Tauc Relation Research Articles

The Optical and Structural Properties of Cu Nanoparticles: Graphene Prepared by Pulsed Laser Ablation in Deionized Water

Background: In this paper, graphene and copper oxide nanoparticles and graphene-based copper oxide nanoparticles have been produced by means of a pulsed laser ablation process (PLA) in a deionized water solution. Methods: The composition ratio of materials has been investigated in the structure of the prepared materials and their optical properties. The absorbance of the samples was obtained by the UV-VIS single beam spectrophotometer in the wavelength range of 290 to 800 nm. Spectroscopic ellipsometry method was used to investigate the linear optical properties of the samples including the real and imaginary parts of refractive index and dielectric function of the samples. The preferred model in the dielectric function modeling was Tauc-Lorentz. Also, the energy band gap of the samples has been calculated using Tauc relation. In addition, the nonlinear optical properties of graphene based copper oxide have been studied by Z-scan technique. Structure of the samples was studied using TEM image. Results: The most and the least absorbance at 532 nm wavelength, and also band gap energy belong to 1.4 ml Gr-0.6 ml Cu and copper oxide, respectively. Conclusion: The band gap energies of the samples were calculated between 3.30 eV and 3.43 eV. The real and imaginary parts of the complex refractive index were obtained in the order of 10-8cm2/W and 10-5cm/W. The results for nonlinear properties show that these samples are suitable for all-optical switching devices.

Optical and Crystal Structure Properties of ZnO Nanoparticle Synthesized through Biosynthesis Method for Photocatalysis Application

In this study, zinc oxide nanoparticles (ZnO NPs) were synthesized from zinc nitrate hexahydrate precursor and mango leaf extract (MLE). The purpose of this research was to investigate the crystal structure and optical properties exhibited by ZnO NPs for photocatalytic applications. ZnO NPs produced from various concentrations of sodium hydroxide (NaOH) and the addition of MLE during the synthesis stage demonstrated intriguing physical structure and optical properties. XRD characterization results revealed the attainment of a pure ZnO phase with a high crystallinity degree in all samples. Biosynthesis with MLE unveiled minor peaks corresponding to the cellulose phase. The achieved crystallite size ranged from 15–28 nm. The FTIR patterns detected in the wavenumber range of 600–4000 cm−1 indicated successful crystallization of all ZnO NPs samples. The band gap energy for each sample (ZnO-A to ZnO-E) is indicated to be in the range of 3.25, 3.25, 3.26, 3.31, and 3.17 eV, as demonstrated by the Tauc relation. The effect of MB degradation by the ZnO-E photocatalyst is revealed by the photodegradation of 96.46%.

The effects of Mn doping on structural, morphological, and optical properties of hydrothermally synthesized h-MoO3 nanorods

Pure and Mn-doped h-MoO3 nanorods with varying doping concentrations (1, 3, 5 M%) have been synthesized via the hydrothermal method. Subsequently, the impacts of Mn incorporation on the microstructural and optical properties of the synthesized nanorods have been examined. The X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) have confirmed the metastable hexagonal phase (h-MoO3) and rod-type morphology, respectively. To explore various crystallographic features, such as crystallite size and lattice strain, the Scherrer formula, Williamson-Hall (W–H), and Halder-Wagner (H–W) techniques were used. In addition, the dislocation density, lattice parameters, and unit cell volume have been evaluated in conjunction with XRD analysis by Rietveld refinement. The optical bandgap was estimated from UV–vis spectroscopy utilizing the Kubelka-Munk (K-M) function and the Tauc relation. The estimated bandgap values ranged from 3.05 to 3.09 eV for the K-M function and 2.92–2.98 eV for the Tauc relation. The optical bandgap increased as the concentration of Mn increased to 3 M% and then decreased. Both approaches showed analogous optical bandgap variation.

