incorporated glass exhibits a higher emission cross-section of 30.55 × 10−22 cm2 and a transition probability of 30.89 s−1 compared to all other glasses. The non-exponential decay profiles of the fabricated samples were plotted by examining the excitation wavelength at 402 nm and emission wavelength at 600 nm. Of all the prepared glasses, the quantum efficiency is found to be higher for the glass sample PBKSrF:Sm (65 %).

Schottky-Barrier-Free Plasmonic Photocatalysts for Solar-Driven Ammonia Synthesis

Ammonia is not only an indispensable feedstock to produce essential industrial chemicals like fertilizers, but it is also a potential hydrogen energy carrier owing to its high energy density and hydrogen capacity. Currently, most ammonia required for humans comes from the Haber–Bosch process, which contributes more than 90% of the annual global ammonia output. However, the harsh reaction conditions of this process result in serious energy and environmental issues. According to the relevant statistics, the ammonia industry consumes about 2% of the total energy and generates about 1.6% of the total CO2 emission annually in the world.It is therefore crucial to develop a green and sustainable strategy for ammonia synthesis. Among various alternative technologies of the Haber–Bosch process, artificial photosynthesis has attracted wide research interests and has been regarded as a promising, environmentally friendly, and energy-saving process. Photocatalytic ammonia synthesis can utilize renewable solar energy to drive the reaction and operate under mild conditions, which possesses the benefits of the simple reaction system, low cost, and safety. Although numerous photocatalysts have been explored over the past several decades, their activity and efficiency have still been low and far from the practical application requirements. It is therefore a huge challenge to design efficient photocatalysts for ammonia synthesis.Localized surface plasmon resonance (LSPR) has recently drawn enormous attention. LSPR can not only endow plasmonic nanomaterials with large absorption cross-sections and intense local field enhancement but also generate energetic hot electrons and hot holes. Owing to the appealing features of LSPR, plasmonic photocatalysis has shown great potential in ammonia synthesis. Plasmonic photocatalysts are usually composed of noble metals and wide bandgap semiconductors. However, the Schottky barrier will form at the metal–semiconductor interface in such hybrid structures due to the mismatch of the band structures between plasmonic metals and semiconductors. Hence, a large portion of the hot electrons cannot cross the Schottky barrier and get lost in the metal through the recombination with the holes. To overcome the drawbacks caused by the Schottky barrier, it is strongly desirable to develop a new type of plasmonic semiconductor photocatalysts, i.e., Schottky-barrier-free plasmonic photocatalyst.The Schottky-barrier-free plasmonic photocatalysts are usually degenerately doped semiconductors containing lattice oxygen vacancies. They possess high free electron densities and strong plasmon resonance because of the high-level doping, which results in abundant hot charge carriers upon plasmon excitation. Moreover, they also have appropriate surface sites that can adsorb reactant molecules and activate them. The photogenerated plasmonic hot charge carriers can get trapped at the defect sites and thereafter drive redox reactions. Compared with traditional metal–semiconductor hybrid plasmonic photocatalysts, Schottky-barrier-free plasmonic photocatalysts enable hot charge carriers to be transported nearly freely in the material, resulting in high charge utilization and photocatalytic efficiency.We have demonstrated the synthesis of Schottky-barrier-free plasmonic MoO3−x nanospheres (NSs) with remarkably high oxygen vacancy (OV) contents by aerosol-spray. The MoO3−x NSs can achieve efficient ammonia photosynthesis through a “killing two birds with one stone” mechanism. On the one hand, the OVs can serve as chemisorption sites for N2 molecules and participate in their activation. On the other hand, the introduction of OVs generates a large number of free electrons near the conduction band, which induces a broad absorption band from the visible to the NIR region owing to the plasmon resonance. The Schottky-barrier-free nature of this plasmonic semiconductor allows free transportation of the plasmonic hot charge carriers, while the defect states introduced by the OVs can effectively trap the hot electrons to prevent rapid electron–hole recombination. As expected, the as-prepared material exhibits a superior ammonia production rate, with the highest apparent quantum efficiency (AQE) of 1.24% at 808 nm and an appreciable solar-to-ammonia conversion efficiency (SACE) of 0.057% for NH3 production. Besides MoO3−x , WO3−x is also an excellent candidate for Schottky-barrier-free plasmonic photocatalysts. We have synthesized square WO3−x nanoplates hydrothermally. The WO3-x nanoplates possess regular morphology, wide light absorption, and great ammonia production performance. Furthermore, by introducing doping elements (Mo, V, Fe, Bi) into WO3−x nanoplates, the N2 activation and dissociation can be improved by refining the defect states. The Mo-doped WO3−x nanoplates exhibit the highest ammonia production rate of 145.50 μmol g−1 h−1 with SACE of 0.011% since the Mo species can promote the chemisorption and polarization of N2 molecules and significantly reduce the reaction barrier. Notably, Mo-doped WO3−x nanoplates are a dual-function photocatalyst that can oxidize water to hydrogen peroxide in a stoichiometric ratio while synthesizing ammonia. Figure 1

