Benzoic Acid-Mediated Oxygen Activation for Efficient Toluene Removal on the Co-Vo-Cu Catalyst via In Situ Ligand Modulation

Carboxylates are commonly formed as intermediates during the oxidation of volatile organic compounds (VOCs) and are often regarded as significant barriers to the complete mineralization of organic pollutants. In this study, we present a novel cobalt-doped copper-based catalyst that employs an in situ benzoic acid-mediated oxygen activation strategy for the photocatalytic degradation of toluene under visible-light irradiation. Unlike traditional systems in which carbonyl intermediates contribute to catalyst deactivation, we demonstrate that benzoic acid, generated during toluene oxidation, acts as a potent ligand to modulate the electronic structure of cobalt sites. This interaction significantly enhances oxygen activation and promotes the generation of reactive oxygen species (ROS), facilitating the complete oxidation of toluene to CO 2 with nearly 100% efficiency. In situ characterization and density functional theory (DFT) calculations reveal that the migration of benzoic acid from copper to cobalt sites under visible light is critical for the oxidation process. This migration induces a pronounced electron-donating effect, enabling activation of the Co center, which drives efficient ROS production and autocatalytic mineralization of benzoic acid. The resulting Co-Vo-Cu catalyst demonstrates exceptional catalytic activity and stability, outperforming previous systems in VOCs degradation. This work offers new insights into the role of organic intermediates in oxygen activation and presents a promising strategy for the development of next-generation photocatalysts for VOCs elimination.