Introduction. Perovskite KTaO₃ is regarded as a promising photocatalyst owing to its high stability and structural adaptability to substitution. The possibility of substituting oxygen with nitrogen or sulfur in its lattice allows the band gap to be reduced and the material response in the visible region of the spectrum to be enhanced. In this work, the oxysulfide perovskite KTaO_3-xS_x is presented, and the effect of sulfur content on its structure and photocatalytic properties under solar-light irradiation is investigated.

Materials and Methods. KTaO_3-xS_x powders were obtained in two steps: KTaO₃ was first synthesised via a solid-state reaction between K₂CO₃ and Ta₂O₅ at 800 °C for 8 h, and then KTaO₃ was treated at 600 °C in an H₂S atmosphere. The sulfur content was determined by means of EDS, and changes in the crystal structure were monitored via XRD. The photocatalytic activity of KTaO_3-xS_x particles was evaluated from the degradation of rhodamine B (RhB), and the contribution of different catalytically active species to the photocatalytic process was assessed by means of scavenger experiments.

Results. Oxysulfide perovskites KTaO_3-xS_x with sulfur contents of 1.8, 4.2 and 7.4 at.% were obtained. The samples are single-phase, and the KTaO₃ structure is preserved over the entire sulfur-doping range studied. The KTaO_2,79S_0,21 sample (4.2 at.% S) exhibits the highest photocatalytic activity under solar-light irradiation: in RhB degradation, its activity is 2.25 times higher than that of pristine KTaO₃, with superoxide anion O₂•⁻ being the main active species.

Conclusions. It is shown that sulfurization of KTaO₃ in H₂S vapor enables controlled formation of the oxysulfide perovskite KTaO_3-xS_x. Sulfur doping increases the photocatalytic activity by more than a factor of two: the composition containing 4.2 at.% S exhibits an activity of 12.5 mg·g^-1·h^-1 in RhB degradation under solar-light irradiation.

This work was supported by the Russian Science Foundation (25-19-00458).

Photocatalytic nitrate (NO₃¯) reduction represents a novel and transformative technology that has the potential to produce harmless gaseous byproducts. The photocatalytic denitrification process is frequently accompanied by the creation of undesirable nitrite (NO₂¯) or ammonium (NH₄⁺), resulting in poor selectivity for dinitrogen (N₂). The catalytic reduction of NO₃¯ ions utilizing bimetallic catalysts necessitates the presence of a noble metal, alongside a promoting transition metal. The transition metal facilitates the reduction of NO₃¯ to NO₂¯ ions through a redox mechanism, which subsequently results in its oxidation. Furthermore, the noble metal's function is to maintain the transition metal in its lower oxidation states via hydrogen spillover. Among oxide photocatalysts, titanium dioxide (TiO₂) has found significant application in photocatalysis and the cleanup of environmental contaminants.

In this report, we present the deposition of platinum (Pt), cobalt (Co), and nickel (Ni) onto the surface of TiO₂ powder through a successive impregnation method. The influence of non-noble metal incorporation over Pt-TiO₂ catalyst was studied by means of powder X-ray diffraction (XRD), diffuse reflectance UV-Vis, and temperature programmed reduction in hydrogen (H₂-TPR) analyses and photoluminescence spectroscopy (PL). The initial activity evaluation focused on the catalytic reduction of NO₃¯ with H₂. The following stage involved the evaluation of the photocatalytic activity of the catalysts by monitoring the reduction of NO₃¯ under the illumination of a UV lamp. A primary goal is to assess these materials for their optimal selectivity in generating benign end products (such as N₂). In the tests conducted under UV light irradiation, the selectivity toward N₂ was around 68%, which is approximately 1.5 times greater than the values obtained during denitrification without light exposure. A preliminary test for water splitting using the Pt-Ni/TiO₂ sample yielded hydrogen. It is hypothesized that hydrogen is generated, yet it is utilized in the process of nitrate photoreduction.

The growing production and extensive use of herbicides have resulted in their frequent detection in various environmental compartments. N-(phosphonomethyl)glycine (glyphosate, GLY) is one of the most widely used herbicides worldwide. Due to its persistence in aquatic environments and its numerous documented negative effects on ecosystems, as well as potential risks to human health, it is considered a highly concerning organic pollutant. Therefore, it is essential to develop efficient and sustainable methods for its removal from water. Among the promising approaches, heterogeneous photocatalysis is a green method characterized by simplicity, environmental friendliness, and the use of renewable energy, which, through simulated solar irradiation and semiconductor materials, such as TiO₂ photocatalyst, successfully degrades organic pollutants in water.

