Tunable selectivity of radical generation over TiO2 for photocatalysis

The realization of controllable radical generation through structural modification of photocatalyst is a challenging goal and is an important strategy for environmental remediation and noncomplete and selective photo-oxidation. Here, we control structural composition of TiO2 through crystalline modification and use photocatalytic dye degradation as a model system to investigate photocatalytic details. Importantly, modified TiO2 materials exhibit tunable mechanism pathway towards photocatalytic decomposing methylene blue (MB) monitored by radical trapping experiments. The anatase-rich TiO2 heterojunction shows preferential hole-mediated decomposition pathway in comparison with superoxide and hydroxyl radicals. In contrast, increasing ratio of rutile in TiO2 favors superoxide-facilitated MB decomposition over hole. The surface chemistry of specific surface atomic configuration is a key factor in tuning the capability of oxygen reduction and hole trapping, resulting in photocatalytic selectivity of radical generation towards photo-oxidation. (C) 2019 Elsevier Ltd. All rights reserved.