Search Results (537)

In this work, we report the synthesis of a photocatalytic system based on impregnating g-C₃N₄ quantum dots (CNQDs) onto the surface of exfoliated graphitic carbon nitride (CN). The CNQDs were prepared using a top-down strategy via a hydrothermal route and then grafted onto exfoliated g-C₃N₄ under solvothermal conditions. The prepared CNQDs/CN composites were characterized using several techniques, including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and nitrogen physisorption. According to XPS analysis, a slight increase in the O 1s signal in the 1-CNQDs/CN sample could indicate a higher amount of adsorbed hydroxyl groups, which would favor the dispersion of the powder material in the aqueous medium. The photocatalytic degradation of the antibiotic levofloxacin (LEVO) was assessed using the CNQDs/CN samples, with the sample impregnated with 1 wt.% of CNQDs demonstrating the highest photocatalytic performance under UV-vis radiation conditions. Likewise, the 1-CNQDs/CN sample also exhibited the lowest photoluminescence emission (λ_exc = 315 nm), indicating that the presence of g- C₃N₄ quantum dots contributed to the decrease in the recombination rate of the photogenerated electron–hole pairs in the photoexcited graphitic carbon nitride. The stability tests revealed a modest performance reduction of 21% over three cycles. From the photocatalytic tests using scavenger agents, it was determined that hydroxyl (·OH) and superoxide (·O₂⁻) radicals are the reactive species that govern the levofloxacin photodegradation under experimental conditions. Consequently, we determined a photocatalytic mechanism consistent with the results. Full article

Heterogeneous photocatalysis has attracted attention as an effective method for the degradation of a wide range of organic contaminants. Despite the growing interest in ceria- and manganese oxide-based photocatalysts, CeO₂/Na-birnessite heterostructures remain largely unexplored. Therefore, CeO₂/Na-birnessite composite materials were synthesized by a hydrothermal method and investigated for photocatalytic water treatment. XRD and WPPF analyses confirmed the coexistence of fluorite-type CeO₂ and layered Na-birnessite, while an additional hausmannite phase was detected in the Mn-rich samples. SEM, TEM and EDS analyses revealed close spatial contact between ceria nanoparticles and layered birnessite structures. The mixed samples exhibited higher specific surface areas than the pure oxides, reaching up to 121.7 m² g⁻¹ for the 50Mn:50Ce composition. UV–Vis DRS showed enhanced visible-light absorption with increasing manganese content. Photocatalytic activity was evaluated through Rhodamine B degradation under UV irradiation at solution pH values below and above the point of zero charge (pH_pzc = 6.46) determined for the 50Mn:50Ce sample. Significantly higher photocatalytic activity was observed at pH 7.5, where the 50Mn:50Ce sample achieved more than 90% Rhodamine B degradation after only 20 min of irradiation. These results suggest that photocatalytic performance depends on the combined effect of high specific surface area and surface charge control. Full article

Rare-earth vanadates constitute an important class of functional materials with potential applications as luminophores, in optoelectronics and catalysis. The research for this work was inspired by the incomplete literature data, including the synthesis, structure and physicochemical properties of europium(III) vanadate(V) with the general formula Eu₅VO₁₀. The primary goal of this work was to supplement the missing data about this compound and identify its potential applications. This compound was synthesized using three methods, including waste-free methods: ceramic, mechanochemical and a modified Pechini method. The obtained Eu₅VO₁₀ was characterized using XRD, DTA–TG, FTIR, UV–Vis–DRS, SEM and gas pycnometry. It was settled that Eu₅VO₁₀ crystallizes in the monoclinic system and is thermally stable up to a temperature of approximately 1310 °C, above which it decomposes in the solid phase. Estimated energy gap (E_g) values ranged from ~3.21 eV to ~3.53 eV depending on the synthesis method used, allowing Eu₅VO₁₀ to be classified as a wide-bandgap electrical semiconductor. The results also showed that the synthesis method affects the crystallite size of the synthesized compound. The development of synthesis methods and characterization of Eu₅VO₁₀ expands our understanding of rare-earth vanadates and their potential applications as functional materials. Full article

