Low Band Gap Research Articles

An investigation of the enzymatic oligomerization of nitro-substituted phenylene diamine: Thermal and fluorescence properties

2-nitro-p-phenylenediamine, an aromatic diamine, was studied for its oxidative oligomerization with H2O2 using enzyme-catalyzed oligomer synthesis. Characterization of molecular structures was performed utilizing ultraviolet-visible (UV-Vis) spectrophotometer, Fourier-transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance (NMR) techniques, identifying phenazine-bridged oligomer resulting from the enzymatic oligomerization process. Based on the results of gel permeation chromatography (GPC) analysis, the synthesized compound was identified as being in an oligomeric form. Conversely, the number of repeating units, as determined by Mw, was found to be 28. The solvent effect on the optical features of the synthesized oligomer in polar solvents was analyzed. The degradation of phenazine-type structures in the oligomer occurred at higher temperatures than that of the monomer. Under visible light excitation, the oligomer exhibited green light emission with a quantum yield (QY) of 6.2% in N,N-dimethylformamide (DMF). 2-nitro-p-phenylenediamine was readily oxidized into an oligomer with ortho-coupled constitutional units, having a lower electrochemical band gap than the monomer, via the enzymatic oligomerization route. Scanning electron microscopy revealed that enzyme-catalyzed oxidation of monomers exhibited a spongy morphology with some pores

CuxS films as photoelectrodes for visible-light water splitting

Copper sulfides are appealing semiconductors for optoelectronics applications requiring visible-light activity, such as solar water splitting, due to their relatively low band gaps and earth-abundance. This study investigates the effect of deposition conditions, including substrate temperature and background gas pressure, on the characteristics and photoelectrochemical performance of copper sulfide (CuxS) films grown by pulsed laser deposition (PLD) on Si (100) substrates. The results reveal that varying the deposition parameters influences the crystalline phases, morphology, and optoelectronic properties of the films. For deposition at room temperature, the films exhibited covellite CuS phase, while elevated deposition temperatures (250 °C and 500 °C) led to the formation of Cu1.8S and Cu2S phases, resulting in narrowing of the band gap, with the increased temperature also enhancing the film crystallinity and surface roughness. As a result of the changes in film morphology and crystal structure, photocurrent density magnitudes increased with higher deposition temperatures, reaching 0.747 mA/cm2 at −0.8 V for films deposited at 500 °C under vacuum, at least an order of magnitude higher than reported in comparable previous studies of the photoelectrochemical performance of CuxS. Background gas pressure only slightly affected the photocurrent density, with changes in photoactivity also correlating with changes in film roughness and band gap. The results demonstrate the good visible-light activity and behavior of CuxS as a stand-alone photoelectrode material, with tunability based on the fabrication conditions, suggesting their potential use in photoelectrochemical and other solar energy conversion applications.

Hydrothermal Synthesis of a Valence State Constant High-Entropy Perovskite Sr(TiZrHfVNb)O3 with Improved Photoresponsiveness.

A vanadium ion valence state constant high-entropy perovskite system was synthesized using the hydrothermal method with a trivalent vanadium ion as the vanadium source. The B-site of the perovskite crystal lattice was loaded with five atoms in equal proportions. We tried to synthesize the Sr(TiZrHfVNb)O3 high-entropy system using different methods. However, the valence state of the vanadium ion could only be kept constant using the hydrothermal process in the valence balanced high-entropy composition system. There was significant vanadium element segregation and second phase in the Sr(TiZrHfVNb)O3 system prepared using the solid-state reaction process. Also, obvious vanadium ion valence state ascending from V3+ to V5+ appeared in this high-entropy system with an increase in calcination temperature. Inconspicuous vanadium element segregation appeared at 900 °C, the significant segregation phenomenon and second phase appeared at 1200 °C, and the particle size increased with the temperature. This meant that the high-entropy value could not only stabilize the crystal phase, but also stabilize the ionic valence state. Moreover, the constant trivalent vanadium ion valence state could provide coordinated performance with a wide optical response range and a low band gap for the high-entropy system. This suggests that the system might grow a potential ceramic material for optical applications.

