UV Vis Diffuse Reflectance Spectroscopy Research Articles

Optimization Photodegradation of Methylene Blue Dye using Bentonite/PDA/Fe3O4@CuO Composite by Response Surface Methodology

This study aims to synthesize bentonite/PDA/Fe3O4@CuO composites as a catalyst for the photodegradation of Methylene blue dye. Composite characterization involves X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM) with X-ray Energy Dispersion Spectrometry (EDS), UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS), and Vibrating Sample Magnetometer (VSM). Response Surface Methodology (RSM) employs Central Composite Design (CCD) to optimize photodegradation by varying dye concentration, irradiation time, and catalyst dose. The bentonite/PDA/Fe3O4@CuO composites exhibit a saturation magnetization value of 54.82 emu/g and a band gap of 2.1 eV. The optimization revealed that concentration and dose significantly impact the photodegradation efficiency. A quadratic model is suitable for modeling the photodegradation of Methylene blue dye using bentonite/PDA/Fe3O4@CuO composites, as determined by analysis of variance (ANOVA). The optimal conditions for achieving maximum photodegradation efficiency were identified as a dye concentration of 10 mg/L, an exposure time of 90 min, and a catalyst dose of 1.67 g/L. Under these parameters, the photodegradation process exhibited a remarkable efficiency of 100%. The Bentonite/PDA/Fe3O4@CuO composites exhibited strong stability, efficiency, and recyclability. After six photodegradation cycles, there was a 5.18% decrease in photodegradation efficiency. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

SrNiO3 perovskite/CeO2 composites as heterogeneous photocatalysts for the 2-propanol oxidation in gas–solid regime

Both SrNiO3 perovskite and CeO2 are materials suitable for photocatalytic purposes. In this work, the preparation and physicochemical characterization of bare SrNiO3 and CeO2 along with composites where CeO2 was enriched with the perovskite from 15 to 70 % in mass of SrNiO3 in the composite are described. The materials have been used for the photocatalytic oxidation of 2-propanol in gas–solid regime in the presence of UV-LED or simulated solar irradiation. The solids were characterized by XRD, SEM/EDX, N2 adsorption/desorption and FTIR and UV–Vis diffuse reflectance spectroscopies. The composite containing 15 % w/w of SrNiO3 and 85 % w/w of CeO2 resulted the most active, giving rise the complete degradation of 2-propanol after 1.5 h or 6.0 h of irradiation by UV-LED and simulated solar light irradiation, respectively. Photocatalytic activity results are discussed considering the physical–chemical properties on the catalysts.

Influence of annealing temperature on the structure, morphology, optical property and antibacterial response of phytochemicals-assisted synthesized zinc oxide nanoparticles

Abstract Antibiotic overuse has caused a variety of bacterial pathogens to develop new resistance mechanisms. As a result, discovering an appropriate replacement for the standard antibiotics has become an immediate concern. The present work demonstrates a facile, eco-friendly and economical method for the synthesis of hexagonal wurtzite zinc oxide nanoparticles (ω-ZONPs) using the ethanolic extract of triphala. Gas chromatography–mass spectrometry analysis of the triphala extract proved the presence of certain secondary metabolites, which aids in the formation of ω-ZONPs. The influence of annealing temperature on the antibacterial action of as-synthesized ω-ZONPs was studied for three different annealing temperatures. X-ray diffraction, dynamic light scattering, field emission electron microscopy and energy dispersive X-ray spectroscopy analyses were used to examine the impact of annealing temperature on the structure, particle size and morphology of ω-ZONPs. Fourier transform infrared spectra revealed the change in intensity of the characteristic peaks in ω-ZONPs with different annealing temperatures. From UV–Visible diffuse reflectance spectroscopy, variation in the band gap of ω-ZONPs with increasing annealing temperature was detected. Kirby Bauer disc diffusion was adopted to examine the antibacterial potential of ω-ZONPs against bacterial strains such as Staphylococcus aureus, Enterococcus faecium, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. The ω-ZONPs annealed at 200 °C inhibited the growth of three bacterial pathogens, E. coli, B. subtilis and P. aeruginosa and exhibited effective antibacterial activity in comparison with ω-ZONPs annealed at relatively high temperatures. Thus, the antibacterial potential of ω-ZONPs could be further explored as disease controlling agents and such prototypes could be made available for commercial mass production.

