Diffuse Reflectance Spectroscopy Techniques Research Articles

Enhancing the Light‐Driven Photocatalytic Degradation Activity of ZnO Nanoparticles With the Synergistic Incorporation of Er and Tb Elements

ABSTRACTThe existence of organic pollutants in aqueous media has become a vital issue and a critical threat to human health, where organic toxic dyes represent the major contaminants in wastewater. Over the past few years, photocatalytic techniques have garnered a lot of interest in dye removal from wastewater. In this study, a series of ErxTbxZn1 − 2xO nanophotocatalysts (where x = 0.00, 0.01, 0.03, and 0.05) were synthesized and coded as ZET0, ZET1, ZET2, and ZET3 NPs (nanoparticles). The chemical and physical characteristics of the NPs were investigated using Fourier‐transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy‐dispersive X‐ray (EDX) spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) techniques. Further examination by performing photocatalytic experiments, ZET1 NPs demonstrated effective Rhodamine B (RhB) dye degradation within 60 min. It was found that the kinetic rate constant values were 0.008, 0.097, 0.050, and 0.040 min−1 for ZET0, ZET1, ZET2, and ZET3 NPs, respectively. Aside from their remarkable photocatalytic degradation efficiency, these ZET1 photocatalysts are highly stable even after five consecutive cycles. In addition, the active species test revealed that the primary oxidation species involved in the photocatalytic process are holes (h+) and hydroxyl radicals (•OH), and a possible photocatalytic mechanism for degrading RhB by ZET1 photocatalysts was tentatively proposed. The enhancement of the photocatalytic degradation efficiency is due to the low recombination rate of photogenerated charge carriers, as well as a strong synergistic impact of Tb, Er, and ZnO components. Thus, the current study could offer a versatile strategy for the design of new and effective nano photocatalysts for wastewater purification in the future.

Facile Biogenic synthesis of Europium doped lanthanum silicate nanoparticles as novel supercapacitor electrodes for efficient energy storage applications

In this work, we demonstrated for the first time, use of Europium doped lanthanum silicate nanoparticles (LS NPs) as electrodes for supercapacitor applications. Europium (Eu3+) doped (5 mol%) LS NPs were synthesized by green solution combustion method using Mexican mint leaf extracts. Various analytical techniques such as High-Resolution Transmission Electron Microscopy (HRTEM), Selected Area Diffraction (SAED), Powder X-ray Diffraction (PXRD), Fourier Transform Infra-Red Spectroscopy (FTIR) and Diffuse Reflectance Spectroscopy (DRS) techniques were used to confirm the morphological and structural characteristics of the synthesized nanoparticles. The HRTEM and SAED patterns confirms the formation of NPs having agglomerated structure with a particle size less than 50 nm. The PXRD patterns reveals crystalline cubic structure for the NPs. Further, the FT-IR spectra reveal the successful doping of Europium in Lanthanum Silicate NPs. The DRS (Diffuse Reflectance Spectroscopy) studies confirm the reduced band gap for Europium (Eu3+) doped (5 mol%) LS NPs. Cyclic voltametric and electrochemical impedance spectroscopy experiments were performed in an alkaline medium to compare the electrochemical activity of Eu3+ doped LS NPs with that of their undoped counterpart. The Eu3+ doped (5 %) LS NPs electrodes attained a specific capacitance of 373.3 Fg-1 at a current density of 0.5 Ag-1 in comparison to pure LS NPs which is about 267 Fg-1. The long-term stability of the Eu3+ doped (5 %) LS NPs electrodes show excellent stability up to 4000 cycles of operation in comparison pure LS NPs electrodes. Doping of Eu3+ had a favourable effect on the conductivity and electrochemical activity of LS NPs. Due to favourable green combustion synthesis, superior electrochemical performance, these Eu3+ doped LS NPs could be potential materials for new generation supercapacitors in energy storage applications.