Bio-synthesized ZnO in cesium based perovskite solar cells: A pathway to sustainable high efficiency

Photovoltaics (PV) having perovskite material have an enormous influence on the progress in solar cell technology. Excluding the high efficiency, stability, and flexibility, the extended impact has now been given on utilizing lead-free environmentally suitable, and much cheaper materials for the PSC fabrication. The material with a volatile free, that is, cesium tin iodide (CsSnI3), is capable for the fabrication of the Perovskite Solar Cell that creates eco-friendly as well as enhanced optical-electronic features for the low bandgap, that is 1.27eV. Sn could increase the steadiness of the lead-free perovskite. However, as widely known, Sn2+ always suffers from oxidation with I2 and O2 and induces instability issues. In the ongoing work, cesium tin iodide, is employed as the primary absorber, in so much the root-extracted naturally manufactured ZnO is used as ETM for less cost in production. Correspondingly, Spiro-OMeTAD is used as HTM for enhancement in hole collection in the device. The inclusive numerical simulation with the bio-synthesized ZnO-NP can be applied in designing the solar cell having an applicable thickness of CsSnI3, suitable temperature, total defect density, and the influence of the resistance, respectively. The current simulation of PSC offers the extraordinary power conversion efficiency (η) of 26.40 % considering CsSnI3 as the absorber. The results described in this investigation may confirm an effective approach to design and the expansion of the lead-free PSC.

Exploration of the effect of multiple acceptor and π–spacer moieties coupled to indolonaphthyridine core for promising organic photovoltaic properties: a first principles framework

Herein, the indolonaphthyridine-based molecules (INDTD1–INDTD8) with A1–π–A2–π–A1 configuration were designed by the end-capped modification of INDTR reference with various acceptors. The density functional theory (DFT) and time-dependent DFT (TD-DFT) analyses at M06/6-31G(d,p) level were reported in this research to explore their optoelectronic and photovoltaic features. Their geometrical structures were initially optimized at the afore-said level and followed by various calculations such as the frontier molecular orbitals (FMOs), UV–Visible, density of states (DOS), transition density matrix (TDM), binding energy (Eb), open circuit voltage (Voc) and fill factor (FF). Moreover, their global reactivity parameters (GRPs) were depicted by using the HOMO–LUMO band gaps obtained from the FMOs study. The tailored molecules demonstrated lower band gaps (2.183–2.269 eV) than INDTR (2.288 eV). They also showed bathochromic shifts in the visible region in chloroform (735.937–762.318 nm) and gas phase (710.384–729.571 nm) as compared to INDTR (724.710 and 698.498 nm, respectively). Further, intramolecular charge transfer (ICT) was demonstrated via the DOS and TDM graphical maps. Among all the entitled chromophores, INDTD7 showed significantly reduced band gap (2.183 eV), red-shifted absorption value (760.914 nm) in chloroform solvent and minimal Eb value (0.554 eV). The presence of –SO3H groups on the terminal acceptors of INDTD7 may enhance the mobility of charges. The results suggested that the newly designed chromophores can be effective candidates for the future organic solar cell applications. Moreover, this study may encourage the experimentalists to develop photovoltaic materials.

Impacts of ultraviolet absorption by zinc oxide nanoparticle modifiers on asphalt aging

Ultraviolet absorption ability of modifiers is essential to protect asphalt from ageing. However, the detailed correlation between them remains unclear. In this study, zinc oxide nanoparticles were used as modifiers, and their ultraviolet absorption ability was manipulated by magnesium and aluminum doping. The influence of ultraviolet absorption ability of the nanoparticles on asphalt ultraviolet ageing was investigated experimentally, and their correlation was revealed in detail by curve fitting. The results show that aluminum doping enhances the ultraviolet absorption ability of nanoparticles, leading to superior anti-aging performance in aluminum-doped zinc oxide modified asphalt compared to pure zinc oxide. Conversely, magnesium doping shows a contrary modification. Evaluating the ultraviolet absorption ability of nanoparticle modifiers by bandgap and absorption intensity, we found that softening point increments, viscosity ageing index, and sulfoxide index exhibit a decreasing trend mainly in the bandgap range of 3.269 to 3.334 eV, whereas carbonyl index shows a decreasing trend mainly in the lower bandgap range of 3.183 to 3.269 eV. This phenomenon is primarily due to the different reactivity of carbon and sulfur with oxygen in asphalt. Curve fitting analysis revealed an exponential correlation between the ageing index of asphalt and the ultraviolet absorption ability of nanoparticles. To achieve superior anti-ultraviolet ageing performance, the nanoparticles should possess an absorption intensity above 0.961 a.u. and a bandgap below 3.299 eV. Moreover, stronger ultraviolet absorption ability of nanoparticles is needed to prevent the formation of carbonyl compounds. The underlying correlation established in the present work has significant implications for selecting suitable modifiers to prevent ultraviolet ageing of asphalt.