Sol–gel synthesis of iron titanates for the photocatalytic degradation of cyanide

Iron titanate mixed metal oxides were synthesized by the sol–gel method through four different routes. The effect of (i) the solvent of iron precursor, (ii) the addition of the chelating agent to the titanium or iron solution and (iii) the molar ratio between the chelating agent and the titanium or iron precursor over the overall percentage of obtained iron titanates was evaluated. Fourier-transform infrared spectroscopy (FTIR) and UV–Vis spectroscopy (UV–Vis) performed on the reaction medium evidenced the formation of acetate complexes of titanium (IV) or iron (III) during the different routes. X-ray diffraction (XRD) patterns of the obtained materials showed the formation of ilmenite (FeTiO3), pseudorutile (Fe2Ti3O9) and pseudobrookite (Fe2TiO5) in different proportions, as well as hematite (Fe2O3), rutile [TiO2 (R)] and anatase [TiO2 (A)]. The materials with the highest content of iron titanates obtained in each route were characterized and evaluated in the photocatalytic degradation of cyanide using visible light irradiation. UV–Vis Diffuse Reflectance Spectroscopy (UV–Vis DRS) showed that the samples exhibited energy bandgap values between 2.31 and 2.90 eV, which agrees with the values reported for iron titanates and evidence the possible activation of the materials under visible light. Scanning electron microscopy (SEM) and nitrogen physisorption results showed that the synthesized materials exhibited nanometric particle size and lower surface area (36.7 ± 4.8 m2·g-1) than TiO2 Degussa P-25 (72–155 m2·g-1). The photocatalytic performance of the synthesized materials toward oxidation of CN− exceeded by 56% the activity of pure TiO2. The content of iron titanates in the synthesized materials was found to be the variable with the greatest influence on the photodegradation of cyanide. In addition, an inversely proportional relationship between the pseudorutile content of the materials and their photocatalytic activity was observed.

A stable and regenerative TiO2/Bi2MoO6 photocatalyst for highly effective degradation of Rhodamine B and Congo Red

ABSTRACT This research unravels a facile method for synthesising TiO2/Bi2MoO6 photocatalysts and their effective applications in degrading industrial dyes. Initially, Bi2MoO6 was prepared as the substrate, followed by the addition of TiO2 to form the TiO2/Bi2MoO6 composite. The photocatalyst was characterised by powder X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). Its photocatalytic properties were evaluated by dye degradation under various conditions, including different dopant loading amounts, the reaction time, the initial concentration of the dye, and pH values. The results indicated that 50 mg of 15% TiO2/Bi2MoO6 achieved the highest photodegradation efficiency: 98.51% for 50 mL 10 mg L−1 Rhodamine B (RhB) within 100 min in a neutral buffer solution and 90.71% for 50 mL 10 mg L−1 Congo Red (CR) within 80 min in an aqueous solution. This material exerted effectiveness across a wide pH range, with removal rates of RhB exceeding 95.41% in both acidic and alkaline conditions. The degradation process conformed to the pseudo-first-order kinetic model. Radical trapping experiments revealed that the dye degradation mechanism involved ∙ O 2 − and h+. Notably, the synthesised TiO2/Bi2MoO6 photocatalyst demonstrated high stability and reusability, maintaining performance even after four degradation cycles. The TiO2/Bi2MoO6 photocatalyst, with TiO2 as the dopant and Bi2MoO6 as the substrate, demonstrated significant versatility and potential for practical dye degradation applications.

