Synergistic effects of Fe₃O₄–graphene composite in photocatalysis and antibacterial applications

Pollution is rising globally due to human activities like industrial discharge, agricultural runoff, and urbanization. Addressing this urgent issue is essential for protecting environmental and public health. The use of composite materials to address environmental problems has evolved significantly, notably in the development of strategies for eliminating pollutants/pathogens from wastewater. This work presents the co-precipitation modification of iron oxide with graphene (Fe₃O₄–graphene). The differential approach was utilized to calculate the optical band gaps for Fe₃O₄ and graphene in nanocomposites (NCs), which were found to be 1.62 and 3.42 eV, respectively. Malachite green degradation under visible-light irradiation was used to measure the photocatalytic activity. The Fe₃O₄–graphene NCs showed better photodegradation efficiency at 97%, outperforming malachite green (MG) degradation without any catalyst (70%). The increased photocatalytic activity is due to lower bandgap energy and a high-rate constant of 0.06367 min⁻¹, confirming first-order reaction kinetics. When tested against fungi, Gram-positive and Gram-negative bacteria, Candida albicans, Methicillin-resistant Staphylococcus aureus isolates 1 and 2, Escherichia coli, and Pseudomonas aeruginosa, the sample was more effective against Gram-positive bacteria than Gram-negative bacteria and fungi. These findings contribute to the ongoing research in environmental remediation by presenting a multifunctional material that combines high photocatalytic and antibacterial efficiency, offering a promising solution for the treatment of contaminated water sources.

Graphical abstract