Fabrication of ZnFe₂O₄@Co-MOF Nanocomposites for Efficient Visible-Light-Driven Degradation of Pollutants and Antimicrobial Applications

In the present research, spinel zinc ferrite (ZF)-doped cobalt-MOF (CM) composite (ZF@CM) is synthesized as a visible-light photocatalyst through the control of the mass ratios of ZF to CM. The photocatalytic activity of the prepared ZF@CM has been tested against a synthetic azo dye, i.e., bis-azo dye (Congo red (CR) as a model). At an equal ZF: CM ratio, ZF@CM achieves photodegradation of a 10 ppm CR dye with the removal efficiency of 87.5% (25 °C, pH 5, 90 min reaction time, and 200 W light intensity) showing an observed quantum yield of 2.79 × 10⁻⁷ molecules photon⁻¹. The increased photon energy for excitation of the doped ZF catalyst should have contributed to the enhanced visible-light harvesting efficiency of doped ZF nanoparticles (NPs) with efficient production of O₂^–· radicals. The combination of cobalt-MOF with ZF is found to synergistically improve photoactivities with the aid of reduction in electron-hole pairs recombination and efficient light absorption with a narrow bandgap. Additionally, the ZF@CM composite established superior antimicrobial activity against Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus) under light linked to dark conditions. This study uniquely reports the first-time synergistic integration of spinel ZF and cobalt-MOF, effectively combining their complementary properties to achieve significantly enhanced visible-light-driven photocatalytic and antimicrobial performance. The promising outcomes of this work provide valuable insights into the rational design of advanced photocatalytic systems for efficient water purification and disinfection applications.