Photo-Regenerable Antimicrobial Air Filter Using Monolithic Cu-Grafted TiO2 Nanotube Mesh

초록

Airborne transmission of pathogens has emerged as a significant public health concern amid recurring pandemics. While conventional air filtration can capture bioaerosols, it poses risks of re-emitting pathogens, necessitating long-term air sterilization. Here, we developed a photo-regenerable antimicrobial air filter by grafting Cu clusters onto a titanium dioxide nanotube mesh (CuxO/mTNT, 1 < x < 2). The in situ grown tubular nanotubes on the mesh support provide a high surface area, and the dispersed Cu clusters exhibited superior disinfection activity. The filter achieved rapid inactivation of Gram-negative Escherichia coli (4.80-log reduction) and Gram-positive Staphylococcus aureus (2.58-log reduction) and respiratory viruses including Influenza A virus (H1N1) and Human coronavirus 229E within minutes. While Cu-based nanomaterials induce antimicrobial effects through direct contact, they gradually lose efficiency as Cu-(I) species oxidize to Cu-(II). When Cu clusters are grafted onto TiO2, the interfacial charge transfer (IFCT) allows for the absorption of visible light and the formation of charge carriers. The Cu clusters dispersed onto the TNT continuously regenerate Cu-(I) under mild visible light through IFCT, achieving sustained recovery of the antimicrobial efficiency. Integrated into a commercial air purifier, the CuxO/mTNT filter achieved efficient space disinfection of bioaerosols, showed reversible photo-regeneration over 10 cycles, and maintained durability for over six months. Field tests demonstrated that this filter achieved disinfection efficiency, whereas conventional filtration-based filters left microbial residuals, which could pose hazards to human health.

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