Efficient photocatalytic degradation of malachite green dye from wastewater using facilely synthesized ternary ZIF-8/Ag/Ag2S nanocomposite: Optimization by RSM (CCD)

The current study compares the photocatalytic potential of zeolitic imidazolate framework-8 (ZIF-8) with ZIF-8 nanocomposites doped with two forms of silver (referred to as AgNPs/ZIF-8 and AgNPs/Ag2S/ZIF-8). Their physicochemical characteristics were evaluated using Fourier-transform infrared, X-ray diffraction, energy-dispersive X-ray, Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), diffuse reflectance spectroscopy (DRS), photoluminescence (PL), photocurrent density, Mott-Schottky, and Brunauer Emmett Teller techniques. The photocatalytic activity of the composites was assessed for degradation of malachite green (MG) under visible light irradiation in a solar-based staircase photoreactor for the first time. The optimization of the photodegradation process was achieved by employing central composite design, 0.020 g of AgNPs/ZIF-8 and ZIF-8photocatalyst (in 20 ml of solution), MG Concentration of 7 mg/l, pH of 8, and the irradiation time of 50 min. The predicted model had R2 and R2adj correlation coefficients of 0.987 and 0.975 respectively, which showed experimental results were very close to the predicted values. The results indicated remarkable efficiency in both degradation and mineralization, achieving the degradation rate of up to 98.6 %, a high-rate constant value of 0.0701 min-¹, and an 80 % mineralization efficiency. AgNPs/Ag2S/ZIF-8 exhibited superior photocatalytic performance in comparison to both AgNPs/ZIF-8 and ZIF-8. Different scavengers were used in the experiment and demonstrated that O2− played a crucial role in the photodegradation of MG. Moreover, the nanocomposite AgNPs/Ag2S/ZIF-8 exhibited robust stability and could be repeatedly utilized up to five cycles without notable decline in efficacy, rendering it an environmentally sustainable photocatalyst with promising prospects for industrial utilization.

Characterization and detailed mapping of C by spectral sensor for soils of the Western Plateau of São Paulo

Soil mineralogy and texture are directly related to soil carbon due to the physical properties of the clay surface. Traditional techniques for quantifying carbon in soil are time-consuming and expensive, making large-scale quantification for mapping unfeasible. The alternative is the use of soil sensors, such as diffuse reflectance spectroscopy (DRS), an economical, fast, and accurate technique for predicting carbon stocks. In this sense, this study aimed to (a) investigate the relationship of C with different soil mineralogical, chemical, and physical attributes for different geological and geomorphological compartments; (b) understand which spectral bands are most important for estimating C content; (c) estimate C content from diffuse reflectance spectroscopy using different mathematical techniques and indicate which one is the best for tropical soil conditions; and (d) map C contents in detail. The study area was the Western Plateau of São Paulo (WPSP), which covers approximately 13 million hectares (~ 48% of the State of São Paulo, Brazil). A total of 265 samples were collected in this area. The attributes clay, silt, sand, crystalline and non-crystalline iron, base saturation, soil density, total pore volume, total C, C stock, kaolinite/(kaolinite + gibbsite) and hematite/(hematite + goethite), hematite and goethite contents, and spectral curves were evaluated. The spectra were recorded at 0.5-nm intervals, with an integration time of 2.43 nm s−1 over the 350 to 2500-nm range (350–800 nm—visible—VIS and 801–2500 nm—near-infrared—NIR). The data were subjected to descriptive statistics, Spearman correlation, stepwise analysis, and cluster grouping for characterization purposes; partial least squares regression (PLSR) and random forest (RF) for estimation purposes; and geostatistics analysis for creation of spatial maps. Our results indicate that the highest C contents are associated with more clayey soils, oxidic mineralogy, higher total pore volume, and lower soil density in highly dissected basalt compartments. The random forest algorithm associated with the Vis–NIR spectral range is more efficient for estimating and mapping C contents. This suggests that integrating diffuse reflectance spectroscopy with machine learning techniques holds promise for shaping public policies related to land use, mitigating CO2 emissions, and facilitating the implementation of carbon credit policies in a rapid and economically efficient manner.

CeO2 nanospheres incorporated with Bi2MoO6/g-C3N4 enhanced photocatalysis towards environmental pollutant Rhodamine B removal.