This study investigates two factors affecting the efficiency of the photocatalytic degradation of GLY: the impact of initial pH value of suspension and the influence of hydrogen peroxide concentration. The influence of catalyst loading (0.5 to 2.0 mg/cm³) on the degradation efficiency was investigated under both acidic and basic conditions, at pH 3 and 10, over a period of 60 min under simulated solar irradiation. The highest removal efficiency was achieved in basic medium with catalyst loading of 2.0 mg/cm³, when 58% of GLY was removed. The impact of hydrogen peroxide concentration was also investigated in the range of 1.0–10.0 mM at catalyst loading of 0.5 and 2.0 mg/cm³ in both acidic and basic medium. After 60 min of irradiation in both media, the most efficient system was the one in which the hydrogen peroxide concentration was 3.0 mM. Overall, the results demonstrate that the photocatalytic degradation of GLY is strongly influenced by both of the investigated factors.

Acknowledgements

The financial support of the Ministry of Science, Technological Development and Innovation of the Republic of Serbia (Grants No. ‪451-03-137/2025-03/ 200125 and 451-03-136/2025-03/200125).

The application of light as an external stimulus to induce polymerization processes can have significant implications in a range of scientific, medical and technological domains. Photoinduced electron/energy transfer (PET) RAFT polymerization, which employs photoredox catalysis in conjunction with the RAFT process, offers a range of advantages over conventional RAFT polymerization. In addition to the inherent benefits of the RAFT technique, this method also provides enhanced control over the polymerization process by varying light wavelength and intensity, while also being environmentally friendly. The PET-RAFT process has been thoroughly investigated with regard to the polymerization of acrylates, methacrylates and acrylamides, while comparatively less attention has been devoted to the polymerization of styrene.

In this study, in order to conduct effective PET-RAFT polymerization of styrene, we have examined a number of organic dyes and sulfur-containing compounds as potential photocatalysts and RAFT agents, respectively. It has been demonstrated that 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid is the most effective RAFT agent, while eosin Y and perylene are the most effective photocatalysts. PET-RAFT polymerization with 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid and eosin Y yielded polystyrene with a molecular weight of up to 9000 g/mol and low polydispersity (Ð ≤ 1.4). Trithiocarbonate functionality was observed on ¹H NMR spectra, which is important from the perspective of further modification and synthesis of block copolymers. Moreover, this photoinitiating system allowed us to polymerize styrene under both blue and green light irradiation; to achieve temporal control of the polymerization process (by switching off/on the light); and to conduct polymerization in air without negative influence from oxygen on the rate and molecular weight characteristics of the obtained polymers.

The continuous growth of the population calls for the production and consumption of pharmaceuticals in large quantities. However, these compounds do not disappear after excretion. Instead, they enter the aquatic environment through wastewater from households, hospitals and pharmaceutical industries, as well as from agriculture and livestock. For instance, antibiotics can foster the development of antibiotic-resistant bacteria, while antipsychotics can interfere with the brain chemistry of non-target organisms.

Advanced oxidation processes, such as photolysis and photocatalysis, are defined as eco-friendly processes based on the formation of reactive species that participate in the degradation/removal of various (in)organic pollutants present in (waste)waters.

Therefore, the efficiency of indirect photolysis and heterogeneous photocatalysis in removing one antibiotic (ciprofloxacin, CIP) and one antipsychotic (sulpiride, SUL) from an aquatic medium, in the presence of H₂O₂, KBrO₃, and (NH₄)₂S₂O₈, was investigated. Moreover, the influence of selected photosensitizers on CIP and SUL removal was examined under ultraviolet (UV) and simulated solar irradiation (SSI). Lastly, the effect of three initial molar H₂O₂ concentrations on SUL removal efficiency was explored under SSI.

Regarding indirect photolysis, after 60 min of irradiation, the (NH₄)₂S₂O₈/UV system removed 97.8%, while the (NH₄)₂S₂O₈/SSI system removed 97.3% of CIP. Furthermore, complete SUL removal was reached with the (NH₄)₂S₂O₈/UV, (NH₄)₂S₂O₈/SSI, and H₂O₂/SSI systems. Additionally, the highest SUL removal efficiency was observed with 3.0 mmol/dm³ of H₂O₂.

Finally, the results of the heterogeneous photocatalysis, conducted under 60 min of SSI using ZnO as a photocatalyst, revealed no significant difference in CIP and SUL removal in the case of all three studied electron acceptors.

Acknowledgements

The authors acknowledge the financial support of the Ministry of Science, Technological Development and Innovation of the Republic of Serbia (Grants Numbers: ‪451-03-137/2025-03/200125 & 451-03-136/2025-03/200125).

