Researchers from the Institute of Oceanology of the Chinese Academy of Sciences have made significant progress in water purification with the development of a 3D-printed polymer substrate coated with a photocatalytic film. Led by Professor Zhang Dun, the team successfully grew a film of bismuth oxyiodide (BiOI) on the polymer substrate using a technique called successive ion layer adsorption reaction (SILAR).
The researchers observed that the substrate was completely covered with a microstructure film resembling flowers. Employing an OH-/I substitution strategy, they engineered I defects into the BiOI film, which caused a change in the color of the substrate from bright white to various shades of yellow. This color variation resulted from the bandgap modification caused by the iodine defect engineering film.
During the film growth process, iodine spaces were introduced into the BiOI crystals, causing an increase in the internal electric field and the electron density of the material. This improvement improved the separation and transmission efficiency of the photoinduced carriers. The iodine defect engineered BiOI film exhibited superior properties compared to stoichiometric BiOI, including smaller grain size, higher specific surface area, electronegativity, photoelectric response, and photocatalytic activity.
The researchers proposed that Bi3+ ions initially adsorbed onto the polymers, providing active sites for pellicle growth. Over time, the films self-assembled into a petal-like BiOI structure due to the high ratio and speed of movement of the I ions.
According to Xu Xuelei, the first author of the study, the developed film demonstrated excellent photocatalytic activity and cyclic stability in the degradation of organic compounds and sterilization of microorganisms. This advancement in water purification technology promises to provide efficient and sustainable solutions to address water pollution challenges.
You can read the full research paper, titled “In Situ Growth of pH Adjusted Iodine Defects, BiOI Film Engineering on 3D Printed Polymer Substrate for Efficient Purification of Organic Contaminants and Microorganisms” in the journal Separation Technology and purification in this link.
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