Effect of pre-hydrolysis on the dissolution of hardwood pulp in double salt ionic liquid

Abstract Ionic liquids (ILs) are potentially alternative solvents for cellulose dissolution. In this article, effect of hemicellulose in cellulose dissolution in ILs and the regeneration process were investigated. Hardwood pulps were produced by kraft (KP) and pre-hydrolysis kraft (PHKP) processes. The α-cellulose and residual pentosan contents were 95.6 % and 4.2 % in PHKP and 84.3 % and 9.9 % in KP, respectively. Both pulps were dissolved in 1-butyl-3-methylimidazolium chloride [C4mim]Cl, 1-butyl-3-methylimidazolium acetate [C4mim]CH3CO2 and their double salt (DSIL), [C4mim](CH3CO2)0.6Cl0.4 at 90 °C. It was observed that PHKP had slightly higher solubility in both ILs and DSIL. The dissolved pulps were regenerated by water and characterized by FTIR, TGA, X-ray diffraction, and viscosity. Regenerated pulp film formed smooth and homogenous surface. The viscosity of regenerated PHKP was higher than the original PHKP, which affected the strength of the produced cellulose film. As observed in FTIR, the regenerated cellulose showed a stronger absorption band at 1,647 cm−1 corresponding to the C–O stretching vibration of C–O–H. The crystalline structures of regenerated KP and PHKP from [C4mim](CH3CO2)0.6Cl0.4 changed to cellulose II form from the original cellulose I form.

Improved Structural and Electrochemical Properties of Mg-Doped Nickel Cobaltite Nanoparticles Synthesized Using Low-Temperature Microwave Hydrothermal Method

The specific capacitance of materials influences the energy storage capacity. A series of MgxNi1-xCo2O4 (x = 0.0 - 0.1) nanoparticles using the low-temperature microwave-hydrothermal (M-H) method at 160 0C temperature, and sintered at 600 °C. The samples were then characterized using X-ray diffraction (XRD), Field Emission Scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). It is observed from X-ray diffraction that all the samples are cubic spinel in nature with space group Fd-3m, and the lattice parameter varies between 8.097 (x = 0.0) and 8.083 (x = 0.10). The nanoparticles have a hexagonal nanoflake-like shape morphology with an average particle size of 180 nm to 350 nm. The tetrahedral and octahedral absorption bands were observed at 561 cm-1 and 654 cm-1, respectively. The valence states of Ni2+/Ni3+, Co2+/Co3+, and Mg2+ were confirmed by X-ray photoelectron spectroscopy. The electrochemical studies using CV and GCD were performed on all the samples. High values of specific capacitance of 332 F g−1, energy densityof 9.05 Wh kg-1, and power density of 224.84 W kg-1 were observed for the sample x = 0.08. Therefore, Mg0.08Ni0.92Co2O4 sintered at 600 °C shows good impedance and electrochemical properties, which are helpful for supercapacitor applications. Figure 1

(Invited) Non-Fullerene Acceptor in Organic Solar Cells Toward Improving Performance as Indoor Light Energy Harvester

