Synergistic photocatalytic and antibacterial properties of Nd2O3/Sm2O3 nanocomposites for wastewater treatment and biomedical applications

Widely used synthetic organic dyes pose severe environmental and health risks due to their stability and resistance to degradation, while conventional metal oxide photocatalysts often exhibit limited efficiency in water remediation. Motivated by this challenge and the need for alternative photocatalytic materials, Sm₂O₃ nanoparticles (NPs), Nd₂O₃ NPs, and Nd₂O₃/Sm₂O₃ nanocomposites (NCs) were synthesized and evaluated for their photocatalytic degradation of commercially obtained dyes—Methylene Blue (MB), Rhodamine B (RhB), Methyl Orange (MO), Methyl Red (MR), and Congo Red (CR)—under UV irradiation. The Nd₂O₃/Sm₂O₃ NCs possess a larger specific surface area (SSA, 42.38 m²/g) as determined by BET analysis, enhancing active site availability and charge carrier mobility, while optical studies showed a lower band gap (4.21 eV), enabling improved photocatalytic performance. XPS confirmed Sm³⁺ and Nd³⁺ states, with distinct O 1s, Sm 3d, and Nd 3d peaks, verifying the formation of NCs. The TEM and SEM analyses of Nd₂O₃/Sm₂O₃ NCs showed spherical particles with a porous morphology, with average particle sizes of ∼91 nm and ∼0.048 μm, respectively, which in turn supports enhanced charge transfer and photocatalytic activity. Consequently, the Nd₂O₃/Sm₂O₃ NCs achieved higher degradation efficiencies 83.21 % (MB), 96.61 % (RhB), 97.92 % (MO), 97.55 % (MR), and 85.55 % (CR), than individual NPs, with faster reaction rate constants and shorter half-lives, while recyclability tests confirmed their stability and reusability. The increased photocatalytic efficiency of Nd₂O₃/Sm₂O₃ NCs, resulting from their larger surface area, reduced band gap, and improved charge separation, suggests their potential for wastewater treatment applications. Their radical scavenger experiments revealed that O₂∗ radical plays a major role in MB and RhB degradation, whereas h⁺ is more influential in the degradation of MO, MR, and CR. Furthermore, antibacterial studies against the bacterial strains Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) demonstrated superior antibacterial performance for Nd₂O₃/Sm₂O₃ NCs compared to individual oxides, emphasizing their potential for biomedical applications.