Low Band Gap Research Articles

Reduced band gap SrTiO3 thin film prepared by magnetron sputtering for the oxygen evolution reaction

The development of non-precious element-based materials that are stable, binder-free and prepared on economical and environmentally sustainable substrates will be fundamental to the growth of the green hydrogen industry. SrTiO3 perovskites (STO) are very interesting materials due to their high bandgap, the possibility of its modulation and high stability. However, their high resistivity causes a decrease in the efficiency of the oxygen evolution reaction (OER). In this work, STO thin films with an average thickness of 70.95 nm were prepared directly on carbon paper (CP) by magnetron sputtering without the use of stabilizing binder. The samples where thermally treated in reductive atmosphere (STO-TT) and results a film with a low optical band gap of 3.06 eV. The electrochemical study for OER reaction reveals a better behavior of the STO-TT sample in terms of overpotential, Taffel slope and stability for 24 hours.

Assessing the electromagnetic shielding effectiveness of coconut coir composites with varying iron particle concentrations

This study investigates the electromagnetic shielding effectiveness of Coconut Coir-based Porous Carbon (CCPC) composites with varying iron (Fe) particle concentrations, specifically focusing on four different weight ratios of CCPC/Fe-80, CCPC/Fe-60, CCPC/Fe-40, and CCPC/Fe-20. The novelty of this work lies in the use of sustainable coconut coir as a base material, emphasizing its eco-friendly and cost-effective attributes for Electromagnetic interference (EMI) shielding applications. The significance of varying iron particle concentrations is highlighted to optimize electromagnetic shielding effectiveness. Comprehensive analyses were conducted on these composites. X-Ray Diffraction (XRD) analysis confirmed the presence of crystalline Fe particles and amorphous carbon, with crystalline sizes determined via Williamson-Hall (W-H) plot, Scherrer Equation, and Strain Size Plot (SSP) ranging from 17.33 nm to 18.01 nm for the former. Raman spectroscopy revealed distinctive D and G bands, with intensity ratios indicating a slight increase in structural disorder with higher Fe content. UV-Visualization spectroscopy demonstrated distinct absorption peaks, with higher Fe content resulting in more pronounced absorbance and lower band gap energies. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analyses provided detailed insights into the material's microstructure and elemental composition, confirming the successful integration of Fe particles within the porous carbon matrix. Vector Network Analyzer (VNA) testing measured the reflection loss (RL), showing values in the range of −26.4 dB to −20.2 dB, for 2 mm thick samples, corresponding to electromagnetic wave attenuation of over 99%. These results underscore the potential of CCPC/Fe composites, particularly in applications requiring effective Electromagnetic (EM) wave attenuation. This research offers a sustainable and cost-effective solution, contributing significantly to the field of materials science by enhancing electromagnetic compatibility in various technological applications.

Synthesis, characterization, in vitro and in silico studies of N, N-dimethyl phenyl chalcone-Schiff’s base hybrid

Three dissimilar N, N-dimethylphenyl chalcone Schiff's base hybrids (CSBHs) were synthesized and characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared (FT-IR) and ultraviolet-visible spectroscopic techniques by the theoretical as well as investigational methods. The molecular weights of the CSBHs were also confirmed by the Electrospray ionization Mass technique. The in vitro antidiabetic, anti-inflammatory and cytotoxicity were tested for the CSBHs using α-amylase inhibitory and protein anti-denaturation methods. The CSBHs showed good antidiabetic and anti-inflammatory activities and the percentage of inhibitions is nearer to standard drugs acarbose and diclofenac sodium. The molecular docking studies for CSBHs were investigated and their docking results are superior and also density functional theory method are performed for CSBHs to support biological and molecular docking results. The CSBHs showed very good hydrogen bonding interactions with amino acid residues of the enzymes and the CSBHs showed lower band gap and higher electrophilicity index values. In addition, (ADMET) Absorption, Distribution, Metabolism, Excretion and Toxicity study and Protox-II toxicity predictions were performed to check the pharmacological properties of CSBHs.

