Dual-Site Synergetic Photochemical Activation of Chlorinated Phenols Triggered by Surface Hydroxyls of Photocatalysts under Visible Light

In this study, abundant surface-bridging hydroxyls and terminal hydroxyls are deliberately and cyclically introduced in multiple photocatalysts via a facile hydrothermal method in ammonia for figuring out how these typical surface hydroxyls function in the photochemical decomposition process of chlorinated phenols (CPs). Experimental and theoretical results unveil that the photochemical reaction between CPs and surface hydroxyls is a dextrous pathway for the dechlorination and degradation of CPs on Bi2MoO6 as well as other similar metal oxide minerals. The bridging hydroxyls mainly serve as adsorption sites to capture CPs with the formation of adsorbed CP species (CPs*), while the adjacent terminal hydroxyls predominantly act as active sites and generate active hydroxyls to attack the CPs* under visible light. This dual-site synergetic activation triggered by surface hydroxyls markedly enhances the effective dechlorination and photochemical decomposition of CPs. This present work well extends the scope of the photochemical transformation process of CPs at a molecular level.