We have adopted a novel CeO2/Bi2MoO6/g-C3N4-based ternary nanocomposite that was synthesized via hydrothermal technique. The physiochemical characterization of as-prepared samples was examined through various analytical techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy TEM, photoluminescent spectra (PL), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), and ultraviolet diffuse reflectance spectroscopy (UV-DRS) technique. In addition, the photocatalytic performance was carried out by degradation of Rhodamine B dye under visible light irradiation using this nanocatalyst. The ternary nanocomposite achieved 94% of the degradation efficiency within 100min which is higher than the pristine and binary composites under the predetermined condition pH = 7, Rhodamine B dye = 5mg/L, and catalyst concentration = 150mg/L. The experimental synergetic effect of CeO2/Bi2MoO6/g-C3N4 ternary nanocomposite has been ascribed to the interfacial charge carrier migration between CeO2, Bi2MoO6, and g-C3N4. The optical absorption range of CeO2/Bi2MoO6/g-C3N4 ternary nanocomposite was enhanced, and the band gap was reduced up to 2.2eV. In addition, scavenger trapping experiment proves that the super oxide anions (O2-.) and photogenerated holes are the major active species. The reusability and stability experiment proved the CeO2/Bi2MoO6/g-C3N4 ternary nanocomposite keeps good durability during the photocatalytic degradation process after the five successive cycles. Furthermore, based on the results, the charge carrier transfer photocatalytic mechanism was also discussed. This CeO2/Bi2MoO6/g-C3N4 ternary nanocomposite may offer the cheapest material and extend the great opportunity for clean and environmental remediation approach under the visible light irradiation.

Blood CO Status Classification Using UV-VIS Spectroscopy and PSO-optimized 1D-CNN Model

Rapid and effective blood carbon monoxide (CO) assessment is of great importance, especially in estimating CO-related morbidity and instituting effective preventive measures. The conventional detection methods using CO breath analysis lack sensitivity, while collecting biological fluid samples for CO level measurement is prone to external contamination and expensive for frequent use. This study proposes a one-dimensional convolutional neural network (1D-CNN) consisting of three stacked biconvolutional layers for binary classification of blood CO status using the diffuse reflectance spectroscopy technique. Iterative particle swarm optimization (PSO) has efficiently found the best network parameters to learn important features from the reflectance spectroscopy data. The findings showed good testing accuracy, specificity, and precision of 92.9%, 90%, and 89.7%, respectively, and a high sensitivity of 96.3% in determining abnormal blood CO among smokers using the proposed CNN network. Comparisons with eight existing machine learning and deep learning models revealed the proposed method’s effectiveness in classifying blood CO status while reducing computing time by 8–13 folds. The findings of this work provide new insights that are valuable for researchers in neural network design automation, healthcare management, and skin-related research, specifically for application in nondestructive evaluation and clinical decision-making.

Effect of metal chalcogenides on modifying the structural and optical properties of ZnWO4 nanostructure

Hydrothermal and thermolysis techniques were used to create ZnWO4 and 0.9ZnWO4-0.1MS (M = Cd, Zn, Pb) samples. The formed phases in each sample and their structure and microstructure were examined using Raman spectroscopy, Fourier-transform infrared spectroscopy and Rietveld refinement of Synchrotron x-ray diffraction data. The composition and morphology of the formed samples were investigated via scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDS). The average crystallite size remains relatively constant regardless of the different metal chalcogenides. MS/ZnWO4 samples have two distinct morphologies. The UV diffuse reflectance spectroscopy (UV-DRS) technique is used to investigate the linear and nonlinear optical parameters for different samples. Alloying ZnWO4 with CdS or PbS affects the photo response region of the sample to include visible light. MS/ZnWO4 (MS=CdS, ZnS, PbS) samples have optical band gap values of 2.56, 2.43, 2.99 and 3.1 eV, respectively. The CdS/ZnWO4 and ZnS/ZnWO4 samples exhibit the highest refractive index and optical dielectric constant values within the visible range. CdS or PbS/ZnWO4 samples show the highest nonlinear optical parameters values within the visible range. The impact of MS samples on the photoluminescence emission of ZnWO4 was explored. The CIE chromaticity diagram reveals that MS/ZnWO4 (M = Zn and Pb) samples display a different degree of blue color while CdS/ZnWO4 sample reveals green-yellow colors.