Investigation on the electrocatalytic oxidation of alcohol using zinc oxide thin films deposited by pulsed electrodeposition on an indium tin oxide surface

To perform electro-catalytic oxidation of alcohols in an alkaline media, zinc oxide (ZnO) thin films were effectively deposited on indium tin oxide (ITO) substrates using the pulsed electrodeposition (PE) method in a zinc nitrate aqueous solution. Analyses of microstructural, photoelectrochemical, and optical characteristics of ZnO thin films were performed as a function of pulsed electrodeposition parameters. XRD analysis was applied to determine structural properties, and SEM and AFM analysis were used to investigate morphological characteristics. X-ray diffraction analyses revealed that the produced films were polycrystalline and had a (002) preferentially oriented, hexagonal wurtzite structure. The morphology of ZnO has improved in the direction of nanorod films, as evidenced by scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. UV transmittance data was used using Tauc's relationship to determine the film's bandgap to be 3.26 eV. The photocurrent response shows that ZnO films have high values, at 305.17 A/cm2, and good optical characteristics. The electrocatalytic oxidation of methanol was finally evaluated on the films. After being optimized in the pulsed electrodeposition mode, ZnO thin film characteristics and methanol electrocatalytic oxidation both saw substantial improvements.

Synthesis, structural characterization and optical studies of Fe2O3 nanoparticles based polymeric materials for flexible electronic devices

In this work, a thin film containing a flexible polymer nanocomposite of iron oxide (Fe2O3) and poly(4-chloroaniline) P(4-ClAni) was successfully synthesized using the green polymerization fabrication method. To confirm the effective synthesis of the P(4- ClAni)/Fe2O3 nanocomposite, the XRD, SEM, and FTIR analyses were used. The SEM pictures revealed that the nanocomposite contain Fe2O3 nanoparticles distributed throughout the polymer matrix. The optical absorbance of the P(4-ClAni) and P(4-ClAni)/Fe2O3 films was measured at room temperature using a UV-vis spectrophotometer from 190 to 1150 nm. The optical properties of P(4-ClAni)/Fe2O3 films were calculated using Tauc's relation. The Urbach energy of the P(4-ClAni) increases from 0.96 eV to 1.65 eV, 1.73 eV, and 1.86 eV, respectively, when mixed with 2%, 4%, and 6% of Fe2O3. On the other hand, the band gap energy of P(4-ClAni) decreases from 3.57 eV to 3.39 eV, 3.07 eV, and 2.84 eV, respectively, with the addition of 2%, 4%, and 6% Fe2O3. Based on the results of this study, the composite P(4-ClAni)/Fe2O3 sheets can be used for flexible electronic devices.

The spectral properties and dispersion parameters of electrospun nanofibers Poly(vinyl alcohol/ Poly(acrylamide)

Electrospun nanofibers based on polyvinyl alcohol (PVA), polyacrylamide (PAAm), and a PVA-PAAm blend (50/50 wt.%) were effectively made a room temperature(RT) and a voltage of (12kV). The products were studied using Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy(FT-IR) and Ultraviolet-visible (UV–Vis) spectroscopy. The result of FESEM analysis showed that the polymer PVA, PAAm, and blend samples produced a random distribution of fine fibres at an average diameter of (214.12, 317.1, 157.65) nm with a smooth surface. In addition, the FESEM images demonstrate the fibres' suitability for use in gas sensing applications due to their branching fibres and porosity surface. XRD showed that the film polymeric of PVA, PAAm polymeric blend PVA-PAAm was seen to have a semicrystalline nature. According to the FTIR analysis, the PVA and PAAm networks in the PVA-PAAm polymer nanofibers were entangled due to the powerful hydrogen bond contact between the PAAm and PVA chains. Observed around (3473.79 and 3414) cm-1 were attributed to the N–H vibration and overlapped to O–H stretching. The spectra of the prepared films exhibit prominent absorption peaks, which are at the wavelength range (200-320) nm. PVA-PAAm polymer nanofibers decrease the energy gap from 3.70eV to 3.40eV. The Wemple-DiDomenico model was used to derive dispersion parameters such as dispersion energy, single oscillator energy, Urbach energy, the static refractive index and the moments of optical spectra the result of calculating by this model was compatible with that value calculated by the Tauc relation. While increased which qualifies them to be used in the electronic devices.

