Highlighting unique function of immobilized superoxide on TiO2 for selective photocatalytic degradation

Abstract

Selective photocatalytic degradation reactions hold great promise for environmental control by utilizing clean and inexhaustible solar energy, but the selectivity and tunability due to uncontrollable oxidation process remains a challenge. Given the photogenerated reactive oxygen species (ROS) as major oxidants in selective degradation systems, we propose that desirable selectivity for organic pollutant degradation can be achieved by adjusting the corresponding photocatalytic radical production processes. Using the anatase-rich and rutile-rich titanium dioxide (TiO2) with methyl orange-methylene blue (MO-MB) dye aqueous mixture as a model system, we investigate tunability and mechanism details for selective degradation via photocatalytic evaluation and trapping experiments. Benefiting from the selective generation of ROS on rutile-rich TiO2 and unique properties of immobilized superoxide, the photocatalysts display outstanding tunability and selectivity. This work provides insights into the actual function of immobilized superoxide on selective photocatalytic degradation reactions by discussing a plausible rational reaction process.