Solar energy catalysis remains an environmentally friendly technology that effectively addresses numerous global issues, including pollution removal, CO₂ reduction or clean hydrogen fuel generation. Dion-–acobson-type layered perovskites are applicable semiconductors for sustainable photocatalytic processes, particularly for the photocatalytic H₂ production as well as for the degradation of organic pollutants. Their effectiveness arises from the capacity to adjust their electronic and structural properties through multiple modification methods, including ion exchange processes. For an efficient photocatalytic system, its activity is decided by factors such as the band gap, crystallinity, morphology, specific surface area, and defects. Therefore, the strict control of the synthesis parameters affecting these properties is decisive.

This study focuses on the synthesis, structure, and properties of perovskite-related layered transition oxyhalides of the type (MeCl)LaTa₂O₇ (Me = Co, Fe) along with their assessment for sustainable photocatalytic processes (e.g. H₂ generation from water splitting). The development of (MeCl)LaTa₂O₇ type functional materials was achieved through ion-exchange reactions, in which the starting compound, LiLaTa₂O₇, was combined with a two-fold molar excess of MeCl₂, under mild conditions (350 °C, 3 h). The XRD analysis confirms the successful incorporation of Co and Fe species within the perovskite-type LaTa₂O₇ layers. The intercalation of transition metal species influences the electronic band structure of materials by creating a new, higher-energy valence band and reducing their band gap values. The preliminary photocatalytic experiments for water splitting, conducted in the absence of a sacrificial reagent, have demonstrated the potential activity of these layered-perovskite-related materials. Subsequent research will aim to enhance reaction rates through the addition of various co-catalysts and understanding the reaction mechanisms, thereby making these materials suitable for practical applications.

Pheophorbide-a (PPBa) is a potent photosensitizer (PS) with some limitations such as poor water solubility, low bioavailability, etc. [1]. As a strategy, liposomes can provide a platform in co-delivery of drugs in cancer therapy [2]. In this study, we synthesized two nanocomplexes (Lipo@AuNPs@PPBa) from PPBa and gold nanoparticles (AuNPs) for photodynamic therapy (PDT) purposes using a 660 nm laser on A549 lung cancer spheroid cells. The thin-film hydration method was used to synthesize Lipo@AuNPs@ PPBa and characterization was carried out using UV-VIS spectroscopy, FTIR, DLS, EDS, and SEM. Thereafter, the cytotoxic effects of nanocomplexes in PDT on A549 spheroid cells were evaluated by morphological changes, MTT, ATP, amd LDH assays and then the apoptotic rate was determined with immunofluorescence (IF), flow cytometry, and real-time PCR.

UV-VIS spectroscopy, FTIR, EDS, and DLS results showed successful co-loading of PPBa and AuNPs in liposomes at 6 µM and 10 µg/mL concentrations, respectively. SEM and TEM images showed the shape of Lipo@AuNPs@ PPBa was a rod-like and the size was 87 nm. Cellular response indicated that IC₅₀ of Lipo@AuNPs@ PPBa was 60 µg/mL and caused significant cellular death, ATP reduction, LDH release, and spheroid shrinkage post-PDT (15 J/cm²). Additionally, IC₅₀ of Lipo@AuNPs@PPBa post-PDT caused 46.4% and 21.4% of early and late apoptotic rates, respectively. Moreover, Lipo@AuNPs@PPBa nanocomplexes induced activation of apoptotic proteins such as BAX, Cyt c, and CASP9 in A549 spheroids post-PDT. Additionally, IF and real-time PCR showed that the nanoformulation of PPBa caused up-regulation of apoptotic proteins and genes more than in its free form post-PDT. In conclusion, AuNPs demonstrated a synergistic effect on PPBa in PDT. Hence, liposomes can provide a remarkable platform for the co-delivery of PPBa and AuNPs.