Research in organic solar cells aims to develop new materials that improve efficiency. The inception of emerging non-fullerene acceptors (NFAs) by replacing the fullerene counterpart in organic solar cells (OSCs) has pushed the bulk-heterojunction based photovoltaics to achieve efficiencies around 18% [1-6]. In order to produce efficient OSCs, it is required to have donor and acceptor materials with matching absorption bands in the Vis-NIR range, high charge-carrier mobility, and a small energy offset to minimize voltage losses. Mainly, the development of Y7 NFA molecule has improved power conversion efficiencies by pairing selected polymer donors, such as PM6 [7, 8]. Nowadays, OSCs have attracted great attention for being used as indoor light energy harvesters. The organic materials in the active layer can have tuned optical band gaps, providing an absorption spectrum that matches with emission spectra of several indoor lights, e.g., halogen lights, LED (light-emitting diodes), and FLs (fluorescent lamp), which have different emitting spectra [9, 10].The use of OSCs for indoor light harvesting applications is promising for integration into low-power indoor electronic devices from microwatts to milliwatts, such as data transfer systems, alarm systems and distributed controls. Moreover, the OSCs have the possibility to be used with power wireless sensor nodes connected to the Internet of Things. At present, LEDs are the most popular low-light level sources which can be found in offices and homes. The intensity of the light emitted by an artificial light source, per unit area of a surface is called illuminance and measured in units of lux (lx). A level 500 lx is typically recommended for office environments and 200 lx for living room environments.In this research, we have been aiming at the performance and stability over time of organic solar cells under LED illumination using fullerene and non-fullerene acceptors. We have chosen as the indoor illumination source an LED lamp with a color temperature of 3000 K and color rendering index (CRI) > 80 following the protocols ISOS [11]. The LED lamp output illuminances were varied in the range from 200 to 1500 lx. We have used PM6 as polymer donor material due to their absorption spectrum and energy band gaps well-matched to the incident LED spectrum. In order to research the improvement of the performance of OSCs under indoor illumination we have compared PC70BM fullerene acceptor with ITIC-M, Y6-O, and Y7 non-fullerene acceptors. As a result, under 1000 lx illumination we achieved PCEs from ~ 12% using Y6-O, ~ 15% using PC70BM, ~16% using Y7 up to more than 18% efficiency using ITIC-M. The study is performed including optical and electrical characterization with the purpose of understanding the behavior and the transport processes taking place in the device. In future work, we focus on the stability of the encapsulated OSCs under continuous LED illumination following the agreed stability testing protocols to study which active layer turns out to be more stable under these conditions. Acknowledgements: This work was supported by the Ministerio de Ciencia, Innovación y Universidades (MICINN/FEDER) PDI2021-128342OB-I00, by the Agency for Management of University and Research Grants (AGAUR) ref. 2021-SGR-00739, and by the Catalan Institution for Research and Advanced Studies (ICREA) under the ICREA Academia Award. M. Ramírez-Como acknowledge to CONAHCYT ref. BPPA-20220624083033039-2364083.

Hydrogen bonding to the electron accepting group controls the absorption spectrum of a push–pull stilbene adsorbed on amorphous silica

The photophysical and photochemical properties of push–pull photoswitches, such as stilbene derivatives, are very sensitive to their surroundings, allowing, e.g., for the control of the spectral properties or alternatively for probing the molecular environment. Here, we investigate how various adsorption motifs of 4-(N, N-Dimethylamino)-4’-nitrostilbene (DANS) on an amorphous glass surface influence its absorption spectra. Particular attention is given to the prominent first bright charge transfer state and the factors governing these modifications. The absorption spectra is simulated using time-dependent density functional theory on a large set of adsorption geometries that exhibit different kinds of molecule–surface interactions. We find that C–H⋯O interactions of the methyl or phenyl moieties with the glass affect the spectrum only marginally, whereas the dispersion interaction of the π system with the surface tends to diminish the intensity of the first absorption band. Moreover, an enhancement of the push–pull properties of DANS and a significant redshift occur whenever O–H⋯O hydrogen bonds with the NO2 group are present, whereas a hydrogen bond O–H⋯N to the NMe2 group results in a blueshift.

Handheld Near-Infrared Spectroscopy for Undried Forage Quality Estimation.

