The revised EU Urban Wastewater Treatment Directive came into force in 2025 and mandates the implementation of quaternary treatments until 2045 for treatment plants with a load equivalent to a population of 150,000 or more. These quaternary treatments involve removing micropollutants, such as antibiotics. The application of solar-driven photocatalysis is a possible strategy to address this challenge. However, many photocatalysts in the literature lack efficiency and/or are difficult to implement, recover, and reuse. First, in this work, different synthesis methodologies (oxidative hydrolysis, hydrothermal treatment, co-precipitation, sonication and calcination, and functionalization and coupling via carbodiimide chemistry) were evaluated to produce a novel photocatalyst based on TiO₂, Carbon Quantum Dots (CQD) and magnetic nanoparticles were proposed for the removal of three antibiotics: amoxicillin (AMX), sulfamethoxazole (SMX), and trimethoprim (TMP). Then, experimental conditions for the selected synthesis methodology (co-precipitation) were optimised using two experimental designs: a central composite design and a full factorial design to maximise antibiotic removal, photocatalyst magnetisation saturation, and synthesis yield. The optimal conditions were tested in triplicate, and the results were compared with the predicted values from the applied experimental designs. Among the synthesis methodologies, the co-precipitation provided photocatalysts with consistent properties and high efficiency in antibiotic removal. The optimal synthesis conditions were a molar ratio of 1.2:1 for Fe:Ti and a mass ratio of 4.0% for CQD:TiO₂. Only 100 mg/L of the so-synthesised magnetic TiO₂/CQD composite removed 34±2% of AMX and 64±5% of TMP in 1 h of irradiation and 46±5% of SMX in 1.5 h of irradiation, presenting a Ms of 38.8±0.6 emu/g and a synthesis yield of 70.5±0.4%. The obtained results provide an excellent starting point for developing a sustainable solution for removing antibiotics from water using magnetic TiO₂/CQD photocatalysts and further application as a quaternary treatment in urban wastewater treatment plants.

The urgent need for advanced wastewater treatment drives the search for efficient photocatalysts. In this study, we have synthesized a single-phase high-entropy zirconate pyrochlore oxide (Ce0.2Pr0.2Zn0.2Nd0.2Tb0.2)2Zr2O7 via a modified Pechini technique. Several characterization techniques, such as X-ray diffraction, UV–visible spectroscopy, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy, were used to explore the physicochemical features of the synthesized nanoparticles. Cationic dye (methylene blue), anionic dye (Congo red), and Cr(VI) were used to test the photocatalytic capabilities of high-entropy zirconate pyrochlore oxide (Ce₀.₂Pr₀.₂Zn₀.₂Nd₀.₂Tb₀.₂)₂Zr₂O₇ . The photocatalytic findings show that the high-entropy (Ce₀.₂Pr₀.₂Zn₀.₂Nd₀.₂Tb₀.₂)₂Zr₂O₇ zirconate pyrochlore oxide that was made could break down dyes and lower Cr(VI) levels. Radical trap experiments indicate that hydroxyl radicals, superoxide radicals, and holes were responsible for the photocatalytic activity. Furthermore, the placement of the valence band and conduction band decided the photocatalytic reaction kinetics. The prepared photocatalyst also exhibited excellent structural stability and reusability, maintaining its high photocatalytic activity over three consecutive cycles without significant loss of performance. These results underscore the high-entropy pyrochlore’s robust activity, stability, and versatility in treating diverse water contaminants. This study establishes high-entropy zirconate pyrochlore oxide (Ce₀.₂Pr₀.₂Zn₀.₂Nd₀.₂Tb₀.₂)₂Zr₂O₇ as a highly promising and effective photocatalyst for broad-spectrum environmental remediation applications.