Effect of Ce-doping on the structural, optical and photoluminescence characteristics of nano Zn0.75Cd0.25S

Nano Zn0.75CexCd0.25S samples with different doping amounts of cerium (x = 0.0, 0.02, 0.04, 0.06) were synthesized using the thermolysis approach. The possibility of Ce ion incorporation into the ZnS0.75Cd0.25S lattice either substitutionally for Zn/Cd or interstitially into the voids of the lattice was examined using Rietveld refinement analysis based on X-ray diffraction (XRD) data. The lattice parameters, crystallite size and microstrain of the formed samples were computed. Particles with homogeneous spherical morphology can be seen using TEM technique with nano size of 2–4 nm, approving the values obtained from XRD. The optical properties of the prepared samples were examined by the diffuse reflectance spectroscopy technique. The optical energy gap value of Zn0.75Cd0.25S is 2.79 eV. As the Ce content rose, this value decreased until it reached 2.68 eV. The refractive index (n) values derived from numerous models, along with the average n values for all samples were calculated. The incorporation of Ce doping into nano Zn0.75-xCexCd0.25S samples results in an increase in their dielectric constants, suggesting their potential role for energy storage applications. With a rise in Ce doping, the non-linear optical parameters of Zn0.75-xCexCd0.25S were improved. Gaussian function fitting was used to decompose the photoluminescence (PL) emission of different samples. Upon doping with Ce, a noticeable reduction in the PL intensity was observed. The sample without any doping showed a cyan color, whereas the doped samples exhibited a cyan-green color.

Supernanoporous SnO2 particles and spheres as sustainable solar cell constituents

This study presents the synthesis and a comparative report of the properties of supernanoporous SnO2 particles SNSP (0D) supernanoporous SnO2 spheres SNSS (3D) formed with an assembly of SNSP with a view to examine their application as effectual photoanodes in sustainable solar energy conversion. Porosity imposed nanoparticles with extended surface area improve photon interaction and charge transfer by increasing the absorption of light, hence addressing the existing efficiency hurdles in solar cells. SNSP with particle size of ∼23 nm and SNSS with particle size and sphere size of ∼26 nm and ∼800 nm, respectively, were synthesized by treating SnCl4 via solvothermal process at different experimental conditions. Important aspects of the as-synthesized SNSP and SNSS samples, such as the crystal structure, particle size, optical behaviour, identification of elements present, were characterized by powder X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Ultra Violet Diffuse Reflectance Spectroscopy (UV-DRS) and Energy Dispersive Analysis X-ray (EDAX) Spectroscopy techniques. Field dependent dark and photoconductivity studies reveal significant rise in the photoconducting nature, opto-electrical and surface properties of SNSP and SNSS. Pore size distribution and specific surface area of SnO2 particles and spheres were measured by Brunauer-Emmett-Teller (BET) analysis. High Resolution Transmission Electron Microscopy (HRTEM) is performed to analyze the size and shape of the porous SnO2 particles and spheres and further to correlate the data derived from FESEM. From other prevailing applications of porosity imposed nanomaterials such as gas sensing, catalytic and photodegradation the innovation of this work is to depict the novelty of porous SnO2 particle and sphere with highlighting thermal stability to instigate into the charge transport property suitable for solar cell application. The results were analyzed evincing the photovoltaic properties of spheres over particles and hence the PSC constituent among SNSP and SNSS with better proficiency was identified as appropriate photoconducting medium for fabrication of sustainable photovoltaic cells.

Optical and dielectric properties of divalent copper based double perovskite compound, Gd2CuTiO6

In this work, we have investigated high temperature dielectric properties and room temperature optical properties on rare earth ion based orthorhombic Gd2CuTiO6 (GCTO). Optical properties like reflectance and band gap were determined from ultra-violet visible (UV–Vis) diffuse reflectance spectroscopy technique and photoluminescence (PL) spectrum. The compound exhibited substantial optical absorption and emission in the visible region. Our findings reveal the presence of an intermediate band, as evidenced by the difference between the band gap values obtained from the Tauc plot using the diffuse reflectance spectrum (3.07 eV) and the PL spectrum (2.4 eV). Furthermore, thermogravimetric analysis demonstrated high thermal stability with <0.4% change in mass over a wide temperature range of 30 °C–1200 °C in air environment. Moreover, lead-halide free compound, GCTO is highly thermally stable oxide double perovskite with wide band gap and absorption in the UV–Vis range are highly suitable for optical applications In addition, dielectric properties of the compound have been examined using impedance spectroscopy as a function of frequency ranging from 500 Hz to 1 MHz and temperature between 300 K and 550 K. Compounds with relaxor behaviour at high temperatures and high thermal stability are desired for several applications. Because of the cation disorders present in this compound, GCTO displays dielectric relaxor behaviour indicative of a distribution of relaxation times. Furthermore, the frequency-dependent modulus illustrated a thermally activated conduction mechanism. Cole–Cole plots of electrical modulus suggest prominent grain contribution above 350 K.