Metal-free polymeric semiconductor graphitic carbon nitride (g-C₃N₄) was synthesized via thermal polycondensation using cyanamide with PVP as a medium, using SiO₂ nanospheres as sacrificial templates to suppress bulk agglomeration. Structural analysis using X-ray diffraction (XRD) confirmed the conservation of the g-C₃N₄ structure, while diffuse reflectance UV-Vis spectroscopy (DRS) showed that there is a slight change in optical absorption, modifying the band gap energy of g-C₃N₄ with the addition of SiO₂. Transmission electron microscopy (TEM) evidenced the formation of interconnected porous architectures, facilitating charge migration. Photocatalytic activity was evaluated under simulated solar irradiation using acetaminophen (ATP) as a model pharmaceutical pollutant. Kinetics experiments demonstrated that the sample containing 7% SiO₂ nanospheres achieved 65% degradation for 180 min. The best photocatalytic performance is attributed to the pore volume, which favors better adsorption, facilitating the degradation of acetaminophen. The participation of different reactive species during the photocatalytic degradation of ATP was determined. Experiments with scavenger agents indicate that the photogenerated holes are the predominant oxidizing reactive species. These results highlight the potential of g-C₃N₄ modified with SiO₂ nanospheres as an efficient photocatalyst for the degradation of emerging contaminants, thus advancing sustainable water treatment technologies. Full article

Solar-driven photocatalysis has attracted increasing interest as an efficient and environmentally friendly approach for the mineralization of pollutants. In this work, carbon-doped g-C₃N₄/V_oBiOBr composites rich in oxygen vacancy (denoted as CCN/V_oBOB) were prepared by combining calcination with a solvothermal method, using glucose as the carbon source. The obtained composites were comprehensively characterized by XRD, TEM, and XPS to investigate their crystal structure, morphology, and surface chemical states, and their photocatalytic activity was evaluated through the degradation of organic pollutants. Among the prepared samples, 3.2 wt% CCN/V_oBOB exhibited the best photocatalytic performance, reaching 98% degradation of Rhodamine B (RhB) and 95% degradation of Methylene Blue (MB) within 90 min, which was significantly superior to that of V_oBOB and g-C₃N₄/V_oBOB. This enhanced activity can be attributed mainly to the synergistic effects of oxygen vacancy, carbon doping, and heterojunction construction. Their combined action not only regulates the band structure of V_oBOB effectively, but also greatly inhibits the recombination of photogenerated electron–hole pairs. These results were further supported by UV-Vis DRS and transient photocurrent measurements. Radical trapping experiments indicated that superoxide radicals (O₂⁻) were the dominant active species during the reaction. In addition, density functional theory (DFT) calculations provided further evidence for the above conclusions. On the basis of both experimental observations and theoretical analysis, a reasonable photocatalytic reaction mechanism was proposed. This work offers a useful strategy for designing highly efficient photocatalysts through the synergistic integration of oxygen vacancy, nonmetal doping, and heterojunction engineering, and thus promotes the application of photocatalytic technology in pollutant degradation. Full article

To explore the treatment-efficient photocatalytic system for organic peroxide production wastewater under visible light, the g-C₃N₄ catalyst, synthesized via thermal polycondensation, exhibited distinct optical absorption properties confirmed by UV-vis diffuse reflectance spectroscopy (UV–vis DRS). Operational parameters—specifically pH, catalyst loading, light intensity, and reaction time—were systematically optimized. Under optimal conditions (pH 5, g-C₃N₄ dosage 1.0 g/L, light intensity 1300 W/m², reaction time 4 h), the system removed 72.8% of the COD, significantly enhancing the wastewater biodegradability (B/C ratio increased from 0.118 to 0.193). Analytical techniques, including gas chromatography–mass spectrometry (GC-MS) and UV-vis absorption spectroscopy, verified the effective decomposition of organic contaminants. Furthermore, radical quenching assays identified superoxide radicals (·O₂⁻) and photogenerated electrons (e⁻) as the primary reactive species driving the photocatalytic process, highlighting the potential of g-C₃N₄ for industrial wastewater pretreatment. Full article

