Titanium dioxide (TiO2) is a leading semiconductor photocatalyst for environmental remediation, valued for its chemical stability, polymorphic phases, and tunable optoelectronics. Its wide band gap (approximately 3.0-3.2 eV), however, limits visible-light activity, necessitating electronic structure engineering via phase modification. The present study explores the effect of tungsten loadings (2.5, 5.0 and 10.0 wt%) on biphasic anatase-brookite TiO2 via the synthesis of WO3-TiO2 heterostructures using a modified sol-gel method. The study aimed at providing insights into the relationship between tungsten concentration, interfacial structural properties, and resulting photocatalytic efficiency. X-ray diffraction (XRD) analysis revealed that modification induced the formation of a distinct secondary WO3 phase alongside the anatase-brookite TiO2, establishing a multi-phase junction that was most pronounced at 10.0 wt% loading. The 2.5 wt% WO3-TiO2 heterostructures exhibited the narrowest optical bandgap (2.46 eV), a favorable pore diameter of 33.62 nm, and a high pore volume of 0.265 cm3 g-1. Photoluminescence spectroscopy showed the strongest emission quenching for 2.5 wt% WO3-TiO2, indicating reduced charge-carrier recombination and improved heterojunction-assisted charge separation. This composition delivered the highest photocatalytic performance, degrading 91.5% of methylene blue under visible light within 60 min, compared with 28.87% for pristine TiO2. These WO3/anatase-brookite TiO2 heterostructures, therefore, represent efficient, robust photocatalysts for textile wastewater treatment.

Abstract The influence of temperature on the product distribution during fructose conversion was systematically investigated using Ce(P), Nb(P), CeNb5(P), CeNb15(P), and CeNb25(P) materials prepared by the Pechini method. Reactions were performed in aqueous medium for 2 h at temperatures ranging from 130 to 160 °C. Increasing temperature enhanced fructose conversion but also modified the relative contributions of dehydration, fragmentation, and consecutive degradation pathways. Nb(P) reached the highest fructose conversion, increasing from 17.6% at 130 °C to 67.9% at 160 °C, but also exhibited a greater contribution from unidentified and degradation products under the most severe conditions. In contrast, the Ce–Nb mixed oxides, particularly CeNb15(P) and CeNb25(P), more effectively directed the identified soluble products toward 5-hydroxymethylfurfural (5-HMF), while limiting some competing pathways. The formation of C3 compounds, including dihydroxyacetone and pyruvaldehyde, indicates the occurrence of C–C bond cleavage reactions, whose contribution increased with temperature and depended on material composition. The observed product distributions result from the combined influence of temperature, acid-site nature, concentration, strength, and accessibility, together with the redox properties of the Ce containing materials. These findings demonstrate that the principal contribution of the studied oxides lies in their catalyst dependent modulation of the fructose reaction network rather than in the effect of temperature alone.

This study evaluates the surface modification of a & ccedil;ai biochar (Al@BC) by aluminum coating via magnetron sputtering, aiming to improve its adsorption performance of clorazepate (CZ) and diclofenac (DC) from aqueous solutions. Sputtering power conditions of 100 W, 150 W, and 200 W were applied, obtaining, respectively, 0.22%, 0.40%, and 3.41% of Al-covering for the adsorbents named Al@100 W, Al@150 W, and Al@200 W. Kinetic analyses fitted to the pseudo-first-order model showed excellent agreement with the experimental data, with better predictive accuracy, particularly for DC. Adsorption equilibrium was achieved at 120 min for CZ and 60 min for DC. Equilibrium isotherms exhibited L2-type profile, suggesting strong adsorbate-adsorbent affinity. The Sips model best described the equilibrium data, evidencing a heterogeneous adsorption process promoted by aluminum deposition. Decreasing Sips (m) parameters with increasing sputtering power reflected enhanced surface heterogeneity and adsorption favorability. The maximum adsorption capacities reached were 260.7 mg g- 1 for CZ and 277.5 mg g- 1 for DC onto Al@200 W, representing an improvement of about 35% compared to raw biochar. Regeneration tests showed excellent reusability through the first five cycles; thereafter, coating deterioration greatly diminished the material's efficacy. Finally, magnetron sputtering proved to be an effective strategy, confirming that adsorption efficiency was governed by both aluminum loading and surface chemical modification, thereby enhancing adsorption capacity, affinity, and durability toward pharmaceutical contaminants.