Assessment of photocatalytic activities of layered double hydroxide@petrochemical sludge biochar for sulfamethoxazole degradation

Layered double hydroxides (LDHs) as one of the popular photocatalysts have the drawbacks of compact structural arrangement and pronounced nano-particle clustering, which affect their photocatalytic performance for the degradation of organic pollutants from water or wastewater. Using biochar as a substrate matrix to support LDHs may be a good way to improve the photocatalytic performance of LDHs by avoiding agglomeration effect, promoting the separation of photogenerated electrons from holes for organics degradation. In this study, the composite of CoFe-LDH and petrochemical sludge biochar (CoFe-LDH@PBC) was fabricated and applied for the first time as photocatalyst for catalytic degradation of sulfamethoxazole (SMX). Results showed CoFe-LDH@PBC800/UV system exhibited excellent photocatalytic activity on SMX degradation than single CoFe-LDH/UV, PBC800/UV, or PBC105/UV system under various reaction conditions (photocatalyst dosage, pH, system speed, and SMX concentration). 100 % of SMX degradation efficiency and 88.98 % mineralization efficiency could be achieved in CoFe-LDH@PBC800/UV system within 100 min. The corresponded pseudo-first-order kinetic rate constant (kobs) of SMX degradation in CoFe-LDH@PBC800/UV system was 0.032 min−1, which was 3.20, 8.00, and 2.46 times higher than that of CoFe-LDH/UV, PBC800/UV, and PBC105/UV, respectively. In photocatalytic process, OH, O2−, and h+ participated in SMX degradation, among which h+ or OH played a major role. The good photocatalytic performance of CoFe-LDH@PBC800 composite was related to its excellent physiochemical properties, such as lower band gap (2.39 eV), high graphitization degree, and high conductivity, enabling efficient e−/h+ separation of photocatalyst for SMX degradation. Four distinct pathways of SMX degradation were proposed based on DFT theoretical calculations and byproducts of SMX degradation identified by LC-MS. Additionally, results from recycling tests suggested CoFe-LDH@PBC800 composite possessed a favorable reusability and could be applied for photocatalytic degradation of SMX at least 3 times. Over all, CoFe-LDH@PBC800 composite was proved to be an efficient photocatalyst for antibiotic degradation in water or wastewater and the reuse of petrochemical wastewater sludge was expected to realize the concept of resourceful and high-value utilization of waste biomass.

Spectroscopic study of wemple-didomenico empirical formula and taucs model to determine the optical band gap of dye-doped polymer based on chitosan: Common poppy dye as a novel approach to reduce the optical band gap of biopolymer

This study investigates the effect of a natural dye extracted from common poppy (Papaver rhoeas) waste flowers on the optical properties of chitosan (CS) films. The extraction of natural dyes from waste flowers can be considered a new field for research in green chemistry. CS films are flexible and biodegradable but have low optical activity and band gap, limiting their applications in optical devices. The doped CS polymer with different concentrations of Papaver rhoeas dye exhibited enhanced optical properties. Also, 30 % glycerol was added as a plasticizer to omit film brittleness. The FTIR examinations is helpful to propose a mechanism that explains the interaction of the dye with the host polymer. The UV–vis spectroscopic examination establish that the optical characteristics of the films can be modified by adjusting the dye concentration. Furthermore, optical absorption properties are described using the Tauc non-direct transition model, revealing an approximate optical band gap of 1.64 eV. This band gap defines the energy required for electron transitions, elucidating the material’s electronic characteristics. The extinction coefficient (k) and refractive index (n) of the CS-doped films’ shows a dispersion behavior at visible regions of EM radiation. The Wemple-DiDomenico single oscillator model was used to investigate the n dispersion and determine the oscillator energy equivalent to the optical band gap. Additionally, calculations have been performed on optical dielectric properties and optical conductivity. The Urbach energy was measured and used to detect the structure of the films. The findings underscore the potential applications of these natural dye-doped CS films in eco-friendly materials and optical devices.

Waste polyethylene terephthalate-derived organic-inorganic hybrid materials as sustainable dual electrodes for Li-ion batteries

