Wettability controlled photocatalytic reactive oxygen generation and Klebsiella pneumoniae inactivation over triphase systems.

• Photocatalytic bacteria inactivation over air-water-catalyst triphase systems. • Direct observation of wettability-controlled interface structures. • 18 times higher H 2 O 2 generation rate than the corresponding diphase system. • Two orders of magnitude reduced colony concentration within 30 min irradiation. • Applicable in the antibacterial of atmosphere-connected water bodies. Antibacterial technology based on photo-generated reactive oxygen species (ROS) represents a promising strategy for antibiotic-resistant bacteria inactivation, but often results in poor activity due to the limited O 2 solubility in traditional water-catalyst diphase system. In this work, we develop an air-water-catalyst triphase system to explore the superiority of air phase-supplied O 2 for the enhancement of ROS generation and Klebsiella pneumoniae (KPN) inactivation efficiencies. Using P25-TiO 2 as model photocatalysts, we demonstrate that Wenzel-Cassie coexistent wetting state is the most conducive for photocatalytic ROS generation, offering a H 2 O 2 generation rate of 1003 ± 52 μM h−1, which is 18 times higher than corresponding diphase system. It also affords an over two orders of magnitude reduced KPN colony concentration within 30 min irradiation, achieving over 99 % light-triggered removal efficiency. The advantages of triphase system for photocatalytic bacterial inactivation will inspire the development of efficient photocatalytic antibacterial systems in atmosphere-connected water bodies. [ABSTRACT FROM AUTHOR]