UV Vis Diffuse Reflectance Spectroscopy Research Articles

Boosting photocatalytic efficiency and nonlinear optical response of graphitic carbon nitride by infusing carbon nanotubes

Nanostructured materials are widely studied for their light-driven physical and chemical processes, which are key to their potential in photophysical applications. We introduce a one-pot solid-state pyrolysis technique for the synthesis of graphitic carbon nitride/carbon nanotube (g-C3N4/CNT) composites. The formation of the composite was characterized through X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. Notably, UV-vis diffuse reflectance spectroscopy indicated a reduction in the bandgap of pure g-C3N4 from 2.6 eV to 2.35 eV with the incorporation of 0.5 wt% CNT. The nonlinear optical transmission of the samples was analyzed at 532 nm using the open-aperture Z-scan technique employing 5 ns laser pulses, revealing a twelve-fold increase in the two-photon absorption coefficient (b) for g-C3N4/CNT0.5 compared to pristine g-C3N4. Remarkably, g-C3N4/CNT0.5 showed enhanced photocatalytic efficiency in degrading bisphenol A (BPA), with the kinetic constant (k) being ten times higher than that of pure g-C3N4. The improved photocatalytic performance of g-C3N4/CNT0.5 is attributed to the presence of CNTs, which act as effective electron acceptors and transfer channels, significantly enhancing the separation of photogenerated charge carriers in g-C3N4, as evidenced by the decreased intensity in the photoluminescence spectrum.

Shear strength and optical bandgap in As2Se3 glasses permanently compacted under GPa pressures

The application of GPa pressures on glassy As2Se3, at temperatures just below and above its glass transition, leads to permanently compacted glasses that exhibit increased densification. Also, melt-quenching of the same glass under a pressure of 7 GPa gives rise to the formation of its crystalline β-phase. The structure of these As2Se3 compacted solids have been explored by X-ray diffraction. Measurements of 10 MHz ultrasound velocities reveal that the density increase is associated with a substantial hardening of the elastic continuum as well as a growing shear strength of glassy solids: the shear modulus G increases by more than 35 % and the Poisson's ratio ν decreases by more than 13 %. The optical properties have been investigated by UV–VIS diffuse reflectance spectroscopy, which shows a well defined linear reduction of the optical bandgap Eg with increased density. All of these observations have been explained by considering a disordered layered structure of glassy As2Se3, where densification produced by compaction under GPa pressures gives rise to a progressive strengthening of the interlayer interactions.

Z-scheme heterojunction of TiO2/NH2-MIL-125(Ti) growing on carbon fibers cloth: Photocatalytic degradation of tetracycline and toxicity analysis

Photocatalysis stands out as a promising and eco-friendly method for antibiotics removal, yet traditional photocatalysts, mainly in powder form, are often prone to detachment and loss, making them difficult to recycle and reuse. In this work, we address this challenge by using carbon fiber (CF) cloth with a large area as a carrier for catalysts. To improve the photocatalytic efficiency, we synthesized TiO2 nanorods on the surfaces of CF cloth and incorporate NH2-MIL-125 (Ti) on them, thus the Z-scheme heterojunctions CF/TiO2/NH2-MIL-125(Ti) was obtained. In order to fully understand the structural properties and performance advantages of CF/TiO2/NH₂-MIL-125 (Ti) composites, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray photoelectron spectroscopy (XPS), UV–visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), Brunauer-Emmett-Teller (BET), Mott-Schottky (M-S) and valence band X-ray photoelectron spectroscopy (VB-XPS). Due to the special electronic transmission path of the Z-scheme heterojunctions, the CF/TiO2/NH2-MIL-125(Ti) composite achieve 95.30 % degradation of tetracycline (TC) within 210 min. The composite also shows exceptional reusability, with a degradation rate of 93.55 % maintained even after four cycles. Finally, we proposed a pathway and catalytic process for the decomposition of TC by CF/TiO2/NH2-MIL-125(Ti) and performed toxicity assessments of TC and its precursors using T.E.S.T. software. This novel photocatalyst composite offers a green and efficient approach for treating antibiotic wastewater, presenting a significant advancement in environmental remediation strategies.