Enhanced photocatalytic removal of Cr(VI) and Rhodamine B from water using plant-mediated CdS nanoparticles: Mechanistic insights and environmental applications

Photocatalytic remediation using semiconductor nanoparticles presents a promising approach for water purification. In this study, cadmium sulfide (CdS) nanoparticles were synthesized via a plant-mediated approach and evaluated for their efficacy in removing Cr(VI) and Rhodamine B contaminants from aqueous solutions under visible light irradiation. The CdS nanoparticles were characterized by X-ray diffraction (XRD), which confirmed the presence of the cubic phase with a crystallite size of 10 nm. UV–visible diffuse reflectance spectroscopy (DRS) indicated bandgap energy of 2.4 eV, facilitating visible light absorption. Photoluminescence (PL) spectroscopy revealed reduced recombination rates of photogenerated charge carriers, enhancing photocatalytic efficiency. The synthesized CdS nanoparticles demonstrated efficient removal of both Cr(VI) and Rhodamine B, achieving degradation efficiencies of 92 % and 95 %, respectively, within 120 min under optimized conditions. Mechanistic insights suggest the generation of reactive oxygen species (ROS) and electron-hole pairs (e-/h+) contributing to pollutant degradation. This study underscores the potential of plant-mediated CdS nanoparticles as effective photocatalysts for environmental remediation applications.

Preparation and performance of g-C3N4/g-C3N5 homojunction photocatalyst activated peroxymonosulfate for ceftriaxone sodium degradation

As the overuse of antibiotics increasingly contaminates the environment, one of modern chemistry's objectives is to identify high-performance photocatalytic materials to degrade antibiotics. This study initially utilized NH4Cl as a gas template to synthesize porous lamellar g-C3N4 (CNS) through a high-temperature calcination process. Building upon this, a homojunction catalyst, CNS/g-C3N5 (S-CN), was developed via a secondary sintering technique using different amount of 3-amino-1,2,4-triazole addition to evaluate its efficacy in activating peroxymonosulfate (PMS) for degrading the antibiotic ceftriaxone sodium. Under neutral conditions, the photocatalytic system composed of S-CN catalysts prepared by 50 mg of 3-amino-1,2,4-triazole addition and PMS (S3-CN/PMS) exhibited degradation rates that were 3.37 and 8.11 times higher than those of the CNS/PMS and g-C3N5/PMS, respectively. At a pH of 8, the S3-CN/PMS system attained a 99.7 % degradation efficiency within 75 min. Based on results from UV–visible diffuse reflectance spectroscopy (DRS), transient photocurrent response, electrochemical impedance spectroscopy (EIS), photoluminescence spectroscopy and radical scavenging experiments, this high efficiency is attributed to a homojunction Z-type charge transfer mechanism that enhances the separation of photogenerated carriers. Furthermore, the study found that the optimal PMS addition was 20 mg and the optimal pH was 8. Chloride ions promoted the reaction, while other ions decreased the reaction rate. In conclusion, this paper provides valuable insights for the morphological modification of carbon nitride homojunction materials and the efficient activation of PMS for pollutant degradation.

Effective sunlight photodegradation of methylene blue dye using zinc oxide doped with mono- and bi-metals of Ag and Ce

Nanosized spherical particles of pure ZnO and their doped ZnO photocatalysts with mono- or bi- Ag and Ce-metal oxides at different weight portions (i.e., 2 and 4 wt%) through the sol-gel route followed by a calcination at 500 °C for 2 h were employed for exploring the photodegradation of methylene blue (MB) dye under direct sunlight. The produced photocatalysts were characterized by X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) surface area, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), fourier transform infrared (FTIR), and UV-Vis diffuse reflectance spectroscopy (DRS). XRD patterns confirmed the formation of hexagonal wurtzite polycrystalline structure of ZnO with good crystallinity. Bi-doped ZnO photocatalysts with smaller particle sizes showed efficient improving in the photocatalytic activity of ZnO under direct sunlight irradiation. The enhanced photodegradation performance of doped samples could be attributed to the reduction in the crystallite size and band gap, as well as the presence of excess oxygen vacancies and Zn interstitial sites in the nanoparticles obtained. The calculated band gap of pure ZnO decreased from 3.07 to 2.79 eV for 2 %Ag-4 %Ce/ZnO. This doped sample degraded the MB dye completely at 60 min, whereas pure ZnO exhibited 100 % degradation of MB at 180 min. Moreover, 2 % Ag-4 %Ce/ZnO photocatalyst has the highest kinetic rate of photodegradation as compared to other samples over two initial concentrations of MB dye (0.09667 min−1 at Co= 10 mg/L and 0.04433 min−1 at Co= 20 mg/L). Hence, the obtained 2 % Ag-4 % Ce doped ZnO showcased the superb breakdown of MB dye under sunlight irradiation for positioning it as a promising material for water remediation.

