This study presents the green synthesis and comprehensive characterization of ZnO–Ag nanocomposites using an eco-friendly approach that incorporates aqueous Tagetes erecta extract via the co-precipitation method. The research systematically evaluates the effect of silver concentration (0.1–0.5%) on material properties and dual applications: solar photocatalytic degradation of methylene blue and antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Advanced characterization techniques, including UV-Vis, XRD, TEM, FTIR, and TGA, confirmed the successful formation of crystalline nanocomposites with spherical and hemispherical morphologies, consisting of hexagonal wurtzite ZnO and face-centered cubic Ag phases. Results demonstrate that strategic silver incorporation significantly enhances ZnO photocatalytic activity by improving charge separation and reducing recombination rates, with the ZnO–Ag (0.3%) nanocomposite exhibiting optimal performance, achieving complete methylene blue degradation within 25 min under solar irradiation. Antibacterial assays showed efficacy against the bacteria used, with a significantly stronger bactericidal effect against S. aureus than E. coli, especially for ZnO–Ag (0.2%) at a 250 μg/mL concentration. This study highlights the synergistic effect between ZnO, Ag, and bioactive compounds from Tagetes erecta, offering a sustainable approach for developing multifunctional nanomaterials with significant potential in environmental remediation and antibacterial applications.

In this work, two series of trimetallic NiMoW sulfide catalysts supported on Al–Mg(x) and Ti–Mg(x) mixed oxides with different content of MgO (x = 5, 10, 15 and 20 wt.% of MgO) were synthesized. The mixed oxides and catalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, N₂ physisorption and Diffuse reflectance spectroscopy (DRS UV–Vis); and evaluated during the hydrodesulfurization (HDS) of dibenzothiophene (DBT) reaction. The NiMoW/Al–Mg catalysts showed a higher dispersion of Ni, Mo and W species than NiMoW/Ti–Mg catalysts resulting in higher catalytic activities. Catalysts with 10 wt.% of MgO showed the highest catalytic activity for both series of catalysts. Most of the synthesized catalysts exhibited higher activities than NiMoWS/Al–Ti reference catalyst. The present comparison study clearly showed that NiMoW/Al–Mg and NiMoW/Ti–Mg catalyst with 10 wt.% of MgO might be a promising and effective catalyst for the HDS-DBT reaction.