Decrease In Gap Energy Research Articles

Boosting Multicolor Emission Enhancement in Two-Dimensional Covalent-Organic Frameworks via the Pressure-Tuned π-π Stacking Mode.

Covalent-organic frameworks (COFs) are dynamic covalent porous organic materials constructed from emissive molecular organic building blocks. However, most two-dimensional (2D) COFs are nonemissive or weakly emissive in the solid state owing to the intramolecular rotation and vibration together with strong π-π interactions. Herein, we report a pressure strategy to achieve the bright multicolor emission from yellow to red in the 2D triazine triphenyl imine COF (TTI-COF). Intriguingly, the TTI-COF experiences a 24-fold enhancement under a mild pressure of 2.7 GPa compared with the initial state. Joint experimental and theoretical results reveal that the restricted intramolecular chemical bond vibrations and the reduced π-π interactions originating from the offset stacking mode account for the significant pressure-induced emission enhancement. Furthermore, such piezochromic behavior may be ascribed to the decreased energy gap and enhanced intermolecular interaction. Our investigation offers constructive guidelines for designing 2D COF materials with high photoluminescence performance.

Sn(IV) Complexes of 5,10,15,20-Tetraaryl-5,15-diazaporphyrinoids: A Promising Platform for Evaluating the 20π-Electron Antiaromaticity.

Porphyrinoids in the 20π-electron state have been extensively studied from the fundamental viewpoint of investigating their structure-antiaromaticity relationships. However, most of the 20π porphyrinoids are highly distorted and unstable in air, which hinder the comprehensive analysis of paratropic ring-current effects derived from planar π-electron systems. Herein, we present the first examples of antiaromatic Sn(IV) complexes of 5,10,15,20-tetraaryl-5,15-diazaporphyrinoids (SnX2TADAPs), prepared by the complexation of the corresponding freebases with Sn(II) chloride under aerobic conditions and subsequent metathesis of the axial ligands, that show paratropic ring-current effects. Notably, both neutral 20π-electron derivatives and 19π-electron radical cations of SnX2TADAP are extremely stable in air owing to the intrinsic electronic effects of the central Sn(IV) unit and meso nitrogen atoms. NMR spectroscopy, cyclic voltammetry, and density functional theory calculations were performed to assess the ring-current effects and orbital energies of a series of the 20π-electron SnX2TADAPs, and the results reveal that the paratropic ring-current effects arising from the planar 20π-electron DAP ring increases with a decrease in the HOMO-LUMO energy gap.

Development and characterization of HPMC/NaAlg-CuO bio-nanocomposites: Enhanced optical, electrical, and antibacterial properties for sustainable packaging applications

Copper oxide nanoparticles (CuO NP) were incorporated into a hydroxypropyl cellulose (HPMC) and sodium alginate (NaAlg) matrix through a casting method to create bio-nanocomposite films. XRD analysis confirmed the semi-crystalline nature of the HPMC/NaAlg matrix, with a broad peak at 2θ = 21.22°, which decreased in intensity as CuO concentration increased, indicating a shift towards an amorphous structure. FT-IR analysis demonstrated changes in band intensity, which can be attributed to the reduced volume fraction of the polymer blend in the presence of the CuO nanofiller. SEM images showed homogeneity at low CuO NP concentrations, but at 0.9 wt% CuO, nanoparticle aggregation became evident. The UV–visible spectra indicated a redshift from 212 nm to 246 nm and a decrease in optical energy gap from 4.78 eV for the pure blend to 2.99 eV at 0.9 wt% CuO, associated with increased localized defect states. AC electrical conductivity and dielectric properties improved with CuO dispersion, enhancing the bio-nanocomposite's suitability for electrochemical and optoelectronic applications. The bio-nanocomposites demonstrated significant antibacterial activity, with films containing 0.4 and 0.7 wt% CuO achieving the largest inhibition zones against B. subtilis, S. aureus, P. aeruginosa, and E. coli. Overall, these findings suggest that HPMC/NaAlg-CuO bio-nanocomposites are promising candidates for use in antibacterial packaging and optoelectronics.