Synthesis of visible-light-driven heterojunction graphitic carbon nitride (g-C3N4/Feo/TiP) material: An efficient photocatalytic agent for degradation of rhodamine 6G from wastewater

In this study, a novel and cost-effective photocatalytic material based on graphitic carbon nitride (g-C3N4) heterojunctions incorporating zero-valent iron (Feo) and titanium phosphate (TiP) was successfully synthesized via chemical reduction method. Various characterization techniques including UV–visible Diffuse Reflectance Spectroscopy, Fourier Transform Infrared Spectroscopy, X-Ray diffraction, Scanning Electron Microscopy, and Energy Dispersive Spectrum were employed to analyze the ternary photocatalyst g-C3N4/Feo/TiP. The study focused on investigating the degradation mechanism of Rhodamine 6G (Rh6G) in aqueous solution under visible light irradiation using synthesized g-C3N4/Feo/TiP heterojunction material. Remarkably, optimal photocatalytic activity was achieved at pH 3, wherein 98 % degradation of 50 mL of Rh6G (10 ppm) was attained within 60 min under visible light irradiation. This activity was consistent across a wide pH range from 3 to 11. This happens due to the exceptional enhancement of hydroxyl radicals, higher photocurrent response and photo-excited holes via Z-scheme of heterojucntion mechanism from g-C3N4/Feo/TiP material compared to g-C3N4 (60 %), TiP (75 %), and Feo/TiP (85 %) against Rh6G. The extraordinary degradation arises due to more visible light absorption capability and enhanced separation of photo-excited electrons and holes through Z-scheme heterojucntion mechanism. This report show the promising clean environmental application prospect of synthesized heterojucntion photocatalyst against organic pollutants from wastewater.

Enhancing photocatalytic dye degradation efficiency through the utilization of shock wave effects on neodymium oxide (Nd2O3)

This article delves into the impact of shockwaves on neodymium oxide (Nd2O3) nanoparticles, aiming to evaluate their physical and chemical stability. Nd2O3 nanoparticles were subjected to varying sets of shock pulses (100, 200, and 300) in photocatalytic dye degradation. The nanoparticles crystallinity and unit cell volume after shockwave exposure were examined using powder X-ray diffraction (PXRD) analysis with unit-cell software. PXRD data revealed no alterations in the crystalline structure, lattice parameter and unit cell volume. Comparisons between pre- and post-shockwave field emission scanning electron microscopy (FE-SEM) portraying data demonstrate that repeated shockwave application causes a decrease in particle size. Raman spectroscopy, under ambient conditions, shows a high intensity after shock conditions intensity will decrease. Furthermore, FTIR spectroscopy revealed the characteristic strong and broad absorption band associated with metal-oxygen (Nd-O) groups in the Nd2O3 nanoparticles. UV–Vis diffuse reflectance spectroscopy (DRS) was used to investigate the bandgap of the Nd2O3 nanoparticles. Initially, the bandgap was measured at 5.96 eV under ambient conditions, but following the shockwave exposure, it was decreased to approximately 5.91 eV. Interestingly, the surface area of the shockwave-treated Nd2O3 nanoparticles is increased and exhibited an increased efficiency in photocatalytic dye degradation. This finding holds promising implications for environmental remediation applications.

Structural and optical properties of CdTe thin film nanoparticles prepared using chemical bath deposition technique with different Te concentration

Abstract The CdTe thin films with different Te concentration were grown by chemical bath deposition technique using glass substrates. The prepared thin films were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV–Visible diffuse reflectance spectroscopy, photoluminescence (PL). The X-ray diffraction (XRD) analysis shows that the prepared thin films are polycrystalline in nature with Zinc blend structure. Decrease in the intensities of XRD peak for decreasing the Te concentration. The characteristic phonon modes of CdTe thin film nanoparticle confirmed by Raman spectra analysis. Optical absorption studies shows that direct transition with decrease in band gap energy with decreasing the Te molar concentration. Green emission was observed for prepared CdTe thin films excited with 325 nm.