Persistent luminescence (PersL) is an extraordinary optical phenomenon defined by the prolonged emission of light lasting from several seconds to hours following the removal of excitation sources. At present, afterglow materials are extensively utilized in security signage, anti-counterfeiting measures, information storage, bioimaging, and nocturnal vision applications due to their long-lasting luminescence after excitation. In comparison to traditional visible afterglow, near-infrared (NIR) PersL provides enhanced tissue penetration, reduced background noise, and superior biocompatibility, rendering it particularly advantageous for biomedical and security purposes. Moreover, since NIR light remains undetectable to the human eye in low-light conditions, such materials facilitate critical nocturnal monitoring activities, including aerial drone detection, vehicular tracking on highways, and surveillance of moving pedestrians. Although advancements have been made in steady-state NIR luminescence, the development of materials exhibiting tunable NIR afterglow and dynamically adjustable emission properties continues to pose significant challenges.

This study introduces a series of NIR PersL solid solutions achieved through the modification of the chemical composition via unit cosubstitution, which enables the modulation of emission characteristics in the deep-red and NIR spectral ranges. These solid solutions were systematically analyzed to clarify the relationship between their structural attributes and luminescent behaviors, as well as to investigate the variations in trap distribution and density induced by compositional changes. This research evaluates the advantages and limitations of chemical unit cosubstitution in the enhancement of NIR persistent phosphors, thereby encouraging further investigation into luminescent materials with unique properties.

Low-dimensional structures, including one-dimensional (1D) carbon dots and two-dimensional (2D) materials, are intensively studied as catalysts for environmental remediation due to their excellent optical and electronic properties and highly developed surface areas. Carbon dots with sizes below 10 nm are characterized by photostability, low toxicity, tunable emission, and easy surface functionalization, enabling effective pollutant degradation and water purification. Meanwhile, 2D materials, such as graphene and transition metal dichalcogenides, offer a high surface area and tunable energy gaps, which promote improved adsorption, photocatalysis, and charge separation, thereby contributing to the elimination of pollutants such as dyes, drugs, and pesticides.

This presentation discusses our recent results on the synthesis of low-dimensional materials and their composites, including coatings, membranes, and hybrid photo- and sonocatalysts. In photocatalytic systems, carbon dot (1D) structures are used to enhance light harvesting, charge separation, and overall energy conversion efficiency. In piezoelectric 2D materials such as Bi₂WO₆, WO₃, and MoS₂, mechanical deformation induces an internal electric field that promotes charge separation and reduces recombination, improving catalytic performance. Two-dimensional materials are also effective in sonocatalysis, where ultrasonic waves generate cavitation, producing localized high-energy conditions that activate catalyst surfaces, enhance mass transfer, and generate reactive species. Coupling light with ultrasound in sono-photocatalysis provides synergistic effects, enabling efficient pollutant degradation and water purification. The combination of photo and sonocatalysts yields synergistic effects, improving remediation efficiency, selectivity, and stability under real-world conditions. Addressing challenges related to synthesis, performance optimization, and scalability, the presentation provides insights into the use of 1D and 2D composites in sustainable environmental technologies, paving the way for practical applications in wastewater treatment.

Acknowledgements

The following European Commission grants supported this work: HORIZON-MSCA-2022-SE-01-01 – Piezo2D (project number 101131229) and H2020-MSCA-RISE-2018 - FUNCOAT (project number 823942)

Photocatalysis is an accepted technique for persistent pollutant remediation. Compared to conventional photocatalytic systems based on a powdered catalyst, the immobilization of the catalyst on a solid support is essential for practical environmental applications. LaFeO₃ is a stable p-type oxide semiconductor with a medium bandgap of 2.48 eV. Undoped-LaFeO₃, like many ABO₃ perovskite-type oxides, presents an extensive recombination rate for photogenerated electron–hole pairs, but it is stable in acidic solutions (pH>3) and non-toxic.