Bismuth molybdate nanoparticles modified graphene oxide: A novel nanocomposite for photocatalytic removal of organic dyes

Utilization of solar energy for the degradation of organic pollutants is a promising sustainable approach. Here in this research work, bismuth molybdate (Bi2MoO6) nanoparticles (NPs) modified graphene oxide sheets (Bi2MoO6@GO) were employed as efficient photocatalysts for the removal of organic dyes under illuminated sunlight. The synthesized nanocomposite was subjected to characterization via XRD, FTIR, Raman, SEM, EDX and UV–Vis spectroscopic analysis. The photocatalytic efficiency of fabricated nanocomposite (Bi2MoO6@GO) has been studied against organic pollutants including rhodamine B and methylene blue in aqueous solution under direct sunlight irradiation. Bi2MoO6 decorated graphene oxide nano-photocatalyst exhibited 91 % and 88 % degradation of methylene blue and rhodamine B within ∼ 70 min with apparent rate constant values of 0.0323 and 0.0246 min−1, respectively. The study showed that fabricated photocatalyst (Bi2MoO6@GO) possesses a comparatively low band gap, heterogeneous morphology and boosted active surface area which makes it an efficient photocatalyst for the effective remediation of organic pollutants.

Structural, electronic, optical, and thermoelectric features of Rb2XSbX’6 (X= Ag, Cu; X’= Cl, Br): Ab-initio calculations

This study investigates the electronic, optical, and thermoelectric properties of lead-free double halide perovskite materials, Rb2XSbX'6, through first-principles calculations employing Density Functional Theory (DFT) and the Wien2k code, complemented by Boltzmann transport theory. By substituting X with Ag or Cu and X’ with Cl or Br in Rb2XSbX’6, we uncover interesting properties. Rb2AgSbBr6, Rb2AgSbCl6, Rb2CuSbCl6, and Rb2CuSbBr6 exhibit low indirect band gaps of 1.18 eV, 2.17 eV, 1.22 eV, and 0.87 eV, respectively, alongside high absorption in the visible region. The studied compounds sustained a high level of structural and thermodynamic stability, which was confirmed by their high bulk modulus and negative formation energy. Furthermore, extensive values were observed for the figure of merit in the thermoelectric study. Given the strong agreement with previous research, these findings position the investigated materials as promising candidates for visible-light solar cell device applications.

High-performance Bi2O3 nanoflakes for advanced energy storage applications

In this work, Bi2O3 nanoflakes (NFs) were synthesized using the co-precipitation method. To understand the crystal structure-surface morphology and their functional properties such as optical band-gap energy, specific capacitance and magnetic properties are examined by various analytical techniques including X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), High-Resolution Transmission Electron Microscopy (HRTEM), Vibrating Sample Magnetometer (VSM), UV–Visible Diffuse Reflectance Spectroscopy (UV-DRS), X-ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy, and Cyclic Voltammetry (CV). FE-SEM confirmed the formation of the nanoflakes, while HRTEM verified their monoclinic crystal structure and provided details on the orientation of the lattice planes. XRD result showed distinctive peaks corresponding to the α-phase, indicating a crystallite size of 8.21 nm. Raman and XPS results are also demonstrated formation of the Bi2O3 NFs with their signature bands. VSM analysis revealed the presence of both magnetic and nonmagnetic phases in the Bi2O3 NFs. Optical studies indicated a promising band gap of 1.9 eV, suggesting potential for optoelectronic applications. Surface analysis confirmed the composition of Bi+ and O2− in the NFs. Additionally, electrochemical assessments through CV demonstrated a significant specific capacitance of 537 F/g at 20 mV/s. Nyquist plot analysis suggested an equivalent circuit R(CR)(CR), indicating an optimal fit. Furthermore, we have made the systematic comparison of optical band gap energy of Bi2O3 with reported different nanostructures such as Peanut, needles, rod and flakes and found that the present study nanoflakes offer much lower band energy compared to above mentioned all other morphologies. Due to the obtained lower energy band gap and specific capacitance performance of the Bi2O3 NFs, it is strongly suggested to the advanced energy storage applications.