The increasing prevalence of antibiotic-resistant bacteria poses a significant global public health challenge, particularly with multidrug-resistant pathogens such as Staphylococcus aureus and Escherichia coli. In this context, silver nanoparticles (AgNPs) have garnered attention as promising alternative antimicrobial materials due to their unique physicochemical properties. In this study, we investigated the green synthesis of AgNPs using bacterial supernatants derived from the larval food of Brazilian stingless bees, a biologically rich and underexplored source of functional metabolites. Using supernatants of Providencia rettgeri and Proteus mirabilis, AgNPs were synthesized via both traditional and microwave-assisted methods, with the latter promoting faster nanoparticle formation and improved colloidal homogeneity. Two AgNP formulations (AgNPs-1B and AgNPs-54B), selected for their distinct synthesis profiles, were characterized by UV-visible spectroscopy, dynamic light scattering, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). TEM analysis revealed predominantly spherical nanoparticles, with average diameters of 24.2 ± 27.4 nm for AgNPs-1B and 8.5-25.2 nm for AgNPs-54B, confirming successful nanoscale synthesis. Both AgNPs exhibited significant antimicrobial activity against multidrug-resistant E. coli and S. aureus. When incorporated into alginate-based membranes, the nanoparticles retained their antimicrobial efficacy, particularly through contact-dependent inhibition of bacterial growth. Toxicity assays using Drosophila melanogaster and human neuron cultures indicated low toxicity in the evaluated biological models. These findings demonstrate the potential of biologically synthesized AgNPs as sustainable antimicrobial materials, combining a unique microbial source with microwave-assisted processing and relevant biomedical and environmental applicability.

W-coated grape waste-based biochars were prepared by tungsten deposition via magnetron sputtering at varying current powers (100-200 W). The effect of deposition conditions on the adsorbents' features and performance in Surfaces Physicochemical Engineering Aspects removing three classes of contaminants, including diclofenac (DCF), crystal violet (CV), and Pb(II), was investigated. Characterization analysis confirmed the successful deposition of W-thin films as tungsten oxides and the increase in tungsten content, from 0.87% to 1.68%, with an increase in current power from 100 to 200 W. Kinetic curves were well represented by the pseudo-first-order and pseudo-second-order models. The Sips model best described the equilibrium data, with increased affinity observed as tungsten content increased. The biochar obtained at a higher current power, named GWBB200W15min, achieved outstanding adsorption capacities of 798.8 mg g-1, 766.4 mg g-1, and 684.0 mg g-1 for DCF, CV, and Pb(II), respectively, at C0 = 300 mg L-1 and optimal pH 7.0 for the organic contaminants and pH 5.0 for Pb(II). These results denote improvements of about 43%, 61%, and 46% compared with the raw biochar. Regeneration assays demonstrated the high reusability potential and stability of the W-coated biochar. Overall, increasing the current power led to increased W content and enhanced surface properties, associated with improved adsorption performance, in which the deposited Wthin films provided new binding sites that engendered strong interactions. These results showed that W deposition via magnetron sputtering has promising potential for obtaining adsorbents with enhanced adsorption capacity, high reusability, and multi-contaminant removal capability.