The growing production and extensive use of pharmaceuticals have resulted in their frequent detection in various environmental compartments. Ciprofloxacin (CIP), a fluoroquinolone antibiotic used for treating respiratory, urinary tract, and gastrointestinal infections, is increasingly present in aquatic environment due to its intensive medical application and incomplete removal in conventional treatment systems. In response to the tightening of environmental regulations aimed at reducing pollutant emissions, the development of efficient and sustainable methods for eliminating pharmaceutical contaminants has become a priority. Among promising approaches, advanced oxidation processes stand out for their ability to generate highly reactive radicals under relatively mild operating conditions, enabling effective degradation of persistent pollutants.

In this study, the photodegradation of CIP was investigated under simulated sunlight using heterogeneous photocatalysis. Degradation kinetics was monitored with particular attention devoted to several operational parameters: catalyst type (ZnO and TiO₂), catalyst loading (0.5–5.0 mg/mL), initial CIP concentration (0.025–0.125 mmol/L), and photoreactor design. Complete removal of CIP was achieved within 60 min using both photocatalysts. The results indicate that increasing catalyst loading slightly decreases removal efficiency within the tested range, with the highest performance obtained at 0.5 mg/mL. Similarly, increasing initial CIP concentration led to a moderate reduction in degradation efficiency, with the most effective removal observed at 0.025 mmol/L. The higher photocatalytic performance observed with the xenon lamp reactor was attributed to its UVA light intensity, which was 26.1 times greater than that of the reactor with the halogen lamp. Finally, the reusability of ZnO was assessed over three successive cycles under identical conditions. A gradual decline in efficiency was observed, likely due to the adsorption of degradation products blocking active sites on the photocatalyst surface.

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 & 451-03-136/2025-03/200125).

Photocatalysis-induced phenomena, such as active motion and superhydrophilicity, have been widely studied [1,2]. In this presentation, we introduce a previously unrecognized effect: photocatalysis-induced electric fields [3]. Using monoclinic bismuth vanadate (BiVO4) films and potassium dichromate (K2Cr2O7) as a model reduction system, we demonstrate that illumination generates long-range electric fields extending hundreds of micrometers into the surrounding solution. Spatially resolved concentration measurements and transport analysis reveal that these fields strongly bias the migration of charged reactants toward the photocatalyst surface. The same behavior is observed in an independent system based on TiO2, indicating that this phenomenon is not limited to a specific material or crystal structure.

Unlike the localized interfacial fields commonly discussed in semiconductor heterojunctions, these extended electric fields enhance dichromate transport by more than three orders of magnitude, thereby maintaining a continuous reactant supply. As a result, the overall photocatalytic reduction rate is significantly improved without additional energy input, catalyst restructuring, or complex reactor engineering. We argue that photocatalysis-induced electric fields represent a new handle for coupling light-driven redox chemistry with ion transport. This concept opens an unexplored design space for optimizing photocatalytic reactors and may be generalizable to other oxidation or reduction processes relevant to green synthesis, solar fuel production, and environmental catalysis.

References

[1] K. Villa, M. Pumera. Fuel-free light-driven micro/nanomachines: artificial active matter mimicking nature. Chem. Soc. Rev., 2019, 48: 4966-4978.

[2] A. Fujishima, X. Zhang, D.A. Tryk. TiO₂ photocatalysis and related surface phenomena. Surf. Sci. Rep., 2008, 63: 515-582.

[3] C. Chen, S. Zhao, B. Zhou, C. Ye, B. Jiang, L. Zhang. Enhancing dichromate transport and reduction via electric fields induced by photocatalysis. iScience, 2025, 28.