Introduction:
Photodynamic therapy (PDT) is based on the photochemical activation of a photosensitizer to generate reactive oxygen species (ROS) that induce cell death. Hypericin is a natural photosensitizer, but its clinical utility is restricted by poor solubility and limited intracellular accumulation. Liposomal encapsulation improves its stability, delivery, and phototoxic performance. This study evaluates cellular uptake, photocytotoxicity, and migration inhibitory effect following PDT using a liposomal hypericin formulation in breast cancer models.
Methods:
Liposomal hypericin was prepared by the thin-film hydration method. Breast cancer cell lines MCF-7 and MDA-MB-231 cells were incubated with free or liposomal hypericin, and cellular uptake was quantified by flow cytometry based on intrinsic hypericin fluorescence. PDT was performed using orange-light irradiation, followed by assessment of cell viability using the MTT assay. The effect of PDT on cancer cell migration was examined with a wound healing assay by observing scratch closure over time.
Results:
Flow cytometry showed time-dependent changes in intracellular hypericin uptake in both cell lines. Despite the lower fluorescence intensity of liposomal hypericin compared to the free compound, the liposomal formulation produced effective and reproducible light-dependent cytotoxicity with minimal dark toxicity, demonstrating high phototoxicity and low toxicity in the absence of light. PDT with liposomal hypericin also significantly reduced cancer cell migration, reflecting ROS-mediated effects.
Conclusions:
Liposomal encapsulation enhances the photochemical safety and therapeutic applicability of hypericin by enabling controlled delivery and effective PDT responses. These findings support liposomal hypericin as a promising photosensitizer with improved translational potential for photodynamic cancer therapy.

In the context of growing energy shortages and environmental issues, photocatalytic technologies are becoming particularly relevant. Using sunlight as the only energy source, photocatalysis enables the production of synthetic fuels, such as hydrogen and methane.

A key factor affecting photocatalytic efficiency is the choice of semiconductor material, which must combine chemical stability, visible-light activity, and favorable textural and surface properties. Graphitic carbon nitride (g-C₃N₄) with a partially oxidized surface is a promising candidate. Oxidation of g-C₃N₄ via hydrothermal treatment in H₂O₂ solution significantly increases its specific surface area, enhances photoinduced conductivity, and introduces O-containing functional groups. These modifications improve hydrophilicity, facilitate reactant adsorption, and ensure strong anchoring of cocatalyst species in the form of nanoparticles or single atoms.

The photocatalytic performance of oxidized g-C₃N₄ loaded with 0.1–1 wt.% Pt was investigated in two reactions: hydrogen evolution (HER) from aqueous organic substrates under LED irradiation (λmax = 440 nm) and simulated sunlight (AM 1.5 G), and CO₂ reduction under LED irradiation (λmax = 405 nm). In the CO₂ reduction reaction, the use of 1 wt.% Pt/g-C₃N₄ produced CH₄ as the primary product at a rate of 2.9 μmol·g_cat⁻¹·h⁻¹, with an overall electron consumption rate of 26.3 μmol·g_cat⁻¹·h⁻¹. The photocatalysts containing 0.5 and 1 wt.% Pt exhibited similar hydrogen evolution rates from glucose solutions of up to 310 μmol·g_cat⁻¹ h⁻¹, indicating the efficient utilization and uniform dispersion of Pt species [1].

TEM, XPS, ATR-FTIR and EXAFS analyses confirmed the structural and chemical stability of the photocatalysts before and after HER, demonstrating that the surface composition and Pt distribution remained unchanged.

[1] Kharina, S.; Kurenkova, A.; Aydakov, E.; Mishchenko, D.; Gerasimov, E.; Saraev, A.; Zhurenok, A.; Lomakina, V.; Kozlova, E. Activation of g-C3N4 by Oxidative Treatment for Enhanced Photocatalytic H2 Evolution. Appl. Surf. Sci. 2025, 698, 163074, doi:10.1016/j.apsusc.2025.163074.

Introduction: Chemotherapy, as a method of fighting cancer, has a number of significant limitations, so the search for new drugs to increase its effectiveness and reduce side effects is relevant. Another therapeutic approach, photodynamic therapy, is less invasive with minimal side effects; however, its spectrum of action does not go beyond the treatment of superficial tumors due to the low depth of light penetration into tissues. The objective of this work was to synthesize and study the biological activity of conjugates of derivatives of natural chlorines and doxorubicin containing thioketal (ROS-sensitive) and disulfide (GSH-sensitive) linkers designed for the controlled release directly into tumor cells and the tumor microenvironment.

Methods: NMR spectra were recorded on a Bruker DPX300 spectrometer. Absorption and fluorescence spectra of the photosensitizer solutions were recorded using a UV1800 spectrophotometer. Bioavailable micellar emulsions of the test compounds were analyzed and characterized using dynamic light scattering. Chromatography–mass spectrometry was carried out using a Dionex UltiMate RS 3000 ultra-high-performance liquid chromatograph with a mass spectrometry system.