The hybrid Fe-Li2TP structure is constructed from waste polyethylene terephthalate (w-PET) derived dilithium terephthalate (Li2TP) and conventional Fe2O3 by hydrothermal reaction. It is being studied for both anode and cathode for LIBs. As an anode, it exhibits a reversible capacity of 505 mAh/g after 100th cycle at 1 C-rate with ∼100 % coulombic efficiency (CE). In addition, as a cathode, it shows highly reversible charge/discharge capacities of 107.50/107.52 mAh/g after the 100th cycle at 0.1 C-rate with 100 % CE. Further, in the cathodic studies via galvanostatic intermittent titration technique (GITT), the average lithium diffusion (DLi+) coefficients are calculated to be 2.96 × 10-10, 3.89 × 10−10 cm2 s−1 and the electrical (µ) mobilities to be 5.86 × 1011 m2 V−1 s−1, 1.12 × 1011 m2 V−1 s−1 for charge and discharge pulses, respectively. The combined nano-rod and nano-spherical morphologies reduce the diffusion length, and adding 10 % SWCNTs during electrode fabrication enhances the electronic conductivity. This organic–inorganic hybrid strategy of Fe-Li2TP strongly mitigates the electrode dissolution, reducing the structural strain and preventing electrolyte decomposition at higher voltage. Computational studies show an optimized Fe-Li2TP structure with a 2.7-fold lower band gap value (1.9040 eV) than the pristine Li2TP.

Photocatalytic and magnetic properties of nanocrystalline Er/Eu-doped ZnO samples

Augmentation of optical and magnetic properties of ZnO system via mono- and co-doping is an efficient approach to achieve enhanced ferromagnetism and photocatalytic activity. In this scenario, we made an endeavor to prepare the nanocrystalline ZnO, ZnO:Eu, and ZnO:(Eu, Er) samples through a co-precipitation technique. Structural analysis ruled out the effectual substitution of Eu and Er in the ZnO lattice without disturbing the original structure. Both ZnO:Eu and ZnO:(Eu, Er) NPs exhibited lower optical band gap values than pure ZnO. In M − H studies at room temperature, ferromagnetic behavior was observed in ZnO, ZnO:Eu, and ZnO:(Eu, Er) NPs. Expectedly, ZnO:(Eu, Er) NPs showed highest H2 evolution than both ZnO and ZnO:Eu NPs beneath solar spectrum. The possible roots behind the extended H2 production are discussed in detail. Hence, ZnO:(Eu, Er) NPs may find in applications is photocatalysis and spintronics.

Effective improvement of lithium-ion battery anode performance of Ti3C2 by alkali metal ion treatment strategy

MXene has emerged as a promising electrochemical energy storage material due to modifiable layered structure and good electrical conductivity. However, its lamellar stacking has severely limited the electrochemical performance during charging and discharging. Herein, the Li-treated Ti3C2 and Na-treated Ti3C2 nanocomposites are prepared by hydrothermal treatment. Li-treated Ti3C2 exhibits the largest discharge specific capacity, with an initial capacity of 551.5 mA h/g at a rate of 0.1 A/g, which is 81.3 mA h/g higher than Na-treated Ti3C2. After 200 cycles, the Li-Ti3C2 possesses a final capacity of 321.1 mA h/g, better than Na-Ti3C2 (151.7 mA h/g) and Ti3C2 (119.3 mA h/g). The Li-Ti3C2 shows superior cycling performance at a high rate of 2 A/g and a capacity retention rate of 84 % after 1000 cycles. During hydrothermal treatment, the in situ generated TiO2 plays a crucial role in the targeted introduction of metal ions. Density functional theory (DFT) calculations verify that LiTiO2 phase in Li-treated Ti3C2 possesses low band gap and lowest Li migration barrier. The synergy of these factors leads to the improved electrochemical performance of Li-treated Ti3C2. This work provides novel design strategies for developing MXene materials as high performance lithium-ion batteries.

Thieno[3,2-b]thiophene flanked para-azaquinodimethane π-extended aromatic-quinoidal polymers

A series of thieno[3,2-b]thiophene (TT) flanked para-azaquinodimethane (p-AQM) based quinoidal conjugated polymers PAQM2TT-T, PAQM2TT-BT and PAQM3TT were designed in a strategy to extend the aromatic-quinoidal π-system. The three polymers were synthesized by Stille polycondensation, and their opto-electronic properties and device performance in field-effect transistors have been explored. From absorption spectroscopy, the polymers show low bandgaps (1.54–1.57 eV) and high HOMO energy levels. They exhibit typical p-type behavior according to the results of the characterization of the field-effect transistors with average charge carrier mobilities of 0.08 cm2 V−1 s−1 for PAQM2TT-T, 0.12 cm2 V−1 s−1 for PAQM2TT-BT and 0.05 cm2 V−1 s−1 for PAM3TT. This report presents an alternative π-extended quinoidal-donor strategy to control the molecular design and properties of new p-AQM-based conjugated polymers.