Thus, we applied a thin active layer of catalyst on the surface of sintered mullite-based ceramic foam. The photocatalyst powder covering the outer surfaces was placed layer by layer through adding the alcohol slurry of LaFeO₃ powder dropwise and then thermal treatment in air at moderate temperature. With this procedure, the catalyst particles remain nanometric. Parallel tests for the photocatalytic degradation of oxytetracycline (OTC) c₀ = 5.0∙10^-6 M under visible-light irradiation in three different configurations were carried out: H₂O₂ c₀ = 3.0∙10^-3 M solution, H₂O₂ + LaFeO₃ supported on the mullite foam, and H₂O₂ + mullite foam without catalyst. In this study, the OTC solution was buffered at pH = 5.0, so OTC had a zwitterionic form. The OTC solutions were stirred in the dark for 20 minutes, and then two fluorescent lamps (daylight, 8 W each) emitting in the 380-780 nm region were turned on for 240 min.

H₂O₂ + mullite foam and H₂O₂ + LaFeO₃ supported on the mullite foam degraded 34% and 50% of OTC, respectively, after 240 min of irradiation. The small addition of H₂O₂ increases the photodegradation rate of organic pollutants by removing the surface-trapped electrons, thereby lowering the electron–hole recombination rate. The final results show that mullite foam with a thin layer of LaFeO₃ has a promising and stable photocatalytic activity for oxytetracycline degradation under visible light.

This study investigates an alternative approach to addressing the water pollution problem caused by dye molecules. The presence of dye molecules in water systems tends to pose significant risks to human health and ecological systems under long-term exposure. Thus, the purpose of this study is to increase the efficiency of sunset yellow (SY) dye degradation utilizing a microcrystalline cellulose (MCC) derived from Dendrocalamus asper bamboo fiber-supported-TiO₂ composite photocatalyst assisted by UVC irradiation. MCC from bamboo can be utilized as reinforcement of bio-composite materials due to its high fiber content, low density, higher mechanical and tensile strength, and high biodegradability features when compared to other biomass materials. In this work, the photocatalysts were synthesized using a simple chemical mixing technique with different MCC to TiO₂ ratios (0.3:1, 0.5:1, and 0.7:1). They were characterized using Fourier transform infrared spectroscopy (FTIR) to determine their functional groups. The synthesis technique was designed to improve charge carrier separation and broaden light absorption, resulting in significant photocatalytic activity; rate constant was obtained by 2.33 × 10^-2 min^-1 associated with pseudo-first-order kinetics, surpassing the performance of pure TiO₂. The main reactive species were identified to be positive holes (h⁺) and hydroxyl radicals (•OH). This work revealed that the MCC-TiO₂ composite photocatalysts exhibit promising potential for degrading dye molecules via heterogeneous photocatalytic mechanism.

Fresh drinking water in the environment is scarce due to the contamination of water bodies by pollutants such as dyes, pharmaceuticals, heavy metals, and other industrial waste. Dyes have been a major concern in industries, especially the textile, paper, and tile production industries. When these dyes are deposited in the environment, they cause various issues, including cancer and disrupt photosynthesis. They are resistant to the oxidizing agent and heat because they do not undergo biodegradation. Therefore, the ability to remove them from the environment has become a serious problem. This project deals with the preparation of biodegradable PLA/TiO₂ composites prepared by the phase inversion method for the photocatalysis of methylene blue. The composite membrane produced was characterised by FTIR to determine the functional groups of the membrane. SEM was used to identify the morphology of these porous membranes. The thermal properties of the composite membrane were determined by TGA and DSC. The adsorption of methylene blue and the photodegradation of the dyes were carried out at room temperature for 80 mins at 10 mins interval. The adsorption by the pure PLA was higher than that of the composite membrane throughout the 180 min time period. The composites containing 10 wt. % TiO₂ showed the highest dye removal.

