Due to their unique physicochemical characteristics, palladium nanoparticles (Pd-NPs) have shown tremendous promise in biological applications. The biosynthesis of Pd-NPs employing Saudi propolis has been designed to be environmental, fast, controlled, and cost-effective. The formation and stability of biosynthesized Pd-NPs by Saudi propolis extract were proved by ultraviolet–visible spectrophotometry (UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), and Zeta potential analysis. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) findings show that the average particle size of Pd-NPs is between 3.14 and 4.62 nm, which is in quantum scale. The Saudi propolis enhanced the antimicrobial activity against B. subtilis, S. aureus, E. coli, K. pneumoniae, and C. albicans. Pd-NPs show effective anticancer activity against ductal carcinoma (MCF-7) with IC50 of 104.79 µg/mL.

A novel two-step wet-chemical synthesis produced neodymium-doped core/shell heterojunctions, Copper(II) oxide (neodymium)/Zinc oxide(CuO(Nd)/ZnO and Zinc oxide (neodymium)/Copper(II) oxide ZnO(Nd)/CuO), with tunable optoelectronic and photocatalytic properties. Structural characterization via x-ray diffraction (XRD) and transmission electron microscopy (TEM) reveals uniform crystallite sizes (6.3–31.4 nanometers- nm) and distinct morphologies: hexagonal for CuO(Nd)/ZnO and spherical for ZnO(Nd)/CuO. Incorporating neodymium induced lattice strain (7.8–10.2 × 10⁻⁴) and increased Urbach energies (5.0–15.3 millielectron volts-meV), enhancing defect states. Tauc analysis demonstrated bandgap narrowing to 2.49–3.17 eV for ZnO and 1.49–1.55 eV for CuO. ZnO(Nd)/CuO achieved a remarkable 94.6% degradation of malachite green (MG) under cost-effective 500 W (W) white light irradiation. This significantly surpasses the performance of undoped systems (by 5%) and generally exceeds that reported for other nanocomposites (≤ 90%) in the literature. Conversely, CuO(Nd)/ZnO exhibited 89.04% ultraviolet blocking efficiency at 280–315 nm (UV-B), outperforming polymethyl methacrylate (PMMA) with ZnO quantum dots (50–60%) and ZnO nanoparticles with polylactic acid composite films (15–75%). These enhancements stem from neodymium(III) (Nd³)-mediated trap states, optimized band alignment, and charge separation at the heterojunction interface. Integrating rare-earth doping with core/shell architecture provides a scalable route for high-performance photocatalytic and ultraviolet-protective materials.