Investigation of physical properties of Mn doped lead phosphate glasses

Mn doped lead phosphate glasses (MnLPG) as (40-x)%P2O5-40 % PbO-16.5%Na2O-3.5%Al2O3-xMnO2 (x = 0, 1, 2, 3 and 4 %) matrix system are prepared by the melt-quenching method. The physical properties have been performed using several techniques such as X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Fourier Transform InfraRed spectroscopy (FTIR), Raman spectroscopy, UV–Visible properties, photoluminescence (PL) and EPR (electron paramagnetic resonance). XRD confirms the amorphous character of the glasses. DSC reveals an improvement of the glass transition temperature Tg values by increasing the density ρ and the oxygen packing density OPD and decreasing the molar volume Vm which leads to have a network glass more compact and tightly packed and reticulates the phosphate groups. The Infrared and Raman results show an opposite behaviour with a broken of the phosphate structure and the disruption of the P–O–P linkages. The optical spectra present absorption bands characteristic of Mn3+ and Mn2+ ions octahedral transition. Mott and Davis model presents a decrease of the band gap energy winth the MnO2 addition. The Urbach energy ΔEurb shows an increase with increase of manganese amount which is related to the increase of the structural disorder degree as the rate of manganese increases. The EPR spectrum of the 4 % Mn doped glass is characterized by a strong resonance signal centered at g near 2.0 another weak signal at g∼4.3 with no hyperfine structure. PL spectra exhibit emission bands corresponded to the oxygen defects presented in the glass and the appearance of a new band assigned to the Mn2+ ions as high as Mn increases.

Li2CO3 as a Modifier for PVA/PVP/PEG Blend Polymer Electrolytes: Effects on Structural Integrity, Electrical Performance, Thermal Behavior and Optical Properties

ABSTRACT The effects of incorporating lithium carbonate (Li2CO3) into a polyvinyl alcohol/polyvinyl pyrrolidone/polyethylene glycol (PVA/PVP/PEG) blend polymer electrolyte were investigated. Electrolytes were prepared via solution casting method, with Li2CO3 added at 10, 20, and 30 wt.% to the PVA/PVP/PEG blend (50/30/20 ratio). Fourier transform infrared spectroscopy analysis revealed interactions between the added salt and the polymer blend. The addition of both PEG and Li2CO3 resulted in increased ionic conductivity, reaching a maximum of 4.51 × 10− 5 S/cm at 30°C with 20 wt.% Li2CO3. Ionic conductivity also exhibited a positive temperature dependence. Optical analysis showed a decrease in the optical energy gap with the addition of PEG and Li2CO3. Differential thermal analysis indicated improved thermal stability with increasing Li2CO3 content, as evidenced by higher onset, endset, and midset temperatures. The enhanced properties of the modified electrolyte suggest its potential applicability in lithium-based electrochemical devices.

Thio and Seleno Derivatives of Angelicin as Efficient Triplet Harvesting Photosensitizers: Implications in Photodynamic Therapy.

Photodynamic therapy (PDT) is widely accepted in medical practice for its targeted induction of apoptosis in cancerous cells. Angelicin (Ang) has traditionally been known for its efficacy in cancer treatment and its capability to enter a photoexcited triplet state. This study has comprehensively assessed the effects of substituting individual chalcogen atoms at three specific positions in Angelicin, with the objective of facilitating access to this elusive triplet state to enhance its role as a photosensitizer in PDT. The study scrutinizes various enhancements and factors that are crucial for efficient triplet harvesting. The decrease in singlet-triplet energy gap (ΔEST) and increased spin-orbit coupling (SOC) values present numerous viable pathways for intersystem crossing (ISC), leading to the triplet manifold. The lifetime of ISC, thus, decreases from 10-5 s-1 in Ang to 10-8 s-1 in thioangelicin (TAng) and finally to 10-9 s-1 in selenoangelicin (SeAng). Additionally, this study investigates the two-photon absorption properties of thio and seleno-substituted Angelicin for their potentialities as non-UV photosensitizers. The interplay between electron-withdrawing and electron-donating substitutions in these derivatives significantly enhances the two-photon absorption cross-sections (σ) to as high as 49.3 GM while shifting the absorption wavelengths towards the infrared region enabling them as efficient PDT photosensitizers.