This study investigates the efficacy of handheld Near-Infrared Spectroscopy (NIRS) devices for in-field estimation of forage quality using undried samples. The objective is to assess the precision and accuracy of multiple handheld NIRS instruments-NeoSpectra, TrinamiX, and AgroCares-when evaluating key forage quality metrics such as Crude Protein (CP), Neutral Detergent Fiber (aNDF), Acid Detergent Fiber (ADF), Acid Detergent Lignin (ADL), in vitro Total Digestibility (IVTD)and Neutral Detergent Fiber Digestibility (NDFD). Samples were collected from silage bunkers across 111 farms in New York State and scanned using different methods (static, moving, and turntable). The results demonstrate that dynamic scanning patterns (moving and turntable) enhance the predictive accuracy of the models compared to static scans. Fiber constituents (ADF, aNDF) and Crude Protein (CP) show higher robustness and minimal impact from water interference, maintaining similar R2 values as dried samples. Conversely, IVTD, NDFD, and ADL are adversely affected by water content, resulting in lower R2 values. This study underscores the importance of understanding the water effects on undried forage, as water's high absorption bands at 1400 and 1900 nm introduce significant spectral interference. Further investigation into the PLSR loading factors is necessary to mitigate these effects. The findings suggest that, while handheld NIRS devices hold promise for rapid, on-site forage quality assessment, careful consideration of scanning methodology is crucial for accurate prediction models. This research contributes valuable insights for optimizing the use of portable NIRS technology in forage analysis, enhancing feed utilization efficiency, and supporting sustainable dairy farming practices.

Incorporation of nitrogen and oxygen in carbon: A highly tuned electrochemistry with facile synthesis and its influence on optical and electrode performance in supercapacitors

A new approach for synthesizing heteroatom-doped carbon nanostructures has been developed, in which nitrogen and oxygen have been effectively infused into the graphitic core using the required precursors. The heteroatoms incorporated into the carbon matrix and their corresponding structural features are examined. The observed X-ray diffraction pattern reveals the presence of amorphous carbon forms that resemble carbon nitride in their structure. The presence of additional N–O and C–O bonds gives strong evidence of a graphitic structure with oxygen and nitrogen incorporation, as shown by the Fourier transform-infrared peaks. The X-ray photoelectron spectroscopy analysis reveals important information regarding the bond formation in the graphitic core of the sample. The study focused on examining the porous and intricately interconnected network structures, showcasing a variety of particle morphologies, and was carried out using scanning electron and transmission electron microscopy. The lattice defects are investigated using transmission electron microscopy-high angle annular dark field technique to explore the surface morphology. The influence of incorporated O and N in carbon structure drastically reduced the electron density of the graphitic core. As a result, the absorption bands observed were around 300–400 nm, showing the semiconductors' absorption characteristics. Three-electrode electrochemical systems are fabricated with working electrodes based on COx and CNx materials. The COx and CNx-modified electrodes were meticulously tested for their performance in supercapacitor applications. The COx samples exhibit a significant specific capacity value of 439.20 C g−1 under a low current density of 4 A g−1. The CNx samples demonstrate a specific capacity of 420.00 C g−1 under 4 A g−1 current density.

Study on the Structure, Morphology, Dielectric, and Piezoelectric Properties of Large-Grain (Ba0.85Sr0.15)1-x Pb x TiO3 Ceramic System for 0.02 ≤ x ≤ 0.08.

Barium strontium lead titanate ((Ba0.85Sr0.15)1-x Pb x TiO3), along with various compositions (x(mol %) = 0, 2, 4, and 8), was synthesized through the conventional sol-gel reaction method. Following this, the resultant powders underwent a carefully controlled calcination process at 1000 °C for a period of 4 h. The examination of the crystalline phase of the calcined ceramics was conducted at room temperature using X-ray diffraction. Rietveld refinement of the XRD data, performed using FullProf, revealed that the samples exhibited a tetragonal structure within the space group P4mm. The impact of Pb doping on the lattice structure of BaSr1-x TiO3 was explored by analyzing the charge density distribution. The FTIR analysis unveiled a distinct absorptive band within the 450-600 cm-1 range, indicative of the stretching and bending vibrations associated with TiO6 octahedra. Notably, sintering the material at 1150 °C for 4 h resulted in improved densification, as observed in scanning electron microscopy images showcasing a nearly uniform distribution of densely packed grains. Through the utilization of Williamson-Hall plots derived from XRD data, the average particle diameter was estimated to fall within the range of 131.87-141 nm, with an associated uncertainty ranging from 5 to 10%. Additionally, the dielectric characteristics unveiled the presence of a negative dielectric constant (εr) spanning the frequency range from 1 kHz to 2 MHz. The (Ba0.85Sr0.15)1-x Pb x TiO3 ceramic displayed a widespread occurrence of negative permittivity, emphasizing the influence of dielectric resonance. The investigation revealed that the sintered ceramic with the formula (Ba0.85Sr0.15)1-x Pb x TiO3 exhibited exceptional piezoelectric properties, achieving the highest piezoelectric constant (d33 = 137 pC/N) and electromechanical coupling factor (k p = 0.49).