Facile one step green synthesis of CdO-CdS hybrid nanocomposite: Its electrochemical and photoluminescence applications

This study reports the fabrication of a CdO-CdS hybrid nanocomposite (CDCS NC) and its application towards electrochemical sensing of dopamine (DA). The synthesis was conducted at various temperatures using Butea monosperma leaf powder as a green fuel and it was noticed in the XRD pattern that 400 °C was ideal for the formation of the CdO-CdS hybrid NC. Also, the samples were characterized by implementing Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX), UV-Vis Diffused Reflectance Spectroscopy (UV-DRS) and Photoluminescence (PL) techniques. The electrochemical activity was investigated using Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) techniques. A working electrode was fabricated by modifying a Glassy Carbon Electrode (GCE) using the CdO-CdS NC and it showed remarkable electrochemical activity towards dopamine (DA). Further, the electrochemical properties were investigated by varying the scan rate, pH and concentration. The fabricated electrode shows a low limit of detection of 23 µM. Hence by its unique composition and inherent properties, the NC stands as a potent tool for advancing the boundaries of electrochemical sensing, heralding a new era of innovation in sensor development.

Pioneering superior efficiency in Methylene blue and Rhodamine b dye degradation under solar light irradiation using CeO2/Co3O4/g-C3N4 ternary photocatalysts

In this research work, we have successfully synthesized the CeO2/Co3O4/g-C3N4 ternary nanocomposite for hydrothermal method for photocatalytic applications. The synthesized nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy TEM, Photoluminescent spectra (PL), X-ray photoelectron spectroscopy (XPS), Brunauer- Emmett-Teller (BET) and Ultraviolet diffuse reflectance spectroscopy (UV-DRS) technique. As per the optical spectroscopic investigations CeO2/Co3O4/g-C3N4 ternary nanocomposite exhibited the high optical absorption range and its band gap is reduced from 2.95 eV to1.83 eV. The PL spectra showed the lowered emission peak intensity of ternary nanocomposite which is revealed that the better charge separation and slow recombination of electron hole pairs. The highest photocatalytic degradation efficiency of CeO2/Co3O4/g-C3N4 ternary nanocomposite showed 93 % and 86 % towards the pollutant methylene blue and Rhodamine B. Moreover, photodegradation of the pollutants followed pseudo-first order kinetics with a very high-rate constant of 0.02211 min−1 and 0.017756 min−1. Additionally, the ternary nano catalyst was delivered the remarkable stability performance even after five cycles. This research may provide a low-cost approach for synthesized visible light responsive catalysts for use in environmental remediation applications.

Evaluation of sol-gel and solvothermal method on titanium dioxide and reduced graphene oxide nanocomposite

The present study compares two synthesis routes to obtain titanium dioxide and reduced graphene oxide nanocomposites that could be used as photoelectrodes in a water-splitting photoelectrocatalytic system. The nanocomposites were obtained using in-situ sol-gel and solvothermal methods as fabrication routes. Subsequently, the materials obtained were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy techniques. The results indicated a strong interaction between reduced graphene oxide and titanium dioxide nanomaterials using both synthesis processes; however, the in-situ sol-gel method exhibited more significant conservation of the aromatic rings of the graphene structure and a lower bandgap (2.45 eV), which are suitable characteristics for its potential use in photoelectrocatalytic processes.

Thermotropic Structure Phase Transitions and Two Types of Thermochromic Behaviors in a Bromoargentate Cluster [Pr-dabco]2Ag4Br6.