Interfacial adsorption of ionic liquids (ILs) on graphitic carbon nitride (g-C3N4) nanosheets: A DFT study

The adsorption of nine common ionic liquids (ILs) on two well-known structures of graphitic carbon nitride (g-C3N4) nanosheets, including Triazine-g-C3N4 and Heptazine-g-C3N4 has been investigated using density functional theory (DFT) method in gas phase and water solvent. The interactions between the ILs and the nanosheets are characterized by several techniques, such as quantum theory of atoms in molecules (QTAIM) analysis, noncovalent interaction (NCI) plots, and energy decomposition analysis (EDA) method. Interestingly, the obtained results showed that electrostatic interactions have the highest contributions to the interaction energies between the ILs and the surfaces, followed by dispersion interactions and orbital interactions (ΔEelec > ΔEdisp > ΔEorb) The most important Van der Waals (vdW) interactions between the ILs and the surfaces include π–π, CH…N, CH…π (CN), and CN…X (X = F, N, O) interactions. On the other hand, the adsorption of ILs is accompanied by charge transfer from the surfaces to the ILs. The calculated adsorption energy (Eads) showed that the [Bmim][PF6] IL has the highest adsorption affinity on the Triazine-g-C3N4 (−28.28 kcal/mol) and Heptazine-g-C3N4 (−26.68 kcal/mol) surfaces. Thermochemistry calculations showed that the Eads, ΔHads, and ΔGads values of IL@surface complexes decrease on moving from gas phase to water media. However, our results showed that the adsorption of ILs on the surfaces is still exothermic and proceeds spontaneously. Upon adsorption of ILs, a decrease in the HOMO–LUMO energy gap (Eg) is observed and is accompanied by an increase in the reactivity and electrophilic character of the surfaces. TD-DFT calculations showed that the weak adsorption of ILs leads to small red or blue shifts in the absorption bands of the Triazine-g-C3N4 and Heptazine-g-C3N4 surfaces. However, no significant changes are observed in the shape of the absorption spectra of the surfaces. Furthermore, the transition density matrix (TDM) heat maps of the IL@surface complexes showed that the electrons and holes are generally concentrated on the Triazine-g-C3N4 and Heptazine-g-C3N4 surfaces in the IL@surface complexes, signifying that the electronic transitions occur mainly on the surfaces.

DFT study of electronic and nonlinear optical properties of alkaline earth metals and superalkalis doped all-cis-1, 2, 3, 4, 5, 6-hexafluorocyclohexane as an efficient excess electron system

