New sun-powered film purifies highly contaminated water in minutes

Researchers at Sun Yat-sen University in China have developed a novel self-floating photocatalytic film powered by sunlight that can purify highly contaminated water by killing over 99.995% of bacteria within minutes. This film uses a specially engineered conjugated polymer photocatalyst called Cz-AQ, which generates long-lived oxygen-centered organic radicals (OCORs) when exposed to sunlight and water. These radicals not only eliminate bacteria such as E. coli and Staphylococcus aureus but also break down pollutants and inhibit bacterial regrowth for at least five days. The film demonstrated the ability to disinfect 10 liters of contaminated water within 40 minutes under low natural sunlight, outperforming conventional photocatalysts that are ineffective in such conditions. The technology addresses critical limitations of existing water purification methods, such as chlorination—which can produce harmful byproducts—and UV treatment, which requires high energy input. Unlike traditional photocatalysts that rely on short-lived reactive oxygen species, the Cz-AQ-based film maintains