2D‐Pyroelectric Materials for Waste Thermal Energy Harvesting and Beyond

AbstractPolar 2D materials hold the emerging functionalities such as ferro‐, piezo‐, and pyro‐electric properties. On account of infrared‐active low bandgap and polar nature at reduced dimensionality, they served as an ideal choice of pyroelectric material. It can cover up a diverse range of applications, such as waste thermal energy harvesting, IR imaging, photodetector, temperature sensors, and several catalytic processes due to the abundance of dynamic thermal fluxes. Recently, 2D pyroelectric materials have manifested a substantial role in thermal energy harvesting. Consequently, it is realized that there are plenty of scopes available to diversify its applicability. Thus, the challenges are spotlighted in this perspective to envision the desired 2D pyroelectric materials to achieve the effective thermal energy harvesting, sensing, and catalytic efficacy. Particularly, the emphasis is given to elucidate the role of spontaneous polarization in 2D materials to ascertain the giant pyroelectricity.

Dual-band topological refractive properties in solid phononic crystals

The lossless transmission of topological edge states and the robustness of defect immunity make topological refractive materials have important application prospects in acoustic communication and integrated acoustic devices. However, most topological refractive materials only have a single operating frequency band, which obviously limits their application in multi-band and multi-function devices. Therefore, a phononic crystal with dual-frequency topological states is designed in this paper, and its dual-topological refractive properties are investigated and discussed. The existence of in-plane bulk elastic wave edge states is demonstrated by calculating the band structure of supercell comprising phononic crystals with different topological phases. Numerical simulations of the constructed acoustic topological waveguide are performed and negative refraction is observed at the low bandgap while zero refraction is observed at the high bandgap. Then, the topological zero refraction is investigated for different incidence angles. The designed dual-band acoustic topological insulator has potential applications in multi-band acoustic communication and acoustic information processing.

Unveiling the potential of FASnI3 solar cells through advanced charge transport materials: A SCAPS-1D perspective

As demand grows for efficient and affordable photovoltaic technology, investigating alternative materials becomes crucial. Tin-based perovskite has a low bandgap, great optoelectronic properties, and higher carrier mobility. It has become an interesting absorber layer for perovskite solar cells (PSCs). However, improving their device performance presents challenges. Copper-based hole transport materials (HTM) and zinc-based electron transport materials (ETM) offer low cost, easy fabrication, and high electrical conductivity. This research analyzes the impacts of these transport materials on the FASnI3 absorber layer using numerical modeling in SCAPS-1D. Through simulation analysis, the study thoroughly examines the effect of these materials on PSC performance parameters such as QE curve, layer thickness, defect density, interface defect, and doping concentration. Moreover, this study identifies the most efficient PSC configurations, achieving good performance by ITO/ZnSe/FASnI3/Cu2O/Au with aVoc of 2.05 V, Jsc of 29.316 mA/cm2, FF of 53.37 %, and power conversion efficiency (PCE) of 32.13 %, providing valuable insights in optimizing FASnI3 solar cells and advancing next-generation solar energy conversion technologies.

Synergistic effects of Fe2O3 supported on dendritic fibrous SBA-15 for superior photocatalytic degradation of methylene blue

Environmental pollution caused by dye effluent has attracted much attention, and thus developing photocatalysts with superior photodegradation performance is an imperative task. A series of Fe supported on dendritic fibrous SBA-15 (Fe/DFSBA-15) catalysts with various Fe contents were prepared using a microemulsion coupled with ultrasonic-assisted impregnation methods. The findings revealed that the structural stability of DFSBA-15 was unaffected by the amount of Fe loaded. As the Fe loading increased, the size of Fe2O3 nanocrystals increased while the catalysts’ surface area decreased. The bandgap energy of the catalyst decreased with increasing Fe loading and became constant after reaching an optimal Fe loading of 10 wt%. The one-factor-at-a-time study revealed that 10Fe/DFSBA-15 degraded 94.72 % of methylene blue (MB) within 180 min at 1.5 g/L catalyst dosage, pH 8, and 10 mg/L of concentration, owing to Si-O-Fe coordination, modest Fe2O3 crystallite size, homogeneous metal distribution, slower recombination rate, and low bandgap energy. The advantageous features of 10Fe/DFSBA-15 resulted in accelerating the photodegradation rate, where 10Fe/DFSBA-15 is found as the optimal catalyst. The addition of Fe particles to the DFSBA-15 largely improved their photocatalytic activity toward MB degradation, making it a potential candidate for removing pollutants from aqueous solutions.