The efficiency of photocatalytic reactions depends critically on the ability of a catalyst to absorb photons with energies that match the activation barrier of the desired chemical process. However, identifying metal–ligand complexes that can absorb a specific photon energy (Ea) remains a major challenge due to the vast diversity of possible combinations and the nonlinear relationship between molecular structure and electronic excitation energy. In this work, we present a machine learning framework that performs inverse design of photoactive complexes—accepting a target energy input (Ea) and predicting metal–ligand combinations capable of absorbing photons with that energy to catalyze a specified transformation.
The model leverages patterns learned from computational and experimental data to identify how structural and electronic features influence photon absorption. By reversing this relationship, the algorithm can suggest promising complexes tailored to the energy requirements of a given reaction. This approach enables a rational, data-driven route to photocatalyst discovery, reducing reliance on empirical screening and expensive quantum chemical calculations. Beyond identifying suitable complexes for specific activation energies, the framework offers a foundation for designing light-responsive materials across a range of catalytic and energy-conversion processes. It represents a step toward fully automated materials discovery, where machine learning can translate energetic requirements directly into molecular design strategies.

Two dinuclear oxovanadium(V) complexes with water solubility, [(L1H)VO(μ-O)]₂ (C1) and [(L2H)VO(μ-O)]₂ (C2), were successfully synthesized via the reaction of VOSO₄ with their respective tetradentate Schiff base ligands, namely [N-(2-hydroxyethylamino)ethyl]-5-methoxysalicylaldimine (L1H) and 2-[(2-(2-hydroxyethylamino)ethylimino)methyl]phenol (L2H), under reflux in methanol. The synthetic procedure afforded the complexes in good yields and with high purity, as confirmed by spectroscopic analyses and elemental composition. These dinuclear Schiff base oxovanadium complexes were systematically evaluated for their catalytic activity in the oxidation of olefins using water as a green and environmentally benign solvent in combination with various oxidizing agents. The experimental results demonstrated high catalytic efficiency, excellent product yields, and remarkable reusability, highlighting the potential of these complexes as sustainable catalysts in aqueous media. Beyond their catalytic applications, these oxovanadium(V) complexes possess significant photophysical and electrochemical properties, including strong absorption in the visible region and tunable redox potentials. These characteristics render them promising candidates for photovoltaic applications, particularly in dye-sensitized solar cells (DSSCs) and other solar energy conversion devices, where efficient light harvesting and electron transfer are essential. The combination of water solubility, catalytic performance, and photophysical features makes these complexes versatile functional materials for both chemical and energy-related applications.

In the present investigation, a novel ternary nanocomposite, MgO/g-C₃N₄/Bi₂O₃, was successfully fabricated via a wet impregnation technique. The photocatalytic efficacy of this hybrid system was thoroughly assessed for the degradation of various organic pollutants, namely the antibiotic amoxicillin (AMX), the pesticide chlorpyrifos (CPF), and the dye methylene blue (MB), under visible light irradiation in an aqueous medium. Extensive physicochemical characterizations were performed employing XRD, SEM, TEM, EDS, XPS, UV-DRS, PL, BET, and EIS analyses. XRD patterns confirmed the coexistence of crystalline phases corresponding to hexagonal g-C₃N₄, monoclinic Bi₂O₃, and cubic MgO, with their respective characteristic planes distinctly discernible in the composite. Morphological investigations using SEM and TEM illustrated a hybrid structure composed of nanosheets interspersed with nanorods. Optical studies revealed enhanced visible light harvesting and a reduced bandgap energy of 2.3 eV, promoting efficient photoexcitation. Under optimized conditions—10 ppm pollutant concentration, pH 6, 100 mg catalyst dosage, and 90 minutes of visible light illumination—the nanocomposite achieved remarkable degradation efficiencies of 96.2% (MB), 74.2% (CPF), and 62.7% (AMX), substantially surpassing the performances of its individual components (g-C₃N₄, Bi₂O₃, and MgO). Radical quenching experiments identified photoinduced holes (h⁺) and superoxide radicals (O₂·⁻) as the primary reactive species orchestrating the degradation pathways. Importantly, the photocatalyst exhibited excellent structural robustness and maintained high photocatalytic activity over three consecutive cycles, demonstrating superior reusability and stability. These findings establish the MgO/g-C₃N₄/Bi₂O₃ nanocomposite as a highly efficient, visible-light-responsive photocatalyst for the sustainable remediation of organic contaminants in aquatic systems.