EXECUTIVE SUMMARY OF ACTIVITIES CARRIED OUT DURING THE IMPLEMENTATION PERIOD
In the first stage of the PhotoActComp project (year 2025), the planned activities were fully accomplished, aiming at the scientific and technological foundation necessary for the development of hybrid photocatalytic materials based on photosensitized ZnO nanoparticles and hydrogel matrices.
· Stage 1/2025 included three main directions: synthesis and characterization of ZnO–xanthene photocatalysts (O1), development and investigation of photocatalytic composites in Xn–PVA hydrogels (O2) and training, dissemination and publication activities (O4). All objectives were fully achieved (100%).
· To achieve objective O1, the extensive synthesis and optimization of ZnO nanoparticles was carried out by varying the precursors (Zn(Ac)₂, ZnSO₄, Zn(NO₃)₂), precipitating agents (NaOH, NH₄OH, PEI), OH⁻/Zn²⁺ ratio, reagent introduction method, stirring speed and heat treatment. The 13 samples obtained allowed the identification of optimal conditions for particles with small dimensions, good dispersion and high crystallinity. FTIR, SEM, STEM, TEM, XRD, DLS and Zeta potential characterizations confirmed the determining influence of the precursor and nucleation processes on morphology, colloidal stability and crystalline purity.
· Next, the nanoparticles were photosensitized with rose bengal (RB) by two strategies – physical adsorption and chemical modification. Four series of hybrid materials (Z2–RB, Z3–RB, Z3–RB/2, Z4–NH₂–RB) were obtained, which facilitated the evaluation of the effect of the immobilization method on the photocatalytic stability and efficiency. Kinetic and dose studies showed a rapid adsorption of RB, reaching equilibrium in 30–60 min, and nanoparticles derived from the sulfate precursor showed the highest capacity. Chemical functionalization led to good dye binding, confirmed by FTIR and by the decrease in XRD diffraction intensities, without modifying the crystalline structure of ZnO.
· UV-Vis and fluorescence characterization revealed specific optical properties of nanometric ZnO, with Eg values between 3.29–3.52 eV and emissions characteristic of lattice defects, relevant for photocatalytic applications. Calcination reduced the band gap and enhanced the visible emission, improving electron transfer in photoinduced processes.
· Within the O2 objective, xanthan and PVA-based hydrogels were prepared by chemical crosslinking and cryogelation, followed by the incorporation of unmodified ZnO or RB-modified ZnO materials. SEM analysis confirmed the homogeneous integration of nanoparticles into the hydrogel networks, and swelling studies highlighted the structural stability of the composites.
· Activities related to O4 included the elaboration of a bibliographic study, the development of the project website, the preparation and submission of an article to Q1/Q2 journals, and participation in scientific conferences. Team members also participated in training activities specific to the field.
· Stage 1/2025 was successfully completed, providing the scientific and experimental basis necessary for the following stages, dedicated to the optimization of photocatalytic composites and the validation of their performances in depollution processes.
· Dissemination of results: 2 published papers, 3 participations in international conferences (1 oral communication and 2 posters).
THE COGNITIVE AND SOCIO-ECONOMIC IMPACT
• The implementation of the 4TE project in the field of photocatalysis, which aims to develop a photosensitized inorganic-organic composite photocatalyst, has a significant cognitive impact on the members of the research team. The complexity of the photocatalyst synthesis process, as well as the analysis of the relationship between structure, properties, and photocatalytic activity in pollutant degradation processes, have contributed and continue to contribute significantly to the development of scientific thinking, critical analysis skills, and interdisciplinary knowledge integration. Due to its experimental and application-oriented nature, as well as the integration of fundamental concepts of photochemistry and chemical synthesis, the 4TE project theme focused on photocatalysis has provided and continues to provide a favorable framework for active learning and advanced cognitive development. The synergy between fundamental and applied research has required and continues to require an interdisciplinary approach based on the correlation of knowledge from fields such as chemistry, physics, environmental science, and materials engineering.
• The socio-economic impact of the 4TE project focused on two aspects. Firstly, it targeted the human resources involved in the implementation of the project, by creating jobs and providing salaries for staff employed on individual employment contracts, in accordance with the skills required for the research topic. In addition, the material infrastructure necessary for carrying out research activities was strengthened through direct purchases from the project budget, contributing to the infrastructure improvement of the "Petru Poni" Institute of Macromolecular Chemistry in Iași. Secondly, the thematic focus of the 4TE project on environmental protection had a significant socio-economic impact, with direct implications for improving quality of life and sustainable economic development. By harnessing light energy in pollutant degradation processes, the photocatalytic technologies developed offer efficient, environmentally friendly, and sustainable solutions for managing environmental problems, with direct and indirect positive effects on society and the economy.
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