Understanding the chemical stability of Gas Electron Multipliers (GEMs) operated in CO_2-based mixtures is essential for improving detector longevity and reliability. In this work, we investigate the interaction between CO_2 molecules and the copper electrodes of GEM foils through near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and complementary Raman mapping. The measurements reveal that CO_2 exposure promotes a mild reduction of CuO to Cu_2O on untreated surfaces, while sputter-cleaned foils remain metallic and chemically stable. Raman spectroscopy confirms the predominance of Cu_2O with spatially heterogeneous contributions from CuO at the micrometer scale, providing structural support for the oxidation-state evolution inferred from XPS. Carbon 1s spectra identify carbonyl (C=O), C-O, carbonate, and hydroxyl species, indicating that oxidized copper sites mediate surface reactions and the formation of oxygenated films. A spectral feature consistent with ionized gas phase CO_2 species is observed in the O 1s region, suggesting that a fraction of the gas phase may become ionized in the near-surface region during acquisition. This is relevant for GEM detectors, where CO_2^+ and other ionized species generated in the avalanche can interact with the copper electrodes. These findings indicate that CO_2 acts not only as a quencher but also as a weakly reactive component capable of establishing self-limiting redox equilibria that favor the formation of thin, inorganic oxygenated layers. Such layers are expected to be significantly less prone to charge accumulation than the polymeric or carbonaceous deposits typically formed in hydrocarbon-based mixtures. The results provide experimental insight into the mechanisms underlying GEM stability and contribute to a deeper understanding of aging phenomena in GEM-based systems.

Exhausted biomass-based adsorbents can be reused as catalysts, contributing to a circular economy, while adding value to waste. A bioadsorbent was produced by chemical modification of sugarcane bagasse with trimellitic and succinic anhydrides, for use in the removal of Co(II) and Ni(II) from water, in mono- and bicomponent systems. Subsequently, the bioadsorbents containing Co(II) and/or Ni(II), in different proportions, were used as catalysts for the total oxidation of the model VOCs n-hexane, n-heptane, benzene, toluene, and p-xylene. The catalysts were characterized using textural, thermogravimetric, X-ray diffraction, X-ray photoelectron spectroscopy, and FT-IR analyses. For the monometallic catalysts, the amounts of Co(II) and Ni(II) adsorbed were 1.59 +/- 0.04 and 1.36 +/- 0.01 mmol g(-1), respectively. For the bimetallic catalysts, the total adsorption capacities were in the range from 1.6 to 2.6 mmol g(-1). The catalysts were especially effective in the oxidation of n-hexane and n-heptane. The conversion temperature was relatively low (<= 150 degrees C) and the only products detected were CO2 and H2O. A long-term test (25 h at 150 degrees C) was also performed with the catalyst most active for oxidation of n-hexane, to assess its stability and durability. The presence of the two metals together in the catalyst showed synergism in the oxidation of the model VOCs, although Ni(II) appeared to be more effective in promoting catalysis, compared to Co(II).

Advances in technological areas such as microelectronics and photonics have paralleled our ability to produce and characterize ultra-thin films, as thick as few nanometers. In this study, we developed a Monte Carlo code in Python specifically for angle-resolved X-ray photoelectron spectroscopy (ARXPS) data interpretation collected from nanometric films. This code allows for the simulation of general 2D structures, requiring only the photoelectron peak cross-section, the corresponding inelastic mean free path, and the atomic concentration as inputs. The peak intensity from each element is then weighted according to the attenuation law. Here, we demonstrated the capability of the ARXPS technique to characterize a nominal 2 nm thick platinum film deposited by DC-sputtering on a native silicon dioxide layer of a silicon substrate, which presents a formation of island structures distributed across the surface. The results were compared to other consolidated and relatively less accessible surface science techniques, namely, medium energy ion scattering (MEIS) and electron Rutherford backscattering spectrometry (ERBS), which are capable of analyzing 2D structures on the surface. The chi-square analysis determined the platinum island height and substrate coverage. The discrepancies in nanostructure distribution and dimensions obtained from these three techniques were less than 6%. The advantages and limitations of each method were also discussed.

The use of NPs has increased massively innumerous fields, including environmental sciences, electronics, and medicine. Because of their unique physical, optical, and biological capabilities, gold nanoparticles (AuNPs) are of considerable interest. These nanoparticles have distinct properties that make them useful as nanoprobes for imaging and nanocarriers for efficient drug delivery systems, for example. To harness their full potential in the biomedical area, it is crucial to accurately characterize their size, shape, and biological activity. In this study, the mu -PIXE technique has been employed to investigate the cellular uptake of these nanoparticles upon interaction with the U87 glioblastoma cell line. This analysis provided information on the internalization and distribution of nanoparticles within the cellular environment. To evaluate the cytotoxic effects of the AuNPs, the MTT assay was performed. This widely used method allows for the assessment of cell viability in the presence of nanoparticles. Lastly, their size was also measured by scanning electron microscopy, yielding a mean diameter of 18 +/- 5 nm, which agreed well with previous MEIS results.