Photocatalytic activity of Ho3+-Yb3+ activated BiVO4 upconverting phosphors

The BiVO4:Ho3+-Yb3+ upconverting phosphors have been synthesized by using the chemical co-precipitation method and optimized with 0.7 % Ho3+ + 6 % Yb3+ combination through frequency upconversion emission study. The synthesized phosphors have been characterized through XRD (X-Ray diffraction), FESEM (Field emission scanning electron microscopy), HR-TEM (High resolution- Transmission electron microscopy), UV–vis diffuse reflectance spectroscopy (DRS), Raman, and FT-IR (Fourier transform infrared spectroscopy). The XPS (X-ray photoelectron spectroscopy) analysis has been performed to study the elemental composition, chemical, and electronic states of the atoms present in the optimized sample. The specific surface area of the pure and optimized phosphors has been determined through BET (Brunauer-Emmett-Teller) analysis. From the XRD analysis, it is clear that on doping, the crystal structure of BiVO4 changes from monoclinic to tetragonal structure. The values of rate constants for the photocatalytic performance of the upconverting codoped and pure BiVO4 phosphors under the illumination with an artificial solar lamp for degradation of MB dye are found to be 0.00498 min−1 and 0.00269 min−1, respectively. To verify these results, the same experiment has also been performed under the visible LED (Light-emitting diode) light illumination. This enhancement of ∼ 85 % in the rate constant of the photocatalytic performance ensured the utilization of the NIR portion of the light by the codoped BiVO4 phosphors through the frequency upconversion process. The material’s recycling photocatalysis experiment for three cycles has been performed to check its reusability. The upconversion emission and XRD analysis of the materials after photocatalysis have been performed. From this study, it is confirmed that the stability of the sample is better even after three cycles of photocatalytic dye degradation experiment.

MOF-derived In2O3/TiO2 S-scheme heterojunction for efficient photocatalytic degradation of tetracycline

It is challenging to engineer a photocatalyst that can degrade antibiotics efficiently. We have successfully developed a series of photocatalysts by annealing In-MOF (BUT-205) with TiO2, namely (a) In2O3/TiO2-I, (b) In2O3/TiO2-II, and (c) In2O3/TiO2-III. These catalysts, particularly In2O3/TiO2-III, exhibited superior efficiency in degrading tetracycline (TC) under visible light. The enhanced photocatalytic performance of In2O3/TiO2-III can be attributed to the formed S-scheme heterojunction, which promoting the separation of electron-hole pairs. The S-scheme heterojunction was confirmed by XPS, in-situ XPS, UV–vis diffuse reflectance spectroscopy, and Mott-Schottky plot, etc. Compared to pure TiO2 and In2O3, the In2O3/TiO2-III demonstrated an 18-fold and 3-fold higher degradation rate constant (k). Various factors affecting the degradation of TC were investigated, including pollutant concentration, catalyst type, solution pH, catalyst dosage, inorganic anions, inorganic cations, and radical species. Photoluminescence (PL) and transient photocurrent density evaluate the separation rate of electron-hole pairs, and EPR experiments (active species trapping) studies confirmed •O2− and h+ as the primary entities in TC photodegradation by In2O3/TiO2-III. HPLC/MS analysis revealed the photocatalytic degradation pathway. The MOF-derived photocatalysts efficiency in TC photoreduction results from the formed S-scheme heterojunction, making it a promising candidate for environmental remediation.

CuO/Bi2O3/g-C3N4 nanoparticles for sunlight-mediated degradation of polyethylene terephthalate microplastic films