X-ray/gamma radiation shielding properties of zinc ferrite nanoparticles synthesised via solution combustion method.

Zinc ferrite (ZnFe2O4) nanoparticles were synthesised via solution combustion method using urea as a fuel. The synthesised samples were characterised with various techniques. The cubic structure with Fd-3m space group is confirmed by Powder X-ray Diffraction and Bragg's reflection. The crystallite size estimated from Scherrer's method was found to be 40nm. The agglomerated irregular shape and sized surface morphology was confirmed by Scanning Electron Microscopy image. The direct energy band gap determined from Wood and Tauc's relation was found to be 5.25eV. Using a NaI (Tl) detector and multi-channel analyser, the described sample was examined for X-ray and gamma ray shielding characteristics in the energy range of 0.081-1.332MeV. The measured shielding values are in good agreement with the theory, however below 356keV, there is a little variation of up to 10%. The current work offers up new possibilities for using this simple, affordable, effective and low temperature approach to create nanomaterials for X-ray and gamma ray shielding.

Enhancement in the Magnetic Properties of Yttrium Orthoferrite Materials by the Addition of BaO–Bi2O3–B2O3 Glass Sintering Aid

The addition of powdered BaO–Bi2O3–B2O3 (BBBO) glass (0.25–1.5 wt%) to yttrium orthoferrite materials (YFeO3) powder facilitates an increased crystallite size, resulting in improved magnetic properties. The required YFeO3 (YFO) materials are synthesized through the sol–gel route using tartaric acid as a chelating agent, while BBBO glass is obtained via the conventional melt‐quenching technique. The crushed glass is added to YFO powders in different wt% and compacted at room temperature, subsequently; the compacted samples are sintered at 1000 °C for 3 h. The X‐ray powder diffraction studies infer that a maximum 1.0 wt% of BBBO glass is incorporated into YFO without showing any impurity phase. The optical bandgap of each sample is calculated using the UV data with the help of the Kubelka–Munk and Tauc relation, decreasing from 2.10 to 2.04 eV with an increase of BBBO content from 0 to 1.0 wt% in YFO. The highest magnetization value (4.02 emu g−1) is observed with 1.0 wt% BBBO added in YFO surpassing pure YFO and other BBBO‐added YFO samples. In conclusion, the improved magnetization value of the 1.0 wt% BBBO added in the YFO sample can be potentially utilized in different applications.

Brownmillerite Calcium Ferrite, a Promising Perovskite-Related Material in the Degradation of a Tight Dye under Ambient Conditions.

Evaluation of effective and low-cost materials as catalysts to combat the threat of pollution is a significant and growing trend. With this aim, we have synthesized calcium ferrite brownmillerite by wet preparation approach as a catalyst for pollution. The structural analysis is established by the X-ray diffraction of Ca2 Fe2 O5 , whereas the tetrahedral and octahedral sites band stretching for ferrite specimen has been deduced using FTIR. The bandgap energy has been estimated by the Tauc relation (2.17 eV). Ca2 Fe2 O5 brownmillerite exhibits a BET surface area of 10 m2 /g and a BJH pore volume of 0.121 cm3 /g with the average particle size of 70 nm. Importantly, the alizarin Red S dye degradation has been studied using the prepared ferrite catalyst, under dark ambient conditions and without the presence of any acidic or basic additives. Degradation is also supported by both FTIR and TOC analysis. Surface properties of brownmillerite Ca2 Fe2 O5 have been characterized using electronic spectroscopy and CO2 temperature programmed desorption (TPD) analysis and revealed that the basic surface of brownmillerite Ca2 Fe2 O5 offers active sites that are suitable for degradation processes. All results show that the preparation of brownmillerite Ca2 Fe2 O5 via the Pechini method is suitable to produce fine surfaces and pores with nanosized particles.

