In this study, nanoparticles of five photocatalytic systems based on pure zinc oxide and with rare earths ions M-ZnO (M = La³⁺, Ce³⁺, Pr³⁺ or Nd³⁺) calcined at 500 °C or 700 °C were synthesized and investigated as potential photocatalysts for the removal of dyes. The addition of rare earth ions causes a decrease in the bandgap of ZnO; therefore, it can be well used to improve the photocatalytic properties. The photocatalytic activity of the synthesized nanoparticles was evaluated by the degradation of Rhodamine B in the presence of H₂O₂ under ultraviolet illumination. The results indicate that all the synthesized nanoparticles show good dye degradation efficiency. The highest degradation efficiency was 97.72% for the Ce-ZnO sample calcined at 500 °C and was achieved in 90 min with an excellent constant of the dye degradation rate k = 0.0363 min⁻¹ following a first-order kinetic mechanism. The presence of oxychlorides as secondary phases inhibits the rate of the photocatalytic reaction.

A chabazite-type zeolite was prepared by the hydrothermal method. Before ion exchange, the chabazite was activated with ammonium chloride (NH₄Cl). The ion exchange process was carried out at a controlled temperature and constant stirring to obtain ion-exchanged chabazites of Ti⁴⁺ chabazite (TiCHA), Zn²⁺ chabazite (ZnCHA), Cu²⁺ chabazite (CuCHA), Ag⁺ chabazite (AgCHA) and Au³⁺ chabazite (AuCHA). Modified chabazite samples were characterized by X-ray diffraction (XRD), scanning electron microscope equipped with energy-dispersive spectroscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), N₂ adsorption methods and UV–visible diffuse reflectance spectroscopy (DRS). XRD results revealed that the chabazite structure did not undergo any modification during the exchange treatments. The photocatalytic activity of chabazite samples was evaluated by the degradation of methylene blue (MB) in the presence of H₂O₂ under ultraviolet (UV) light illumination. The photodegradation results showed a higher degradation efficiency of modified chabazites, compared to the synthesized chabazite. CuCHA showed an efficiency of 98.92% in MB degradation, with a constant of k = 0.0266 min⁻¹ following a first-order kinetic mechanism. Then, it was demonstrated that the modified chabazites could be used for the photodegradation of dyes.

The synthesis of AlN and TiB₂ by spark plasma sintering (SPS) and the effect of Nb₂O₅, Y₂O₃ and ZrO₂ additions on the mechanical properties and densification of the produced composites is reported and discussed. After the SPS process, dense AlN and TiB₂ composites with Nb₂O₅, Y₂O₃ and ZrO₂ were successfully prepared. X-ray diffraction analysis showed that in the AlN composites, the addition of Nb₂O₅ gives rise to Nb₄N₃ during sintering. The compound Y₃Al₅O₁₂ (YAG) was observed as precipitate in the sample with Y₂O₃. X-ray diffraction analysis of the TiB₂ composites showed TiB₂ as a single phase in these materials. The maximum Vickers and toughness values were 14.19 ± 1.43 GPa and 27.52 ± 1.75 GPa for the AlN and TiB₂ composites, respectively.

Chabazite (CHA) was synthesized by the hydrothermal fusion method, and zinc oxide/cerium oxide nanoparticles (ZnO/CeO ₂ -NPs) supported on CHA were subsequently synthesized by the sol-gel method. The incorporation of the ZnO/CeO ₂ -NPs (up to 25 wt.%) on structural, morphological and optical properties has been studied, and the applications of the materials in antibacterial studies have also been evaluated. XRD analysis confirmed the preservation of the zeolitic structure with progressive reduction of relative crystallinity. FTIR results showed that the CHA framework bands were preserved, although with evidence of surface interaction with the metallic phases. SEM and TEM images revealed a progressive coverage of the support with well-dispersed ZnO/CeO ₂ spherical NPs with average particle sizes between 8 and 9 nm, and EDX confirmed the homogeneous incorporation of ZnO/CeO ₂ -NPs. UV-vis showed a shift of the absorption edge towards the visible range, attributed to Ce doping and modification of the electronic structure. BET analysis indicated an initial decrease in surface area due to pore blocking, followed by a recovery in samples with higher ZnO/CeO ₂ -NPs loading, associated with a surface redistribution of the ZnO/CeO ₂ -NPs and increased textural accessibility. Antimicrobial assays against Pseudomonas aeruginosa (P. aeruginosa) , Enterococcus faecalis (E. faecalis) and Staphylococcus aureus (S. aureus) showed concentration-dependent inhibition, being the gram-negative strains more sensitive. The synergistic antimicrobial effect was related to adsorption, generation of reactive oxidative species (ROS) and release of Zn ²⁺ . These multifunctional materials are promising for biomedical applications.