Photocatalytic Biocidal Coatings Featuring Zr₆Ti₄-Based Metal-Organic Frameworks

The world is currently suffering socially, economically, and politically from the recent pandemic outbreak due to the coronavirus disease 2019 (COVID-19), and those in hospitals, schools, and elderly nursing homes face enhanced threats. Healthcare textiles, such as masks and medical staff gowns, are susceptible to contamination of various pathogenic microorganisms, including bacteria and viruses. Metal-organic frameworks (MOFs) can potentially address these challenges due to their tunable reactivity and ability to be incorporated as porous coatings on textile materials. Here, we report how incorporating titanium into the zirconium-pyrene-based MOF NU-1000, denoted as NU-1012, generates a highly reactive biocidal photocatalyst. This MOF features a rare ligand migration phenomenon, and both the Ti/Zr center and the pyrene linker act synergistically as dual active centers and widen the absorption band for this material, which results in enhanced reactive oxygen species generation upon visible light irradiation. Additionally, we found that the ligand migration process is generally applicable to other topology Zr-MOFs. Importantly, NU-1012 can be easily incorporated onto cotton textile cloths as a coating, and the resulting composite material demonstrates fast and potent biocidal activity against Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcus epidermidis), and T7 bacteriophage virus with up to a 7-log(99.99999%) reduction within 1 h under simulated daylight.