In this study, polyhedral self-assembled spherical titania (TS) photocatalyst was successfully synthesized via a one-step hydrothermal method from titanium chloride, sodium dodecyl sulfate and sulfuric acid. Titania modification with iron was carried out through the same procedure by the addition of different amounts of iron(III) chloride to the substrate mixture. Various methods were applied for sample characterization, e.g., XRD, SEM, TEM, XPS, UV-vis DRS, and photo-electrochemical measurements, such as EIS, CV, transient photocurrent, whereas photocatalytic activity was investigated for hydrogen evolution under UV/vis and oxidative decomposition of antibiotics under UV and/or vis, including also tests with scavengers. It has been found that iron was both incorporated in the titania structure (doping) and adsorbed on its surface. Although iron presence has hardly influenced the properties (slight changes in morphology, bandgap energy, and crystallite size), the photocatalytic activity has increased significantly. Therefore, it is proposed that iron might work as an electron sink, hindering the charge carriers’ recombination. Linear evolution of hydrogen, recycling experiments and characterization of samples after recycling have confirmed a good stability of iron-modified titania. Full article

This study investigates the mechanochemical synthesis of silver molybdate (Ag₂MoO₄). Three silver precursors (AgCl, AgNO₃, Ag₂SO₄) in combination with sodium molybdate dihydrate as the molybdenum precursor were used. Three corresponding sodium salts, which are also formed as byproducts, were employed as process control agents (PCAs) to investigate the possibility of obtaining fine-grained silver molybdate. Milling was performed in a planetary mill at 600 and 100 rpm, and for 2 h, 15 min, and 5 min. X-ray diffraction analysis (XRD) revealed that AgCl is completely unreactive in this type of reaction, whereas AgNO₃ and Ag₂SO₄ form crystalline Ag₂MoO₄. Additional sample characterization included Fourier transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and simultaneous differential thermal and thermogravimetric analysis (DTA-TGA). The results indicate that the silver molybdate formation reaction is favorable and rapid. Even under the mildest conditions, including the presence of PCA, micron-sized silver molybdate particles were obtained. A greater rotation rate and longer milling time resulted in a decrease in particle size, but also an increase in sodium content. However, unlike the few existing reports on the mechanochemical synthesis of Ag₂MoO₄, which, despite harsh milling conditions, did not yield a phase-pure product, our approach produced well-crystallized and pure silver molybdate even under the mildest synthesis conditions. Full article

1-Methylnaphthalene and the products of hydrogenation exhibit a high hydrogen storage capacity (6.6 wt.%), which makes them extremely promising as liquid organic hydrogen carriers. In this work, effective monometallic catalysts, 15Ni/Al₂O₃, 15Ni/Al₂O₃-SiO₂, and 15Ni/Sib-ox, were synthesized and first investigated for hydrogenation of 1-methylnaphthalene to 1-methyldecalins. The prepared catalysts were characterized using a set of physicochemical analysis methods: SEM-EDX, TEM, XRD, N₂ adsorption–desorption, FTIR and UV-vis-DRS. The catalytic activity of the samples in the hydrogenation reaction of 1-methylnaphthalene (100 min, 4 MPa, 240 °C) was studied in comparison to the traditional catalyst of hydrogenation, Ni Raney. The 15%Ni/Sib-ox catalyst showed a 100% conversion and high selectivity of 85.2% with respect to the target product 1-methyldecalins, while in the presence of Ni Raney, a selectivity of 74.3% was achieved with complete conversion of the substrate. Full article