Cover Picture: Novel low‐band gap non‐fullerene acceptors based on IDIC core as potential photovoltaic materials (BKCS 9/2024) Radhiha Ravindran, Inchan Kim, Yun‐Hi Kim, Soon‐Ki Kwon

Organic photovoltaics (OPVs) attracted a lot of research attention owing to its advantages such as convenient processing technique, unsubstantial weight, low cost, flexibility and use of environmentally benign materials. In general, these are bulk heterojunction (BHJ) OPVs obtained through a solution process and the large‐area OPV production is achieved via roll‐to‐roll process. In OPVs, the BHJ active layer consists of electron donor (D) and electron acceptor (A) materials blended together by dissolving them in a common organic solvent. The new low band gap non‐fullerene based acceptors could be used as potential candidates for the fabrication of OPVs in combination with suitable donor polymers. More details are available in the article by Radhiha Ravindran, Inchan Kim, Yun‐Hi Kim, Soon‐Ki Kwon image

Prediction of X2AuYZ6 (X = Cs, Rb; Z = Cl, Br, I) double halide perovskites for photovoltaic and wasted heat management device applications

We used density functional theory to study the phase stability, the opto-electronic properties, and the thermo-electric behavior of X2AuYZ6 (where X = Cs, Rb, and Z = Cl/Br/I) double halide perovskites. The compounds belong to the cubic perovskite arrangement and are verified by the tolerance and octahedral factor. Formation enthalpy and binding energy primarily meet the requirements for structural stability. The positive frequency of phonon dispersion shows that all compounds are dynamically stable except for Rb2AuYI6. The negative formation energy considering the competing phase also confirmed that all compounds are thermodynamically stable. The Pugh's ratio, Poisson's ratio, and Cauchy pressure validated their ductile nature in the analysis of thermo-mechanical behavior. The electronic characteristics of Cs2AuYZ6 (Rb2AuYZ6) [Z = Cl, Br, I] double halide perovskites (DHP) have been investigated using the TB-mBJ technique, yielding band gap values of 2.85 (2.91), 2.35 (2.40), and 1.74 (1.78) eV, in that order. The optical properties are calculated, revealing the maximum absorption coefficients with respect to wavelength in the visible range of the titled compounds are 0.23 (0.35) × 105 cm−1, 1.01 (1.06) × 105 cm−1, and 1.42 (1.48) × 105 cm−1, respectively, indicating their potential for photovoltaic applications. The thermo-electric transport properties were also studied. The investigated compounds [Cs (Rb)-based] exhibit ZT values of 0.51 (0.55), 0.53 (0.62), and 0.58 (0.75) at room temperature with Cl, Br, and I, respectively. As a result, the studied compounds, particularly those Rb-based with halides, have significantly greater potential than Cs in thermoelectric fields. So, among the compounds, X2AuYI6 (X = Cs, Rb) shows the most promise for the technological applications mentioned above due to its lower band gap, high absorption coefficient, and high ZT value.

Synthesis, characterization, anticancer activity, molecular docking and DFT calculation of 3-acetylcoumarin thiosemicarbazones and Schiff’s bases

The new thiosemicarbazones (3a-d) of 3-acetylumbelliferone and Schiff’s bases (4a-b) of 3-acetylcoumarin were synthesized, characterized by elemental analysis, UV–Vis, FT-IR, NMR, and ESI-HR MS, and evaluated for their anticancer potency against the human breast cancer (MCF-7) cell line. All the tested compounds exhibited good to moderate anticancer efficacy in a dose-dependent manner. The synthesized compounds exhibited potent preferential inhibition effects against the MCF-7 cell line, with IC50 range of 147.8–505.1 µg/mL. The most potent compound, (E)-N-(1-(7-hydroxy-2-oxo-2H-chromen-3-yl) ethylidine)-2,6-dimethylmorpholine-4-carbothiohydrazide (3c), showed significant cytotoxicity with an IC50 value of 147.8 µg/mL against the tested cell line. It showed a higher proportion of cells in G1 (37.21 %) and S (26.86 %) phases and a lower proportion of cells in G2 phase (26.37 %), with respect to control. Molecular docking of all the synthesized compounds with target proteins VEGFR2 and EGFR demonstrated their significant binding affinity and interactions with key residues compared to the reference drug (erlotinib). DFT-based analysis showed that all the compounds have effective reactivity due to the low band gap energy of HOMO and LUMO relative to the reference drug, erlotinib (4.26 eV). The reactivity-related quantum mechanical parameters η, S, χ, μ, and ω indicated that these compounds have a high efficacy towards the target enzymes VEGFR2 and EGFR. All of the synthesized compounds had drug-like action, according to ADMET predictions.

