Deactivation-Tolerance of Heterojunction Anatase and Bronze TiO2 in the Photocatalytic Mineralization of Toluene

Abstract

Heterojunctioning anatase (A) and rutile (R) TiO₂ is considered a benchmark strategy for high photocatalytic activity. In this study, we synthesized heterojunctions of anatase (A) and bronze (B) TiO₂ via hydrothermal and annealing processes using low-cost commercial A-TiO₂. The as-synthesized AB-TiO₂ shows remarkable activity for toluene mineralization and a strong tolerance to deactivation. The activity and durability of AB-TiO₂ far exceed those of A-, R-, B-, and AR-TiO₂, which are bare and even Pt-deposited (a total of 10 TiO₂ samples). AB-TiO₂ exhibits highly active {001} facets for the generation of hydroxyl radicals and oxygen vacancies beneficial for O₂ adsorption. Transient absorption and time-resolved photoluminescence spectroscopies reveal the characteristic lifetimes of electrons and holes. Density functional theory calculations demonstrate facile charge separation and identify the catalytically active surface for oxidation as the anatase surface in AB-TiO₂. The observed high activity and durability are analyzed in terms of photochemical and catalytic factors.