Iron-exchanged bentonites derived from a natural montmorillonite-rich clay (Taganskoe deposit, Kazakhstan) were prepared through a simple aqueous ion-exchange route using Fe(II) or Fe(III) inorganic salt precursors, yielding final Fe contents of ca. 5–7 wt.%, while preserving the smectite layered framework. A mild thermal treatment under air was applied to tune iron coordination without triggering major structural collapse. The resulting materials were characterized by ED-XRF, PXRD, FE-SEM/EDX, DLS/ζ-potential and DR UV–Vis–NIR spectroscopy, revealing predominantly exchanged Fe species with a limited fraction of surface iron-oxide clusters, whose contribution increases after activation. Structure–reactivity relationships were probed under mild conditions in liquid-phase ethyl acetate using dimethyl methylphosphonate (DMMP) and 2-chloroethyl ethyl sulfide (2-CEES) as organophosphorus and organosulfur hazardous chemicals and chemical warfare agent simulants, respectively. Fe(III)-bentonite enabled very fast DMMP removal (ca. 93% within 0.5 h) with a remarkable improved performance with respect to Fe(II)-bentonite and the pristine mineral clay. For 2-CEES, the presence of H₂O₂ markedly enhanced oxidation on Fe-containing clays, reaching quantitative abatement within 24 h (up to >90%), with strong retention of oxidized sulfur products by the clay matrix. These results highlight Fe-exchanged natural bentonites as robust, cheap and multifunctional adsorption/catalytic solids for decontamination and water-treatment applications. Full article

To improve the visible-light response and antibacterial performance of titanium dioxide, a TiO₂/GO/CdS mesoporous nanocomposite was prepared via an ultrasound-assisted sol–gel method in this study. Systematic characterizations including XRD, XPS, SEM, TEM, BET, UV-Vis DRS and FTIR were carried out to analyze the structure, morphology and optical properties of the material. The results show that the composite exhibits a typical mesoporous structure with a specific surface area of 197.0962 m²/g and a pore size distribution of 2–14 nm. CdS is successfully doped into the TiO₂ matrix and forms a heterostructure with GO. UV-Vis diffuse reflectance spectra indicate that the synergistic effect of CdS and GO significantly broadens the visible-light absorption range of TiO₂ and suppresses the recombination of photogenerated carriers. Antibacterial tests using Escherichia coli as the target strain demonstrate that the TiO₂/GO/CdS composite exhibits remarkably better visible-light photocatalytic bactericidal activity than pure TiO₂ and the TiO₂/GO composite. This work provides a new strategy for the modification of TiO₂-based photocatalytic antibacterial materials, and the as-prepared composite shows promising application prospects in the antibacterial field. Full article

Ternary heterojunction photocatalysts enhance the separation and transport of photogenerated charge carriers, thereby boosting their redox activity for use in environmental and sustainable energy applications. This study focuses on the synthesis of a TiO₂/Bi₂O₃/g-C₃N₄ heterojunction composite via a ceramic method with TiO₂ loadings of 80%, 85%, and 90% (denoted 80T-BC, 85T-BC, and 90T-BC, respectively) to investigate structure–property–performance relationships in photocatalytic dye degradation. The structural, optical, and morphological properties of the synthesised materials were characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance UV–Vis spectroscopy (DRS). The photocatalytic performance was evaluated by measuring the degradation of Rhodamine B under visible light irradiation. Under optimised conditions (pH 6, initial RhB concentration of 5 mg/L, and a reaction time of 120 min), a degradation rate of 99% was achieved. Furthermore, the semiconductor demonstrated significant antibacterial activity against both Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. This study presents a promising strategy for modifying TiO₂-based semiconductors by incorporating different metal oxides. The formation of the resulting heterojunction significantly enhances photocatalytic efficiency, demonstrating strong potential for practical environmental remediation. Full article

This study presents the rational design of a visible-light-responsive TiO₂/polyaniline (PANI) nanofiber heterostructure via in situ oxidative polymerization to overcome the limited visible-light absorption and rapid charge recombination of TiO₂. Comprehensive characterization using XRD, FT-IR, XPS, SEM, UV–Vis DRS, and EIS confirmed the successful integration of TiO₂ nanoparticles within a conductive polyaniline nanofiber network, enabling efficient interfacial charge transfer. The optimized TiO₂/PANI-30 composite exhibited outstanding photocatalytic performance, achieving ~99% degradation of Basic Fuchsin dye within 40 min under visible light, significantly outperforming pristine TiO₂. The enhanced activity is attributed to improved visible-light absorption, reduced bandgap energy, and suppressed electron–hole recombination, supported by optical and electrochemical analyses. Kinetic studies indicated pseudo-first-order behavior, with TiO₂/PANI-30 showing the highest rate constant. Radical trapping experiments identified superoxide and hydroxyl radicals as the main active species, with •OH playing a dominant role. A direct Z-scheme charge transfer mechanism was suggested, preserving strong redox potentials and promoting reactive oxygen species generation. Additionally, the photocatalyst demonstrated excellent stability and reusability. These findings highlight the suggested potential of TiO₂/PANI systems as efficient and sustainable photocatalysts for wastewater treatment. Full article