Investigation on luminescent characteristics of Tb3+/Dy3+co-doped boro-phosphate glass for cool white LED and radiation shielding applications

The Tb3+/Dy3+ co-doped Boro-Phosphate Glass (BPANZDyTb) was produced (40 B2O3 + 39P2O5 + 5 Al2O3 + 5 NaF + 10 ZnO + 0.5 Tb2O3 + 0.5 Dy2O3) using melt-quenching technique. X-ray diffraction measurements, Raman, and Fourier Transform Infrared were used to evaluate the structural behavior of the prepared glass. Powder-XRD spectra, in the 10–90° range showed that the prepared glass was amorphous. FTIR analysis reveals that the network contains a variety of structural groups, including B-O-B, BO4, BO, P-O, PO2, P-O-B, and PO4 units. The UV–visible diffuse reflectance spectroscopy was used to record and study the optical linear properties of Tb3+/Dy3+ co-doped Boro-Phosphate Glass (BPANZDyTb). The photoluminescence excitation peak was obtained at 348 nm. The emission peaks were located at 484 nm (4F9/2 → 6H15/2 → blue), 576 nm (4F9/2 → 6H13/2 → yellow), and 662 nm (4F9/2 → 6H11/2 → red). Tb3+ ions are located at 412 nm (5D3 → 7F5), 441 nm (5D3 → 7F4), 546 nm (5D4 → 7F5), and 625 nm (5D4 → 7F3). The result of CIE 1931 chromaticity coordinates indicate that the prepared glass is suitable material for cold white light emitting diode applications due to its color coordinates x = 0.3106 and y = 0.3240 and correlated color temperature (CCT) values about 6768 K. The gamma-ray parameters such as half-value layer (HVL), mass attenuation coefficient (μ/ρ), mean free path (MFP), and effective atomic number (Zeff) of the BPANZDyTb glass were studied using Phy-X software. The results of the gamma-ray parameter show that the Dy3+ ions and Tb3+ ions co-doped BoroPhosphate glass is an appropriate material for radiation shielding applications.

Construction of S/g-C3N4@β-Bi2O3 heterojunction and its photocatalytic degradation of toluene in the gas phase.

In this paper, a modification of g-C3N4 was carried out by combining non-metal doping with the construction of heterojunctions, and a type II heterojunction composite, S/g-C3N4@β-Bi2O3, was prepared. The phase structure, morphology, elemental composition, valence band structure, and light absorption performance of the photocatalyst were analyzed using characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The performance of the composite photocatalyst in the photocatalytic degradation of gaseous toluene, one of the typical volatile organic compounds (VOCs), under simulated solar light was studied. The effects of preparation conditions, toluene concentration, and recycling on the photocatalytic performance of the composite photocatalyst were investigated. The results show that under the optimal preparation conditions, S/g-C3N4@β-Bi2O3 achieved a degradation efficiency of 74.0% for 5ppm toluene after 5h of light irradiation. Although the degradation efficiency decreased to 61.2% after five cycles, it maintained 83% of its initial activity, indicating good stability of the composite photocatalyst. Free radical quenching experiments demonstrated that h+ was the main active species in the photocatalytic degradation of toluene, followed by ·O2-. Based on all experimental results, the migration law of photo-generated charges was analyzed, and a possible photocatalytic mechanism was proposed. In this study, a new material was obtained for the photocatalytic removal of VOCs by improving the photocatalytic properties of g-C3N4.

Ball-Milling Enhanced UV Protection Performance of Ca2Fe-Sulisobenzone Layered Double Hydroxide Organic Clay.

