Novel dual bactericidal mechanism of TiO2 ‘solution’ during photocatalytic sterilization

Titanium dioxide (TiO 2 ) has become a prominent material in photocatalysis research, particularly for antibacterial applications in the post-pandemic era. However, conventional solid TiO 2 nanoparticles tend to agglomerate, reducing the contact area between the catalyst and bacteria, which limits their antibacterial efficiency. To overcome this, an ultra-simple hydrolysis strategy was used to create a highly dispersed TiO 2 “solution” catalyst, rich in hydroxyl groups. The resulting TiO 2 colloid exhibited excellent dispersion in water and showed the Tyndall effect. Experimental results demonstrated that the TiO 2 achieved a 100% sterilization rate within 5 min of light exposure, surpassing commercial P25. This outstanding photocatalytic antibacterial performance is due to its smaller particle size and improved dispersion, which enhance superoxide radical production and provide more active sites. Moreover, an innovative bactericidal mechanism was proposed: when hydroxyl-rich TiO 2 adsorbs onto bacterial surfaces, it dehydrates the bacteria, similar to the effect of a salt solution. This research offers a new, straightforward strategy for developing highly photocatalytically active catalysts that combine both photocatalytic and dehydration-based antibacterial mechanisms.