Organic-inorganic silver halide hybrids show abundant phase transitions and thermochromism. However, it is very rare that silver halides exhibit thermochromism related to thermotropic structure phase transition. Herein, a bromoargentate hybrid, [Pr-dabco]2Ag4Br6 (1) (Pr-dabco+ = 1-propyl-1,4-diazabicyclo-[2.2.2]octan-1-ium), with tetranuclear [Ag4Br6]2- clusters was prepared and characterized by microanalysis, ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, and thermogravimetric (TG) and differential scanning calorimetry (DSC) techniques. Interestingly, 1 undergoes an irreversible structure phase transition at ∼436 K in the first heating process, which is accompanied by an abrupt color change from colorless to yellow; however, a reversible color change between pale yellow and yellow is observed in the next heating-cooling cycles. Notably, DSC measurement revealed that a reversible phase transition is associated with the change in color between pale yellow and yellow, while the powder X-ray diffraction (PXRD) patterns corresponding to pale yellow and yellow phases are quite similar to each other. These observations demonstrate that thermochromism in the next heating-cooling runs is associated with a reversible structure phase transition, which perhaps concerns the disorder-order transformation of alkyl chains in the cationic ligand [Pr-dabco]+, and relevant to the anharmonic fluctuations of the Ag-Br and Ag-N bonds, a strong electron-phonon coupling effect is seen within the bromoargentate cluster.

Ultra-deep photocatalytic oxidative desulfurization of liquid fuels by Ti@CeO2/ZnO nanophotocatalyst under visible light and mild operating conditions

Herein, various Ti@CeO2/ZnO nanophotocatalysts (TxCZ, x: the molar ratio of Ti to Ce and Zn) were synthesized using the solvothermal method in two stages. After that, the effectiveness of the fabricated catalysts in the photocatalytic oxidative desulfurization (PODS) reaction were assessed. The physicochemical properties of the synthesized samples were analyzed through the implementation of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence spectroscopy (PL), and electron paramagnetic resonance (EPR) techniques. The study evaluated the impact of varying levels of titanium loading on the physicochemical characteristics of nanoparticles and the elimination of sulfur compounds. Under the optimal reaction conditions of T = 50 °C, 1.5 g/L of photocatalyst dosage, an oxidant to sulfur molar ratio of 6, and a solvent to fuel volume ratio of 1, the TxCZ sample exhibited superior performance by completely removing dibenzothiophene (DBT) from the model fuel. Kinetic studies indicate that the PODS reaction adheres to the pseudo-first-order kinetic model, with an observed activation energy of 69.25 kJ/mol−1.

Laser power and high-temperature dependent Raman studies of layered bismuth and copper-based oxytellurides for optoelectronic applications.

Layered metal oxychalcogenide materials have gained significant attention in recent years due to their numerous applications in various emerging fields. The bismuth (Bi) based ternary and quaternary oxychalcogenide materials have become popular due to their excellent potential in optoelectronic, thermoelectric, and semiconducting applications. Adding copper (Cu) to these building matrices has enhanced their usefulness in various ways. In this work, Bi and Cu-based ternary and quaternary layered oxytellurides are synthesized using a unique, rarely used "microwave (MW) assisted method," and their temperature and laser power-dependent Raman measurements are carried out. All the samples are prepared at the same MW power and at a fixed irradiation time. Crystallographic studies show that the good crystallinity of the synthesized materials matches well with the phases reported previously. Nanosheet-like morphology was observed for all the prepared samples. The optical properties and band gap energies of these materials were obtained using the diffuse reflectance spectroscopy technique, which are in the range of 1.15-2.52 eV. The photoluminescence spectrum shows broad peaks around orange-red regions, indicating the potential applicability of these materials in various optoelectronic applications. The effect of high temperature and laser power on the Raman spectra of the oxytellurides is demonstrated, where the appearance of different vibrational modes along with a redshift in peak positions with the increase in temperature and power is observed.