Using a co-precipitation technique, the anionic form of sulisobenzone (benzophenone-4) sunscreen ingredient was incorporated into the interlayer space of CaFe-hydrocalumite for the first time. Using detailed post-synthetic millings of the photoprotective nanocomposite obtained, we aimed to study the mechanochemical effects on complex, hybridized layered double hydroxides (LDHs). Various physicochemical properties of the ground and the intact LDHs were compared by powder X-ray diffractometry, N2 adsorption-desorption, UV-Vis diffuse reflectance, infrared and Raman spectroscopy, scanning electron microscopy and thermogravimetric measurements. The data showed significant structural and morphological deformations, surface and textural changes and multifarious thermal behavior. The most interesting development was the change in the optical properties of organic LDHs; the milling significantly improved the UV light blocking ability, especially around 320 nm. Spectroscopic results verified that this could be explained by a modification in interaction between the LDH layers and the sulisobenzone anions, through modulated π-π conjugation and light absorption of benzene rings. In addition to the vibrating mill often used in the laboratory, the photoprotection reinforcement can also be induced by the drum mill grinding system commonly applied in industry.

Constructing interfacial electric field with rich oxygen vacancy modulated heterojunction FeVO4-MgZnAl LDH for enhanced photocatalytic degradation of doxycycline

FeVO4 nanorods were synthesized and integrated with plate-like MgZnAl layered double hydroxide (LDH) using a combination of sonochemical coprecipitation and hydrothermal methods. The resulting FeVO4-MgZnAl LDH nanocomposites (FeVO4-MZA NCs) were engineered to enhance photocatalytic performance through an S-scheme charge transfer mechanism. These NCs exhibited exceptional photocatalytic activity, achieving 93.7% degradation of doxycycline (DXY) which is significantly outperforming its counterparts, FeVO4(29.8%) and MgZnAl LDH (49.8%). Detailed analysis using scavenging tests and electron spin resonance (ESR) analysis confirmed that the photoexcited charges follow the S-scheme pathway, leading to the generation of hydroxyl (•OH) and superoxide (O2•⁻) radicals. This mechanism remarkedly improves the catalytic efficiency of FeVO4-MZA NCs with a kinetic rate constant of 4 - 9 times higher than those of its individual components. The photocatalyst's were comprehensively characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (UV-vis-DRS), photoluminescence (PL) spectroscopy, and electrochemical impedance spectroscopy (EIS). The FeVO₄-MZA NCs demonstrated remarkable stability and reusability, indicating their suitability for large-scale water treatment applications. Additionally, the non-toxic nature of FeVO4-MZA NCs, coupled with effective charge carrier separation and reduced recombination rates, establishes them as highly efficient photocatalysts for the removal of pharmaceutical contaminants from aquatic systems.

Exploring the Defect Formation and Ionic Migration in A2Zr2O7 (A = La, Ce, Nd, and Gd) Pyrochlore Solid-State Electrolytes

This study investigated the potential of A2Zr2O7 pyrochlore phase oxides (A = La, Ce, Nd, and Gd) as solid oxide fuel cell (SOFC) electrolyte materials. A2Zr2O7 ceramics were synthesized using the sol-gel process, and their disordered pyrochlore structure was confirmed by X-ray Diffraction and Rietveld refinement. Field Emission Scanning Electron Microscopy (FE-SEM) was used to examine the morphology of the materials, while X-Ray Photoelectron Spectroscopy (XPS) confirmed a high oxygen ion concentration. UV-Vis Diffuse Reflectance Spectroscopy (DRS) and density of states calculations consistently showed similar bandgap patterns in all zirconate pyrochlore. Density Functional Theory (DFT) simulations provided insights into the electronic structure and migration pathways. A two-probe conductivity study confirmed the relation between the ionic conductivity and ordering degree of pyrochlore. At 750°C, LZO, CZO, and GZO exhibited ionic conductivity values of 5.44x10-3 S/cm, 3.00x10-3 S/cm, and 2.01x10-3 S/cm respectively, while NZO demonstrated a conductivity of 1.27x10-2 S/cm at 700°C, which is higher than that of the other samples. This study favours the use of the sol-gel route for processing zirconate pyrochlore materials, highlighting its ability to achieve high densities at lower temperatures and exhibit enhanced ionic conductivity. A2Zr2O7 has emerged as a promising oxide-ion conducting solid electrolyte for intermediate temperature SOFC applications within the 600-750°C temperature range.

