Modulating Bi₂Fe₄O₉ and its performance in inactivating marine microorganisms

In this study, Bi₂Fe₄O₉ photocatalysts were prepared using hydrothermal synthesis. Different morphologies of Bi₂Fe₄O₉ with a mullite-type structure were prepared using various hydrothermal synthesis methods while controlling the concentration of the mineralizer NaOH. The characterization of photocatalysts involves the use of various methods such as X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy, and electrochemical impedance spectroscopy. The photocatalytic performance of the samples was evaluated by testing their sterilization effect on natural seawater. The study found that when exposed to simulated sunlight using a small amount of H₂O₂, Bi₂Fe₄O₉ cubes exhibited exceptional photocatalytic activity in deactivating marine microorganisms. This was attributed to the fact that the primary exposed surface of the Bi₂Fe₄O₉ cubes was (001), which has a low recombination rate of photoelectrons and holes. Electrons can react with H₂O₂ to generate more hydroxyl radicals, thereby enhancing the photocatalytic sterilization performance. The experiment on free radical capture demonstrated that the ·OH radical was the primary active substance in the sterilization process. This paper introduces a novel concept for the photocatalytic purification of seawater.