Creation of a Triphasic Reaction Interface to Boost Colloidal Photooxidation under Visible Light

Semiconductor-mediated photodegradation (SMPD) is a tempting photocatalytic technique that utilizes visible light to decompose toxic organic pollutants but has often hit a bottleneck of poor mineralization. In this study, a triphasic interface is created by fabricating hydrophobic hollow TiO2 nanospheres (HB-HTS) to promote the generation of reactive oxygen species, such as •O2– and •OH, and thereby the kinetics of photo-oxidation reactions. Mechanistically, improving the surface hydrophobicity of hollow catalysts not only facilitates gas storage and augments the O2 supply, but also enhances surface adsorption of dye molecules via hydrophobic interactions, contributing concertedly to the faster photodegradation rate and higher degree of mineralization. Consequently, the optimal photocatalytic system based on HB-HTS, compared to the unmodified and uncarved controls, exhibits much faster kinetics of dye degradation up to 15-fold with almost complete mineralization. This study underlines the regulation of the reaction interfacial microenvironment to leverage the geometrical nanostructure and surface property of semiconductor nanoparticles for enhanced photocatalytic performance.