Ternary system based on polyaniline, graphene, and acrylic matrix applied to thermoelectric systems

AbstractThermoelectric (TE) materials have attracted attention for offering a green option for power generation, due to their ability to convert thermal energy into electricity. In recent years, a promising way to achieve efficiency in TE properties has been proposed based on composites of conjugated polymers, such as polyaniline (PANI), and carbon nanomaterials such as graphene (GR). Since polyaniline and GR composites are promising fillers for organic thermoelectric materials (OTE), we expanded their investigations for a ternary system (TS), providing materials with multiple functionalities, and high performance. In this research work, a TS based on an acrylic matrix (ACR), GR, and PANI was successfully prepared through the combination of in situ polymerization of aniline in contact with GR and mechanical mixture of the resulting hybrid with an ACR. Structural and morphological characterization confirmed that GR affected PANI morphology and crystallinity. The band gap determination by Tauc's relation indicated the occurrence of π‐π interaction between the chains and an increase of the electrical conductivity of the composites allowed to infer a synergistic effect. The measured Seebeck coefficient reached a maximum value of −17.02 μVK−1 and the highest power factor obtained was 4.94 μWm−1 K−2 for the ACR/PANI sample, indicating a material with promising thermoelectric properties.

Photocatalytic Scheme with External Magnetic Field on Coffee Waste in Hydrogen Production

Photocatalytic is considered a deadlock-breaking technology for renewable energy and lowering environmental pollutants. Photocatalytic efficiency efforts are improved by activating the photocatalyst to introduce an external magnetic field. This review highlights recent breakthroughs by comparing original coffee waste, activation of coffee waste with the addition of catalysts, and manipulation of spin electrons by applying external magnets. Characterization was done with FTIR to look at chemical bonds, UV-Vis with Tauc's Relation approach to measure bandgap, and material morphology using SEM EDX. The increase in photocatalyst activation aligns with the decrease in bandgap value. The rate of decline in bandgap is in line with the rate of acceleration of hydrogen production. Adding an external magnetic increases hydrogen production up to 1.5 times greater than the original photocatalytic.

Enhancing the optical, electrical, dielectric properties and antimicrobial activity of chitosan/gelatin incorporated with Co-doped ZnO nanoparticles: Nanocomposites for use in energy storage and food packaging

The solution casting method was utilized to produce a brand of new nanocomposites made of chitosan (Cs), gelatin (Ge), and co-doped ZnO nanoparticles (NPs). The physicochemical characteristics of these nanocomposites were examined using a variety of methods. The doped samples' XRD patterns clearly demonstrated changes in the structural features of the Cs/Ge host polymer, with the widening of the peak at 2θ = 20.31 becoming more prominent as Co-doped ZnO NPs concentration increased. Tauc's relation was utilized to describe the direct and indirect bandgap energies using UV–Vis analysis. By including 3.5 wt% of Co-doped ZnO NPs, the optical energy gap direct and indirect of pure Cs/Ge was reduced from 5.22 to 4.92 eV to 4.90 and 4.42 eV, respectively. Co-doped ZnO NPs reinforcing has a significant impact on the in ac conductivity, dielectric constant and loss tangent values. An ionic conductivity of 1.089 × 10−7 S/cm at Cs/Ge-3.5 wt% Co-doped ZnO NPs was observed. The nanocomposites' antimicrobial effect on bacteria and fungi was tested. The adding of 3.5 %Co-doped ZnO NPs improved the activity against S. aureus (22 mm), E. coli (13 mm), A. niger (29 mm), and C. albicans (27 mm) despite the fact that the investigated pure mix had no effect on the microbiological strains. The current research's remarkable findings in terms of optical, dielectric, electrical, and antimicrobial effects indicate that Cs/Ge-coated ZnO film will have significant uses in both food packaging and energy storage devices.