Fabrication and Characterization of Activated Carbon/ZnO Nanocomposite Films for Use as a Photocatalyst in Degradation of Organic Compounds

The activated carbon/ZnO nanocomposite films were successfully prepared by a simple doctor blade method. The obtained films were characterised by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy and Photoluminescence techniques. The photocatalytic properties of all films were carried out by degrading rhodamine B (RhB) dye under solar light irradiation. From the study, it was found that an increment of the efficacy of photocatalytic activities showed in activated carbon/ZnO nanocomposite films as compared to the pure activated carbon and pure ZnO. Moreover, the effect of concentration of activated carbon on the photocatalytic activity of as-prepared nanocomposite films was studied. Results were found that the optimal concentration of 5 wt% activated carbon on the surface of ZnO exhibited the highest efficiency.

A facile microwave-assisted synthesis of bismuth copper oxytelluride for optoelectronic and photodetection applications

Over the last few years, quaternary-based bismuth copper oxychalcogenide BiCuOCh (Ch = S, Se, and Te) materials have caught much attention due to their exciting optoelectronic, thermo-electric, and semiconducting applications. Bismuth copper oxytelluride (BiCuOTe), among the other family members, possesses the highest ZT value. Though many studies are already done on this 2D material, most are based only on thermoelectric properties or first principle calculations. Very little attention has been given to exploring other potential characteristics of this material. In this work, we have synthesized BiCuOTe using the facile “Microwave (MW) assisted method,” which has not yet been reported for preparing this material. BiCuOTe samples were prepared with varying MW powers at a fixed irradiation time. A few sharp and well-defined diffraction peaks appeared from the crystallographic studies, which are in good accordance with the previously reported phases. All the prepared samples show nanosheet-like morphology. The diffuse reflectance spectroscopy technique was used to study the optical nature and calculate the band gap energy of this material. The band gap observed for this material falls in the range of 2–2.6 eV, and the broad photoluminescence emission spectrum with peaks centered around yellow–red regions makes this material suitable for various optoelectronic applications. Results from the photo-response study suggest the potential applicability of this material as a photodetector.

Efficient visible-light-driven photocatalytic removal of Acid Blue 92, E. coli, and S. aureus over Ag-AgCl nanoparticles-decorated bismuth sulfide microparticles

Bismuth sulfide particles were modified with Ag-AgCl nanoparticles to make a visible light active plasmonic photocatalyst. The powder x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), elemental mapping, nitrogen adsorption–desorption isotherms (BET-BJH), photoluminescence (PL), and diffuse reflectance spectroscopy (DRS) techniques were served to analyze the morphological and structural properties. To evaluate the photocatalytic performance, Acid Blue 92 (AB92) azo dye was degraded in the aqueous solution under visible light irradiation. According to the results, 0.025 g of the photocatalyst powder was able to remove more than 98% of AB92 at 15 ppm concentration under neutral acidity, following pseudo first-order kinetics. Superoxide anion radicals (O2 •−) were also recognized as the most key species promoting the photodegradation pathway. Also, the antibacterial activity of the materials was explored against E. coli and S. aureus pathogenic bacteria under irradiation and dark conditions. Using transmission electron microscopy (TEM) images of the treated cells, it was found that the plasmonic photocatalyst damaged the cell wall structure of both gram-positive and negative bacteria within 2 h significantly, which could be attributed to the efficient production of destructive superoxide anion radicals on the surface of Ag-AgCl/Bi2S3 particles under illumination.

Breast Cancer Diagnosis Using Extended-Wavelength-Diffuse Reflectance Spectroscopy (EW-DRS)-Proof of Concept in Ex Vivo Breast Specimens Using Machine Learning.

This study aims to investigate the feasibility of using diffuse reflectance spectroscopy (DRS) to distinguish malignant breast tissue from adjacent healthy tissue, and to evaluate if an extended-wavelength range (450-1550 nm) has an advantage over the standard wavelength range (450-900 nm). Multivariate statistics and machine learning algorithms, either linear discriminant analysis (LDA) or support vector machine (SVM) are used to distinguish the two tissue types in breast specimens (total or partial mastectomy) from 23 female patients with primary breast cancer. EW-DRS has a sensitivity of 94% and specificity of 91% as compared to a sensitivity of 40% and specificity of 71% using the standard wavelength range. The results suggest that DRS can discriminate between malignant and healthy breast tissue, with improved outcomes using an extended wavelength. It is also possible to construct a simple analytical model to improve the diagnostic performance of the DRS technique.