A novel photodegradable CuO/Bi2O3/g-C3N4(copper oxide/bismuth oxide/graphitic carbon nitride) nanoparticle (NP) was synthesised using the sol-gel method and sunlight-mediated degradation of polyethylene terephthalate (PET) microplastics (MPs) films. The optical and structural properties of the sol-gel method were investigated using a variety of characterization methods, like UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Fourier transform infrared (FT-IR), X-ray diffractometer (XRD) analysis, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis. Degradation study results suggest that the photocatalytic activity of CuO/Bi2O3/g-C3N4/PET nanocomposites (NCs) films was greater than that of pure PET, CuO/PET, Bi2O3/PET, g-C3N4/PET, CuO/g-C3N4, Bi2O3/g-C3N4, and CuO/Bi2O3/PET films. Because of their increased optical absorption and efficient suppression of photo-produced charge carriers’ recombination, the CuO/Bi2O3/g-C3N4/PET NCs films showed higher photocatalytic degradation than PET films. Thus, PET films with CuO/Bi2O3/g-C3N4 (5:5:2 % wt) NPs showed a degradation of around 41.60 % among pure PET, CuO/PET, Bi2O3/PET, g-C3N4/PET, CuO/g-C3N4/PET, Bi2O3/g-C3N4/PET, and CuO/Bi2O3/PET NCs films under visible light over a short period of 30 days (240 h). When compared to the original PET MPs, the CuO/Bi2O3/g-C3N4/PET NCs films showed a significant decrease in crystallinity and carbonyl indexes, as much as 29.2 % lower. The present research also suggests a photocatalytic mechanism, which may explain the increased photocatalytic activity.

Unveiling the Structural Properties, Optical Behavior, and Thermoelectric Performance of 2D CsSn2Br5 Halide Obtained by Mechanochemistry.

Metal halide perovskites with a two-dimensional structure are utilized in photovoltaics and optoelectronics. High-crystallinity CsSn2Br5 specimens have been synthesized via ball milling. Differential scanning calorimetry curves show melting at 553 K (endothermic) and recrystallization at 516 K (exothermic). Structural analysis using synchrotron X-ray diffraction data, collected from 100 to 373 K, allows for the determination of Debye model parameters. This analysis provides insights into the relative Cs-Br and Sn-Br chemical bonds within the tetragonal structure (space group: I4/mcm), which remains stable throughout the temperature range studied. Combined with neutron data, X-N techniques permit the identification of the Sn2+ lone electron pair (5s2) in the two-dimensional framework, occupying empty space opposite to the four Sn-Br bonds of the pyramidal [SnBr4] coordination polyhedra. Additionally, diffuse reflectance UV-vis spectroscopy unveils an indirect optical gap of approximately ∼3.3 eV, aligning with the calculated value from the B3LYP-DFT method (∼3.2 eV). The material exhibits a positive Seebeck coefficient as high as 6.5 × 104 μV K-1 at 350 K, which evolves down to negative values of -3.0 × 103 μV K-1 at 550 K, surpassing values reported for other halide perovskites. Notably, the thermal conductivity remains exceptionally low, between 0.32 and 0.25 W m-1 K-1.

SnO2 nanoparticles: synthesis, characterization and photocatalytic activity

SnO2 nanoparticles have been synthesized using precipitation method and heat treatment. Firstly, SnCl4.5H2O was reacted with NaOH solution, and than the precipitate heat treated at 350 oC, 450 oC and 550 oC. The obtained materials were characterized by X-Ray diffraction (XRD) infrared spectra (IR) energy-dispersive X-ray spectroscopy (EDS) scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic degradation of rhodamine B (RhB) using SnO2 nanoparticles was investigated. The results show that the SnO2 nanoparticles exhibited a significantly enhanced photocatalytic activity. The photoactivity of SnO2 nanoparticles photocatalysts can be ascribed to the enhanced electron-hole separation.

Operando UV–Vis diffuse reflectance spectroscopy insights into the methane dehydroaromatization reaction over Mo/H-ZSM-5 catalysts

Methane Dehydroaromatization (MDA) is proposed as a possible way to valorize stranded natural gas, e.g., arising during crude oil drilling. In this study, we used operando UV–Vis Diffuse Reflectance Spectroscopy (DRS) in combination with Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) to distinguish the MDA reaction phases of activation, induction, and deactivation. We identified three spectral components, which describe these distinct reaction phases. When the catalyst was activated in CO, two spectral components alone sufficiently described the operando UV–Vis DRS data. We further found that the preparation method of the Mo/ZSM-5 catalyst has little influence on the observed spectral features. However, the different preparation methods impact the dispersion of Mo, resulting in faster deactivation for the catalyst with more Mo-clusters compared to the catalyst with a higher Mo dispersion. This study shows that operando UV–Vis DRS in combination with the MCR-ALS methodology is a powerful analytical tool to disentangle and study the three MDA reaction phases.