Comprehensive investigation of sputtering deposition pressure effects on a-InGaZnO Schottky diodes

The effects of Ar sputtering deposition pressure on the optical, structural, morphological, and electrical properties of amorphous InGaZnO thin films were investigated. The InGaZnO thin films, which have amorphous structures determined by grazing incidence x-ray diffraction, contained In, Ga, Zn, and O confirmed by secondary ion mass spectrometry method. Additionally, when the thicknesses of the deposited thin films are examined, it was seen that the profilometer measurement results of the crater formed by secondary ion mass spectrometer and scanning electron microscope measurement results are nearly similar, and it is approximately 100 nm. The surface roughness, obtained from Atomic Force Microscopy results, show that decreased up to a particular value with the increase of the working pressure, and then the surface roughness increased. The optical band gaps of the films were obtained in the range of 3.50 eV−3.58 eV via Tauc relation by using the Ultraviolet-Visible measurements carried out in the wavelength range of 200 nm−1100 nm. It was seen that the optical band gap was decreased with the increase in Ar pressure. The electrical properties of InGaZnO thin film-based Schottky diodes, such as the barrier height, ideality factor, saturation current, series resistance, and shunt resistance, have also been studied comprehensively. The electrical results showed that diode properties change with increasing deposition pressure.

Synthesis, Structural, Spectroscopic, Fluorescence, and Dielectric Studies of Bis-(4-Aminopyridine)-Zinc(II) Acetate: A Metal-Organic Crystal.

The advancement of crystalline growth and characterization tools allows us to investigate novel nonlinear optical substances suitable for photonic applications. Bis-(4-aminopyridine)-zinc(II) acetate (B4AZA), a metal-organic crystal was produced in this study using the slow evaporation procedure at room temperature. Analytical studies such as X-ray crystallography, Fourier transform infrared (FT-IR), UV-visible (UV-Vis), fluorescence, second harmonic generation (SHG), and dielectric tests were used to characterize the as-grown B4AZA crystals. According to the solubility data, the sample has a positive temperature coefficient of solubility. The crystallographic findings show that the B4AZA crystallized in a monoclinic structure with the P21/n space group. Molecular vibrations and functional groups in the substance were determined using the FT-IR technique. The UV-Vis absorbance and transmittance spectra have shown the wide transparency and minimum absorbance of the B4AZA in the near UV and entire visible regions of the electromagnetic spectrum. The bandgap of the B4AZA has been calculated using the Tauc relation and found to be 4.32eV. The fluorescence spectra have shown a prominent emission peak at 584nm with an excitation wavelength of 280nm. The larger Stokes shift found in the fluorescence spectra is advantageous for practical applications. The SHG study revealed that the powdered B4AZA samples generated a second harmonic output. The dielectric test revealed frequency-dependent changes in the dielectric constant and loss factor. Both the dielectric constant and the loss factor decrease exponentially as frequency increases, reaching low values at higher frequencies. The experimental results illustrate the suitability of the B4AZA crystals for photonic applications.

Synthesis of Flower‐Like FeS2 and NiS2 Microspheres Based on Nanoflakes and Nanoparticles: Electronic Structures, Magnetic and Optical Properties

Flower‐like spherical micrometer‐sized particles of FeS2 and NiS2 are synthesized using the solvothermal method. The microstructure, phase composition, saturation magnetization and optical characteristics of the synthesized FeS2 and NiS2 are described, and the atomic structure, electronic structure, and optical characteristics of the materials are calculated systematically founded upon the first principles of density functional theory. This work shows that the magnetic saturation intensity of FeS2 and NiS2 is respectively 0.36 and 0.02 emu g−1. The FeS2 and NiS2 bandgaps are separately 0.81 and 2.07 eV, calculated by Tauc's relation. Through the comparison of optical properties, the maximum absorption coefficient of FeS2 and NiS2 is separately 3.26 × 105 and 3.3 × 105 cm−1, and the two crystals’ absorption coefficient accordingly drops to 0 at 23.8 and 25.8 eV, indicating that the maximum absorption value and energy absorption range of NiS2 are higher than those of FeS2. The reflectivity above 60% ranges from 15.3 to 20.6 eV and 15.2 to 21.5 eV for FeS2 and NiS2, respectively, which indicates that the reflectivity of NiS2 is stronger than that of FeS2.

Biosynthesis, Spectroscopic, and Antibacterial Investigations of Silver Nanoparticles.