Exploring the potential of end-capping acceptor designing on highly soluble and efficient Schiff-based Hole-Transporting materials for High-Efficiency perovskite solar cells

Photovoltaic materials, especially perovskite solar cells (PSCs) are promising candidates for rising global energy demands. Here, five phenothiazine-based hole-transporting materials (AZOM1, AZOM2, AZOM3, AZOM4, and AZOM5) are designed by Schiff base chemistry with A-π-D-π-A framework for PSCs. We executed density functional theory calculations to explore the electronic, photo-physical, photovoltaic, and charge-transporting properties of the studied hole-transporting materials (HTMs). Our results indicate that AZOM1-AZOM5 HTMs possess more negativeHOMO energies (−5.64 to − 5.49 eV), lower bandgaps, and superior solubility as compared to Spiro-OMeTAD (HOMO energy = − 4.47 eV) and reference AZO-II (HOMO energy = − 4.68 eV), which enhanced their hole extraction and open-circuit photo-voltage (VOC). The transition density matrix and hole-electron distribution analyses show that AZOM1- AZOM5 molecules have ultrafast charge transmission, low overlapping between holes and electrons, and a higher dissociation rate than the Spiro-OMeTAD and AZO-II HTMs. The designed HTMs have smaller exciton binding energies than the Spiro-OMeTAD and AZO-II, allowing electron-hole pairs to dissociate into positive and negative charges smoothly. AZOM1-AZOM5 HTMs have higher hole charge transfer integral than the AZO-II, facilitating high hole mobility in PSCs. All designed HTMs have higher VOC (1.49 to 1.64 V) and lower energy losses (0.63 to 1.03 eV) than the Spiro-OMeTAD and AZO-II HTMs. Moreover, the AZOM1-AZOM5 HTMs demonstrated deeper HOMO energies, high solubility, more stability, and high open-circuit photo-voltages than the recently reported HTMs at “MPW1PW91/6-31G (d, p)” level of theory. Overall, the AZOM1-AZOM5 HTMs are very effective in boosting the solubility, charge-transporting ability, and efficiency of PSCs.

Exploration of novel crystal structures of CsPbBr3 and RbPbBr3 via density functional theory

We report the screening of low-energy crystal structures of CsPbBr3 and RbPbBr3 from approximately 740 structural prototypes using high-flux density functional theory (DFT). These structures are well compared in terms of thermodynamics, band structures and optical properties. Calculated phonon spectra and Gibbs free energy indicate that the Pbnm structure possesses the best kinetic and thermodynamic stability. Band-structure calculations reveal that many CsPbBr3 and RbPbBr3 structures have direct band gap. Optical calculations show a positive correlation between the band gap and photon energy. The structures with low band gap have faster light response, while structures having wider band gap exhibit better optical properties because of their higher photon energies.

Ni-Pt nanoparticle decorated, C, N-doped titania microparticles with low band gap energy as an efficient catalyst for hydrogen generation from hydrous hydrazine