Efficient photocatalytic activity and selective adsorption of UiO-67 (Zr)/g-C3N4 composite toward a mixture of parabens

In this study, UiO-67 (Zr)/g-C3N4 composites (U67N) were synthesized at wt.% ratios of 05:95, 15:85, and 30:70 using the solvothermal method at 80 °C for 24 h followed by calcination at 350 °C. The composites were characterized using UV–Vis diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy–energy-dispersive X-ray spectroscopy, transmission electron microscopy, and nitrogen physisorption analysis. In addition, thermal stability analysis of UiO-67 was conducted using thermogravimetric analysis.The photocatalytic performance of the composites was assessed during the degradation and mineralization of a mixture of methylparaben (MeP) and propylparaben (PrP) under simulated sunlight. The adsorption process of U67N 15:85 was characterized through kinetic studies and adsorption capacity experiments, which were modeled using pseudo-first-order and pseudo-second-order kinetics and Langmuir and Freundlich isotherms, respectively.The influence of pH levels 3, 5, and 7 on the photocatalytic degradation of the mixture was investigated, revealing enhanced degradation and mineralization at pH 3. The U67N composite exhibited dual capability in removing contaminants through adsorption and photocatalytic processes. Among the prepared composites, U67N 15:85 demonstrated the highest photocatalytic activity, achieving removal efficiencies of 96.8% for MeP, 92.5% for PrP, and 45.7% for total organic carbon in 300 kJ/m2 accumulated energy (3 h of reaction time). The detoxification of the effluent was confirmed through acute toxicity evaluation using the Vibrio fischeri method.The oxidation mechanism of the heterojunction formed between UiO-67 (Zr) and g-C3N4 was proposed based on PL analysis, photoelectrochemistry studies (including photocurrent response, Nyquist, and Mott–Schottky analyses), and scavenger assays.

Enhanced room temperature ferromagnetism and versatile optical properties in MgFe2O4 spinel ferrite prepared under different calcination temperatures

This study employs the sol-gel auto combustion technique fueled by diethanolamine (DEA) to synthesize nanocrystalline magnesium ferrite (MgFe2O4) powders. During the study, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL), and vibrating sample magnetometry (VSM) were then used in order to determine how differing calcination temperatures influence the structure, chemical bonding, surface texture, morphology, optical, fluorescence, and magnetic properties of the resulting MgFe2O4 powders. The findings from the XRD and FT-IR analysis indicate that a single-phase spinel structure is formed in each of the MgFe2O4 samples. According to UV-DRS analysis, optimal calcination improved sample reflection levels in comparison to the visible and infrared spectral findings for the as-synthesized sample. The calcined samples exhibited bandgap energy (Eg) ranging from 2.11 eV to 2.14 eV, which was greater than the 2.02 eV of the as-synthesized sample. Examination of the PL spectra in the range of 380–700 nm revealed various light emission bands for the samples, which increased significantly in intensity at higher calcination temperatures. Furthermore, higher calcination temperatures also increased the magnetization of the MgFe2O4 spinel powders, while coercivity dropped significantly.

Enhanced visible light photocatalytic activity of SDBS/C/Nd/TiO2 synthesized by using anionic surfactant SDBS as template agent

<p>The catalyst SDBS/C/Nd/TiO2 was synthesized by sol-gel method using TiO2 co-doped with C and Nd and anionic surfactant SDBS as template agent. The prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron (SEM), X-ray photoelectron spectrometer (XPS) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and so on. Experimental results show that the crystal structure of the catalytic material is anatase type. Since doped elements change the energy band structure and electronic structure of TiO2, photogenerated electrons and holes can transition through the intermediate energy level, resulting in a decrease in the required excitation energy, thereby increasing the distance of its absorption edge moving toward the long wave direction, and meanwhile improving the utilization rate of visible light. The bandgap energy of the catalyst SDBS/C/Nd/TiO2 was 2.78 eV. Compared to pure TiO2 (3.1 eV), the band gap is reduced by 0.32eV. The photocatalytic experiments show that the degradation rate of the catalyst SDBS/C/Nd/TiO2 for methyl orange solution can reach 67%, and the catalytic performance is much improved than that of pure TiO2.</p>