Silver nanoparticles can be produced by an array of procedures, such as chemical, physical, and biological processes. The process of biosynthesis is more economical and significantly more environmentally friendly. We describe an environmentally compatible method (biosynthesis) of producing silver nanoparticles (Ag: NPs) with the capping component Artocarpus heterophyllus in this research work. Powder-X-ray crystallography (P-XRD), Fourier Transform Infrared (FT-IR), UV-visible (UV-Vis), Photoluminescence (PL), Field emission scanning electron microscopy (FE-SEM), and an antimicrobial test were all used to examine the synthesized samples. The P-XRD analysis revealed that the produced NPs have an FCC form with a typical particle size of 23nm. FT-IR spectra further demonstrate the availability of the functional groups in the synthesized nanoparticles. The absorbance and transmittance spectra of the UV-Vis study have shown substantial transparency and less absorbance of the Ag: NPs in the entire visible region. The bandgap of the Ag: NPs was found tobe 3.25eV using the Tauc relation. In the PL study, an emission peak at 472nm was found, suggesting the fluorescence emission of Ag: NPs. The FE-SEM micrographs provide confirmation of the surface-wide aggregate of nanostructural homogeneities. The FE-SEM micrographs illustrate that Ag: NPs are homogeneous aggregates of very small spheres. Variations in particle size and surface area-to-volume ratios of synthesized NPs have been proven to be responsible for the antibacterial activities. According to the antibacterial study, Ag: NPs restrain the development of both normal and harmful bacteria and so have the potential to be utilized for coating surgical equipment for aseptic operators in the healthcare industry.

Multifunctional properties of tin oxide nanoparticles synthesized by green and chemical approach

Herein, we report the synthesis of SnO2 nanoparticles by combustion method using two reducing agents. One with urea as a fuel (SnO2U) and another one with Azadirachtaindica leaves extract as a reducing agent (SnO2N) and calcined at 500oC for 3 hrs. The synthesized samples are characterized using different techniques. The Bragg reflections confirms the formation of pure tetragonal SnO2 NPs. The surface morphological analysis clearly indicates the formation of irregular shaped agglomerated NPs. The agglomeration and particle size was found to be more in SnO2U NPs. The estimated direct energy bandgap using Tauc's relation was found to be 3.75 and 3.37 eV for SnO2U and SnO2N respectively. Further, Photoluminescence excitation, emission, CIE and CCT analysis was performed. Thus, the present sample might be used as a nanophosphor material in Cool and Warm blue light emitting diodes. The cytotoxic properties against HeLa and MCF7 cells and compared the percentage of viability and cell death with standard chemotherapy drug Cisplatin. Theoretically, X-ray/gamma ray absorption properties such as mass attenuation coefficient (MAC) SnO2U and SnO2N NPs were evaluated which might finds an application in nuclear radiation dosimetry.

Improving the optical, photoluminescence, and electrical properties of PEO/NaAlg-WO3 nanocomposites for optoelectronic and nanodielectric applications

Nanocomposites based on polyethylene oxide (PEO)/Sodium Alginate (NaAlg) with varying content of tungsten trioxide nanoparticles (WO3 NPs) have been synthesized by using a green solvent casting method. Through the use of X-ray diffraction (XRD), Fourier transforms infrared (FTIR), and Ultraviolet–visible spectroscopy (UV–Vis.), the interaction of mixed components has been evaluated. Studies using spectroscopy have shown that WO3 nanoparticles and the blend's component parts interact strongly at their interfaces. XRD confirms the increasing amorphous propensity of the PEO/NaAlg film with increasing nanofiller loading. FTIR implies the development of molecular complex of the polymer with the nanofiller. From UV–Vis analysis, Tauc's relation was used to specify the direct and indirect bandgap energy. The Eg (direct) of pure PEO/NaAlg was considerably decreased from 4.23 to 3.04 eV by adding 2.0 wt% of WO3 NPs. The fluorescence for various WO3 NPs concentrations in PEO/NaAlg blend films was analyzed. The PEO/NaAlg blend's fluorescence intensity decreased with increased doped with WO3 NPs. The films made of nanocomposites also had their dielectric behavior and electrical conductivity examined. In contrast to the electrical conductivity (AC), the dielectric constant and dielectric loss of PEO/NaAlg-WO3 nanocomposites drop as the frequency of the electric field rises. The investigation revealed that an increase in WO3 concentration led to a corresponding rise in the nanocomposites' dielectric loss and dielectric constant values. The fabricated system of PEO/NaAlg-WO3 NPs nanocomposites films showing improved in AC conductivity and dielectric characteristics and could be suggested in optoelectronic and nanodielectric devices.

