Three-phase interface photocatalysis for the enhanced degradation and antibacterial property

Semiconductor photocatalysis, as a means of utilizing stranded renewable solar resources, is now emerging as a viable and promising approach for increasingly severe water pollution. In this work, a high-performance photocatalytic system has been fabricated by immobilizing spiky TiO₂/Au nanohybrids on one side of hydrophobic nanoPE substrate (PE-TiO₂/Au) that forces the enabling of air-liquid-solid triphase photocatalytic interface. Such a triphase system allows efficient oxygen access to the photocatalyst surface, which is feasible for charge separation and reactive oxygen species (ROS) production. Two modes of triphase systems with different gas flow paths were constructed, in which PE-TiO₂/Au was floating on the aqueous solution surface (exposed mode) or immersing in aqueous phase (immersed mode). It is worth mentioning that the exposed PE-TiO₂/Au enables a more efficient oxygen supply, thus leading to a 5.5-fold and 1.8-fold higher reaction kinetics as compared to normal liquid-solid diphase system and immersed PE-TiO₂/Au. Meanwhile, PE-TiO₂/Au also exerts bactericidal effect under visible light irradiation, which effectively inactivates S.aureus (>99.9%) in a lean period of 30 min. The qualities of high lethality rate and short reaction time are endowed to PE-TiO₂/Au due to the co-effect of unique triphase interface microenvironment and elaborate heterojunction of spiky TiO₂/Au nanohybrids. In this paper, we have revealed for the first time that the antibacterial efficiency can be effectively improved by increasing the oxygen supply with the construction of three-phase interface, which represents a promising option in designing highly efficient photocatalytic systems for sewage purification applications.