Results: In this work, a number of compounds for combined photodynamic therapy were obtained. The structures of the prepared conjugates and the fragments formed during their cleavage under various conditions were analyzed using high-resolution chromatography–mass spectrometry. The destruction of labile linkers was studied using chromatographic/mass spectrometric monitoring. Biological studies in vitro were performed on the MCF-7 human breast adenocarcinoma cell line.

Conclusions: A strategy for the synthesis of chlorin–doxorubicin conjugates containing various linker molecules was proposed and developed. Studies of photoinduced and cytotoxic activity in vitro on human MCF-7 cells have demonstrated the high efficiency of the synthesized compounds. The confocal microscopy results demonstrated that conjugates with labile linkers showed chlorin internalization in the cytoplasm and doxorubicin in the nucleus, which indicates the effectiveness of the chosen strategy.

Photoredox catalysis has emerged as a powerful strategy for driving redox reactions under exceptionally mild conditions by using light as a clean and controllable energy source. A suitable photocatalyst capable of harvesting light energy and promoting electron-transfer processes is essential for this methodology.¹ Common classes of purely organic photocatalysts include xanthene, acridinium dyes, perylenediimides, and cyanoarenes.²

In 2014, dicyanopyrazine DPZ was introduced as organic photocatalyst, which has been employed in numerous photoredox transformations so far.³ Its mechanism of action and catalytic activity were investigated,⁴ while a recent study revealed that, under blue-light irradiation, DPZ undergoes a Mallory-type photocyclization to dithienoquinoxaline (DTQ).⁵ Its double excited DTQ⁻^· proved to be an exceptionally strong organic reductant capable of chemodivergently reducing nitroaromatics. Hence, utilizing ³DTQ or *DTQ⁻^· and a single blue light source, diethienoquinoxaline can be employed either as a one-electron oxidant or reductant via PET and conPET processes.

DTQ was further immobilized through copolymerization with styrene, generating a polymer-bound photocatalyst (iDTQ). Both powdered material and a flexible monolithic column based on iDTQ were prepared, each retaining the key photophysical and catalytic features of the homogeneous DTQ. iDTQ was successfully applied in both batch and continuous-flow heterogeneous photocatalytic processes.⁶

1 N. A. Romero, D. A. Nicewicz, Chem. Rev. 2016, 116, 10075.

2 H. Wang, C. Zhao, Z. Burešová, F. Bureš, J. Liu, J. Mater. Chem. A 2023, 11, 3753.

3 Z. Burešová, F. Bureš, Chem. Rec. 2025, 25, e202500134.

4 Z. Burešová, H. B. Gobeze, M. Grygarová, O. Pytela, M. Klikar, R. Obertík, R. Cibulka, T. Islam, K. S. Schanze, F. Bureš, J. Catal. 2024, 430, 115348.

5 Z. Burešová, M. Grygarová, E. Prokopová, M. Klikar, O. Pytela, J. Váňa, A. M. M. Fahim, K. Jana, E. Zubova, J. Bartáček, J. Tydlitát, Z. Růžičková, R. Cibulka, K. S. Schanze, F. Bureš, J. Catal. 2025, 445, 116033.

6 M. Klikar, Z. Burešová, J. Bartáček, E. Prokopová, M. Grygarová, J. Svoboda, R. Bulánek, F. Bureš, J. Catal. 2025, 450, 116323.

Due to their pronounced fluorescence in the near-UV and visible spectral regions, polycyclic aromatic hydrocarbons (PAHs) are widely regarded as model photoluminescent systems. The attachment of heteroatoms or functional groups generally reduces fluorescence intensity, primarily due to structural distortions and the emergence of additional non-radiative relaxation pathways. However, the photoluminescent response critically depends on the type, position, and number of substituents.

This work focuses on quantifying the photoluminescent contribution of an epoxide group attached to peripheral sites of coronene. Owing to the high symmetry of coronene (D6h), two distinct edge positions were identified and selected for functionalization. Geometry optimization and the calculation of absorption and emission edge wavelengths for both pristine and functionalized structures were performed using the density functional theory multireference configuration interaction method (DFT/MRCI).

For pristine coronene, the calculated absorption and emission edges are 300 nm and 397 nm, respectively, in good agreement with experimental data. When the epoxide bridges two carbon atoms within a single benzene ring, the absorption edge undergoes a redshift, while the emission wavelength is slightly blueshifted—a trend consistent with typical substituent effects. In contrast, epoxidation across two adjacent benzene rings induces a pronounced bathochromic shift in both absorption and emission bands and, unexpectedly, an increase in the oscillator strength of the S1 → S0 transition.

These findings underscore that the substitution position is a critical factor governing the optical properties of PAHs. They further suggest that precise control over functionalization sites can not only mitigate fluorescence quenching but also enable deliberate tuning—and potentially even enhancement—of photoluminescence efficiency in functionalized carbon-based materials.