The recent studies demonstrated superior catalytic activity and higher selectivity of carbon doped defect-rich catalysts in hydrogen production via dehydrogenation of hydrazine hydrate (HH). The synthesis of a new defect-rich catalyst capable of providing high hydrogen evolution rate in either catalytic or photocatalytic dehydrogenation of HH was aimed. For this purpose, “polymerization-induced colloid aggregation” (PICA) was proposed for the synthesis of carbon and nitrogen doped-mesoporous, gravel-like TiO2 microparticles (m-CN/TiO2 MPs) with a reduced band-gap energy of 2.3 eV. The Ti(III) content and oxygen vacancy concentration of pristine m-CN/TiO2 MPs were 6.06 % and 22.57 %, respectively. A defect-rich catalyst with high Ti(III) content (40.25 %) and high oxygen vacancy concentration (39.14 %) was obtained by the decoration of m-CN/TiO2 MPs with nickel-platinum nanoparticles (Ni-Pt NPs) via NaBH4 reduction (Ni-Pt/m-CN/TiO2 MPs) for the first time. The charge unbalance stimulated by Ti(III) species supported the formation of oxygen vacancies on m-CN/TiO2 MPs. The unique approach based on the synthesis of a C, N doped-mesoporous TiO2 based support by PICA and the deposition of Ni-Pt NPs by NaBH4 reduction in the presence of m-CN/TiO2 MPs allowed to obtain a heterogeneous catalyst with a low band energy of 1.7 eV for hydrogen production. The turnover frequency (TOF) values up to 1140.7 h−1 were achieved with 100 % H2 selectivity using the catalyst containing an active metallic site composed of 78.3 % mol Ni and 21.7 % mol Pt on m-CN/TiO2 MPs in the catalytic dehydrogenations performed at 323 K. The TOF values up to 530 h−1 with 100 % H2 selectivity were obtained by using Ni-Pt/m-CN/TiO2 MPs as a photocatalyst in the visible light driven photocatalytic dehydrogenation of HH at room temperature.

Device optimization of all inorganic CsPbBr3/LNMO based multi-layered perovskite light harvesters for broader capturing of solar spectrum

All inorganic Cesium lead bromide (CsPbBr3) planar perovskites have garnered enormous significance in photovoltaic applications owing to its outstanding stability against oxygen, heat and moisture. However, the power conversion efficiencies of the CsPbBr3 planar perovskites are quite low primarily due to the inferior range of light absorbance and interfacial charge recombination losses. This issue can be successfully resolved with a novel multi-absorber architecture approach which incorporates dual absorbers consisting of a lower band gap Lanthanum Nickel Manganese Oxide (La2NiMnO6 or LNMO) material along with the wider band gap CsPbBr3 material so that the light absorbance regime could be well extended for maximal utilization of the solar spectrum. Therefore, this article incorporates numerical modeling and guided optimization of all inorganic ITO/ETL/CsPbBr3/La2NiMnO6(LNMO)/HTL dual absorbers-based heterojunction structure to improvise the power conversion efficiency of CsPbBr3 based single absorber PSCs. The critical device’s parameters, such as; absorber layer and carrier transport layer thickness, defect density, temperature, doping concentration, frequency response, capacitance effects, Mott-Schottky effects as well as series and shunt resistances are thoroughly optimized and evaluated using Solar Cell Capacitance Simulator (SCAPS-1D) simulator. The proposed dual absorber layer composition produces a substantial enhancement in performance with a peak power conversion efficiency (PCE) of 26.98 %, short circuit current (Jsc) of 39.75 mA/cm2, open circuit voltage (Voc) of 0.85 V, and fill factor (FF) of 77.98 % at a device defect density of 1015 cm−3 outperforming the 11 % of PCE attained with the experimentally reported CsPbBr3 single junction counterpart along with PSCs with various dual absorbers-based composition.

Shielding against erosion: Exploring the effectiveness of pre-erosion surface corrosion inhibitors

This study investigates the corrosion inhibition effect and adsorption process of two imidazoline corrosion inhibitors, HEIE and TDEI, on pre-eroded X65 steel surfaces. Analysis of weight loss and electrochemical measurements suggests that the irregular structure of pre-eroded surfaces may impede the uniform adsorption of corrosion inhibitors, resulting in reduced effectiveness pre-erosion. Particularly, at a 30° angle of pre-erosion, corrosion inhibition efficacy is observed to be at its lowest. The corrosion inhibition rates of HEIE and TDEI on X65 steel surfaces are found to be 11.9 % lower under pre-eroded conditions at a 30° angle compared to non-eroded surfaces at the same angle. Molecular dynamics (MD) simulations support these findings, indicating that TDEI exhibits lower energy bandgap values and more negative adsorption energies (Eads) compared to HEIE, aligning with experimental results. Moreover, TDEI demonstrates a smaller diffusion coefficient for corrosive agents than HEIE, suggesting stronger adsorption efficiency and a more pronounced protective effect. Study of the corrosion inhibition effect on pre-eroded surfaces provides new ideas and methods for improving protective measures.