Continual advancements are being pursued to discover innovative strategies for developing materials with remarkable nonlinear optical (NLO) response. Herein, electronic, geometric, thermodynamic and NLO properties of excess electron systems based on stacked Janus dimer, all-cis-1,2,3,4,5,6-hexafluorocyclohexane (C6H6F6)2 are thoroughly investigated. The excess electron systems are designed by doping alkaline earth metals (AEMs) on fluorine face and superalkalis on hydrogen face of Janus dimer. The higher values of vertical ionization energies (VIE) and interaction energies (Eint), confirm the electronic and thermodynamic stabilities of the designed complexes, respectively. Natural bond orbital (NBO) analysis is performed, and the excess electron character of the complexes is confirmed through frontier molecular orbital (FMO) analysis by highest occupied molecular orbital (HOMO) iso-densities. FMO shows a significant decrease in energy gaps (Egap) of the complexes (i.e., Eg = 1.80–3.12 eV), compared to the stacked Janus dimer (i.e., Eg = 9.41 eV). The transparency of the complexes to UV region is confirmed through UV–vis analyses, revealing their maximum absorption in visible and near-IR regions. The higher NLO response of the designed excess electron systems is further proved by the greater values of first hyperpolarizability (β o ) i.e., up to 1.70 × 106 au. Moreover, the time dependent-density functional theory (TD-DFT) computations and two-level model are employed to investigate the controlling factors of hyperpolarizability, illustrating the contribution of transition energy (∆E3), change in dipole moment (∆μ) and oscillator strength (f o ) in controlling the β o . Ab-initio molecular dynamics (AIMD) simulation further confirm that the designed superalkalide complexes are kinetically and thermally stable. The thorough investigation of these excess electron systems proves them an appropriate candidate for NLO applications.

DFT Study on the Second-Order NLO Responses of 2-Phenyl Benzoquinoline Ir(III) Complexes by Substituents and Redox Effects.

Metal complexes have received extensive attention in nonlinear optical (NLO) materials because of their advantages, such as shorter response times and more flexible structural properties. Density functional theory is used in investigating the geometric structures, electronic structures, charge centroid, and first hyperpolarizability (βtot) of a series of selected 15 coordinated Ir(III) complexes. The substitute effect and one-electron redox process effects on the structures and properties of 15 coordinated Ir(III) complexes are considered. When the electron-withdrawing group is introduced into the ligand, the HOMO-LUMO energy gap decreases and the βtot value increases, positively correlating with the electron-withdrawing ability. The single electron redox process can also improve the NLO responses of complexes, especially the reduction process. The βtot value of complex 4- is the largest, 2078 times higher than that of complex 4. The analysis shows that the variation of NLO responses of complexes is ascribed to the change of electronic structures and the charge transfer modes induced by the ligand modification and redox process, which are considered to be two effective methods in enhancing the NLO responses of 2-phenyl benzoquinoline Ir(III) complexes. This study aims to offer design insights into high-performance nonlinear optical materials.

N 2 + Meinel band quenching coefficients for vibrational levels 0 and 1.

Experimental rate coefficients for the quenching of vibrational levels 0 and 1 of the N2+A2Πu state by N2 are presented. The experiments were performed using near-infrared observations of the N2+ Meinel bands excited by electron impact at several pressures of the N2 target/quenching gas. The total removal rate coefficients were derived from a Stern-Volmer analysis of the Meinel band intensities as a function of N2 density and yielded rate coefficients of (2.5 ± 0.5 × 10-10) and (5.6 ± 0.6 × 10-10) cm3⋅molecule-1⋅s-1 for vibrational levels 0 and 1, respectively. It is shown that rate coefficients increase with increasing vibrational level and decreasing energy gap. Our results impact modeling studies of the disturbed atmosphere and ionosphere as the reduced quenching rate coefficients for the preferentially excited A-state vibrational levels <2 lower the quenching altitude in the atmosphere by one scale height, or about 6 km.

EXPLORING THE STRUCTURAL AND ELECTRONIC CHARACTERISTICS OF AMORPHOUS Ge – Te - In MATERIAL THROUGH AB INITIO METHODS

This study employs density functional theory (DFT) and molecular dynamics to meticulously investigate the structural and electronic properties of ternary chalcogenide compounds, specifically (GeTe4 ) 1-x Inx, and (GeTe5 )1-x Inx across a range of compositions ( x = 0, 5, 10, 15, 20 at %). Utilizing the local density approximation within the framework of first-principles calculations, we comprehensively analyze the pair correlation function, static structural factor, electronic density of states, and electronic band gap energy. Our results reveal a notable decrease in the energy band gap of Germanium-Tellurium with the incorporation of Indium atoms. The structural changes observed in the Ge-Te matrix with Indium doping, as evidenced by the changes in the pair correlation function and static structure factor, are consistent with and supportive of the observed decrease in the band gap energy. This phenomenon is primarilyattributed to the significant contribution of Indium atoms to the conduction band edge, offering new insights into the material’s electronic behaviour.