Green synthesis of TiO2@g-C3N4 nanocomposites for the photocatalytic degradation of pesticides and toxic organics present in water and wastewater

To address the environmental challenges caused by toxic organics in aquatic systems, photocatalytic degradation is a promising option. This study investigates the green synthesis of TiO2@g-C3N4 nanocomposites by coupling Titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4) in different mass ratios through solvothermal technique due to their photocatalytic properties. Leaf extract from the Ziziphus jujube plant was utilized as a green template making the synthesis environmentally friendly, utilizing renewable resources, and employing facile and cost-effective methods. The nanocomposites were characterized using various analytical techniques including UV–Vis Diffuse reflectance spectroscopy (UV–Vis DRS), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDS) to analyze the structural and morphological properties. The wavelength ranged from 385 to 454 nm and band gap energies ranged from 3.22 to 2.73 eV for the synthesized materials. The pure green TiO2 showed the highest band gap energy while pure g-C3N4 showed the lowest band gap energy among the synthesized materials. The photocatalytic activity of the synthesized nanocomposites was evaluated through the degradation of Bisphenol A and Malathion pesticide under UV light irradiation. The results indicated 71 % degradation of Bisphenol A with the 50 % TiO2@g-C3N4 nanocomposites exhibiting 1.422 x 10-2 min−1 rate constant and 74 % degradation of Malathion degraded over 20 % TiO2@g-C3N4 which depicted rate kinetics of 1.022 x 10-2 min−1. Moreover, both showcased higher performance than the individual TiO2 and g-C3N4 nanostructured materials.

Photodegradation of Methylene Blue Dye Using BiVO₄/g-C₃N₄ Composites under Visible Light Irradiation

This study evaluates the degradation of methylene blue through photocatalysis using BiVO4/g-C3N4 material with the help of visible light. Material characterization was conducted using X-ray diffraction, scanning electron microscopy, and UV-Vis diffuse reflectance spectroscopy data. The characterization results show that the crystal structure of BiVO4/g-C3N4 is a heterojunction between monoclinic BiVO4 and hexagonal g-C3N4, with a crystal size of about 10.16 nm and a band gap energy value of about 2.16 eV. The morphology formed is a combination of sheet and rod-like. This study optimized the photocatalytic activity of the composite by analyzing the variation of g-C3N4 concentration, degradation time, and methylene blue pH. The results show that the BiVO4/g-C3N4 sample has optimal photocatalytic and adsorption properties in sample B (1:3) with pH 7 and a degradation time of 150 minutes. Under these conditions, the BiVO4/g-C3N4 composite successfully degraded methylene blue by 94.14%. The rate kinetics of the photocatalytic reaction followed first order, with *OH species playing the most role in the degradation mechanism. These findings highlight the potential of BiVO4/g-C3N4 as an effective photocatalyst material for organic pollutant degradation applications, offering a sustainable solution for wastewater treatment.

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).