Impact of using dual back surface field layers of different materials on GaAs single junction solar cell performance

This research aspires to investigate the impact of employing dual BSF layers on the performance of single junction GaAs solar cells using the Silvaco TCAD simulator. A layer of GaAs, InGaP, and InAlGaP has been implemented as a second BSF layer on top of the original BSF layer of the n-InGaP/n-GaAs/p-GaAs/p-InAlGaP structured solar cell. The results show that using GaAs as a second BSF layer has increased the carrier’s recombination and degraded the cell efficiency due to its lower energy bandgap, which creates a potential well that lessens the number of photogenerated carriers flowing through the conduction band toward electrodes. However, adding InGaP and InAlGaP as a second BSF layer decreases the recombination rate and generates a broad electric field region leading to extra photogenerated carriers drifting through the cell, which increases the efficiency from 29.42% to 29.81% for the case of using InGaP and 30.33% for the case of using InAlGaP. Furthermore, increasing the thickness and doping of the second BSF layer reduces the carriers’ recombination at the boundaries of this layer, which implies efficiency enhancement.

Enhanced sunlight-driven photocatalysis of non-metal doped zinc oxide via wet impregnation for the removal of organic compounds

Zinc oxide (ZnO), a commonly used photocatalyst, suffers from the rapid recombination of photogenerated charge carriers, and the inability to harvest visible light. Therefore, the green synthesized ZnO from Garcinia mangostana pericarp is modified via non-metal (X) doping of N, P, S, Br, and B with a mass content of 5 % to tackle the aforementioned. The obtained materials were characterized through various modern characterization techniques. The results reveal that amongst the X-doped sample, ZnO-B demonstrates the highest photocatalytic performance. The characteristics of ZnO include good crystallinity as well as a low band gap energy of 2.094 eV, revealing an enhanced visible light absorption activity of the sample. The photoactivity of surveyed ZnO-B was investigated through the degradation of malachite green, methyl orange, and tetracycline, achieving a removal rate of 96.29, 86.59, and 90.32 %, respectively. Simultaneously, the antibacterial properties of the ZnO-X were evaluated for Staphylococcus aureus under sunlight illumination. Moreover, the photocatalysis mechanism of the studied materials was elucidated through the band structure, toxicity, and total organic carbon removal of the post-catalysis solution. The selected boron-doped zinc oxide catalyst also showed excellent reusability after 10 cycles of photocatalysis, retaining ∼ 80 % of its original activity. The obtained results reveal the potential application of non-metal-doped zinc oxide in environmental remediation and water disinfection.

Filterless Near‐Infrared Narrowband Photodetectors Based on Mixed Metal Perovskite Single Crystals

AbstractIodine‐based Sn‐Pb mixed perovskite single crystals (SCs) are promising candidates for near‐infrared (NIR) narrowband photodetectors due to their low bandgaps. However, they are highly defective when grown in ambient air due to the extremely poor air stability of Sn2+ ions in precursor solutions. It is discovered that the oxidation of Sn2+ to Sn4+ ions not only consumes Sn2+ ions but also increases the precursor solution viscosity. The increased viscosity slows down the solute diffusion and hinders the anisotropic growth of SCs, leading to Sn‐Pb perovskite SCs with curved convex surfaces and unevenly distributed composition. By preventing the solute‐diffusion‐limited growth mode with hypophosphorous acid (H3PO2), high‐quality Sn‐Pb perovskite SCs can be robustly grown in ambient air with low trap density of 6.58 × 109 cm−3 and high carrier mobility‐lifetime product (µτ) of 1.5 × 10−3 cm2 V−1. Accordingly, a series of filterless NIR narrowband photodetectors with gradually tuned detection centers and dual detection modes has been achieved, delivering a maximum external quantum efficiency of 15.2% and detectivity of 1.19 × 1010 Jones.

