VO2 is promising sensing material for gas selection, and it has appealed to great attention. The structures of VO2 (M) and VO2 (R) crystal have been studied through the first principles. We ...investigated band structure, the density of states (DOS) and charge density difference of phases of VO2, the results show that when VO2 (M) is transformed into VO2 (R), the structure changes from semiconductor to conductor. The special property is expected to be used in gas sensors, lithium batteries, catalysis, supercapacitors and other fields. The basic findings of this calculation will be conducive to better comprehending of the characteristics and performance of VO2 crystal as a gas sensor material.
The adsorption and sensing capabilities of CO and NO on pristine and metal-decorated (8,0) SWCNT were analyzed by DFT. Both gases cause a slight deformation of the nanotube curvature in the direction ...of molecular adsorption. The molecule's adsorption and sensing performance are enhanced with the transition metal (Sc, Cr, Fe, and Ni) decoration on SWCNT. Decorated nanotubes are suitable for high-temperature sensors. According to relative energies for NO, the operational range is 900–1200 K. For CO/Cr- and Sc-SWCNT between 100 and 200 K and close to 550 K in the cases of decoration with Fe and Ni. From the recovery time analysis, the metal-decorated materials exhibit better performance at high temperatures and low pressures for NO compared to CO. Changes in magnetic moment suggest that Cr-decorated SWCNT could serve as a magnetic sensor for both molecules.
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•The pristine CNT is more reactive to NO than CO.•The transition metal (TM) doping enhances the adsorption energy and sensing performance for NO and CO.•TM-doped SWCNTs are better for sensing NO at high temperature and low pressure.•Recovery time shows that the best sensors for NO are Cr and Ni decorated CNT.•At room temperature, TM-SWCNTs could be effective for absorbing material to clean both gases.
•A novel monovalent copper-based SrCu1.88□0.12O1.94□0.06 photocatalyst containing Cu and O vacancies was designed for the first time.•SrCu1.88□0.12O1.94□0.06 photocatalyst is rich in pore structure ...and covered with a layer of nanosheets.•The mechanism of vacancies enhanced photocatalytic performance was proposed based on DFT.
A novel SrCu□O□ photocatalyst containing Cu vacancy and O vacancy was synthesized for the first time based on solid-phase sintering. The crystal structure, elemental composition, microscopic morphology, optical properties and energy band structure of the samples were characterized and analyzed in detail. The vacancies in the material were determined by ICP-MS and EPR, first-principles calculations showed that the introduction of vacancies extends the forbidden band of the photocatalytic to the visible band. The photocatalytic performance of SrCu□O□ was evaluated by degrading MB and TCHCI. Our results show that SrCu□O□ enhances the degradation performance of organic compounds due to rich vacancies that promote electron-hole pair separation and improve photogenerated carrier separation efficiency. Vacancy-containing metal oxide catalysts have broad application value in environmental remediation.
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•C4-substituted coumarins (X= –CH3, –OH, –NH2, –CONH2, –CHO, and –NO2) are characterized using UV–vis and IR techniques.•Identifying planar geometry for C4-substituted coumarins, except -NO2 ...substitution.•Acceptor functional groups reduce the energy of lowest 2P-actived state and enhances TPA cross-section.•Identification of maximum TPA cross-section of 18.82 GM (at 1.36 eV) in aqueous solution.•Polar solvents, like water, can effectively enhance the TPA cross-section.
The versatile applications of coumarin derivatives in materials processing, fluorescence imaging, data storage, and photodynamic therapy have sparked considerable interest in scientific community. In this research paper, we explore the UV–vis spectra, IR spectra, and two photon absorption (TPA) characteristics of biological active coumarin derivatives under the influence of electron withdrawing (specifically X = CONH2, CHO, and NO2) and electron donating (X= -CH3, -OH, -NH2) functional groups at C-4 position. To delve into the absorption spectra, we employ time-dependent density functional theory calculations. Results revealed that acceptor functional groups (specifically R = CONH2, CHO, and NO2) not only lower the energy of the lowest two photon active state but also increase the corresponding TPA cross-section. Furthermore, using the Conductor-like Polarizable Continuum Model (CPCM), the influence of solvent polarity on C-4 substituted coumarin derivative was also investigated. Our findings effectively capture how substitutions and solvents impact the nonlinear optical response in coumarins, as evidenced by the measurement of the two-photon absorption cross-section (σTPA). This study offers valuable insights for identifying and designing novel coumarin derivatives with C4 substitutions, unlocking new and intriguing possibilities for their practical applications.
