Preparation and Photocatalytic CO Oxidation Performance Study of Au/Oxygen-Deficient (Anatase/B-Phase) TiO2 Heterojunction Microspheres

Abstract

Multi-heterojunctions are more promising than single heterojunctions in photocatalysis due to the availability of more interfaces between each component. However, photocatalytic activity is highly dependent on the contact mode of individual components. In this work, we assembled gold nanoparticles/oxygen-deficient (anatase/B-phase) TiO2 multi-heterojunction microspheres using spray pyrolysis and focused on their contact mode-governed photocatalytic activity. The results reveal that using oxygen-deficient (anatase/B-phase) TiO2 microspheres as building blocks could significantly enhance the absorption of visible light and the photocatalytic activity of a gold–TiO2 system toward the photocatalytic carbon monoxide oxidation. Furthermore, loading gold nanoparticles onto B-phase TiO2 could facilitate a more prominent enhancement of activity than that of pure B-phase TiO2, benefiting from the two-electron reduction of oxygen at the interface of TiO2/Au. Meanwhile, the high crystallinity of B-phase TiO2 microspheres allows for a gold loading amount of 1 wt% in the gold/(anatase/B-phase) TiO2 system, which is 1.67 times more active than pure B-phase TiO2 microspheres, in the photocatalytic oxidation of carbon monoxide to generate carbon dioxide.