Zircon-Type CaCrO4 Chromite Nanoparticles: Synthesis, Characterization, and Photocatalytic Application for Sunlight-Induced Degradation of Rhodamine B.

The degradation of organic dye pollutants is a critical environmental issue that has garnered significant attention in recent years. To address this problem, we investigated the potential of CaCrO4 chromite (CCO) as a photocatalyst for the degradation of cationic and anionic dye solutions under sunlight irradiation. CaCrO4 was synthesized via a sol-gel auto-combustion route and sintered at 900 °C. The Rietveld refined XRD profile confirmed the zircon-type structure of CaCrO4 crystallized in the tetragonal unit cell with I41/amd space group symmetry. The surface morphology of the sample was investigated by field emission scanning electron microscopy (FESEM), which revealed the polyhedral texture of the grains. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) studies were carried out to analyze the elemental composition and chemical states of the ions present in the compound. Fourier transform infrared (FT-IR) spectroscopy analysis revealed the vibrational modes corresponding to the tetrahedral and dodecahedral metal oxide bonds. The optical band gap was approximated to be in the range of 1.928 eV by using the Tauc relation. The CaCrO4 catalyst with different contents (5, 20, 35, and 50 mg) was investigated for its photocatalytic performance for the degradation of RhB dye solution under sunlight irradiation using a UV-Vis spectrometer over the experimental wavelength range of 450-600 nm. The degradation efficacy increased from 70.630 to 93.550% for 5-35 mg and then decreased to 68.720% for 50 mg in 140 min under visible light illumination. The comparative study demonstrates that a higher degradation rate was achieved for cationic than anionic dyes in the order RhB > MB > MO. The highest deterioration (93.80%) was achieved for the RhB dye in 140 min. Equilibrium and kinetic studies showed that the adsorption process followed the Langmuir isotherm and pseudo-second-order models, respectively. The maximum adsorption capacity of 21.125 mg/g was observed for the catalyst concentration of 35 mg. From the cyclic test, it has been observed that the synthesized photocatalyst is structurally and morphologically stable and reusable. The radical trapping experiment demonstrated that superoxide and hydroxyl radicals were the primary species engaged in the photodegradation process. A possible mechanism for the degradation of RhB has been proposed. Hence, we conclude that CaCrO4 can be used as an efficient photocatalyst for the remediation of organic dye pollutants from the environment.

Deep yellow emission and high energy device applications of copper doped orthorhombic zirconium titanate nanoparticles

For the first time, Zirconium titanate doped with copper (1–9 mol %) was synthesized by an aloe vera-mediated combustion route followed by calcination at 700oC. The high crystallinity and pure orthorhombic structure are confirmed through Bragg reflections. The surface morphology consists of larger particles along with agglomeration. The lattice d-spacings and selected area electron diffraction patterns confirm the purity of the sample. The crystallite size increases, whereas the energy band gap determined from Wood and Tauc's relationship decreases. The photoluminescence analysis excited at 471 nm and the Commission Internationale de L'Eclairage (CIE) and color-correlated temperature (CCT) values confirmed that the synthesized sample is a promising candidate for display technology as a yellow nanophosphor. The cyclic voltammetry analysis is performed on the oxidation and redox peaks. Electrochemical impedance spectroscopy (EIS) revealed the ion transport kinetics and supercapacitance values obtained from galvanostatic charge/discharge (GCD) analysis. Specific capacitance values are found to be in the range 290–350 F/g for ZTO:Cu (1–9 mol %) nanoparticles (NPs), respectively. Thus, the present synthesized material might find applications in the fields of display technology and energy storage materials.