Acid Mediated In‐Situ Catalytic Cleavage/Making of C=N Bonds in Bis‐Hydrazone Uranyl Complexes: Exploration of Photophysical, Electrochemical, Dye Sorption Properties and DFT Studies

AbstractTwo new uranium complexes [UO2L2(H2O)] (where L2=diacetyl bis‐isonicotinoyl hydrazone) complex 1, and [UO2(L1)2] (where L1=diacetylmonoxime isonicotinoylhydrazone) complex 2, have been synthesized by precisely adjusting the pH values of the reaction system. Complex 1 was formed in an acidic ethanolic solution (pH=3) through an in‐situ acid catalytic reaction of diacetylmonoxime isonicotinoylhydrazone and UO2(NO3)2.6H2O, while complex 2 was acquired in a neutral medium (pH=7) through self‐assembly of two ligands and one uranium (VI) metal centre. Both complexes were thoroughly characterized by elemental analysis, UV‐Visible spectroscopy, IR spectroscopy, NMR, TGA, cyclic voltammetry, and powder X‐ray diffraction. The studies indicate that the bis‐hydrazone in complex 1 is a dianionic tetradentate N2O2 donor, whereas in complex 2 it is a monoanionic tridendate N2O donor. The formation of complex 1 was further confirmed by a single‐crystal X‐ray diffraction study, which revealed the role of a water molecule in forming a pentagonal bipyramidal geometry of [UO2L2(H2O)]. Photophysical studies revealed that complexes 1 and 2 exhibited low band gap values of 2.07 and 2.12 eV, respectively, indicating their semiconducting nature. From the CV measurements, the higher negative potentials of the complexes 1 & 2 {1, −0.6 V and 2, −0.5 V vs. ferrocenium/ferrocene (Fc+/Fc)} in DMSO are assigned to the presence of {UO2}2+/{UO2}+ couple signifying their redox active nature. Dye adsorption studies show that both the complexes were able to remove 90 % of Methylene blue (MB) and Rhodamine B (RhB) from the solutions with the concentration of 10−5 M. The structural insights and electronic properties of Ligand HL1 and complex 1 were further explored by density functional theory (DFT) calculations.

Tuning the Structural and Electronic Properties of Zn-Cr LDH/GCN Heterostructure for Enhanced Photodegradation of Estrone in UV and Visible Light.

Estrone is an emerging contaminant found in waters and soils all over the world. Conventional water treatment methods are not suitable for estrone removal due to its nonpolarity and low bioavailability. Heterogeneous photocatalysis is a promising approach; however, pristine semiconductors need optimization for efficient estrone photodegradation. Herein, we compared Zn-Cr LDH/GCN heterostructures obtained by three different synthesis methods. The influence of the GCN content in the heterostructure on photoactivity was also tested. The morphology, structure, and electronic properties of the materials were analyzed and compared. The photocatalytic kinetic tests were conducted with 1 ppm of estrone in both UV and visible light, separately. The HLDH-G50 material, obtained by the hydrothermal route and containing 50 wt % of GCN exhibited the highest photocatalytic efficiency. After 1 h, 99.5% of the estrone was degraded in visible light. In UV light, the pollutant concentration was below the detection limit after 0.5 h. The superior effectiveness was caused by numerous factors such as high homogeneity of the formed heterostructure, lower band gap energy of hydrothermal LDH, and increased photocurrent. These characteristics led to prolonged lifetimes of charge carriers, a wider light absorption range, and uniformity of the material for predictable performance. This study highlights the importance of a proper heterostructure engineering strategy for acquiring highly effective photocatalysts designed for water purification. In particular, this work provides innovative insight into comparing different synthesis methods and their influence on materials' properties.

Mesoporous silica stabilized perovskite quantum dots for the preparation of ultra-stable green flexible film.

CsPbBr3 perovskite quantum dots (QDs) have attracted much attention in the optical field because of their low band gap, wide absorption spectrum and high color purity. However, their poor stability in extreme environments such as water, light and heat severely limits their application in optical fields. Here, we prepared m-SiO2/CsPbBr3 composite luminescent material using an aqueous phase method combined with high temperature calcination. The material can retain 87% of the initial photoluminescence quantum efficiency after 60 days of storage under ambient conditions (humidity ∼80%; temperature ∼25 °C), its photoluminescence intensity only decreased by 33% after immersion in water for 90 min. This indicates that the material retains good stability under a high humidity environment. Finally, PMMA@m-SiO2/CsPbBr3 flexible films were prepared by aqueous solution polymerization. The flexible film has excellent green light emission properties and exhibits (0.092, 0.625) CIE coordinates.