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Different concentrations of zirconium with a fixed quantity (4 wt%) of chitosan (CS) doped nickel cobaltite (NiCo2O4) nanorods were synthesized using a co-precipitation approach. This cutting-edge ...research explores the cooperative effect of Zr-doped CS-NiCo2O4 to degrade the Eriochrome black T (EBT) and investigates potent antibacterial activity against Staphylococcus aureus (S. aureus). Advanced characterization techniques were conducted to analyze structural textures, morphological analysis, and optical characteristics of synthesized materials. XRD pattern unveiled the spinal cubic structure of NiCo2O4, incorporating Zr and CS peak shifted to a lower 2θ value. UV–Vis spectroscopy revealed the absorption range increased with CS and the same trend was observed upon Zr, showing a decrease in bandgap energy (Eg) from 2.55 to 2.4 eV. The optimal photocatalytic efficacy of doped NiCo2O4 within the basic medium was around 96.26 %, and bactericidal efficacy was examined against S. aureus, revealing a remarkable inhibition zone (5.95 mm).
In this study, we have investigated the electronic , structural, elastic, optical and thermodynamic properties of the copper-based ternary semiconductors, that is, KCuZ (Z= Te, Se). The properties of ...these materials have been precisely determined based on first-principle calculations. The lattice constants, bulk modulus and equilibrium total energies were obtained from Murnaghan equation of state and have a good agreement with other theoretical and experimental methods. The absorption spectra was analyzed to determine the active window of electromagnetic spectrum of the compounds. The elastic constants of these materials were elucidated and hence provided vital information about the material’s ability to withstand external stress. The results indicate that the materials conform to the stability criteria with brittle behavior and anisotropic nature in the HCP structure. The electronic band structures and density of states were computed and the results obtained suggests that the these materials have a band gap of 1.25 eV and 1.1 eV for KCuTe and KCuSe respectively and therefore they are suitable for photovoltaic applications. The materials are also found to posses desirable optical properties i.e. the materials have a good optical absorption since highest absorption peaks occur within the UV region, small reflectivity and high dielectric constant indicating that the materials is suitable for use as solar absorbers.
•KCuTe and KCuSe are both hexagonal in nature and belong to space group P63/mmc.•KCuTe and KCuSe structures are mechanically and thermodynamically stable.•All the two compounds are brittle.•Band gaps of 1.1 eV for KCuSe and 1.25 eV fo KCuTe.
We present a theoretical investigation of the structural, electronic and optical properties of few layer graphene/TiO2 composites involving either single or bilayer graphene and the (101) surface of ...TiO2 anatase, in view of the importance of carbonaceous materials such as graphene to enhance solar light-driven photocatalytic activity of TiO2. Calculations have been performed by combining periodic DFT calculations to TD-DFT carried out on finite clusters extracted from the periodic structures and embedded in an array of point charges devised to reproduce the periodic electrostatic environment. Although van der Waals interactions dominate the graphene/TiO2 interaction, TiO2 properties are significantly affected by its combination with graphene in the composite materials. In particular, we found that such materials present favorable key features for photocatalysis applications, with high charge carriers mobilities, an increase of the absorption in the visible range together with a red-shift of the photoresponse of TiO2. These results confirm that graphene can enhance solar light-driven photocatalytic activity of TiO2, especially when few layer graphene-based composites are considered. Furthermore, the proposed computational approach appears as a reliable and effective tool to model both the electronic and the optical properties of heterostructures at low computational cost.
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•A reliable and effective computational protocol is proposed to model composites.•Gr-based composites offer better properties than TiO2 for photocatalysis.•Few layer Gr-based composites offer better properties than single layer ones.
•4-Substituted thiophene and benzoic acid-based azo dyes.•Effect of substituent on DSSC and NLO properties.•DFT and TD-DFT computational analysis for photovoltaic and NLO properties.•With increasing ...donating strength at position 4 of the thiophene ring, enhancement in DSSC efficiency, and NLO activity.
The effect of altering the donating strength of secondary donors at the 4th position of the thiophene ring in a series of dyes labeled AB1 to AB9 is investigated in this study. According to the findings, the orientation of the secondary donor has a considerable impact on molecular planarity, resulting in changes in charge transfer (CT) properties within the thiophene-azo-benzoic acid backbone. The time-dependent density functional theory (TD-DFT) study supports these findings, indicating that the vertical absorption maximum of the dyes increases with the secondary donor's donating strength. From AB1 to AB5, photovoltaic parameters show an increase in DSSC performance. Furthermore, dye@TiO2 cluster experiments suggest the possibility of these dyes interacting with TiO2, resulting in red-shifted absorbance of dye@TiO2 clusters.
Theoretical predictions are confirmed by the synthesis of AB1 to AB4, with initial absorption in dimethylformamide (DMF) and energies of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) following a similar pattern as observed in density functional theory (DFT) studies. TGA results show that AB1 to AB4 have remarkable thermal stability, enabling their practical application in DSSCs. The efficiencies of the constructed DSSCs varied, with AB4 having the highest (1.90 ± 0.1) and AB1 having the lowest (1.29 ± 0.1). Secondary donors play a critical role in determining molecular characteristics and device performance, according to the theoretical and experimental DSSC results.
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