The porous engineering of clay nanoarchitectures (PCN) achieved from a well-known but little-explored commercial organoclay C-20A is reported. Thorough characterizations (by XRD, TGA, N2 sorption, ICP, SEM, TEM, 27Al MAS NMR, DR UV-Vis, XPS, Py-FTIR and H2-TPR) confirmed a delaminated structure presenting a specific surface area of 504 m2 g- 1, twelve times higher than the sodic montmorillonite used as reference and featuring a new pore system comprising a size range from supermicropores to small mesopores (1.3-10 nm). The role of these PCN as support of manganese oxide for the gas-phase total catalytic oxidation of volatile organic compounds (VOCs) was evaluated. PCN with 5 % of Mn resulted in a higher nanoparticle dispersion (10 nm) compared to the sodic montmorillonite (17 nm). The highest catalytic activity was reached with PCN containing 10 % of Mn achieving a benzene, toluene and ortho-xylene oxidation of 54 %, 39 % and 34 %, respectively, at 350 degrees C. The catalyst was stable up to 36 h under these conditions.

We investigated the effectiveness of N-doping pre-carbonized waste and explored how the nitrogen source and pyrolysis conditions influence the morphology and optical properties of the resulting materials for environmental applications. Ten N-doped materials were obtained by mixing different urea percentages (21.7-78.3 %) with wastes from biogenic silica production. It was revealed that the doping was effective for all samples without affecting the crystalline structure of graphitic carbon. By modulating the urea ratio, it was found that its higher concentrations increased pore size (4.46-4.83 nm) and basicity (6.8-7.1), decreasing the surface area available (894-698 m2 g-1). The addition of lower concentrations of urea was shown to decrease the band gap (2.5-2.17 eV), improving the catalytic properties of the materials. The N-doping unlocked carbocatalytic features of the waste-derived materials in photo-assisted reactions, being effective for the degradation of paracetamol and diclofenac in aqueous systems. Thus, this study demonstrates that N-doping not only stabilizes the structures but also allows for the tuning of specific properties to suit targeted applications.

In this work, we report the synthesis of catalysts based on ceria nanorods (CeO2NRs) doped with 3% and 5% mol gadolinium. The supports were obtained from cation co-precipitation hydrothermal synthesis over which gold nanoparticles (AuNPs) were deposited by the deposition-precipitation (DP) methodology, allowing the Au nanoparticles size control at around 3 nm. The catalysts were evaluated in water gas shift reaction and showed high activity under a H2 rich stream (7%CO/7%CO2/14%N2/42%H2/30%H2O) with steam/process gas molar ratio (S/G) of 0.3 at 300 and 250 degrees C. The results revealed that Gd-doping increased the oxygen vacancies concentration due to the insertion of a trivalent cation in ceria lattice. In addition, the synergistic effect between AuNPs and Gd-doped CeO2 provided the increase of reducibility and oxygen storage capacity (OSC). These properties were associated with the catalytic activity in water gas shift reaction. The nanostructured materials decreased the CO concentration under conditions of H2 rich stream, indicating the catalysts potential for industrial applications after further studies. The catalyst doped with 5% mol Gd was the most active and achieved 24% of CO conversion at 300 degrees C.