Halloysite nanotubes (HNTs), composed of an aluminosilicate framework, are naturally abundant, biocompatible, and sustainable clay minerals with a tubular morphology and tunable surface chemistry, making them attractive platforms for targeted, multifunctional drug delivery systems. In this study, a zinc ferrite integrated halloysite nanocomposite (ZnFe₂O₄/HNT) was developed via a one-pot synthesis approach for sustained release of cisplatin (Cp), aiming to reduce systemic toxicity and enhance cell-specific activity. The nanocomposites were further functionalized by integrating Cp (Cp: ZnFe₂O₄/HNT ratio 0.05) and folic acid (ZnFe₂O₄/HNT/Cp: FA ratio 0.05), followed by PEGylation (0.17 µL/mg of ZnFe₂O₄/HNT/Cp/FA/PEG). The structural and surface characteristics, phase, interfacial interactions (FA and Cp), and colloidal stability of nanoformulations were systematically investigated using powder X-ray diffraction analysis (XRD), Fourier transformed infrared (FT-IR) spectroscopy, zeta potential analysis, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), high-resolution transmission electron microscopy (HRTEM), and diffuse reflectance UV–visible (DRS-UV-Vis) spectroscopy. The results confirmed that ZnFe₂O₄ integration preserved the clay’s tubular framework while inducing nanocrystallization of both ferrite and cisplatin, indicating molecular dispersion within the clay matrix. Functionalization with FA (ZnFe₂O₄/HNT/Cp/FA) promoted amide bond linkage, modulated Cp-FA interactions, and significantly enhanced cumulative Cp release compared to the non-functionalized system ZnFe₂O₄/HNT/Cp (10.3% at 72 h vs. 34.4% at 72 h) under tumor acidic conditions (pH 6.6). PEGylation maintained the controlled release profile while improving dispersion stability. In vitro cytotoxicity studies revealed that FA-conjugated nanocomposites exhibited enhanced, time-dependent anticancer activity against HeLa cervical cancer cells, with reduced toxicity toward normal fibroblasts, indicating preferential cellular uptake via folate receptor-mediated mechanism. Overall, this work demonstrates that FA-functionalized ZnFe₂O₄/HNT nanocomposite provides an effective clay-based platform for modulating Cp release and enhancing folate receptor protein-mediated targeted therapy for cervical cancer. Full article

CO₂ methanation is considered a key process in achieving carbon neutrality. Expanding on our previous study of supercritically dried Ni-Al aerogels, this work compares two gel-based catalyst families prepared via two different routes—supercritically dried Ni impregnated Al aerogel-based catalysts and oven-dried one-pot Ni-Al xerogel-based catalysts—to assess how the synthesis route affects catalyst structure and CO₂ methanation performance under light irradiation. The catalysts were subsequently characterized via different techniques, such as ICP-OES, N₂ adsorption–desorption isotherms, XRD, H₂-TPR, UV-vis DRS, XPS, and TEM. Catalytic activity was tested in a photoreactor at a range of temperatures from 300 °C to 450 °C and 10 bar pressure, and two different light sources were used (λ = 365 nm, λ = 470 nm). Both light sources enhanced catalytic activity in most cases; the xerogels with higher Ni loadings were the most active materials. These catalysts reached CO₂ conversions and CH₄ selectivities near 70% and 100%, respectively. The results indicate that drying gels is a promising method for synthesizing catalysts active in the Sabatier reaction, given the properties of the materials. Full article