Two novel donor–acceptor (D–A)-type indole-based organic dyes, In-C8-BA and In-C8-TBA, were synthesized and thoroughly characterized for advanced photoactive applications. These dyes integrate indole as a robust electron-donating moiety with either barbituric acid (BA) or thiobarbituric acid (TBA) as strong electron-withdrawing acceptors, facilitating pronounced intramolecular charge transfer (ICT). Comprehensive structural validation was performed using ¹H/¹³C NMR, FT-IR, and mass spectrometry, confirming successful molecular construction. Optical studies revealed broad and intense absorption bands in the visible region, with In-C8-TBA exhibiting a red-shifted profile due to the enhanced electron affinity of the sulfur-containing acceptor. Thermal gravimetric analysis (TGA) demonstrated high thermal stability, crucial for device integration. Cyclic voltammetry established well-aligned HOMO–LUMO energy levels suitable for both p- and n-type semiconductor interfaces, enabling versatile photosensitization capabilities. Photoelectrochemical measurements in protic electrolytes (e.g., aqueous phosphate buffer) yielded stable, reproducible photocurrents, suggesting active participation in proton-coupled electron transfer (PCET)—a key mechanism in solar fuel generation. Density functional theory (DFT) computations and molecular electrostatic potential (MESP) maps corroborated experimental data, revealing asymmetric charge distribution favoring directional ICT from indole to the acceptor. These combined attributes underscore In-C8-BA and In-C8-TBA as promising candidates for dye-sensitized solar cells, organic photodetectors, and photocatalytic systems, where efficient light harvesting and interfacial charge dynamics are paramount.

The ability of porphyrins and their derivatives to generate reactive oxygen species (ROS) upon irradiation allows these compounds to serve as mild and highly selective agents for various photooxidation reactions. The wide range of possible modifications at the periphery of the heterocycle, as well as variation of the coordinated metal cation, enables precise tuning of the photophysical properties of the macroheterocycles and increases the rate of singlet oxygen generation under light exposure.

In this research, we present a novel synthetic route to β-arenimidazolylphenyl porphyrins. A series of target compounds was synthesized and fully characterized using standard physicochemical methods. We employed a set of tetraarylporphyrins to investigate the influence of meso-substituents on the reaction pathway, solubility, and photocatalytic efficiency.

In order to evaluate the effect of the arenimidazolyl fragment on the photocatalytic activity of porphyrins, we used the oxidation of sulfides as a model reaction. Even with a very low catalyst loading (0.5 × 10⁻⁴ mol %) and under blue-light irradiation (λ = 430-505 nm, 5 W), complete substrate conversion was achieved with >99% selectivity toward the corresponding sulfoxides. We also measured the photostability of the obtained free-base porphyrins. No significant photodegradation was observed for more than five hours of irradiation, which is comparable to the performance of existing industrial photocatalysts.

The high efficiency in model photooxidation reactions, combined with excellent photostability, allows us to consider target substances as potential photocatalysts in production of medicinal substances, bearing sulfoxide functional groups.

This work was performed with financial support from the Ministry of Science and Higher Education of the Russian Federation.

Functionalization of the ether fragment is a challenging task for classical organic chemistry. Meanwhile, radical C–H activation of ethers has emerged as a powerful synthetic tool. However, most transformations of this kind are described for aliphatic ethers. Thus, the search for a method of C–H activation of phenol-derived ethers may significantly expand the existing set of synthetic approaches for this class of compounds.

In this work, a method for radical C–H activation of phenol-derived ethers is proposed, affording the corresponding α-halogenated ethers. Subsequent addition of potassium tert-butoxide gives the corresponding α-halogenated ester instead of elimination. In contrast, the mixing of tBuOK with DMSO before the addition led to unsubstituted ester.

As a result, radical bromination of a series of ethers followed by the addition of a base was carried out, a mechanism of radical C–H activation was proposed, and the influence of the alkyl fragment and photocatalyst was investigated. In the second stage, the effect of the amount and nature of the base on the final product was studied. The yields and structures of the products of the first stage were confirmed by NMR spectroscopy. The second stage was monitored by GC. The work was performed with financial support from the Ministry of Science and Higher Education of the Russian Federation.