Hydrothermal synthesis of Fe2O3-Ag2O nanocomposites supported on pristine, N/S doped graphene oxide for photocatalytic and biological applications

Abstract

Addressing the dual challenges of industrial contamination in wastewater and antimicrobial resistance is crucial for environmental preservation and global health, aligning with sustainable development goals. This study investigated the biological and photocatalytic potential of pure bimetal oxides, nanocomposites (NCs) and their counterparts incorporating graphene oxide (GO) and nitrogen- and sulfur-doped GO. A set of samples, namely Fe₂O₃-Ag₂O, Fe₂O₃-Ag₂O@GO, Fe₂O₃-Ag₂O@N-GO, and Fe₂O₃-Ag₂O@S-GO NCs, was synthesized using the hydrothermal method. The synthesized NCs underwent comprehensive structural and compositional analyses using XRD, FTIR, EDX, SEM, and UV-visible spectroscopy. Their photocatalytic performance was evaluated for methylene blue (MB) dye degradation under direct sunlight at varying pH levels, dye concentrations, and reaction times. The photocatalytic tests revealed a significant enhancement in methylene blue (MB) degradation efficiency, which generally increased with rising pH, albeit with some deviations. Among all samples, Fe₂O₃-Ag₂O@S-GO NC exhibited the highest photocatalytic activity, achieving maximum degradation at 240 min. The biological properties of NCs were assessed through protein kinase inhibition studies and antimicrobial assays, while hemocompatibility was determined via hemolytic activity. All samples exhibited both bacteriostatic and bactericidal effects, as indicated by the presence of a bald zone alongside a clear zone. The Fe₂O₃-Ag₂O NC demonstrated the most notable antibacterial activity, achieving the MIC of 12.5 against S. aureus. The antibacterial assay further demonstrated enhanced inhibitory effects against both resistant and non-resistant bacterial strains, confirming that iron- and silver-doped composites exhibited superior antibacterial properties. Among all the NCs, Fe₂O₃-Ag₂O@GO NC displayed significant antifungal activity against five different strains, with the highest effectiveness against Aspergillus niger and Mucor, achieving a zone of inhibition of 9 ± 0.01 mm. The hemolytic assay indicated that all NCs exhibited hemolysis levels below 1%, confirming their safety for biological applications. This study highlighted the potential of these NCs for enhancing the photocatalytic degradation of MB dye in water while also demonstrating their biological significance.

Fig. 1. XRD patterns of Fe₂O₃/Ag₂O, Fe₂O₃/Ag₂O/GO, Fe₂O₃/Ag₂O/S-GO and Fe₂O₃/Ag₂O/N-GO NCs.

Fig. 2. FTIR spectra of Fe₂O₃/Ag₂O, Fe₂O₃/Ag₂O/GO, Fe₂O₃/Ag₂O/S-GO, Fe₂O₃/Ag₂O/N-GO NCs.

Fig. 3. UV-visible spectra of Fe₂O₃–Ag₂O, Fe₂O₃–Ag₂O@GO, Fe₂O₃–Ag₂O@S-GO and Fe₂O₃–Ag₂O@N-GO NCs.

Fig. 4. EDX spectra for (a) Fe₂O₃–Ag₂O, (b) Fe₂O₃–Ag₂O@GO, (c) Fe₂O₃–Ag₂O@S-GO, (d) Fe₂O₃–Ag₂O@N-GO NCs.

Fig. 5. (a–d) SEM images of Fe₂O₃–Ag₂O, Fe₂O₃–Ag₂O@GO, Fe₂O₃–Ag₂O@S-GO and Fe₂O₃–Ag₂O@N-GO NCs.

Fig. 6. Photocatalytic activity of Fe₂O₃–Ag₂O, Fe₂O₃–Ag₂O@GO, Fe₂O₃–Ag₂O@N-GO and Fe₂O₃–Ag₂O@S-GO NCs at different pH levels.

Fig. 7. Photocatalytic activity of Fe₂O₃–Ag₂O, Fe₂O₃–Ag₂O@GO, Fe₂O₃–Ag₂O@N-GO and Fe₂O₃–Ag₂O@S-GO NCs at different time intervals.

Fig. 8. Photocatalytic activity of Fe₂O₃–Ag₂O, Fe₂O₃–Ag₂O@GO, Fe₂O₃–Ag₂O@N-GO and Fe₂O₃–Ag₂O@S-GO NCs at different concentrations.