Muneer M. Ba-AbbadAbdelbaki BenamorHafiz Muhammad Uzair AyubNg Law YongChing Yin NgSri Rizki Putri PrimandariMohd S. TakriffAbdul Wahab Mohammad2026-10-152026-10-152025-10-2310.1557/s43578-025-01724-2https://dspace-cris.utar.edu.my/handle/123456789/11753This study focused on enhancement of ZnO nanoparticle properties by doping Fe3? ions and co-doping with Ag nanoparticles (Ag co-doped Fe/ZnO) via sol–gel technique. XRD confirmed Fe3? integration into ZnO wurtzite lattice, suppressing crystallinity, while Ag formed cubic structures on Fe/ZnO surfaces. Morphological analysis revealed homogeneous Ag nanoparticles (4–12 nm) distributed on agglomerated spherical Fe/ZnO. Optical analysis showed a narrowed band gap, shifting absorbance from UV (ZnO) to visible regions (Ag co-doped Fe/ZnO). Antimicrobial tests against E. coli demonstrated a three times larger inhibition zone for Ag co-doped Fe/ZnO compared to ZnO, which could be attributed to Ag distribution. Congo red photodegradation efficiency reached 99% for Ag co-doped Fe/ZnO versus 36% for ZnO, linked to enhanced generation of •O?¯ and •OH radicals. The synergistic effects of Fe3? doping and Ag co-doping significantly boosted photocatalytic and antibacterial performance making it as a promising composite for environmental and biomedical applications. © The Author(s), under exclusive licence to The Materials Research Society 2025.en-USAgCompositeDopantFermiOptical propertiesDoping (additives)Energy gapIron compoundsMedical applicationsMetal nanoparticlesPhotocatalytic activityPhotodegradationZinc sulfideZnO nanoparticlesCo-dopedCo-dopingCongo redOptical-Photocatalytic degradationPropertyZnOComposite materialsII-VI semiconductorsjournal-article