The use of nanoparticles has significantly increased in many areas, such as biomedical research, being highly useful as nanoprobes for imaging and as nanocarriers for drug delivery applications. Nevertheless, this potential can only be achieved with the correct characterization of the nanoparticles, since their size and shape can directly affect their biological behavior. In this study, we propose a novel approach for a monolayer deposition of gold and platinum nanoparticles on Si substrates suitable for medium energy ion scattering (MEIS) analysis. The samples were prepared using poly(ethylene glycol) 6000 (PEG 6000) as a coating agent for the substrates, utilizing a spin coater-a versatile, cost-effective, and practical technique. The samples were first analyzed with the RBS technique to assess the adhesion and the overlapping of the nanoparticles in the substrates coated with PEG 6000 and then characterized through the MEIS technique. The analysis through MEIS allowed the determination of the shape, size, and coverage area of the nanoparticles. Scanning and transmission electron microscopy were also performed on the samples, with the results corroborating the findings of the MEIS experiment. Together, the data obtained with microscopy and the MEIS technique suggests the effectiveness of the method in the production of monolayer samples.

Styrene is an important building block of the plastics industry being produced by ethylbenzene dehydrogenation. The commercial catalysts have the disadvantages of deactivation by potassium loss and coke deposition, and chromium toxicity. To overcome these drawbacks, a new catalyst was developed by investigating the effect of magnesium on the catalytic properties of hematite in ethylbenzene dehydrogenation. Hematite was detected for all fresh catalysts and magnetite for the spent ones. Magnesium was found as magnesium ferrite and magnesium oxide, depending on the magnesium amount. Magnesium compounds affect the crystal sizes, the amount of defects and the reducibility of iron oxides, the predominance of each one depending on the composition of the solids. These effects caused important differences in activity, selectivity and stability of the catalysts. The catalyst with Mg/Fe = 0.09, consisting of aggregates of hematite, MgO and magnesium ferrite, showed the highest yield, being the most promising for commercial applications.

This work focused on the uptake of ivermectin from aqueous media using chitosan derivative as an adsorbent material. The adsorbent was synthesized through the co-precipitation approach, controlling the iron oxide quantity on the polymer surface. FTIR, XRD, SEM, EDS, XPS, textural properties, and surface charge characterized magnetic chitosan (CS & sdot;Fe3O4). & sdot; Fe 3 O 4 ). The adsorption efficiency was affected by different experimental conditions, especially by adsorbent dosage and ionic strength. The shifts in the FTIR spectrum of CS & sdot;Fe3O4 & sdot; Fe 3 O 4 after adsorption suggest the occurrence of hydrogen bonds between the adsorbent surface and adsorbate molecules. The kinetic modeling showed that the Elovich model was well suitable to describe the kinetic data. Meantime, the Sips and Liu models described well the adsorption isotherms. The maximum adsorption capacity (81.86 mg g- 1 ) was reached at pH 7.0 and 298 K, using an adsorbent dosage of 0.6 g L- 1 . Thermodynamic parameters indicated that the process was spontaneous and exothermic. The regeneration and reuse assays displayed that the recovery of adsorbent was more effective using ethyl alcohol than sodium hydroxide.

Advances in technological areas as microelectronic and photonics came along with our capability to fabricate and characterize ultra-thin films. Here we applied angle-resolved X-ray photoelectron spectroscopy (ARXPS), medium energy ion scattering (MEIS) and electron Rutherford backscattering spectrometry (ERBS) to investigate a nominal 2 nm thick platinum film deposited by DC-sputtering over a native silicon dioxide layer on a silicon substrate. A homogeneous thin film could not explain the experimental findings, and only the formation of island structures distributed over the surface was in agreement with all the techniques employed. In order to analyze the ARXPS data a Monte Carlo code was developed in Python language. Chi-square analysis was applied for the platinum island height and the substrate coverage. The disagreement on the nanostructures distribution and dimensions obtained from these techniques was smaller than 6%. Pros and cons of each technique were discussed.

