Efficient photocatalytic aerobic oxidation of bisphenol A via gas-liquid-solid triphase interfaces

As a promising environmental treatment technology, photocatalysis has been investigated for decades and even tentatively practiced in actual large-scale applications. However, most researches focus on photocatalytic kinetics (excitation, charge transfer, and surface reaction) but ignore the significant impact of oxygen interfacial mass transfer for photocatalytic aerobic oxidation in aqueous media. Here, we use finite element simulation to demonstrate that during photocatalysis, the remained local oxygen concentration for photocatalysts at a gas-liquid-solid triphase interface is much higher than that dispersed in a bulk liquid phase. Photocatalyst consisting of Au/TiO2 nanoparticles supported at triphase interface shows a non-diffusion limited charge separation for oxygen photoactivation, therefore achieving a photodegradation efficiency of about 85% toward bisphenol A. Furthermore, we develop a flowing triphase photocatalytic system that exhibits a tunable one-way photodegradation efficiency from 10% to 60% and a photostability for up to 50 h of continuous irradiation, further demonstrating the potential for large-scale applications.