High-performance Bi2O3 nanoflakes for advanced energy storage applications

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

Sustainable photocatalytic process using non-silver agent ZnO/P-g-C3N4/Sr2MgSi2O7:Eu2+,Dy3+ for antibacterial activity

Antimicrobials have become a necessity in the post-pandemic era. In contrast to traditional silver-based antimicrobial materials, which are sterilized by silver ions, photocatalytic materials are mainly sterilized by generating reactive oxygen species, but they are limited by light. In this study, the composite coupling of semiconductor photocatalysts with long afterglow materials was designed to form ZnO/P-g-C3N4/Sr2MgSi2O7:Eu2+,Dy3+ (ZPS) for antibacterial ceramics application. The morphological, chemical structure, and optical properties of ZPS were analyzed by scanning electron microscope (SEM), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR), and UV visible diffuse reflectance spectroscopy (UV–vis DRS). The sustainable photocatalytic properties of as-synthesized composites were explored. Furthermore, the antimicrobial ceramics were prepared by incorporating this antibacterial agent into ceramic glazes, which were found to be highly effective against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with a suppression rate of more than 99 %. The results of active species capture and electron spin resonance (ESR) experiments suggested that •O2- was the significant active species of the photocatalytic antimicrobial agent with a contribution of 47.17 % and that ZPS could continuously produce active species in the dark state.

Green nanoarchitectonics Ce-Co₃O₄/BiVO₄ (p-n) heterojunction nanocomposite: Dual functionality for photodegradation of Congo red and supercapacitor applications

In this work, we synthesised a new Ce-doped Co₃O₄/BiVO₄ heterojunction photocatalyst by a green synthesis strategy utilizing Magnifera indica leaf extract for Co₃O₄ and a precipitation method for pure BiVO₄. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), UV–Visible diffuse reflectance spectroscopy (UV-DRS), Brunauer-Emmett-Teller (BET) surface area analysis, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV) were used to investigate the material's structural, optical The Ce-Co₃O₄/BiVO₄ heterojunction decreased the band gap energy to 1.92 eV, resulting in increased visible light absorption. The photocatalytic activity of the developed heterojunction was evaluated by degrading the anionic dye Congo red (CR) under different circumstances such as pH, catalyst dose, dye concentration, and irradiation period. At pH 4, 98 % degradation was obtained using a dye concentration of 50 ppm, a catalyst dose of 40 mg, and 50 min of sun light exposure. High-resolution mass spectrometry (HR-MS) validated the effective degradation of CR and offered information on the potential degradation process. Kinetic investigations revealed that the photodegradation of CR followed a pseudo-first-order kinetic model. This study demonstrates the effectiveness of Ce-Co₃O₄/BiVO₄ heterojunctions in photocatalytic applications, namely for the removal of dye contaminants from wastewater using visible light. Furthermore, the heterojunction showed a substantial rise in specific capacitance, reaching 1353 F/g, 5.4 times that of pure Co3O4. The Nyquist plot displayed a smaller arc radius, indicating improved electrochemical characteristics and a possible application as a semiconductor. These results highlight the Ce-Co₃O₄/BiVO₄ heterojunction as a promising photocatalyst with outstanding dye degrading capabilities and increased electrochemical performance, appropriate for diverse environmental and energy storage applications.

Partial substitution of rhodium with ruthenium in Pd-Rh nanoalloys and its impact on catalytic characteristics

In the present work, alumina-supported trimetallic Pd-Rh-Ru catalysts were synthesized and studied in comparison with the bimetallic Pd-Rh reference sample. The alloy nanoparticles were formed on the surface of the alumina support by thermolysis of the complex salts [Rh(NH3)5Cl][Pd(NO2)4] and [Rh(NH3)5Cl]0.5[Ru(NH3)5Cl]0.5[Pd(NO2)4], preliminary deposited via an incipient wet impregnation method. The influence of the conditions of the thermolysis process on the phase composition of the final products and the size of the trimetallic particles was established. Thus, nanoscale trimetallic (Rh-Ru-Pd) alloy particles of a given composition were obtained. The catalytic performance of the alumina-supported samples was examined in a CO oxidation reaction under prompt thermal aging conditions. It was ascertained that the addition of ruthenium only improves both the initial activity and thermal stability of the catalytic system. The state of each metal in the alloy nanoparticles was characterized by diffuse reflectance UV–vis spectroscopy and X-ray photoelectron spectroscopy.

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.