Computational study of substituent effects on molecular structure, vibrational and electronic properties of fluorene molecule using density functional theory

Density functional theory (DFT) provides a powerful tool for investigating the effects of halogen (F, Cl and Br) substitution on the electronic and structural properties of fluorene. The B3LYP/6-31G (d,p) protocol is a commonly used method in DFT calculations for the optimisation of molecular structures and the calculation of various molecular properties by Gaussian 09 W program. In the case of the fluorene molecule with halogen substitutions, (TD–DFT) calculations can be used to predict its UV–Vis spectrum. The B3LYP density functional model with a 6-31G(d,p) basis set is a common choice for performing (TD–DFT) calculations on molecules. The results showed a decrease in gap energies when electron-withdrawing groups were present in the molecule. A decrease in the gap energy indicates that the molecule is less stable and more reactive.

Enhancing electrical and optical properties of anatase TiO2 nanotubes through electrochemical lithiation

In presented paper, anatase TiO2 nanotubes (NTs) were obtained by anodic oxidation of Ti-foil followed by subsequent annealing in air at 400 °C. After thermal treatment, TiO2 nanotubes (NTs) were electrochemically lithiated by means of galvanostatic (GS) discharge, as a part of GS cycling, at 25°C and 55 °C. Microstructural properties of the as-prepared material were observed by scanning and transmission electron microscopy (SEM, TEM), while changes in chemical bonding with lithiation were examined by X-ray photoelectron spectroscopy (XPS). Specific electrical conductivity, obtained by 4-point probe method, showed multifold increase after Li-ion insertion in TiO2 NTs, at both temperatures. By using diffuse reflectance spectroscopy (DRS), the decrease in energy gap, from 3.04 eV for the as-prepared TiO2 NTs to 2.81 eV for lithiated TiO2 NTs, was observed. The photoluminescence (PL) measurements suggest that Li-ion intercalation led to suppression of deep-level trap states within the bandgap, of TiO2 NTs, and promoted shallow defects associated to F-centers. Open-circuit photovoltage decay (OCVD) measurements confirm the promotion of shallow defect states. Furthermore, HER measurements indicate that the electrochemical lithiation is a promising strategy for enhancing the catalytic performance of TiO2.

Boron modified Ag3PO4 powders for UV and visible light photocatalytic degradation of various dyes

Pure and boron modified Ag3PO4 powders with different boron contents (0–5 wt.%) were prepared. XRD, ATR-FTIR, XPS, SEM-EDX, UV-Vis DRS and PL analyses were conducted for the characterization of the prepared powders. Characterization studies indicated the reduction in the band gap energy, the presence of boron and no change in the morphology due to boron modification. The results of photocatalytic experiments showed that boron modification increased the activity of Ag3PO4. The UV light dye degradation efficiency increased from 63% to 84% for methyl orange (MO) and from 41% to 65% for methyl red by 3% boron modification. The reaction rate constant for MO increased by a factor of 1.7. Under visible light, the activity was similarly enhanced by boron modification. The photocatalytic degradation efficiency increased from 31% to 58% and the reaction rate constant increased by a factor of 2.3 by boron modification for MO under low intensity visible light. These results showed that boron modification enhanced the photocatalytic dye degradation activity of Ag3PO4 under both UV and visible light. This enhancement was attributed to the decrease in the band gap energy and the increase in the interaction of the dye molecules with the photocatalyst surface through boron species.

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).