The discharge of synthetic dyes from different industrial sources has become a global issue of concern. Enormous amounts are released into wastewater each year, causing concerns due to the high toxic consequences. Photocatalytic semiconductors appear as a green and sustainable form of remediation. Among them, graphitic carbon nitride (g-C3N4) has been widely studied due to its low cost and ease of fabrication. In this work, the synthesis, characterization, and photocatalytic study over methylene blue of undoped, B/S-doped, and exfoliated heterojunctions of g-C3N4 are presented. The evaluation of the photocatalytic performance showed that exfoliated undoped/S-doped heterojunctions with 25, 50, and 75 mass % of S-doped (g-C3N4) present enhanced activity with an apparent reaction rate constant (kapp) of 1.92 × 10-2 min-1 for the 75% sample. These results are supported by photoluminescence (PL) experiments showing that this heterojunction presents the less probable electron-hole recombination. UV-vis diffuse reflectance and valence band-X-ray photoelectron spectroscopy (VB-XPS) allowed the calculation of the band-gap and the valence band positions, suggesting a band structure diagram describing a type I heterojunction. The photocatalytic activities calculated demonstrate that this property is related to the surface area and porosity of the samples, the semiconductor nature of the g-C3N4 structure, and, in this case, the heterojunction that modifies the band structure. These results are of great importance considering that scarce reports are found concerning exfoliated B/S-doped heterojunctions.

We report a photocatalytic device based on gold nanoparticles (AuNPs/TiO2) coated with an ionic liquid (IL) as a very active, stable, and versatile system for hydrogen evolution re-actions (HERs) via methanol photo reforming (MPR) and photocatalytic water-splitting (WSR) reaction. The devices prepared by magnetron sputtering yield hybrid materials with direct Au-TiO2 interactions that were subsequently coated with BMIm.NTf2 (IL@Au@TiO2). The IL presence critically enhances the photocatalytic performance given its interaction with the AuNPs and TiO2 surfaces by decreasing the flat band energy levels and the Schottky barrier thickness. The results show an increase in the number of charge carriers yielding a capacitor-like effect generated by interactions of IL and Au@TiO2 par-ticles. Apparent quantum yield (AQY) up to 28.3% under UV irradiation (365 nm) and 22.9% at 405 nm irradiation were observed in the HER employing the as-prepared materials.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

ZnO has been intensively studied as a photocatalyst for the decomposition of organic molecules under light irradiation in both the UV and visible spectra regions. Herein were have chemically synthesized ZnO powders aiming to comprehend their photocatalytic activity for the decomposition of rhodamine B in the UV region. The electronic and structural characterization was performed using X-Ray Diffraction (XRD), Diffuse Reflectance Spectra (DRS), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and DFT calculations using the Slater transition method. The physicochemical characterization of the samples enabled the assessment of crystallite sizes, band gap, Urbach tail energy, morphology as well as the surface chemical states. The results revealed that the highest photocatalytic activities were observed for samples with a more balanced surface stoichiometry and smaller (100/002) XRD peak ratio, which were achieved with the spherical-shaped samples. The presence of oxygen vacancies, indicated by the O 1s XPS spectra, is also associated with the decrease in the photocatalytic activity. The XPS results corroborate the relevance of the surface properties for the photocatalytic activity.

Single-phase oxygen stoichiometric LaMnO3 and doped La0.8A0.2MnO3 (A = Ca, Sr, Ba) perovskites have been prepared by a simple one-step auto-combustion method. Cation-deficient LaMnO3+δ and La0.8A0.2MnO3+δ were obtained by calcination of the former samples in air at 750 °C. The samples were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction, temperature-programmed oxygen desorption, and N2 physisorption in order to apply them as catalysts in the complete catalytic oxidation of acetone as a model volatile organic compound. The studied phases show the expected orthorhombic and rhombohedral perovskite crystal structures. Catalytic experiments performed with all the samples show measurable activity already at 100 °C. At 200 °C, doped La0.8A0.2MnO3 samples show higher activity than undoped LaMnO3, with increasing conversion with larger A-cation size. Calcined samples also show higher activity than as-prepared ones making La0.8Ba0.2MnO3+δ the best catalyst at this temperature. All doped samples show >95% acetone conversion at T ≥ 250 °C with a weak dependence on the sample processing or A cation doping. The collected evidence confirms that the most important factors for the catalytic activity of these oxides are the Mn4+/Mn3+ molar ratio on the surface of the samples and the cation-deficiency of the bulk perovskite structure. In addition, increasing the symmetry of the bulk crystal structure appears to have an additional favourable effect. Despite the observation of the presence of surface carbonates, we show that it is possible to use the as-prepared samples without further thermal treatment with good results in the oxidation of acetone.