Dyes pollution is a serious environmental problem and heterogeneous catalysis has been proposed as a remediation method. In this study, a set of catalysts of synthetic mordenite with iron oxides was synthesized by a simple chemical co-precipitation method assisted by subsequent thermal treatment with an oxidation process. Physicochemical characterization of prepared materials was performed by a variety of techniques, including XRD, SEM, EDS, S_BET, UV–Vis DR, and XPS. Photocatalytic methylene blue (MB) degradation by the synthesized catalyst was evaluated with visible light excitation. From the studied set of catalysts, the sample prepared with a thermal treatment at 100 °C in air atmosphere for 3 h was capable of degrading ~ 90% of MB after 120 min with visible light of λ = 420 nm exposition and a small portion of H₂O₂ added. The catalyst used three processes to degrade MB: (1) adsorption of organic residues in the mordenite matrix support for electrostatic interactions, (2) photocatalysis heterogeneous reaction with visible light and (3) Fenton reaction catalyst with a small portion to H₂O₂ by Fe₃O₄–Fe₂O₃ presence. The catalytic efficiency to dye degradation was improved by a simple and economical thermal treatment without changing reaction conditions like pH, temperature, dose, or other. Studied mordenite iron oxide catalysts can be retrieved and reused at least five times without noticeable degradation, taking advantage of their magnetic properties. These catalysts could be proposed an economical, simple, and non-toxic alternative for eliminating organic dye pollution using visible light or solar irradiation in wastewater remediation related to textile, food, and pharmaceutical industries.

Polypyrrole adhesion to indium–tin oxide electrodes was improved by adding pre-hydrolyzed alkoxysilanes to the electrodeposition media. The pyrrole oxidation and film growth rates were studied by potentiostatic polymerization in acidic media. The morphology and thickness of the films were studied by contact profilometry and surface-scanning electron microscopy. The bulk and surface semiquantitative chemical composition was studied by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Finally, the adhesion was studied by scotch-tape adhesion test, where both alkoxysilanes showed a significant improvement in adhesion. We proposed a hypothesis for the improvement in adhesion, that involves the formation of siloxane material as well as in situ surface modification of the transparent metal oxide electrode.

The persistence of antibiotic pollutants in aquatic environments poses a significant threat to public health and ecosystems, driving the need for effective solar-driven water treatment technologies. This study synthesized and evaluated a series of black titanium oxide (B-TiO₂) and B-TiO₂/Fe₃O₄ composites for the visible-light-driven degradation of tetracycline, via photocatalysis and photo-Fenton processes. B-TiO₂ was prepared through NaBH₄-assisted reduction, introducing Ti³⁺ species and oxygen vacancies that narrowed the bandgap and enhanced visible-light absorption. Fe₃O₄ was incorporated via co-precipitation in varying proportions (12.5–50 wt%), generating heterostructures that improved charge separation and Fenton reaction. Comprehensive characterization by Transmission Electron Microscopy, x-ray Diffraction, Ultraviolet–Visible Diffuse Reflectance Spectroscopy and x-ray Photoelectron Spectroscopy confirmed the structural, optical, and surface chemical features responsible for enhanced photocatalytic activity. Photocatalytic degradation tests revealed that the composite sample B-TiO₂ with 12.5% of Fe₃O₄ (BT-Fe12.5) exhibited the highest activity under visible light, attributed to improved light harvesting and heterojunction-assisted charge transfer. However, under photo-Fenton conditions, performance increased with Fe₃O₄ content, the composite sample B-TiO₂ with 50% of Fe₃O₄ (BT-Fe50) achieving the highest rate constant (k = 0.02867 min⁻¹) and shortest half-life (∼24 min), due to enhanced hydroxyl radical generation. This work demonstrates the synergistic mechanism and tunability of B-TiO₂/Fe₃O₄ composites, highlighting their dual functionality and potential for cost-effective, sunlight-driven antibiotic removal from water.

The intrinsic strong bonding network limits controlled two-dimensional (2D) nanosheet exfoliation of non-van der Waals materials. We report here the successful stabilization and 2D nanosheet exfoliation of 2D γ -Fe _₂ O _₃ (maghemite) nanosheets through the application of ultrasound-assisted liquid-phase exfoliation with the aid of cetyltrimethylammonium bromide (CTAB) as the stabilizing agent. Atomic force microscopy (AFM) confirms the existence of ultrathin nanosheets of thickness ∼0.5–2 nm corresponding to the monolayer and few-layer structures. X-ray diffraction verifies the broadening of the peaks and the characteristic shifting of the peaks of compressive strain in the nanosheets of the exfoliated structure. X-ray photoelectron spectroscopy corroborates the existence of hydroxyl (–OH) functional groups on the nanosheet surfaces and the existence of the CTAB molecules that achieve stabilization through electrostatic and steric interactions. A prominent peak in the 200–250 nm region with the extended broad absorption to the visible region is observed through the application of UV–Vis spectroscopy and it is assigned to defect states formed during the process of exfoliation. Such structural and surface modifications are expected to modify the 2D γ -Fe _₂ O _₃ ’s physical and chemical properties, making it a promising material for a wide range of applications in materials science, nanotechnology, and environmental or energy-related technologies. We demonstrate here an effective route to the production of processable and stable 2D γ -Fe _₂ O _₃ nanoparticle nanosheets and shed light on the structural transformation during the exfoliation process.

Dyes pollution is a serious environmental problem, heterogeneous catalysis has been proposed as a remediation method. In this study, a set of composite catalysts formed by synthetic mordenite with iron oxides was fabricated by a facile chemical co-precipitation method assisted by a subsequent partial thermal oxidation process. Physicochemical characterization of prepared materials was performed by a variety of techniques, including XRD, SEM, EDS, UV-Vis, and XPS. Photocatalytic methylene blue (MB) degradation by the synthesized composite catalyst was evaluated with visible light excitation. From the studied set, the sample prepared with a thermal treatment at 100°C in an air atmosphere for 3 h was capable to degrade ~ 90% of MB after 120 min with visible light of λ = 420 nm exposition and a little portion of H₂O₂ added. The catalyst composite obtained used three processes to eliminate methylene blue dye organic residue: adsorption of pollution, photocatalysis heterogeneous reaction and Fenton reaction. It is possible to modulate the catalytic properties by thermal treatments in the air atmosphere of synthesized mordenite Fe₃O₄-Fe₂O₃ composites. Mordenite iron oxide composites can be retrieved taking advantage of their magnetic properties and can be reusable. Mordenite Fe₃O₄-Fe₂O₃ composite could be an economical, facile, and non-toxic alternative for eliminating organic dye pollution using visible light irradiation in wastewater.