Revolutionizing textile wastewater treatment: Enhanced degradation of dyes using bimetallic Zinc Ferrite-GO nanocomposites

A novel bimetallic nickel-copper doped zinc ferrite based catalyst has been synthesized using the hydrothermal method. The nano-sized bimetallic (Ni-Cu) zinc ferrites were embedded with graphene oxide (GO). The characterization of nano-sized bimetallic (Ni-Cu) zinc ferrites with graphene oxide (GO) involves a comprehensive set of analytical techniques to determine their elemental composition, structural properties, and morphological features. The prepared materials were also subjected to structural and morphological evaluation through FTIR, Raman, XRD, TGA, UV–vis spectroscopy, and SEM with EDX. The experiment for the photodegradation of the selected model pollutant dye, methylene blue was conducted using the prepared materials. This means that the present photocatalyst has a high efficiency of degrading the pollutant to a tune of 99 % within 3 h. When the amount of GO in the prepared nanocomposite was 40 %, there was the perfect result in terms of no degradation of MB. It reduced and deteriorated the degree of band gap energy of the MB dye. The photocatalyst activity was proven to be repeatable; the sample's use was again possible. A decrease in the band gap energy implies that the improved photocatalyst material becomes more efficient at absorbing light energy. This enhanced light absorption promotes the generation of electron-hole pairs, which are essential for catalytic reactions. Therefore, the reduction in band gap energy likely contributes to the catalyst's heightened ability to initiate the degradation of the MB dye, ultimately leading to more effective pollutant removal. In the future, the synthesized sample can be reused without significant loss in its catalytic efficiency, underscoring the stability and durability of the material. The current study has paramount importance for real-world applications; reliable performance over multiple cycles ensures that the catalyst remains effective in addressing pollution challenges over prolonged periods.

Influence of (Co+Al) co−doping on structural, micro-structural, optical and electrical properties of nanostructured zinc oxide

This study investigates the effect of (Co + Al) co−doping on the physical properties of the ZnO nanoparticles, synthesized via the simple co−precipitation method. X−ray diffraction (XRD) analysis revealed a hexagonal structure for all samples, with a formation of Al2O3 phase in both Zn0.98Co0.01Al0.01O and Zn0.94Co0.01Al0.05O nanoparticles. The crystallite size increased from 26.5 nm for ZnO to 16.6 nm for Zn0.94Co0.01Al0.05O nanoparticles. Scanning electron microscopy (SEM) technique showed a notable alteration in the morphology of ZnO upon the incorporation of Al. A transition from spherical nanoparticles in ZnO and Co doped ZnO to irregular, dendritic-like structures in (Co + Al) co−doped nanoparticles is observed. Transmission electron microscopy (TEM) substantiated the presence of the Al2O3 phase in the co−doped samples. Raman and FTIR spectroscopy confirmed the incorporation of Co and Al into the ZnO lattice through the presence of Co–O–Co and Al–O bonds. Optical characterization indicated a decrease in the band gap energy from 3.18 eV in ZnO to 2.84 eV in Zn0.94Co0.01Al0.05O nanoparticles. Electrical conductivity measurements revealed an increase from 1.2 × 10−4 Ω−1 cm−1 to 1.8 × 10−3 Ω−1 cm−1 as the Al content increased from 0 % to 5 % at the frequency of 103 Hz and the temperature of 423K. Likewise, dielectric constant raised from 775 in ZnO to 5455 in Zn0.94Co0.01Al0.05O nanoparticles at the temperature 423K. These results highlight the potential of (Co + Al) co−doped ZnO nanoparticles for advanced optoelectronic applications.