Cu2+ ions implanted porous titania for efficient dye sensitized solar cells

In the quest to unlock the remarkable potential of nanotechnology, the sol-gel method was employed to craft a porous TiO2 nanostructured film, meticulously deposited onto FTO glass substrates. This endeavor marked a significant leap as a controlled bombardment of Cu ions, accelerated at 700 keV, at varying flux rates of 2x1013, 2x1014, and 2x1015 ions/cm² was introduced to these ingeniously engineered films. A comprehensive assessment of these nanocrystalline TiO2 structures, both before and after Cu+2 ion irradiation, revealed a fascinating array of results. he anatase tetragonal structure's permanence was validated by X-ray diffraction (XRD), which improved the material's stability and integrity. In the present study, an interesting observation was made that band edges show a dynamic behavior in Cuirradiated samples in UV-Vis spectroscopy. At 2x1014 ions/cm2, the phenomena peaked, revealing an intriguing redshift and an exceptionally low band gap value of 3.39 eV. In photoluminescence spectra, the peaks corresponding to the lattice defects show a significant reduction when the flux of the Cu ions on TiO2 is adjusted to 2 x 1014 ions/cm2. It is an indication that film quality and purity have improved. This arrangement for photoanode modification helps in the development of dye-sensitized solar cells with tremendous characteristics. The fabricated device with this novel approach results in high values of open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), and maximum photoconversion efficiency of 5.10%. These findings indicate a new era of possibilities in the field of renewable energy, since these nanostructured materials have the ability to significantly alter the solar field.

Advanced Z-scheme H-g-C3N4/Bi2S3 nanocomposites: Boosting photocatalytic degradation of antibiotics under visible light exposure

Abnormal concentrations of antibiotics found in aquatic environments have raised serious environmental concerns. For the efficient degradation of antibiotics, it is necessary to develop photocatalysts that react to visible light. In this work, calcination and hydrothermal methods were used to synthesize bare H-g-C3N4 and Bi2S3, respectively. Various analytic methods, such as XRD, XPS, FT-IR, HR-SEM, and HR-TEM, were utilized to verify the accomplished synthesis of the materials produced. The results of ultraviolet–visible diffuse reflectance spectroscopy (UV–DRS) showed that the synthesized nanocomposites exhibited a lower band gap than the bare materials and thus greater visible-light absorption. The degradation efficacy of the bare materials and hydrothermally synthesized nanocomposites over ciprofloxacin were investigated. A high degradation efficiency of 92 % was demonstrated for ciprofloxacin using the H-g-C3N4/Bi2S3 (5 %) nanocomposite. This remarkable efficiency underscores the potential of this nanocomposite in removing antibiotic pollutants from wastewater. In addition, the electron transfer dynamics amid the two materials (H-g-C3N4 and Bi2S3) within the heterojunction was elucidated. The findings provide valuable insights into the mechanisms underlying the enhanced photocatalytic activity of nanocomposites, paving the way for further optimization and development of advanced photocatalytic systems for environmental remediation.

First Principle Study of Tunnel Magnetoresistance of Various Oxide Materials

In this paper, the first principle study of tunnel magnetoresistance (TMR) for various oxide materials has been done. More than 30 materials have been taken into consideration and divided into four different categories based on their bandgap. The four categories are 2-4 eV bandgap materials, 4-6 eV bandgap materials, 6-8 eV bandgap materials, and 8-10 eV bandgap materials. The first principle simulations and the device-level simulations of various MTJ configurations were executed using the various oxide materials. The results reveal that maximum TMR ratio is observed in oxide materials having lower bandgap value and it reduces with the increase in oxide material bandgap. The maximum TMR ratio is observed in Cu2O material and minimum TMR is observed in BeO material. The oxide materials with bandgap less than 3ev are the best materials for device level fabrication and they provide 100% TMR for the oxide thickness up to 3 nm.

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