Room-temperature electrodeposition of Cu2O layers and its low-temperature annealing for photoelectrochemical water splitting applications

Cuprous oxide layers were obtained on a conductive glass substrate via room-temperature electrochemical deposition from the electrolyte containing 0.4 M CuSO4, 3 M lactic acid (pH = 12) at −0.5 V vs. SCE for various durations (from 0.25 to 3 h). Physicochemical properties of as-received FTO/Cu2O materials were characterized using SEM, PXRD, and UV–Vis DRS. The photoelectrochemical (PEC) properties of the obtained electrodes were evaluated in detail by analyzing the influence of the energy of monochromatic radiation, and the applied polarization on the resulting photocurrent transients. It was found that Cu2O crystals are getting bigger and sharper with prolonged electrosynthesis duration and a slight decrease in the band gap energy from 2.4 to 2.1 eV with increasing deposition duration was observed. Moreover, this trend was also reflected in PEC properties of resulted material, higher photocurrents were generated by the material deposited for 3 h. More importantly, this PEC response was enhanced by low-temperature (100 °C, 200 °C) annealing. Thermal treatment at 100 °C led to a noticeable improvement in the photoactivity of the samples. Further increasing post-treatment temperature to 200 °C resulted in a further six-fold increase in photocurrents. Finally, the calculated values of accumulated and dissipated charges indicated significantly lower surface recombination after thermal treatment.

A comparative study on antibacterial properties of EuO, CuO, and ZnO dopped ZrO2 sol-gel coatings

ZnO, CuO, and EuO doped ZrO2 films were prepared using a sol-gel dip coating technique, and the effects of the doping on the film thickness, crystallite size, surface roughness, band gap energy, adhesion strength, and antibacterial properties of the coatings were investigated. It was found that the addition of small amounts of ZnO and EuO can significantly improve the uniforminty of the sol-gel coating, while the greater the difference in the coefficients of thermal expansion (CTEs) of the coating and the substrate, the higher the probability of developing surface microcracks. The XRD patterns of the coatings synthesized based on ZrO2 as well as EuO, ZnO, and CuO dopants showed that the ZrO2 structure was tetragonal for all of the compounds. In addition, it was revealed that with an increase in the calcination temperature, the crystallite sizes of the coatings containing ZrO2 and ZnO increased, and in contrast, the crystallite sizes of ZrO2:ZnO, ZrO2:ZnO,CuO and ZrO2:ZnO,EuO compounds decreased. The evaluation of the reflectance of visible light functions showed that adding 30 % ZnO led to a decrease in the band gap energy from 3.19 eV for ZnO2 to 3.01 eV for ZrO2 + 30 % ZnO. Moreover, the lowest band gap energy (2.81 eV) was achieved for the compound containing EuO. Finally, it was concluded that the ZrO2:ZnO,EuO sol-gel coating with the least band gap energy shows better antibacterial activity.

Investigation of corrosion inhibition and adsorption properties of quinoxaline derivatives on metal surfaces through DFT and Monte Carlo simulations

Abstract This work presents a multiscale theoretical investigation into the potential of quinoxaline derivatives (Q1–Q6) as corrosion inhibitors for various metals (Fe(110), Cu(111), and Al(110)). Employing a combined approach combining density functional theory (DFT) and Monte Carlo simulations, we explore the relationship between molecular structure, electronic properties, and adsorption behavior. Density functional theory (DFT) and molecular dynamics simulations (MDS) were used to investigate the electronic characteristics of diverse compounds. The study included key parameters including highest occupied molecular orbital energy (E HOMO), lowest unoccupied molecular orbital energy (E LUMO), energy gap (E g) between E LUMO and E HOMO, dipole moment, global hardness, softness (σ), ionization energy (I), electron affinity (A), electronegativity (χ), back-donation energy E b−d, global electrophilicity (ω), electron transfer, global nucleophilicity (ε), and total energy (sum of electronic and zero-point energies). These properties, alongside adsorption energies (following the trend Q6 &gt; Q2 &gt; Q3 &gt; Q4 &gt; Q5 &gt; Q1), are used to identify promising inhibitor candidates and establish structure–property relationships governing their effectiveness. The results suggest that inhibitor efficiency increases with a decreasing energy gap between frontier orbitals. Notably, the protonated state of Q6 exhibits high reactivity, low stability, and strong adsorption, making it a potential candidate for further exploration. This comprehensive theoretical approach offers crucial insights for the conceptual development of new and powerful corrosion inhibitors.